International Dentistry Australasian Edition Vol.16 No 2

PERFORMANCE PERFORMANCE PRICE and TECHNOLOGY PRICE and TECHNO

VO L. 16 N O. 2 I N T H I S I SS U E

PERFORMANCE PRICE and TECHNOLOGY

Andre W van Zyl and Johan Hartshorne Masterclass in Implant Dentistry: Anatomic implant impression technique: Transferring soft tissue contour to the lab Peet van der Vyver and Martin Vorster Masterclass in Endodontics: Identification and management of Radix Entomolaris Roberto Sorrentino Innovative resin-modified glass-ionomer cement for zirconia restorations: a case report Troy Schmedding Anterior matrix systems - essential to provide proper anatomical form and function to restorations EdgeEndo solutions – an interview with Dr. Charles J. Goodis João Mauricio Ferraz da Silva and Danilo de Souza Andrade Aesthetic anterior tooth restorations with nano-ceramic hybrid CAD/CAM blocks Gary Bloomfield Maximizing efficiency using 3M impression products Linda Greenwall and Benedict Harrison A simple chairside digital workflow Johan Hartshorne and Andre van Zyl COVID-19 risk management in dental practice: The 10 pillars of SARS-CoV-2 control in clinical dental practice

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4

Contents Volume 16 No. 2

04

6

Anatomic implant impression technique: Transferring soft tissue contour to the lab Andre W van Zyl and Johan Hartshorne

06

Masterclass in Endodontics: Identification and management of Radix Entomolaris Peet van der Vyver and Martin Vorster

8

Clinical

Innovative resin-modified glass-ionomer cement for zirconia restorations: a case report Roberto Sorrentino

16

8

20

24

32

16

Masterclass in Implant Dentistry:

34

42

User Report

Anterior matrix systems - essential to provide proper anatomical form and function to restorations Troy Schmedding

Interview

EdgeEndo solutions – an interview with Dr. Charles J. Goodis

Clinical

Aesthetic anterior tooth restorations with nano-ceramic hybrid CAD/CAM blocks João Mauricio Ferraz da Silva and Danilo de Souza Andrade

User Report

Maximizing efficiency using 3M impression products Gary Bloomfield

Clinical

A simple chairside digital workflow Linda Greenwall and Benedict Harrison

Clinical

COVID-19 risk management in dental practice: The 10 pillars of SARS-CoV-2 control in clinical dental practice Johan Hartshorne and Andre van Zyl

57

Products

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2 1

Pay it forward

Vol. 16 No. 2 ISSN 2071-7962

For the month of May the team at Henry Schein committed to paying it forward and HS staff undertook different initiatives to give back to the community.

PUBLISHING EDITOR Ursula Jenkins

Week 1: The first week saw the team come together for a sausage sizzle to raise money for a family in need. We raised an amazing $900 dollars which we hope will make a difference and possibly take off some pressure that this family are currently experiencing.

ASSOCIATE EDITORS Prof Cecilia Goracci Prof Simone Grandini

Week 2: As winter is fast approaching and the weather is turning very chilly, we initiated a beanie and glove drive for the homeless.

Whilst living on the street is not something that we never hope to experience we are hopeful that these winter woollies will make a difference to those who are sleeping rough.

Week 3: We turned our attention to gratitude. Too often we go through life without letting someone know how amazing they are, how much they are appreciated or just simply saying thank you. It only takes a moment to be kind but often can change someone’s day. So the message for week 3 was Be kind it is easy and so very much appreciated, you might even day someone’s day!!

We rounded off the month May with pack for the homeless, full of warm winter beanies, gloves, snacks, and essential hygiene items.

Winter is tough enough but imagine being cold and hungry with no place to go. We hope that these small contributions made someone’s day a little easier. Remember it is important to acknowledge and care for those who are unseen by the wider community.

EDITOR Prof Andre W van Zyl

EDITOR-IN-CHIEF EMERITUS Prof Dr Marco Ferrari EDITORIAL REVIEW BOARD Prof Paul V Abbott Dr Marius Bredell Prof Kurt-W Bütow Prof Ji-hua Chen Prof Ricardo Marins de Carvalho Prof Carel L Davidson Prof Massimo De Sanctis Dr Carlo Ercoli Prof Roberto Giorgetti Dr Johan Hartshorne Dr Patrick J Henry Prof Dr Reinhard Hickel Dr Sascha A Jovanovic Dr Gerard Kugel Prof Ian Meyers Prof Maria Fidela de Lima Navarro Prof Hien Ngo Dr Hani Ounsi Prof Antonella Polimeni Prof Eric Reynolds Prof Andre P Saadoun Prof Errol Stein Prof Lawrence Stephen Prof Zrinka Tarle Prof Franklin R Tay Prof Manuel Toledano Dr Bernard Touati Prof Peet van der Vyver Prof Laurence Walsh Prof Fernando Zarone International Dentistry - Australasian Edition is published by Modern Dentistry Media CC, 15 Martinique, Calderwood Rd, Johannesburg 2062, South Africa Tel: +27 11 702-3195 • Fax: +27 (0)86-568-1116 E-mail: dentsa@iafrica.com www.moderndentistrymedia.com

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No editorial matter published in International Dentistry - Australasian Edition may be reproduced in any form or language without the written permission of the publishers. While every effort is made to ensure accurate reproduction, the authors, publishers and their employees or agents shall not be held responsible or in any way liable for errors, omissions or inaccuracies in the publication whether arising from negligence or otherwise or for any consequence arising therefrom.

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2 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

Published in association with

Masterclass in Clinical Practice Implant Dentistry with Prof Andre W van Zyl Dr Johan Hartshorne

Anatomic implant impression technique: Transferring soft tissue contour to the lab

Gingiva is anchored to a tooth by junctional epithelium and more importantly, by dento-gingival fibres. This will ensure that there is minimum distortion of the gingiva when taking an impression, giving the dental technician a precise impression of the dento-gingival complex. The dental technician has further guidance from the shape of the tooth in creating the perfect emergence and shape of the final crown.

However, when taking an impression of a dental implant, especially in the aesthetic zone, we have no fibre attachment and the shape of the implant plays no role in determining the shape of the crown. To create the ideal aesthetics with an implant crown, one should use a provisional crown to guide the soft tissue. This may take weeks and in extreme cases months.

Within seconds of removing a healing abutment or provisional crown for the impression, the gingiva starts sagging inward, losing its shape. In order to transfer the exact soft tissue contour to the lab, an impression of the soft tissue is needed, with no distortion. However, when a conventional impression is taken, the tissue sags inward as described and is then distorted by the pressure from the impression material and pushed outward. In the aesthetic zone this may be worse than posterior as we often have 4-5mm of unsupported buccal gingiva with no fibres keeping it in place- thereby exacerbating the distortion. When taking a digital impression, one may also lose the exact shape of the gingiva within seconds as it sags inward, and it may impact on the accuracy of soft tissue contour.

The described technique enables an exact transfer of the soft tissue contour according to the shape of the provisional crown. This guides the dental technician in preventing a buccal over contoured crown, which in turn may lead to recession of the buccal gingiva with resultant aesthetic complications.

Step by step procedure for an anatomical impression: • Step 1 is the use of a correctly shaped provisional crown to achieve ideal gingival contour (Figure 1). Before removing provisional crown from the mouth, mark the gingival margin for reference (Figure 2).

• Step 2 is to use the provisional crown to create a customized impression post by using an implant analog embedded in plaster/ acrylic as shown (Figures 3-7).

• Step 3. The impression post is placed in the mouth. This will create a slight pressure due to the collapse of soft tissue in the minutes it takes to customize the impression pin. It will however not distort the tissue as it will push it back to where it was before removing the provisional crown (Figure 8).

• Step 4 is to take a conventional impression. As no impression material will be pushed into the subgingival space, no distortion of tissue is possible (Figure 9-10).

Conclusion The lab should be instructed to follow the subgingival component exactly to ensure no tissue distortion is done. In Figure 11 we see over contouring of a crown which may have been caused by the impression material pushing the gingiva buccally. The technician has no way of knowing how much distortion has taken place and will have no choice but to follow the impression, thereby creating an over contoured crown.

4 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

M AST E R C L ASS I N I M P L A N T D E N T I ST RY

Figure 1: Provisional crown with flowing lines mimicking the natural tooth

Figure 2: Before removing crown from mouth, mark the gingival margin with a pencil

Figure 3: An analog is embedded in acrylic with 2 mm of analog protruding. Crown is placed on analog and the buccal is marked on the acrylic with a pen

Figure 4: Impression or lab putty is adapted to simulate gingiva around provisional crown up to pencil marking

Figure 5: An exact copy of the gingiva as it is in mouth is now obtained. Note marking for buccal on acrylic

Figure 6: Composite is flowed into the space between impression post and “gingiva” just up to the crest. The difference between this and in the mouth is that putty cannot distort, thereby creating an exact copy of provisional crown/gingiva

Figure 7: Before removing the impression post from analog, mark buccal of impression post with permanent marker as shown

Figure 8: Impression post is in position with no distortion or pressure on gingiva. Ensure that buccal markings are positioned correctly

Figure 9: Impression material is flowed around impression post in the usual manner

Figure 10: Final result with composite making up the subgingival part of impression where it is essential not to distort soft tissue

Figure 11: Over contouring of crown on buccal may be due to distortion of gingiva during impression taking

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2 5

Masterclass in Clinical Practice Endodontics

with Prof Peet van der Vyver Dr Martin Vorster

IntroductIon According to Swartz, Skidmore and Griffen, mandibular first molars have a significantly lower success rate compared with other teeth.1 Missed canals and the failure to remove all the microorganisms and pulp remnants from the root canal system are probably the main reasons for persistent infection around endodontically- treated molars. It is therefore important that clinicians have an awareness and good understanding of the variations in root canal morphology of the mandibular first molar.

Permanent mandibular first molars in Caucasian populations are generally two rooted teeth (one mesial and one distal root) with two mesial and one distal root canals.2 The two mesial root canals can end up in two distinct apical foramina or they can merge together at the root tip end into one apical foramen.3 The number of roots for the mandibular first molar teeth may also vary. Carabelli4 was the first to report on mandibular first molars with supernumerary roots. The third root was located on the disto-lingual side and was called Radix Entomolaris (RE). In very rare cases, the mandibular first molar can also present with an additional root at the mesio-buccal side and is called Radix Paramolaris.3 Prevalence of RE The presence of RE in the mandibular first molar is associated with certain ethnic groups. In populations with Mongoloid traits (for example Chinese, Eskimo and American Indians) the frequency can range from 5-30%.5-10 However, in Eurasian and Indian populations it is less than 5% and in African populations less than 3%.11 Radix Entomolaris can be found on first, second and third mandibular molar teeth, occurring least frequently on second molars. Studies have also reported a bilateral occurrence with a frequency of 50-67%.12

Identification and management of Radix Entomolaris

Scan to view video of Case Report 1

References 1-15 are available on request from: Email: dentsa@iafrica.com Website: www.moderndentistrymedia.com

Morphology of RE The coronal third of the disto-lingual root of RE can be fixed partially or completely to the distal root. Based on the curvature in a buccal-lingual orientation, the separate RE variants can be classified into three types according to De Moor et al.13 Type I refers to a straight root/root canal.

Type II refers to an initially curved entrance, which continues as a straight root/root canal. Type III refers to an initial curve in the coronal third of the root canal and a second curve beginning in the middle and continuing to the apical third.13 RadiographIc DiagnosIs of RE A major limitation of conventional radiographic images is to compress three-dimensional (3D) anatomy into a two-dimensional (2D) image or shadow- graph. In an attempt to overcome this drawback of conventional radiography in order to detect the presence of RE, it is helpful to take additional exposures changing the horizontal angulation of the main x- ray beam. Wang et al.14, demonstrated that 25-degree mesial radiographs were significantly better than 25-degree distal radiographs for RE visibility and determination of optimum diagnosis.

According to Clark’s rule (Also known as SLOB rule or Waltons projection), an object that moves in the same direction as the cone is located toward the lingual.15 Conversely, an object that moves in the opposite direction from the cone is located towards the buccal. Therefore, the RE image that moves distally is superimposed on the distobuccal root image that moves towards the mesial, when taking radiographs with small distal angulations.

Cone-Beam Computed Tomography (CBCT) provides dentistry with a practical tool for non-invasive and 3D reconstruction imaging for the use in endodontic applications and morphologic analyses. CBCT imaging allows for visualizing a new dimension, eliminate superimpositions, provide additional information for diagnosis and therefore enables a more predictable management of complex endodontic conditions compared with intraoral radiographs alone. CBCT imaging allows ascertaining the identification, exact location, curvature and angulation of the RE in order to prevent iatrogenic events that might occur in relation

6 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

M AST E R C L ASS I N E N D O D O N T I C S

1a

1b

1c

Figure 1: (a) Pre-operative radiograph of mandibular, left first permanent molar that was restored with a ceramometal crown, showing evidence of decay on the mesial gingival margin (b) CBCT- midroot axial view revealed the presence of a mesial root (M), distal (D) and Radix Entomolaris on the lingual aspect (RE) (c) A 30 degrees, mesial angulated view of the four obturated root canal systems.

2a

2b

2c

Figure 2: (a) Pre-operative radiograph of mandibular, right first permanent molar that was poorly root treated 2 years previously (b) CBCT- midroot axial view shows the presence of a mesial root (M), distal (D) and Radix Entomolaris on the lingual aspect (RE) (c) A 30 degrees, mesial angulated view of four obturated root canal systems.

to canal curvature like instrument separation, perforation and ledge formation.

Case Report 1 The patient, a 45-year-old female presented with pain and discomfort on her mandibular left first molar, previously restored with a ceramo-metal crown. A pre-operative radiograph revealed evidence of extensive decay on the mesial margin as well as unusual root morphology (Figure 1a). The ceramo-metal crown was removed, caries excavated and a temporary crown placed. A CBCT, axial coronal slice confirmed the presence of two roots (mesial and distal)(Figure 1b). A CBCT, axial coronal slice confirmed the presence of two roots (mesial and distal) (Figure 1b). Another axial slice in the midroot area, revealed the presence of distal root bifurcating into two separate roots. The additional root, branching off on the lingual aspect, confirmed the presence of Radix Entomolaris (Figure 1c). Note the curvature in the apical part of the RE that was maintained during canal preparation and obturation.

Case Report 2 The patient, a 38-year-old female presented with discomfort on her mandibular right first molar that was root canal treated approximately 2 years ago. A periapical radiograph revealed an incomplete root canal treatment and evidence of an additional distal root (Figure 2a). A high resolution CBCT scan confirmed the diagnosis of Radix Entomolaris (Figure 2b). Figure 2c depicts the final result after retreatment. Note again the curvature in the apical part of the Radix Entomolaris root.

Conclusion CBCT technology as well as proper angulation when acquiring radiographic images proves helpful in locating canals in especially first mandibular molars with a high incidence of anatomical variations. A thorough understanding of the prevalence of RE, its anatomical variations as well as radiographic diagnosis will provide the clinician with a better understanding of its complexity in order to ensure successful treatment outcomes.

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2 7

CLINICAL

Innovative resin-modified glass-ionomer cement for zirconia restorations: a case report Roberto Sorrentino1

Due to the increasing patients’ demand for aesthetics and its optimal biomechanical and optical properties, zirconia is widely used in prosthodontics as a material of choice for indirect ceramic restorations 1-4. Recently, cubic translucent zirconia has been introduced in the market to improve the optical characteristics and reduce material ageing 3,5,6.

Due to the absence of any glassy matrix, zirconia is free from silica and, consequently, cannot be conditioned with conventional acid etching techniques 1,7,8. Several surface treatments were suggested in the literature but to date data are still controversial 9,10. On the basis of the physical-chemical properties of zirconia, in the presence of retentive preparation geometries and full coverage prostheses, conventional water-based luting agents (i.e. glass ionomer and zinc phosphate cements) and hybrid cements (i.e. resinmodified glass ionomer cements) should be considered the first choice materials for cementation 9,11,12.

Case history A 43-year-old male patient treated and stabilised for a previous severe chronic periodontitis asked for the aesthetic rehabilitation of both dental arches, complaining about aesthetic as well as functional problems (Figs. 1-2). After achieving good occlusal stability and proper vertical dimension of occlusion by means of implant-supported metal-ceramics single crowns in the posterior regions, a careful evaluation of the maxillary front teeth was performed, in order to formulate a proper biomechanical and aesthetic treatment plan. Particularly, the patient presented with the following problem list: diastema, tooth wear, high caries activity, moderate staining, unsatisfactory composite restorations, altered interdental proportions, gingival recessions and moderate bone resorption (Fig. 3).

Prof. Roberto Sorrentino DDS, MSc, PhD Research Professor of Prosthodontics and Digital Dentistry at the University Federico II of Napoli.

1

Co-founder of the dental blog and community Zerodonto (www. zerodonto.com).

Figure 1: Extraoral pre-operative view.

8 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

CLINICAL

Figure 2: Intraoral pre-operative view.

Figure 3: Pre-operative detail of the maxillary front teeth.

Treatment According to the patient’s requests and taking the aesthetic needs and biomechanical drawbacks of the case (i.e. deep bite, long lever arms) into consideration, 6 cubic translucent zirconia single crowns were planned, in order to achieve a natural tooth-like appearance of the restorations and optimal mechanical resistance during function.

Minimally invasive vertical tooth preparations were performed on the maxillary front teeth, removing the previous composite restorations and secondary decays and keeping satisfactory total occlusal convergence. The prosthetic margins were iuxtagingivally placed and all the teeth were kept vital (Figs. 4-6). Temporary acrylic resin restorations were used for 3 weeks to allow the soft tissues to recover from preparation and impression procedures.

Subsequently, 6 cubic translucent zirconia single crowns were fabricated (Fig. 7). The buccal surfaces were layered with a dedicated veneering ceramics, so as to extol the aesthetic appearance, whereas the palatal functional aspects were left in the monolithic configuration and glazed,

in order to avoid any risk of chipping. Because of the excellent biocompatibility of zirconia, the prosthetic iuxtagingival margins were manually polished and left unglazed to promote the formation of an epithelial attachment and optimise the biological integration of the restorations.

The inner zirconia surface of each crown was conditioned with mild sandblasting using 110 µm alumina particles at 0.2 MPa. An innovative paste-paste resin-modified glass ionomer luting agent (FujiCEM Evolve) was used to cement the restorations (Fig. 8). As this type of luting agent does not require complete field isolation and allows to perform a conventional cementation procedure, PTFE tapes were used to protect the adjacent teeth (Fig. 9). After seating the restorations, cement gelification was achieved by means of light-curing; this passage is not mandatory but allows for a faster setting of the luting agent. Then, cement excess was removed with a urethane dimethacrylate curette, in order not to damage the glazed surface of the ceramic crowns (Fig. 10), and dental floss was used to clean the interproximal spaces (Fig. 11). The same approach was used to cement the

Figure 4: Maxillary front teeth preparations Figure 5: Detail of the right side tooth for single crowns. preparations.

Figure 6: Detail of the left side tooth preparations.

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2 9

SORRENTINO

Figure 7: Layered cubic zirconia anterior single crowns. A: internal view; B: buccal view.

Figure 8: Maxillary central incisor zirconia crowns filled with resin-modified glass-ionomer cement.

zirconia crowns onto lateral incisors (Fig. 12) and canines (Fig. 13). Finally, post-curing was performed after applying an oxygen barrier so as to achieve complete setting of the cement at marginal level (Fig. 14).

Thanks to the excellent biocompatibility of zirconia, to the precision of the prosthetic margins and to the optimal performance of FujiCEM Evolve, 2 weeks after cementation

the aesthetic and biological integration of the zirconia crowns was ideal, with good recovery of the gingival health and proper periodontal maturation (Figs. 15-17).

Due to economic reasons, the patient decided to have the severely worn and malpositioned mandibular front teeth (Fig. 18) restored with composite restorations. Consequently, the area was restored by means of direct restorations applied

Figure 9: PTFE- assisted cementation of the maxillary central incisors.

Figure 10: Cervical cement excess removal from central incisors.

Figure 11: Interproximal cement excess removal from central incisors.

Figure 12: PTFE- assisted cementation of the maxillary lateral incisors.

Figure 13: PTFE- assisted cementation of the maxillary canines.

Figure 14: Light-curing of the prosthetic margins of the zirconia crowns through the oxygen barrier.

10 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

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Figure 15: 2-week soft tissues healing after cementation: front view of the cubic zirconia single crowns.

Figure 16: Post-operative right side detail of the cubic zirconia single crowns.

Figure 17: Post-operative left side detail of the cubic zirconia single crowns.

Figure 18: Pre-operative view of the mandibular front teeth.

Figure 19: Restoration of the mandibular front teeth by means of the composite injection technique with G-ænial Universal Flo.

Figure 20: Post-operative view of the mandibular from teeth restored with injected direct composites.

Figure 21: Post-operative view: layered cubic zirconia single crowns at the maxillary arch and injected direct composite restorations at the mandibular arch.

Figure 22: Functional occlusal check at the maxillary arch.

Figure 23: Functional occlusal check at the mandibular arch.

using the flowable composite (G-ænial Universal Flo) injection technique (Figs. 19-20).

Proper dynamic and occlusal functions were restored and carefully checked (Figs. 21-23). Moreover, the final outcome showed a good aesthetic restoration of the patient’s smile line (Fig. 24).

Outcome Different advantages were noticed using FujiCEM Evolve, like ease of use (the possibility to use the automixing dispenser makes cement application very slightly dependent on the operator’s skill), moisture tolerance (ideal in the presence of iuxta- or sub-gingival margins and requiring no isolation)

12 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

better science, better implants is osseointegration enough?

Only the Laser-Lok surface has been shown using light microscopy, polarized light microscopy and scanning electron microscopy to also be effective for soft tissue attachment. 1,2

Colorized SEM shows connective tissue physically attached to the Laser-Lok surface.1

Colorized SEM of Laser-Lok® microchannels shows superior osseointegration3

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1. Human Histologic Evidence of a Connective Tissue Attachment to a Dental Implant. M Nevins, ML Nevins, M Camelo, JL Boyesen, DM Kim. International Journal of Periodontics & Restorative Dentistry. Vol. 28, No. 2, 2008. 2. Histologic evidence of a connective tissue attachment to laser microgrooved abutments: a canine study. M Nevins, DDS, DM Kim, DDS, DMSc, SH Jun, DDS, MS, K Guze, DMD, P Schupbach, PhD, ML Nevins, DMD, MMSc. Accepted for publication: IJPRD, Vol 30, No. 3, 2010. 3. Maintaining inter-implant crestal bone height via a combined platform-switched, Laser-Lok® mplant/abutment system: A proof-of-principle canine study. M Nevins, ML Nevins, L Gobbato, HJ Lee, CW Wang, DM Kim. Int J Periodontics Restorative Dent. Volume 33, Number 3, 2013.

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SORRENTINO

Figure 24: Extraoral post-operative view.

and versatility (suitable for different restorative materials).

Particularly, in the present case this luting agent was used to cement both zirconia crowns in anterior areas and metalceramics crowns onto posterior implants, showing the same flowability and easiness in cement excess removal, due to its user-friendly rubbery consistency, very useful to avoid the entanglement of any particle within the soft tissues.

Furthermore, no ceramic pre-treatment is mandatory before the application of the cement and the dual-curing technology allows for a faster setting using light-polymerisation.

Thanks to its innovative features, FujiCEM Evolve allowed to avoid any post-operative sensitivity and its radiopacity makes the identification of possible sub-gingival excess very easy.

Acknowledgements The author would like to thank MDT Mr. Vincenzo Mutone for the dental laboratory support.

References 1. Zarone F, Russo S, Sorrentino R. From porcelainfused-to-metal to zirconia: clinical and experimental considerations. Dent Mater 2011;27:83-96.

2. Fabbri G, Fradeani M, Dellificorelli G, et al. Clinical evaluation of the influence of connection type and restoration height on the reliability of zirconia abutments: A retrospective study on 965 abutments with a mean 6-year follow-up. Int J Periodontics Restorative Dent 2017;37:19-31.

3. Shahmiri R, Standard OC, Hart JN, Sorrell CC. Optical properties of zirconia ceramics for esthetic dental restorations: A systematic review. J Prosthet Dent 2018;119:36-46.

4. Zhang Y, Lawn BR. Evaluating dental zirconia. Dent

Mater. 2019 Jan;35(1):15-23.

5. Camposilvan E., Leone R, Gremillard L, et al. Aging resistance, mechanical properties and translucency of different yttria-stabilized zirconia ceramics for monolithic dental crown applications. Dent Mater 2018;34:879-890.

6. Rodrigues CDS, Aurélio IL, Kaizer MDR, Zhang Y, May LG. Do thermal treatments affect the mechanical behavior of porcelain-veneered zirconia? A systematic review and meta-analysis. Dent Mater. 2019 Mar 4. pii: S01095641(18)31467-2.xs.

7. Zarone F, Sorrentino R, Vaccaro F, et al. Acid etching surface treatment of feldspathic, alumina and zirconia ceramics: a micromorphological SEM analysis. Int Dent South Afr 2006;8:50-56. 274.

8. Maroulakos G, Thompson GA, Kontogiorgos ED. Effect of cement type on the clinical performance and complications of zirconia and lithium disilicate tooth-supported crowns: A systematic review. Report of the Committee on Research in Fixed Prosthodontics of the American Academy of Fixed Prosthodontics. J Prosthet Dent. 2019 Mar 15. pii: S00223913(18)30712-1. doi: 10.1016/j.prosdent.2018.10.011.

[Epub ahead of print].

9. Pilo R, Dimitriadi M, Palaghia A, Eliades G. Effect of tribochemical treatments and silane reactivity on resin bonding to zirconia. Dent Mater 2018;34:306- 316.

10. Schünemann FH, Galárraga-Vinueza ME, Magini R, Fredel M, Silva F, Souza JCM, Zhang Y, Henriques B. Zirconia surface modifications for implant dentistry. Mater Sci Eng C Mater Biol Appl. 2019;98:1294-1305.

Reprinted with permission from GC get connected.

14 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

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D McPhee. “Prevalence and Risk Factors of Hand Problems and Carpal Tunnel Syndrome among Dental Hygienists.” Journal of Dental Hygiene, vol. 75, no. II, 2001, pp. 130–134. 8) Mulimani P, Hoe VCW, Hayes MJ, Idiculla JJ, Abas ABL, Karanth L., Ergonomic interventions for preventing musculoskeletal disorders in dental care practitioners. Cochrane Database of Systematic Reviews 2018, Issue 10. Art. No.: CD011261. DOI: 10.1002/14651858.

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Learn how to scale in perfect Harmony at Hu-Friedy.com/Harmony

Hu-Friedy, Crosstex and Palmero are now proud members of

Hu-Friedy, Crosstex and Palmero are now proud members of Hu-Friedy,Crosstex Crosstexand andPalmero Palmeroare arenow now proud members Hu-Friedy, proud members of of

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ID_21_08

USER REPORT

Anterior matrix systems - essential to provide proper anatomical form and function to restorations Troy Schmedding1

Introduction Composite resins are, and for the foreseeable future, the most widely used direct restorative material for restorations involving anterior teeth. Today’s composite materials offer practitioners tremendous physical properties but also optical properties to deliver lifelike restorations on a consistent basis. Proper finishing and polishing, together with the right occlusal scheme can provide the opportunity for these restorations to last a long period of time.

Though the handling characteristics of modern composites are vastly improved dentists still struggle with the development of good inter-proximal contacts and proper anatomical contours. Utilizing an anterior matrix system can be paramount in achieving this objective. Matrix systems in the anterior region are numerous in respect to creativity but the majority can be classified into flexible and rigid. Flexible matrices include the popular mylar strip and soft splint templates that can be challenging as they lack the ability to contour large areas leading to irregular contours and contacts. Rigid matrices include putty indexes and pre-contoured posterior sectional matrix, both viable options in certain situations but the majority of time posterior matrices are cumbersome and difficult to use when restoring multiple surfaces.

To overcome a majority of these aforementioned limitations Garrison Dental has introduced the Fusion Anterior Matrix System. A simple matrix designed to be used for anterior restorations such as class III, IV as well as composite veneers. The firm stainless steel matrix easily slides into the sulcus all while maintaining the proper shape and contour without deformation. Properly placed the ideal anatomical curvature is achieved in a gingival - incisal and facial - lingual direction. To help maintain this ideal anatomical position the Fusion Anterior Wedge is used to ensure a firm seal at the cervical margin from facial to lingual. These radically curved wedges help free up your hands to allow one to concentrate on composite placement and simplify the restorative process.

This article is a case report of a direct composite restoration on a maxillary anterior tooth where the proximal contact and incised edge position were developed using the Fusion Anterior Matrix System.

Troy Schmedding, DDS, AAACD Private practice in Walnut Creek, Ca., USA Email: Troyschmeddingdds@gmail.com 1

Case Report A 74 year old male presented with an old class III composite on the distal portion of his left lateral incisor (Figure 1). Re-current decay was noted both visually as well as radiographically. Treatment options were discussed with patient and it was decided we

16 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

USER REPORT

Figure 1: Failing Class III composite on the distal - facial of the Maxillary lateral incisor.

Figure 2: Fusion Anterior Matrix in place with Fusion Wedge to stabilize matrix and allow easy access for placement of phosphoric acid.

Figure 3: Fusion Matrix being held from the facial while placing composite from the lingual.

Figure 4: Instrumentation of the composite performed to push the composite against the facial side of the Fusion Matrix.

would replace the restoration with a new direct composite restoration. Small amounts of composite were placed on to the tooth and light cured to get an idea of what shade or shades would be utilized.

The patient was anesthetized with 1/2 carpule of 4% Articaine (Septodont) with 1:100,000 epinephrine. Isolation was obtained with a ComfortView® Lip & Cheek Retractor (Premier Dental). A pear shaped diamond bur (Meisinger) was used to remove the old restoration. A #2 round bur in a slow speed handpiece was used to remove all remaining decay and finally an 856 diamond bur (Meisinger) was used to bevel the facial margin and create a butt margin on the lingual. A short anterior Fusion Band (Garrison Dental) was then placed inter proximal past the finish line of the preparation and gently into the sulcus. A medium sized anterior Fusion Wedge (Garrison Dental) with its radical

curvature was placed to ensure a firm seal at the cervical margin all while not distorting the anatomical contour, unlike the mesial aspect of this same tooth where a wood wedge was used to seal the margin of that particular restoration (Figure 1). A smaller wedge may have been an option in this case as you can you see the orange wedge rotated slightly when placed but due to the lack of distortion of the band and the great seal achieved I did not change. Access to both the facial and lingual of the preparation achieved a 35% phosphoric acid (K-Etchant Kuraray) was placed in a selective etch protocol and allowed to sit for 30 seconds prior to rinsing off (Figure 2). Universal Bond Quick (Kuraray) was then applied to the preparation in agitating motion for 10 seconds, air thinned and light cured for 20 seconds from both the facial and lingual to ensure polymerization. In the case of using a metal matrix that doesn’t promote light

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2 17

USER REPORT

Figure 5: Application of composite continues from the lingual til preparation is sufficiently filled.

Figure 7: Final polished restoration with wonderful aesthetics and ideal anatomical form and function.

passage as friendly as a clear matrix I felt more comfortable taking the extra time to polymerize. The flexibility of the Fusion Matrix system allows you to sculpt composite in an open fashion where you have access from the lingual as well as the facial while still benefiting from the anatomically correct inter-proximal contours. In this particular case I took the approach of using my finger to push the matrix from the facial while adding a small increment of Majesty ES-2 Universal composite (Kuraray) from the lingual (Figure 3). Composite instrument was then used from the lingual to manipulate the composite (Figure 4) and then light cured for 20 seconds. Repeated this process (Figure 5) until the restoration was filled to completion and light curing finished from the lingual. The matrix was then peeled away on the facial side and again cured for 20 more seconds to ensure complete polymerization. Anterior Fusion Wedge and Matrix were then removed to show minimal excess composite on the facial surface as well as ideal anatomical contours

Figure 6: Removal of the matrix reveals proper contact, contours and minimal flash on the facial surface.

(Figure 6). A fine flame diamond and a fine football shaped diamond (Meisinger) did most of the heavy refinement and adjustment of occlusion. The final polish was achieved using a two step diamond polishing system (Meisinger)(Figure 7).

Understanding the limitations of the material in every situation and adapting newer techniques should be our focus to make our restorations more predictable and durable. The case presented featured a great new product that can help you establish good contacts and contours in the anterior region where paramount importance is not just from an aesthetic but also a functional point of view.

References 1. Ayush Goyal, Vineeta Nikhil, and Ritu Singh, “Diastema Closure in Anterior Teeth Using a Posterior Matrix,” Case Reports in Dentistry, vol. 2016, Article ID 2538526, 6 pages, 2016.

2. Fellippe L. A., Monteiro S. Jr, De Andrada C. A., Di Cerqueira A. D., and Ritter A. V.. 2005. Clinical strategies for success in proximo-incisal composite restorations.

Part II. Composite application technique. J. Esthet. Restor.

Dent. 17:11–21.

3. Flávio F Demarco, Kauê Collares, Fabio H Coelho-deSouza , Marcos B Correa, Maximiliano S Cenci, Rafael R Moraes, Niek J M Opdam. 2015 Oct;31(10):1214-24. doi: 10.1016/j.dental.2015.07.005. Epub 201Aug21.Anterior composite restorations: A systematic review on long-term survival and reasons for failure 4. A systematic approach to contouring and polishing anterior resin composite restorations: A checklist manifesto. Vargas MA, Margeas R. J Esthet Restor Dent. 2021 Jan;33(1):20-26. doi: 10.1111/jerd.12698. Epub 2020 Dec 25.

18 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

INTERVIEW

EdgeEndo solutions – an interview with Dr. Charles J. Goodis

Dr Charles J. Goodis

Introduction Henry Schein has been offering the endodontic solutions portfolio of EdgeEndo®, one of the world’s largest NiTi rotary file suppliers, successfully for two years and has just enlarged this range by EdgeFile® X7, the number one selling EdgeEndo® NiTi system in the United States.

EdgeEndo® is conducting business in 35 countries around the world. The company’s mission is to deliver high quality dental products and solutions at affordable prices which in turn benefits practitioners and patients everywhere.

US based Endodontist, Dr. Charles J. Goodis, Founder of EdgeEndo®, received his DDS from the University of Michigan, his GPR residency at the University of Minnesota, and his Endodontic residency at the University of Connecticut. Dr. Goodis has dedicated his career to constantly improving the root canal procedure. His findings led him to create more effective root canal instruments and procedures. He’s been working as an endodontist in Albuquerque, New Mexico, USA for 25 years.

Dr. Goodis, please tell us something about the company and the main products.

My background in mechanical engineering and training in endodontics, as well as trying to help the patient and dentist do the best they can, inspired me to found EdgeEndo. Edge has been in the US market since 2012. In this short time, we have become one of the largest endo companies in the world. We now offer our products in 35 different countries.

Our main products are NiTi files that are heat-treated through our proprietary FireWire process. Our best-selling system is the EdgeFile X7. It’s one of the leading files used by endodontist in the US, Canada, New Zealand, Australia and many countries in the Middle East. EdgeTaper Platinum and EdgeOne Fire have also been very successful systems in these markets. EdgeEndo has been well received in the industry. In addition to files, we also sell a full assortment of accessory products including gutta percha and paper points.

What are the benefits of the EdgeEndo files and which endodontist will benefit mostly from these files?

The patient of course wants a quick root canal procedure because any time you can reduce chair time, they appreciate. And the patient wants a precise root canal clean-up to get rid of the pain but preserve the tooth. Both is supported by the flexibility paired with the stability, our files provide and thus allow endodontists to perform an accurate and fast procedure. In addition, the reasonably-priced files make the treatment also more efficient in respect of costs.

How do you achieve the balance between offering high-quality endodontic products at low price?

Quality and value are paramount in importance at EdgeEndo. We have a very detailed quality system that allows us to produce a consistent, high quality product.

20 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

INTERVIEW

Unfortunately, being an endodontist treating patients, I saw how high costs are and I thought to myself we can still offer a great product at a good price which provides value for the money. I think reasonable prices are important to a dental practice because as the dental fee structure changes in the US some dentists are making less money than they did before, and I believe offering a high-quality instrument at a lower price really helps dentists succeed.

Do customers need new motors for the application of the files?

The motor currently being used by dentists should be able to work with our files. The only time we advise purchasing a new motor is when a dentist wants to use one of our reciprocating systems, such as EdgeOne Fire, which works in a reverse-reciprocating motion and can’t be used with a rotary motor.

Which is the most important instrument for rootcanal preparation? How many files does one require as a rule?

My personal preference is EdgeFile X7, it is super flexible, efficient and unbelievably strong. Each system varies somewhat. As a rule, most root canals can be completed with between 1 and 3 files.

We’ve simplified the technique for systems to help the dentist and eliminate waste. As an endodontist, I never used all of the different sizes in an assortment pack. With my file systems you can purchase the files needed and follow the techniques we’ve worked on with other dentists to develop.

The heat treatment process of the EdgeEndo files seems to play a big role in the quality and thus differs from files of other manufacturers. Can you describe the advantages to us?

We spent a lot of time creating geometrically the best instruments out there. The proprietary FireWire heat-treatment process vastly improves the NiTi metallurgy, delivering excellent strength and flexibility, improving resistance to cyclic fatigue or in other words, reducing the chances our files will separate. Another benefit of FireWire NiTi is it enables EdgeEndo files to not “bounce back”, preserving canal anatomy, and carefully follows the canal as they shape.

A common concern within root canal preparation is the cyclic fatigue. How resistant are the EdgeFiles (perhaps with reference to a clinical study)?

Our file systems are very resistant to cyclic fatigue. We’ve done both internal and 3rd party peer reviewed testing to ensure our files are more resistant. Dentist can refer to all of the published research on our site that back up our claim (https://web.edgeendo.com/studies/).

What if I already have a working system and technique? Are the EdgeFiles compatible?

Yes, I designed many systems to be an easy transition for the doctor to integrate Edge into their practice utilizing the same technique and motor settings. If a dentist switched to Edge they can still use the gutta percha points, paper points and obturators they have in stock.

How do you minimize the risk of file breakage with your files and are there any improved properties here compared to the files of other manufacturers?

Our files combine the attributes of being highly efficient and flexible, due to the proprietary FireWire heat treatment process, while being extremely safe and resistant to fracture.

They are designed with a safe-unwinding feature. The files start unwinding before breaking. Unwinding signals to a practitioner that the file is fatigued and can break if they keep instrumenting with the file. This helps with stress and results in a more enjoyable procedure for the practitioner and patient.

The patient is only in the chair for the time intended and this saves time and cost for both.

Thank you, Dr. Goodis, for these interesting insights.

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2 21

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The gke Orange PCD is a 2-in-1, dual purpose monitoring system that can be used for your Bowie Dick and Helix Test as well as for routine monitoring of all loads.

The device can be reused for up to 10,000 cycles - saving you money, and reducing your amount of waste meaning its environmentally friendly!

Many other products on the market have a limited lifespan of 250 cycles. The patented stainless steel helix means the gke device is highly durable. It also means that we are simulating the sterilisation challenge posed by stainless steel instruments we are sterilising.

The gke Orange PCD simulates the penetration requirements of EN 867-5 and covers you no matter what you are sterilising, be it complex hollow instruments (burs and handpieces), solid instruments (mirrors) or porous loads (gauze).

For more informaon on the gke products contact gke Australia 1300 889 201 or sales@gkeaustralia.com We proudly and exclusively partner with Henry Schein www.gkeaustralia.com

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gke Steri-Record® Orange PCD Why can the Orange PCD be used as a Bowie Dick Test and a Helix test?

The Australian Standard for Office Based Practice (AS/NZS 4815:2006) is derived from International Standards. EN 13060:2004 and EN 867-5:2001 are the International Standards for Small Steam Sterilisers.

penetrated all internal surfaces. We can imagine it is easy to sterilise a solid instrument like a mirror as there are no internal surfaces. Similarly porous items are easy to remove the air from and distribute steam to. Therefore, as the gke Orange PCD meets the requirements of the Hollow Load Test defined in EN 867-5, it is also capable of monitoring the sterilisation of solid and porous items in our loads

EN 867-5 defines the specifications for the test to be used in daily start-up testing of small steam What is Routine Monitoring? sterilisers. This test is known as a “Daily Air Removal and Steam Penetration Test” in AS/NZS Routine monitoring of every load represents best practice for your facility and more importantly, 4815:2006. your patients.

A Bowie Dick Test was the first test of its kind for If miniscule amounts of air remain trapped within start-up testing of porous loads in large steam instruments, the air can block steam from getting sterilisers back in 1963, however this sort of test inside the instruments. Meaning the instruments only makes sense nowadays for porous type could be released without an Internal Sterility loads in large steam sterilisers. As such “Bowie Assurance Level (SAL). To overcome this Dick Tests” are only defined in EN 285, which is possibility it is recommended that the gke PCD be the International Standard for large steam used in every load, i.e. routine monitoring. sterilisers.

The terminology - Bowie Dick Test | Helix Test | Daily Air Removal and Steam Penetration Test are all synonymous by definition. They are the mandatory first test we do in our steriliser at start-up in an empty chamber to make sure our steriliser is capable of air removal and steam penetration in our instruments we will be sterilising throughout the day. It is a functionality check of our steriliser.

Why should we monitor every load?

Our daily start-up test is only a functionality test of the steriliser and not a test for sterility. Additionally our chart print-out cannot tell us about what is happening inside our instruments, only that the critical parameters have been met for the process.

Also, if the vacuum pump in our steriliser becomes faulty throughout the day, without the use of the PCD, this fault would go undetected Therefore in accordance with the requirements of until the next day’s start-up air removal and steam EN 867-5 - a test meeting this standard is the only penetration test. Meaning any instruments used test we must conduct in our empty chamber at during that day would not have an internal SAL, start-up. meaning potential risk to the patient.

How can the Orange PCD simulate complex Easy Usage and Interpretation hollow instruments, solid instruments and The indicator strips can be evaluated easily. porous loads?

Errors in a process can be quickly identified with Complex hollow instruments, like hand pieces and the 4 bar indicator graduated colour change. burs, are more difficult to sterilise than solid Pass/Fail sheets are also available to assist staff instruments and porous items like gauze, in recognising correct colour change. Indicators because it is more difficult to remove the air that are self-adhesive and can be adhered to process may be trapped inside the instrument, and notes for documentation and tracking. subsequently more difficult to ensure steam has For more informaon on the gke products contact gke Australia 1300 889 201 or sales@gkeaustralia.com We proudly and exclusively partner with Henry Schein www.gkeaustralia.com

1300 65 88 22 henryschein.com.au ID_21_09

CLINICAL

Aesthetic anterior tooth restorations with nano-ceramic hybrid CAD/CAM blocks

João Mauricio Ferraz da Silva1 and Danilo de Souza Andrade2

Prof. Dr. João Mauricio Ferraz da Silva and Danilo de Souza Andrade, 1, 2

São Paulo State University, São José dos Campos, Brazil

Introduction For decades now we have been observing a rise in the desire among patients for aesthetic improvements to their smiles. A multidisciplinary treatment makes it possible to achieve a harmonious and healthy smile by adapting the shape, colour, size and positioning of the teeth on the basis of facial parameters. Thanks to scientific progress overall and advances in the materials and techniques used, it is now possible to effect such changes with less invasive procedures. One such treatment technique is ceramic veneers (Belser et al., 1997; Radz, 2011; Rotoli et al., 2013).

The production of veneers begins with minimal preparation of the tooth in such a way that as much healthy dental hard tissue as possible is preserved on the one hand and changes to the shape and even small changes to the colour of the tooth are possible on the other. This novel concept was introduced under the term “minimally invasive dentistry” (Radz, 2011).

The material most commonly employed in the production of ceramic veneers is lithium disilicate-based ceramic, which displays good mechanical properties thanks to its resilience, offers excellent visual properties thanks to its ability to reproduce natural tooth characteristics well and is also bio-compatible with the neighbouring oral tissues (Chen et al., 2018; Palla et al., 2018; Zhi et al., 2016).

Composite-based blocks are also used to produce indirect restorations with the aid of CAD / CAM technology. During the production process, they are exposed to heat and pressure for polymerisation and, as a result, display superior mechanical properties in comparison with direct composite restorations (Mainjot et al., 2016). In terms of their modulus of elasticity and strength, the composite-based CAD / CAM blocks achieve values similar to those of natural tooth substance, i.e., enamel and dentine. These properties can be controlled by the percentage of resin matrix in the constituents of the blocks. In addition, this material displays greater resistance to fatigue compared with ceramics (Alamoush et al., 2018; Magne et al., 2010), and such properties make this material an excellent choice for durable, indirect restorations. Grandio blocs (VOCO GmbH, Cuxhaven, Germany) is an example of a hybrid ceramic block for CAD / CAM systems – it is a nano-ceramic hybrid material containing 86 % inorganic fillers in a polymer matrix. The composite systems for CAD / CAM are indicated for the indirect production of permanent single-tooth restorations such as inlays, onlays, full crowns and veneers.

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CLINICAL

Figure 1: Portrait photo before and after treatment.

Figure 2: Close-up of smile before and after treatment.

Figure 3: Digital smile design.

Alongside the mechanical advantages, the composite blocks also offer the possibility of shade adaptation directly after the milling process without any need for additional crystallisation, as is the case with ceramic blocks. This represents another advantage of this production technique (Allen et al.). A further interesting factor worthy of note when these blocks are used is that, compared with ceramics, the margins of the restoration do not display any microcracks and are more homogeneous (Tsitrou et al., 2007). The restorations produced using composite-based materials are easier to repair intraorally if and as required, if necessary by freshening up the area, silanising the restoration afterwards, applying an adhesive system and performing the repair directly with the composite (Tsitrou et al., 2010).

This clinical case thus aims to illustrate the possibility for using CAD / CAM technology and composite-based blocks for the indirect restoration of anterior teeth.

Case report A 50-year-old patient presented in the clinic of the university project Construindo Sorrisos Confiantes (Building Confident Smiles) run by the Department of Dental Materials and Prosthetics at the Institute for Science and Technology at the Federal University of São Paulo in São José dos Campos, Brazil. The patient was unhappy with his smile and particularly did not like the gaps between his teeth or their shade. In the first session, the patient’s medical history was recorded, a clinical examination performed and photographs taken for the purpose of the diagnosis and subsequent treatment planning (Fig.1, Fig. 2).

The examinations revealed that the patient was in good general health and maintained good oral hygiene without any systematic conditions which might affect and / or hinder dental treatment.

The extraoral photographs, comprising a front portrait

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Figure 4: Mock-up.

Figure 5: Preparation on the mock-up.

photograph with lip retractor and forced smile, 45º from the side and a photograph in the 12 o’clock position, and the intraoral photographs, comprising a close-up of the smile, maximal intercuspidation with lip retainers and the maxillary teeth against a black background, were taken prior to the start of treatment (Fig. 3). This was followed by 2D digital smile design (DSD) using the diagnostic photographs, based on the main problem and with the aim of resolving it.

The ideal smile was constructed on the basis of the patient’s facial features and the function of the stomatognathic system.

The parameters employed when designing the smile were the smile line and the position of the lips, the gingival zenith, tooth proportions, the face format and the increase in size in accordance with the principles of the RED correlations (Stanley et al., 2018). Once the final 2D smile design was complete, the data were sent along with the patient’s models to the dental laboratory for production of a diagnostic waxup for the patient.

The model with the diagnostic wax-up was then used to produce a silicone impression, which replicates the proposed new dental anatomy and allows production of a mock-up on the patient’s teeth without the need for any tooth preparation, solely with the aim of simulating the proposed aesthetic restoration for the patient. The dentist uses this simulation to analyse the aesthetics and function for the case in question and either recommends or rejects the plan. In addition, the trying-in of the mock-up is ideal for giving the patient an idea of how the proposed aesthetic restoration will look and building up his confidence in the planned treatment.

The mock-up is made using bis-acrylic, which boasts material characteristics such as low heat emission during the

polymerisation reaction. It also reproduces the shape of the tooth copied using the silicone tray well and has a similar colour to natural dental tissue. The Structur 2 bis-acrylic composite (VOCO GmbH) was used. It was introduced into a silicone tray with the tip of the mixing tip always in the deepest part of the impression so as to avoid air bubbles.

Once filled, the tray was inserted into the patient’s mouth and the excess material removed during the early stages of the polymerisation. The material was then allowed to cure completely. Once fully polymerised, the silicone tray was removed from the patient’s mouth and the surface of the finished mock-up wiped with a piece of gauze soaked in alcohol in order to remove any remaining monomer (Fig. 4).

Once the patient and dentist were both satisfied with the completed planning, a treatment plan for attaining the treatment goal described in the first phase was submitted to the patient. The following treatment was proposed to the patient: tooth whitening to achieve a homogeneous tooth shade and production of veneers made from hybrid blocks (Grandio blocs – VOCO GmbH) for six teeth from tooth 13 to 23 in order to redesign the shape of the teeth.

The technique proposed by Kern & Ahlers (2015) was used as a reference for the preparation of the teeth, with the mock-up serving as a guide for removal of the dental substance. A 4141 grinding bur (KG Sorensen, Cotia, Brazil), characterised by diamond-coated rings, was used to carve reference grooves into the vestibular surfaces of the respective teeth, taking into consideration the incline of the tooth in each third, and an approximately 0.5 mm thick layer of substance removed from mesial to distal. An extra-fine 3145FF diamond bur was then used to remove a second layer of substance from each vestibular surface

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Figure 6: Dry try-in.

Figure 7: Application of Ceramic Bond on veneers.

until the groove placed during the first step was levelled out.

The preparation was completed with an extra-fine 3203FF diamond bur, with the cervical and proximal preparation margins being defined so as to achieve better marginal integrity for the respective veneers and determine the exact size of the veneers (Fig. 5).

The impression was taken in the same treatment session following the preparation and a single #000 knitted cord (Ultrapak – Ultradent Products Inc., South Jordan, USA) used for the gingival retraction in advance. The cord was soaked in a little haemostatic solution and placed into the gingival sulcus. The impression was performed in two stages with an addition-curing silicone (Virtual – Ivoclar Vivadent AG, Schaan, Liechtenstein). The DSD planning and the model were sent to the laboratory as references and for the production of the restorations.

For insertion of the restorations, a dry try-in was performed in the mouth in advance in order to assess the marginal integrity and final position of the veneers and make any

proximal adjustments if and as necessary (Fig. 6). The interior sides of the veneers were produced in the following way in accordance with the manufacturer’s specifications: sandblasting with aluminium oxide (25-50 µm), followed by cleaning of the pieces in an ultrasound bath for 5 minutes. The surface was then treated with the bonding agent Ceramic Bond (VOCO GmbH) (Fig. 7): an applicator brush was used to apply the agent to the interior sides of the veneers before it was allowed to work for 60 seconds and then dried quickly with compressed air. The teeth were pretreated with 37% phosphoric acid for 30 seconds as the preparation of the teeth occurred exclusively in the enamel, then rinsed thoroughly with air and water and dried with compressed air.

The adhesive Futurabond U (VOCO GmbH) was applied to the tooth surface and massaged in for 20 seconds, followed by removal of the excess material with a fine suction device and light stream of air (Fig. 8).

Following the preparation of the veneers and the teeth, the next step was the final insertion of the composite. The dual-

Figure 8: Preparation of the teeth: 37% phosphoric acid for 30 seconds, apply Futurabond U and massage in for 20 seconds.

Figure 9: Removal of excess Bifix luting material.

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Figure 10: Removal of excess material with scalpel and polishing with the Diamanto polishers.

Figure 11: The restoration on the model and in its final position in the mouth.

curing composite-based luting system Bifix QM (VOCO GmbH) was applied to the interior side of the veneers, the veneers brought into their final position and a check for excess material performed. Following removal of the excess material with a brush, the material was light-cured for five seconds to stabilise the veneers. With the restorations fixed in this way, the next step was to remove the excess material using dental floss on the proximal surface and a no. 11 scalpel on the cervical surface (Fig. 9).

This was followed by the final light curing for 40 seconds on each side of the veneer. Once polymerisation was complete, the remaining excess material was removed using a periodontal curette and an interproximal saw. The occlusion was then ground in on the basis of the markings using occlusal articulating film (Accufilm – Parkell Inc., Edgewood, USA) on a holder in accordance with the criteria for optimal occlusion with double-sided and even contact and clearly defined guide surfaces.

Following the grinding, the veneers were finished and polished using Diamanto diamond polishers (VOCO GmbH), giving them their final smooth and lustrous surface (Fig. 10).

The patient was instructed in the essential care and monitoring of the restoration before being discharged with the first follow-up appointment scheduled for 48 hours later.

After two follow-up sessions in which the marginal integrity, possible excess material, occlusal contact points and oral hygiene were assessed without any complaints, the patient was briefed on the importance of maintaining good oral hygiene and the requirement for a check-up every six months and then permanently discharged (Fig. 11).

Conclusion This case illustrates clearly that the CAD / CAM technique is already a clinical reality and will soon become the only practised means of producing indirect restorations. In addition, we should take the use of alternatives to ceramic materials, which have already established themselves in the scientific literature, into consideration for aesthetic restorations in the anterior region. The hybrid material described displayed good aesthetic and mechanical characteristics in this case, although further clinical studies into the longevity of the material remain necessary.

References 1. Alamoush RA, Silikas N, Salim NA, Al-Nasrawi S, Satterthwaite JD. Effect of the Composition of CAD / CAM Composite Blocks on Mechanical Properties. Biomed Res Int. 2018;2018. doi: 10.1155/2018/4893143.

2. Allen KL, Schenkel AB, Estafan D. An overview of the

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CEREC 3D CAD / CAM system. Gen Dent. ;52 (3):234–5.

PMID: 15206254.

3. Belser UC, Magne P, Magne M. Ceramic laminate veneers: continuous evolution of indications. J Esthet Dent.

1997;9(4):197–207. PMID: 9468884.

4.Chen X, Zhang Y, ZhouU J, Chen C, Zhu Z, Li LEI. Effect of different surface treatments and retainer designs on the retention of posterior Pd-Ag porcelain-fused-tometal resin-bonded fixed partial dentures. Exp Ther Med. 2018;15(2):2006–14. doi: 10.3892/etm.2017.5630.

5. Kern M, Ahlers MO. Controlling the depth of ceramic veneer preparations by using a color marker in the depth grooves. J Prosthet Dent. 2015;114(6):862–4. doi: 10.1016/j. prosdent.2015.06.010.

6. Magne P, Schlichting LH, Maia HP, Baratieri LN. In vitro fatigue resistance of CAD / CAM composite resin and ceramic posterior occlusal veneers. J Prosthet Dent. 2010;104(3):149–57. doi: 10.1016/S00223913(10)60111-4.

7. Mainjot AK, Dupont NM, Oudkerk JC, Dewael TY, Sadoun MJ. From Artisanal to CAD-CAM Blocks. J Dent Res. 2016;95(5):487–95. doi: 10.1177/0022034516634286.

PMID: 26933136.

8. Palla E-S, Kontonasaki E, Kantiranis N, Papadopoulou

L, Zorba T, Paraskevopoulos KM, et al. Color stability of lithium disilicate ceramics after aging and immersion in common beverages. J Prosthet Dent. 2018;119(4):632–42. doi: 10.1016/j.prosdent.2017.04.031.

9. Radz GM. Minimum Thickness Anterior Porcelain Restorations. Dent Clin North Am. 2011;55(2):353–70. doi: 10.1016/j.cden.2011.01.006. PMID: 21473998.

10. Rotoli B, Lima D, Pini N, Aguiar F, Pereira G, Paulillo L. Porcelain Veneers as an Alternative for Esthetic Treatment: Clinical Report. Oper Dent. 2013;38(5):459–66. doi: 10.2341/12-382-T. PMID: 23550911.

11. Stanley M, Paz AG, Miguel I, Coachman C. Fully digital workflow, integrating dental scan, smile design and CADCAM: case report. BMC Oral Health. 2018;18(1):134. doi: 10.1186/s12903-018-0597-0. PMID: 30086753.

12. Tsitrou EA, Helvatjoglu-Antoniades M, van Noort R. A preliminary evaluation of the structural integrity and fracture mode of minimally prepared resin bonded CAD / CAM crowns. J Dent. 2010;38(1):16–22. doi: 10.1016/j. jdent.2009.07.003. PMID: 19683378.

13. Tsitrou EA, Northeast SE, van Noort R. Brittleness index of machinable dental materials and its relation to the marginal chipping factor. J Dent. 2007;35(12):897–902. doi: 10.1016/j.jdent.2007.07.002. PMID: 17977638

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USER REPORT

Maximizing efficiency using 3M impression products Gary Bloomfield1 Introduction Making an acceptable impression in dentistry requires not only the use of precision impression material but also the use of adjunct materials to help support the accuracy of the final impression. 3M introduced a line of products that are intended to be used together to maximize the efficiency of taking an impression while offering predictablity to the clinican.

The following products were selected for this case: • 3M™ Retraction Capsule • 3M™ Intra-oral Syringes • 3M™ Impression Trays • 3M™ Imprint™ 4 Penta™ Heavy and Imprint™ 4 Light VPS Impression Material

1

Gary Bloomfield, D.D.S

Figure 1. Prepared tooth #6.

Clinical Case An 80-year-old male presented with a fractured and decalcified upper right canine (tooth #6). After reviewing clinical and radiographic findings it was determined that a full porcelain crown was the best treatment of choice. Initial impressions were obtained including a template for temporary fabrication, a study model and an opposing full arch mandibular impression (using 3M impression tray). After placing local anesthetic, the tooth was prepped for a full porcelain crown (Figure 1). Prior to the final impression, 3M retraction capsule (3M) paste was injected into the sulcus of tooth #6 (Figure 2). The retraction paste contains 15% aluminum chloride and is intended to provide temporary tissue retraction and enable a clean, dry and controlled sulcus. 3M retraction capsule paste material can be used alone or in conjunction with retraction cord. The soft and narrow tip of the 3M retraction capsule corresponds in size and shape to a periodontal probe; designed for direct placement in the sulcus (Figure 3).

While the retraction paste is in place, a 3M impression tray (Figure 4) is fitted. The trays come in three sizes and require no adhesive. The self-retentive strips are designed to direct the flow of the impression material, minimizing defects and voids.

The 3M intra-oral syringe is loaded with the appropriate amount of Imprint™ 4 Light (Figure 5). The syringes are single use, ergonomically designed, and can be prepared in advance (Figures 6-7). The syringe is designed for the loading of consistent amounts of wash for both single and multiple preps. There are markings and characteristics on

Figure 2. 3M retraction paste in place around preparation.

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Figure 3. 3M™ Retraction Capsule and periodontal probe tips are similar in size.

USER REPORT

Figure 4. 3M™ Impression Tray

Figure 5. 3M™ Intra-oral Syringe connects easily to a cartridge.

Figure 8. Loading 3M™ Imprint™ 4 material into the 3M™ Impression Tray using a 3M™ Pentamix™ 3 Automatic Mixing Unit.

Figures 6-7. 3M™ Imprint™ 4 Light is placed from the 3M™ Garant™ Dispenser into a 3M Intraoral Syringe, and the tip can be directed for precise application.

Figure 9. Full-arch final impression.

the syringe that will accommodate specific amounts. Using the syringe is much easier than trying to guide the 3M™ Garant™ cartridge with extended mixing tips. The 3M intra-oral syringe uses less material and allows more accurate placement.

Once the Retraction Capsule material is placed, simply rinse the material at the time limit making sure no residue remains in the sulcus.

Next, Imprint 4 material is extruded from a Pentamix mixing unit into a 3M impression tray (Figure 8). Since the 3M intraoral syringes can be prepared in advance, the material can be syringed around the prep while the tray is being loaded.

The tray is gently placed and allowed to set. Imprint 4 Light (regular set material) has a maximum 1:00 minute intraoral syringing time at room temperature. Intra-oral set time for Imprint 4 regular set material is 2:00 minutes. When the impression is set, remove it and check for blue residue and excess pieces of impression ‘flash’. These may be on teeth or soft tissue. The final impression (Figures 9-10) shows excellent marginal detail. The color contrast is easy to read, crisp and accurate, with no delamination.

Worth noting: In addition to providing a precise impression medium, Imprint 4 material (3M) has an active self-warming feature that accelarates the intraoral setting time. The setting time starts after placement and speeds up with body temperature.

A temporary crown (Figure 11) is fabricated using the

Figure 10. Detail of impression.

Figure 11. Temporary crown.

Figure 12: Final restoration.

pre-prep impression template. The Imprint 4 impression and models were sent to the lab where an all porcelain crown was fabricated. The patient returned 10 days after the prep work for delivery of the restoration (Figure 12). No complications or problems occurred during temporization.

The restoration was tried in, adjusted and bonded into place.

The patient is comfortable and pleased with the final result.

Conclusion The 3M products used in this restorative process helped create a beautiful restoration. The materials and delivery system are excellent.

These products are designed to be used sequentially and gives the clinician confidence in accuracy of both impression and final restoration.

Reprinted with permission by The Dental Advisor Number 41 – May 2016

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CLINICAL

A simple chairside digital workflow

Linda Greenwall1 and Benedict Harrison2

Intraoral scanning equipment has been rapidly introduced in dental practices as there are improvements to the technology in the last decade.

Computer-aided design (CAD) and computer-aided manufacture (CAM) is available to dental practitioners for the production of in-surgery restorations and devices using milling and printing technology.

This article will outline an overview of 3D scanning, its uses in general practice and discuss a simple chairside digital workflow of an indirect restoration.

Dr Linda Greenwall BDS MGDS MRS RCS MSc FFGDP FICD BEM, Specialist Prosthodontist, London, UK 1

Dr Benedict Harrison BDS, Private Practitioner, London, UK 2

A brief historical background Dental biomaterials have been used in general dentistry for many years. Fillings inserted into crowns have been reported as early as the Neolithic period 6,500 years ago, with beeswax being the material of choice.

Historically a dental impression was needed for a technician to cast and construct a prosthesis.

Recent innovations in intraoral scanning have drastically improved their ability to acquire precise and accurate information with speed and ease. This enables dentists and technicians alike to view and design in an accurate virtual environment (Bernardini et al, 2012).

In recent years, computer technology and the development of CAD/CAM has allowed dentists and technicians to manufacture prosthesis using a digital workflow, and enabled them to make restorations out of millable materials such as composite, ceramic and zirconia and polymethyl methacrylate (PMMA) (Russo et al, 2019; Kilhara et al, 2019).

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Figure 1: Preoperative photo of the clinical situation showing the distal fracture that had developed.

Figure 2: Preoperative radiograph showing significant crack in the distal marginal ridge of LL7.

Figure 3: After removal of composite and reduction in cusp height to remove fractured cusps. Once the caries is removed and fracture chased out we can decide on the most appropriate material for the restoration.

Figure 4: Scan of preparation and automatic margin detector. This margin is adjusted to the clinician’s specification.

Types of CAD/CAM systems There are three different CAD/CAM production concepts in dentistry described in the literature:

1. Chairside production – all components in the CAD/CAM system are located in the dental surgery 2. Laboratory production – a traditional working sequence

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Figure 5: Restoration is designed using Cerec. Patients occlusion can be visualised with colour pressure areas. Restoration contacts can be turned on and off.

Figure 6: Lower model can be removed from the design to help add and remove from the virtual wax up. This is particularly useful when designing the restoration contact point.

Figure 7: Once happy with your design, position the sprue on your restoration to a favourable position.

Figure 8: Cementation process – etch 20 seconds (Super Etch 37% phosphoric acid).

Figure 9: Washed and dried.

Figure 10: Application of Stae bond after Hurriseal application.

between a dentist and a laboratory. Once a laboratory receives impressions, these are cast then the CAD/CAM production starts by scanning the models. This enables the laboratory to digitally design and manufacture the prosthesis 3. Centralised production – laboratories send a design to a centralised production centre for milling, printing or pressing, this avoids the need for laboratories to purchase expensive production equipment (Baroudi and Ibraheem, 2015; Beuer et al, 2008).

The CAD/CAM in surgery system in dentistry comprises of four major components (Baroudi and Ibraheem, 2015; Beuer et al, 2008): 1. Digital scanner – a tool to convert physical geometry to digital information (such as Primescan, Trios 4, Emerald S, Itero Element 5D) 2. Software component – computer aided design software (Cerec, Trios, Planmeca) 3. Milling machine (Cerec MC-XL, Roland DWX-4W, Planmill 40/E4D Mill) 4. Millable block – ceramic, composite, PMMA and zirconia.

Scanning Intraoral scanning devices have been around for many years, but have recently taken huge steps to make them a viable and effective tool for the general practitioner.

Historically, powder had to be used in conjunction with the scanner to provide an optical efficient environment to collect data. Scanners available on the market today are powderless and colour accurate. Many have adjunctive tools, such as shade analysing and caries detection.

Accuracy of scanning There is not an exhaustive amount of research on the accuracy of digital scanning when compared to conventional analogue impression techniques.

The pace at which technology is improving makes it hard for research to stay up to date and relevant as digital scanning is constantly changing.

Some studies have reported better accuracy of scanned preparations using optical scanning (Abduo and Elseyoufi, 2018). However, a review by Abduo et al (2018) showed that intraoral scanning was just as accurate as conventional impressions in short spans, but during full arch scanning there

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Figure 11: Application of D/E resin.

Figure 12: Application of Relyx Unicem.

was more perceptibility to inaccuracies.

Ultimately, for diagnostic and short span scanning, digital impressions are comparable to conventional impressions (Abduo and Elseyoufi, 2018).

Acquisition of a good quality virtual model 1. Dry field – the use of a three in one and a vigilant nurse with a saliva ejector can make obtaining the scan much easier. A device such as an Optragate (Ivoclar Vivadent) that deflects the lips is also beneficial to clear the scanning field 2. Dark environment – the dental light, as well as surgery lights, should be switched off to enable the scanner to work more effectively 3. Good preparation design – clear, smooth margins, ideally supragingival. Use of retraction cord essential for margins sub or juxtagingival 4. Half arch impression – this reduces inaccuracies in the

Figure 13: Seating and curing of the restoration.

impression and also makes designing the restoration easier when moving the virtual model on the software program 5. Obtain the bite registration and opposing arch before preparation – this reduces the scanning time after preparation. Ideally, the bite registration should be taken in an upright position with the patient biting together, but not clenching.

A simple case is highlighted step by step to show the digital work flow.

Case: Preparation of a ceramic combination inlay/onlay This patient, due to a clenching habit, developed a deep distal crack on the lower left second molar. The crack was situated on the distal marginal ridge of the tooth and had developed a fracture on the occlusal surface where decay had penetrated into the crack.

Table 1: (Mangano et al, 2017) Advantages and disadvantages of chairside scanning Advantages

Disadvantages

More time efficient

Deeper margins more difficult to scan

Less patient discomfort

Learning curve

Better communication between dentist and technician

Cost of purchasing equipment

Better communication between dentist and patient

Ensuring good isolation to record accurate details

Less waste

Dry field is essential to pick up accurate details of the prep

Accurate fit of restorations due to better identification of Initial learning curve can take more time to do margins More time needed to learn the software and design software

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Figure 14: Final restoration LL7.

To preserve and protect the tooth from further fracture, it was decided the best and most conservative options would be to design an inlay/onlay combination, overlaying the distobuccal and distolingual cusps and keeping the inlay design/occlusal design (Figures 1 to 14).

Treatment time was 90 minutes from start to finish. This helped to save the patient a second appointment and patient did not have to have a temporary restoration.

The overall outcome was a conservative onlay made to protect the tooth from further breakdown and preserve the remaining tooth structure.

Conclusions Using the digital scanner and Cerec digital design software, an onlay was created chairside using a milling machine and ceramic block.

It was an effective way to undertake restorative and aesthetic dentistry. More research is needed and more training is needed, as further materials and software are introduced onto the dental market.

References Abduo, J, Elseyoufi M (2018) Accuracy of Intraoral Scanners: A Systematic Review of Influencing Factors. The European Journal of Prosthodontics and Restorative Dentistry 26(3): 101-121 Baroudi K, Ibraheem SN (2015) Assessment of Chair-

side Computer- Aided Design and Computer-Aided Manufacturing Restorations: A Review of the Literature.

Journal of International Oral Health 7(4): 96-104 Bernardini F, Tuniz C, Coppa A, Mancini L, Dreossi D, Eichert D, Turco G, Biasotto M, Terrasi F, De Cesare N, Hua Q, Levchenko V (2012) Beeswax as dental filling on a neolithic human tooth. PloS one 7(9): e44904 Beuer F, Schweiger J, Edelhoff D (2008) Digital dentistry: an overview of recent developments for CAD/CAM generated restorations. British Dental Journal 204(9): 505-511 Goracci C, Franchi L, Vichi A, Ferrari M (2015) Accuracy, reliability, and efficiency of intraoral scanners for full-arch impressions: a systematic review of the clinical evidence. The European Journal of Orthodontics 38(4): 422-428 Kihara H, Hatakeyama W, Komine F, Takafuji K, Takahashi T, Yokota J, Oriso K, Kondo H (2019) Accuracy and practicality of intraoral scanner in dentistry: A literature review. Journal of Prosthodontic Research Lo Russo L, Caradonna G, Biancardino M, De Lillo A, Troiano G, Guida L (2019). Digital versus conventional workflow for the fabrication of multiunit fixed prostheses: A systematic review and meta-analysis of vertical marginal fit in controlled in vitro studies. The Journal of Prosthetic Dentistry 122(5): 435-440 Reprinted with permission from Aesthetic Advances December 2019.

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CLINICAL

COVID-19 risk management in dental practice: The 10 pillars of SARS-CoV-2 control in clinical dental practice Johan Hartshorne1 and Andre van Zyl2

Keywords: coronavirus, COVID-19, SARS-CoV-2, infection control, prevention, dentistry, airborne transmission, PPE, surface disinfection, ventilation, immune boosting, antibodies, vaccine.

Johan Hartshorne B.Sc., B.Ch.D., M.Ch.D., M.P.A., Ph.D., (Stell), FFPH.RCP (UK) General Dental Practitioner, Intercare Medical and Dental Centre, Tyger Valley, Bellville, 7530, South Africa 1

Email: jhartshorne@kanonberg.co.za

Andre van Zyl M.Ch.D. (Stell) Specialist in Oral Medicine and Periodontics Honorary Professor: Department of Oral Medicine and Periodontology University of Witwatersrand Johannesburg, South Africa Private practice: 9 College Road, Hermanus, South Africa Email: info@andrevanzyl.co.za 2

Introduction The practice of dentistry exposes dental health care professionals and patients to infectious disease pathogens.1 In addition, the SARS-CoV-2 pandemic has become a major infection control and prevention challenge for dentistry primarily due to transmission of infectious respiratory droplets and aerosols;2-9 and direct contact with the oral cavity and saliva, a recognized reservoir and portal of exit and entry for SARSCoV-2.8-11 Patients seen by dentists may be asymptomatic carriers of SARS-CoV-2. Oral health is integral to general health care and therefore a potential risk for COVID-19 severity.13 COVID-19 infection control and prevention policies world-wide for healthcare workers have focussed on the use of PPE. The importance of source control at oral level to reduce the spread of contaminated droplets and aerosols has not received the same recognition as that of PPE. Infection control and prevention globally seems to be a point of considerable confusion within the dental profession.14 Internationally the recommendations for re-opening dental services have no referenced, underpinning evidence, and some areas are unlikely to ever have strong (or any) research evidence.15 Most recommend avoiding or minimizing the use of aerosol generating procedures (AGPs) to reduce the risk of transmitting virus contaminated aerosols.15 As the COVID-19 pandemic continues to explode, hospitals and dental practices are scrambling to implement and intensify infection control measures to protect themselves and patients from exposure to the coronavirus. This has to be done in an ethical manner.

Purpose and Methodology The purpose of this Covid review is: (i) to outline contemporary evidence on enhanced precautions for infection control and prevention (ICP), with focus on SARS-CoV-2 source control to reduce generation of contaminated droplets and aerosols, (ii) to explore the relevance of enhanced precautions for dental professionals, and (iii) to outline the limitations of the current evidence relating to ICP within the dental practice.

Emerging literature on COVID-19 is rapidly evolving and scattered over various sources, is characterized by incomplete or uncontested evidence-based data and by a plurality of voices within the health care, academic, environmental research community and media. This makes it difficult to clearly and rapidly synthesize and articulate scientific evidence.

A comprehensive literature search of multiple bibliographic databases was conducted, including Medline PubMed, Embase, the Cochrane Collaboration

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and Google Scholar. COVID-19 repositories with lists of grey literature sources (e.g., LitCOVID, COVID-END and WHO-COVID-19) and pre-print servers or repositories for biological and medical sciences (e.g., medRxiv, bioRxiv) were also included.

Search keywords used in this review include: coronavirus, COVID-19, SARS-CoV-2, infection control, source control, dentistry, airborne transmission, fomites, standard precautions, enhanced precautions, dental workplace, screening, hand sanitation, procedural rinse, mouth wash, rubber dam, high volume suction, PPE, surface disinfection, ventilation and Boolean search terms AND/OR. Electronic databases were searched to August 31, 2020.

Standard precautions, policies and legal requirements for ICP Standard ICP measures are designed to prevent or reduce the potential transmission of pathogen or disease from patient to dental health care workers (DHCWs), from DHCWs to patient, and from patient to patient in dental practices. These standard precautions apply to all patient care.

Infectious respiratory airborne disease has now entered the arena and dentists have to modify existing bloodborne ICP measures to reduce the risk of SARS-CoV-2. The Centers for Disease Control (CDC)16 and United States Occupational and Safety Health Administration (OSHA)17 both stipulate that dental practices require enhanced precautions to protect the DHCWs and patients from AGPs. While there are differences in the standard of care for dental infection control globally, most countries follow the same basic policies and procedures, namely that of the CDC,18,19 European Centre for Disease Prevention and Control,20 and Organisation for Safety Asepsis and Prevention.21 Standard precautions22-26 and Government policies guidance regarding ICP of COVID-19 and SARS-CoV-2 in the dental workplace21,27,28 do not fall within the scope of this review.

Enhanced precautions for reducing contaminated aerosols and risk of SARS-CoV-2 transmission Understanding the characteristics of the infection chain pathway is critical in the adoption of appropriate ICP strategies in the dental practice. Breathing, talking, sneezing, coughing and AGPs are all implicated in the transmission of virus-laden droplets and aerosols from the oral cavity.

The infection chain can be blocked at various levels, most importantly at its source by applying appropriate ICP

measures. This reduces the viral load in saliva/oral cavity and the risk of exposure and spreading of infection. (for review of this refer to Part 2) Enhanced ICP measures to limit airborne contagion and transmission of SARS-CoV-2 in the dental practice setting are based on the following 10 pillars derived from the infection control chain pathway.

Pillar 1. Screening and isolation for high-risk patients and DHCWs All patients entering a dental practice or phoning to schedule an appointment should be screened and triaged for signs and symptoms of COVID-19 prior to dental treatment.29 DHCWs should also be subjected to daily screening protocols. Anyone with symptoms of COVID-19 or suspect cases should be properly managed and advised to selfquarantine. Most recommend patient triage by telephone, whilst others recommend temperature screening at reception to screen for COVID-19 cases.15 This should be observed in addition to procedures required by the Occupation Health and Safety Act and workplace safety regulations of the Department of Labour and Employment 27 to limit exposure to potential infectious patients.

However, transmission of SARS-CoV-2 can occur in asymptomatic and pre-symptomatic persons, therefore screening offers no assurance of identifying infected individuals. In addition, testing prior to dental care at this stage in time is not an option due to costs, time constraints and false negative results. Because triage is currently unable to identify infected individuals, the only safe and realistic approach is to consider all patients infectious. 7 Pillar 2. Facial masking Evidence related to other respiratory viruses indicate that facial masking can protect the wearer from becoming infected by blocking viral particles.30 Public health authorities define a significant risk of exposure to COVID-19 as face-to-face contact within 6 feet with an infected patient, sustained for at least 10-30 minutes.31 Therefore it is prudent to accept the principle of universal masking for DHCWs and patients within the dental practice. More compelling is the possibility that wearing a mask may reduce the likelihood of transmission from asymptomatic and minimally symptomatic DHCW’s to other providers or patients.31 Current scientific evidence suggests that masking or face covering as a protective measure alone significantly reduces the number of asymptomatic cases and severity of COVID-19 infections.32,33 This possibility is consistent with the theory that

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the severity of diseases is proportionate to the viral inoculum received.

Universal masking of all healthcare workers has significantly reduced the rate of health-care acquisition of SARS-CoV-2, thereby flattening the health-care associated COVID-19 infection epidemiologic curve. This mitigated the spread from asymptomatically infected or minimally-symptomatic individuals, thus reducing the strain on healthcare systems.35

Pillar 3. Hand sanitation Human to human transmission contributes a major part to this infection pandemic.36 Coronavirus transmission is spread via droplets, aerosols, and contaminated hands/surfaces.37 Transmission can be prevented/reduced by frequent disinfection of hands with water/soap or alcohol-based hand-sanitizer. Ethanol (60-70%) and isopropyl alcohol (7072%) is the optimum strength that is recommended. Frequent use of alcohol based hand sanitizers may wash out the oils from the skin surface resulting in dehydrated skin. Therefore hand washing with soap remains the most effective strategy for reducing this mode of transmission.38 Soap molecules emulsifies the lipid content of the material adhering to the hand, and convects it away.39 Soap molecules dismantles the lipid envelop of SARS-CoV-2, thereby deactivating it.40 Alternatively hypochlorous acid (HOCL) used for hand sanitizers are effective at 100-200 ppm strengths.41 DHCWs should be aware of what they touch, including computer keyboard and mouse, unit instrument tray handles, dental lights, drawers and handles and x-ray tubes. Hand sanitize whenever interacting with these items and apply appropriate disinfection of these surfaces after each patient visit.

Pillar 4. Pre-procedural mouth rinse Recent research recommend the use of pre-procedural mouth rinses to reduce transmission of SARS-CoV-2 in dental practices.15,42-45 It should be emphasized that natural saliva is a viscoelastic liquid and thus, is a mitigating factor in the process of aerosolization.46 Emerging studies increasingly demonstrate the importance of the throat and mouth as sites or reservoirs of virus replication, shedding and transmission in early COVID-19 disease.42,47 DHCWs are in close contact with the upper respiratorydigestive tract and therefore at high risk of exposure to SARSCoV-2 from the patient.48,49 Recent research suggests that the viral load in the oropharynx with SARS-CoV-2 infection is as high in asymptomatic versus symptomatic patients.50

Oral rinsing with hydrogen peroxide (H2O2), povidoneiodine (PVD-I), chlorhexidine and cetylpyridium chloride are known for their ability to disrupt the viral lipid membrane through oxidation. This has the potential to inactivate the virus and reduce transmission of SARS-CoV-2.42,51 The purpose of using a pre-procedural mouth rinse/gargle is to reduce the viral load expectorated or produced during AGPs.45,52 Routine use of a mouth rinse/gargle preoperatively is recommended to render contamination from the oropharyngeal complex less infective as well as from the oral cavity to other internal systems (i.e. lungs).53,54

•Povidone-Iodine PVD-I is a water-soluble iodine complex widely used as a pre-surgical skin antiseptic and as a mouthwash.55 PVD-I has an excellent safety profile and broad spectrum antiviral, antibacterial and antifungal effect.56 PVD-I mouthwash or spray is typically used in a 1% concentration for prophylaxis of oropharyngeal infections and prevention of ventilatorassociated pneumonia.45,51,57 PVD-I has higher virucidal activity than other antiseptic agents, including H2O2,58 CHX and benzalkonium chloride.59 Its effectiveness has been well demonstrated by in vitro studies against multiple viruses, including SARS-CoV, MERSCoV, influenza virus and SARS-CoV-2.58-61 The use of 0.2% PVD-I as gargle /mouth rinse is suggested for reducing the virus load in the oral cavity thus minimizing the risk of SARSCoV-2 transmission.51 According to available literature the most effective method for reducing viral load and reducing the risk of SARS-CoV-2 transmission during AGPs is through pre-procedural rinsing and gargle with PVD-I. (0,2% to 1%)55,58,61-63 Based on the current evidence, preprocedural rinsing with dilutes of PVD-I may be preferred over hydrogen peroxide during CoVID-19 pandemic.58 It is safe and does not produce tooth or tongue discoloration or taste disturbances.64,65 PVD-I is not recommended during pregnancy or for patients with active thyroid diseases, those undergoing radioactive therapy or individuals that are allergic to iodine.

•Hydrogen peroxide Hydrogen peroxide is an odourless, clear and colourless liquid with no adverse effect on soft tissue. Hydrogen peroxide causes disruption of lipid membranes. Since SARSCoV-2 is vulnerable to oxidation, preprocedural mouth rinses containing oxidative agents such as 1% H2O2 have been suggested to reduce the salivary viral load.2,43,66

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Recent studies reported that 0.5% H2O2 inactivated coronavirus and other enveloped viruses.67,68 However, H2O2 has a low substantivity as it is rapidly inactivated in the oral environment.69

•Chlorhexidine (CHX) CHX is a broad-spectrum antiseptic that acts against bacteria, viruses and fungi by increasing the permeability of the cell membrane, causing its lysis.70 Chlorhexidine formulations have been shown to retain oral antimicrobial activity for up to 12 hours.72 A recent meta-analysis showed that chlorhexidine (rinse or gel) can reduce the risk of ventilator associated pneumonia in patients undergoing mechanical ventilation.73 Recent evidence suggest that chlorhexidine, although considered as the gold standard for reducing bacterial load, has decreased effectiveness due to lack of oxidative action, while use of 1% hydrogen peroxide and 0.23-1% Povidone-Iodine (PVD-I) are more effective alternatives.2,8,74 •Cetylpyridium chloride Cetylpyridium chloride (CPC), a quaternary ammonium compound that is safe to use in humans,75, 76 was recently shown to have virucidal activity against influenza virus through direct disruption of the viral envelope.76,77 These findings suggest that 0.05% CPC could be effective against other enveloped viruses such as SARS-CoV-2.45,78 CPC is used in medicated oral rinses at concentrations between 0.025-0.075%.77 Pillar 5: Personal protective equipment (PPE) •Importance and relevance of PPE in clinical dental practice PPE including gloves, masks, respirators, protective outerwear, protective surgical glasses, goggles and face shields are required to provide a physical barrier or shield that could prevent or minimize risk of exposure to infectious pathogens such as SARS-CoV-2. 2,3,8,36,79 PPE is of critical importance for all DHCWs due to working in close proximity with potentially infected patients.80-85 Recommendations about the appropriate use of PPE have been controversial and at times conflicting.79 In the absence of direct evidence from studies in a dental setting, we have to apply the general evidence regarding PPE in health care settings.84 A physical barrier at the checkpoint (mouth, nose and eyes) may reduce the spread of droplet or aerosol mediated viral infection.36,66 The suggested minimal composition of PPE to be used in

healthcare settings to prevent contact, droplet and airborne transmission of SARS-CoV-2 are: (i) respiratory protection (surgical masks, N95/FFP2 or N98/FFP3 respirators), (ii) eye protection (goggles or face shields), (iii) body protection (long sleeve water resistant gown), and (iv) hand protection (gloves).20

• Respiratory protection devices - Surgical mask or filter face-piece (FFP) respirator?

A mask is a core component of PPE to protect DHCWs.31 It has been shown that in dental practice, central areas of the face such as the inner part of the eyes and around the nose and mouth were the most contaminated areas.85 It is therefore recommended to use protective means such as a mask, goggles and protective shield when performing AGPs. The effectiveness of face masks however has generated significant controversy during the COVID-19 pandemic.86-88 Knowledge about specific characteristics of surgical masks and respirators is of utmost importance to select the appropriate type according to the clinical setting and procedure.79 Respiratory protection devices (masks) have been classified into 2 groups depending on the filtering efficiency capacity. (i) Medical or surgical mask (SMs) SMs are indicated for low risk routine clinical procedures where no AGPs are performed or where a rubber dam is used.

SMs are loose fitting source barriers, primarily designed for one way protection of vulnerable patients. Contrary to belief, SMs are not designed to protect the wearer and most SMs do not have a safety rating assigned to them.

An obvious flaw with surgical masks compared to respirators is their lack of tight face fit, which leaves gaps around the edges through which viruses and other infectious pathogens can be inhaled or exhaled.89 SMs are for single use only and must be discarded after every procedure.

With the scarcity of N95 respirators and considering cost implications, dentists may opt to resort to wearing a face shield over surgical mask for additional protection.

SMs contaminated with aerosols/biofluid/moisture not only loses protective characteristics but also provides a suitable environment for microbes to breed.36 Cloth masks are also not indicated for clinical use. (ii) Filter face-piece respirators (FFRs) FFRs are tightfitting to create a facial seal and designed

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to provide ‘inward’ protection by filtering virus-laden aerosolized particles and ‘outward’ protection by trapping virus-laden droplets expelled by an infected person.30 Respirators are primarily designed to protect the wearer up to the safety rating of the respirator. The effectiveness of a respirator is determined by two significant factors, the filtration efficiency and fit.90 FFRs are tight fitting, available as disposable half face or full face design, and designed to filter airborne droplet nuclei (< 5 micron in diameter). The US National Institute for Occupational Safety and Health (NIOSH) classifies FFRs into nine categories N95,(95%) N99 (99%), N100 (100%), P95 (95%), P99 (99%), P100 (100%), R95 (95%), R99 (99%), and R100 (100%).91 The letters N designates ‘not resistant to oil’, R ‘resistant to oil’ and P ‘oil proof’, whereas the numeric characters describe the minimum filtration efficiency. The European Standard (EN149:2001) classifies FFRs into three classes , FFP1 (80%) , FFP2 (94%), FFP3 (99%).92 FFRs are the most appropriate barrier against aerosol because they provide a tight seal to the facial skin.

Their principle function is to protect the wearer from the environment, and therefore indicated when performing high risk AGPs. The current gold standard respiratory protection device for protecting the wearer and the patient in dentistry is a N95 respirator.79 The most recent indications of the WHO about the use of PPE during COVID-19 pandemic, recommend the use of N95 or equivalent FFP2 for AGPs performed on patients with COVID-19.93 The CDC have also updated their guidance for dental settings, emphasizing the use of N95 masks and eyewear during high risk procedures.94

•Risks and limitations of FFRs N95 or FFP2 respirators are not intended to be one-sizefits -all. Filtering performance strongly depends on fitting.

DHCWs should test different devices to find the best fitting model and size for their face (i.e.the presence of a beard can alter the sealing).79 Powered and air supply respirators are reusable devices that can be disinfected and have interchangeable high efficiency particulate filters (HEPA). Concerns about the clinical use of re-usable respirators are difficult communication, and the exposure of personnel in charge of disinfection to an additional biological risk.79 Moreover, respirators are more expensive than medical masks.

Wearing a face shield over a N95 , or use of a local

exhaust ventilation system are likely to reduce respirator surface contamination.95,96 Common mistakes that occur in dental practice is removing the mask with contaminated gloves or by touching possible contaminated surfaces of the mask.89 The correct procedure for removing a N95 mask is to remove contaminated gloves first, hand sanitize, put on a new pair of gloves, and remove the mask by the strings. A mask will not protect providers against SARS-CoV-2 infection if it is not accompanied by meticulous hand hygiene, eye protection, gloves and gown.31 Evidence suggests that surgical masks and N95 respirators offer similar protection against viral respiratory infection, including coronavirus in health care workers during nonAGPs. N95 respirators should only be considered for highrisk AGPs when in short supply.97

•Can masks with exhalation valves or valved respirators be used in dental practice?

The outward protection afforded by masks has emerged as a particularly important issue in the COVID-19 pandemic because SARS-CoV-2 transmission may occur in asymptomatic or early pre-symptomatic infections.98-100 FFRs are available with and without an exhalation valve.

Valved masks only filters air breathed in to protect the wearer from inhaling aerosols containing the virus and reduce excessive dampness and warmth in the mask from exhaled breath.

Valved respirators are designed to make it easier to exhale air and to prevent fogging of goggles and shields. This make them more comfortable to wear and creates less moisture build-up inside the respirator.79 Respirators with exhalation valves protect the wearer from SARS-CoV-2, but may not prevent the virus spreading from wearers (dentists and chairside assistant) to patients. Exhaled air passes unfiltered into the environment defeating one important purpose – protecting the patient.101-103 Respirators with exhalation valves are therefore not recommended for use in dentistry.89 •Practical guidelines on extended use versus reuse of N95 masks Shortages of N95 masks may occur during disease outbreaks. Wearing a N95 respirator for hours at a time (extended use) or re-using a respirator several times are practices used to ease shortages and reduce costs.

Studies support prioritizing extended uses over reuse because of the following104 (i) The reported pathogen transfer

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risk from N95s is high by contact transmission donning and doffing; (ii) The reported pathogen transfer risk from N95s is low by aerosol spread by breathing through a used mask; (iii) Use of surgical masks or a similar disposable cover over N95s during extended use, are unlikely to cause any significant adverse effects on breathing or gas exchange to the user; (iv) Mechanical failures (e.g., broken straps and poor sealing) with only a few re-uses were common across N95s; (v) Commonly used effective disinfection methods (i.e., autoclaves, bleach, H2O2 vapor or ultraviolet light irradiation) can achieve adequate disinfection with some filter performance loss.

•Can I decontaminate and reuse N95 respirators?

In general N95 respirators are designed for single use.

Different methods have been suggested to decontaminate masks from infectious SARS-CoV-2, including Heat (70oC), 70% Ethanol, UV Irradiation (260-285nm) and vaporized H2O2. (VHP) A recent study was done to assess the effectiveness of these methods on the reduction of contamination with infectious SARs-CoV-2 and their effect on respirator function.105 This study found that VHP exhibits the best combination of rapid inactivation of SARS-CoV-2 and preservation of N95 respirator integrity. UV radiation kills the virus more slowly but preserves respirator function. Dry heat kills the virus with similar speed to that of UV and is likely to maintain acceptable fit for 2 rounds of decontamination. Ethanol decontamination is not recommended due to loss of N95 integrity. This study suggests that N95 respirators can be re-used in times of shortages for up to 3x when decontaminated with UV and VHP, and up to 2x with dry heat.105 •Face and eye protection - Goggles/Face shield Mucous membranes of the eyes are also a possible portal of entry.106 Therefore eye protection with face shields, goggles, plastic glasses or visors have become a mandatory part of PPE during the COVID-19 pandemic. Another advantage of a face shield is its protection of masks from splashes.107 Eyes and face masks should be protected with goggles or a full-face shield in all AGPs.89 After AGPs, PPE must be disposed of or disinfected.

Hard plastic glasses were the most effective means of protection against conjunctival contamination during orthopaedic AGPs (83%). Modern prescription glasses provided only 17% protection, and are not recommended as sole eye protection during AGPs.108 Loupes on their own provided only 50% protection, and facemasks and eye

shields 70% protection.

A modification of a visor mask to allow use of loupes and a head light has been described whilst maintaining adequate aerosol/air droplet protection.109 Common mistakes by DHCWs: (i) Using common prescription glasses as protection, (ii) Using only dental loupes or microscopes, (iii) removing protections after each procedure by touching the external shield surface.

Protective safety glasses and face shields should undergo thorough disinfection with 70% isopropyl after each procedure.

•Hand protection - Gloves Gloves are for single use purposes only, and should be discarded after each procedure and patient use.

Sterile gloves should be used for all invasive procedures that require surgical asepsis.

The use of nitrile gloves is preferred over latex gloves because of their resistance to some chemicals, including disinfectants such as chlorine and alcohol.36 An unacceptable practice is using the same pair of gloves for different procedures and/or for different patients and not washing or sanitizing hands before and after using gloves.89 •Body, head and shoe protection Transmission via surfaces like clothing can be prevented by careful behaviour (no touch) or by wearing protective clothing.

When conducting high risk AGP’s or sterile surgical procedures, donning a comprehensive set of PPE (including head cover and surgical gown), will reduce the risk of transmission.20 Head caps and covers and gowns can be disposable or reusable. PPE for body protection must meet the following criteria: sterility if reusable, long sleeves to cover arms and must be water resistant.

Plastic aprons are not recommended as they do not provide full body and arm cover.110 The WHO recommends long-sleeved non-sterile gowns and gloves for both AGPs and non-AGPs to provide protection from contamination of clothes.110 Current guidance on PPE in the context of COVID-19 does not specifically mention shoe covers.111 Covering more of the body leads to better protection. It does increase cost and decreases user comfort.112 •Key concerns and limitations of PPE The available evidence was judged to be low to very low.84

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Common reasons for lack of compliance amongst DHCWs were: (i) policies and practices were inconsistent, (ii) PPE was not available in many facilities and its use was limited to high risk situations, (iii) face masks and gloves were the most commonly used PPE, (iv) reuse of PPE was common, (v) lack of training in proper use and knowledge on when and what PPE to use, and (vi) the high cost implications of complying with appropriate PPE use.113,114

Pillar 6: Use of rubber dam Patients, dentists and assistants as well as surfaces and objects in the operative area are at a risk of exposure to airborne contamination up to 3X greater than the norm.115 Rubber dam provides a barrier protection from the primary source and can virtually eliminate all pathogens emerging from AGPs.15,116 Studies have shown that during conservative dental procedures (15-30 minutes) without use of rubber dam, the airborne bacterial load increased from 8.8 to 25.1 colony forming units (CFUs). Various other studies have also shown that use of rubber dam isolation during AGPs resulted in a 98.8% bacterial reduction.118-22 This reduction increased with use of antiseptic mouth rinse used before rubber dam application.

The use of dental rubber dam to reduce exposure to contaminated aerosols during treatment is very important.123 Several published guidelines recommend the use of rubber dam wherever possible.66 Another device that delivers quick, easy, reliable isolation with uninterrupted retraction and continuous evacuation of fluids and oral debris with a reduction of aerosol is the Isolite (Zyris™)124.

Extra high-volume suction for aerosol and spatter should be used during rubber dam procedures in conjunction with regular suction.125 Pillar 7: High volume suction and suppression of aerosolization •High volume evacuation (suction) (HVS) The use of HVS of the aerosol generating field in the oral cavity is an essential and important method for reducing aerosolrelated transmission of pathogens.15,117 Aerosols and splatter produced when air rotary handpieces, ultrasonic, sonic and air polishing devices are used in dental procedures, contain contaminated saliva, blood bacteria and periodontal pathogens.18,122 Once airborne, aerosol particles can linger in the surgery for an hour or more while droplets land on surfaces immediately surrounding the treatment area. This

poses a risk for the spread of infectious diseases such as COVID-19.126 Studies have shown that HVS can reduce aerosols by 80% to 98% regardless of the source.127,128 There is no single solution that will provide complete protection in the clinical environment. Thus a combination of protective measures, including PPE, pre-procedural rinses, rubber dam, and HVS is suggested to reduce risk of exposure to infectious disease such as COVID-19.

Combining pre-procedural rinse and rubber dam with HVS are more efficient compared to the individual methods.122,129

• Suppression of aerosolization The generation of pathogen contaminated aerosols in dentistry, an unavoidable part of most dental treatments, creates a high-risk situation with the potential for airborne transmission of SARS-CoV-2. The avoidance of all AGPs is one approach advocated during the pandemic, or to reduce procedural times as a means of reducing the total aerosol generated. This is not sustainable and counter-productive in the long-term for routine dentistry.

A new novel approach has been developed to suppress aerosolization in dental procedures by adding high molecular weight polymers to the water supply to alter the physical or visco-elastic response of water to AGPs. The generation of aerosol particles and the distance any aerosol may spread beyond the point of generation can be markedly suppressed or completely eliminated in comparison to water for AGPs.117 Complete suppressions of aerosolization from an air turbine rotary handpiece and an ultrasonic scaler was demonstrated using diluted aqueous solutions of FDAapproved polymer [2wt.% polyacrylic acid (PAA)] (20 gm PAA + 1L H2O) or hydrogel [0.8 wt.% xanthan gum] (8gm xanthan gum + 1L H2O).117 The integrated pressurized fill bottle of a dental chair allows control of the fluid being delivered to rotary or ultrasonic instrumentation. These FDA -approved additives alter the physicochemical properties of the irrigation solution, suppressing droplet formation without altering flow behaviour, thereby reducing the risk of aerosol transmission of infectious diseases.117 Pillar 8: Cleaning and disinfection •Background Contaminated surfaces can become a reservoir of infectious material with the potential to spread to health care personnel and patients.130 Prevention of transmission of infectious contagion from contaminated surfaces (fomites) is best accomplished by reduction of any source of contamination. It is therefore critical to incorporate surface

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Table 1: Comparison of low-level disinfectant products recommended for inactivating SARS-CoV-2 Disinfectant

Sodium hypochlorite (bleach) (NaOCL)

Hypochlorous acid Alcohol (HOCL Ethanol Isopropyl alcohol

Quaternary AmHydrogen peroxide monium compounds H2O2 (QACs)

Recommended concentration

0,05% to 0.1% (500-1000ppm)

80-200ppm

70-90%

0.1%

>0.5% 1.5% - 3%

Contact time

10-30 min

10 min

2-5 minutes

3-10min

1.5% - 10 min 3% - 20min

Compatibility with surface

Corrosion of metal Compatible with metal and plastic surfaces and fabrics Discoloration of plastics & fabrics

Toxicity & Safety

Irritation of skin, eyes and mucous membranes

Safe & Non-toxic to Toxic and irritant to EPA registered skin & eyes skin & eyes Non-irritating

Eye irritant Low EPA toxicity Environmental friendly

Ease of use

Spray and wipe Mist & Fogging

Aerosol spray Fogging

Wipes Sprays

Stability

Decays rapidly when exposed to UV-light. Stable for 30 days in opaque containers.

Prepare fresh solutions every day

Increasing stability Stable with good Stable with with decreasing pH detergent properties good detergent Less stable when properties exposed to sunlight, UV radiation, contact with air and increased temperature

Other advantages/ Odour and leaves Odourless No residue disadvantages residue Corrosiveness to metals

Surface compatible Surface compatible May cause hardening, cracking of rubber and plastics

Wipes Sprays

Wipes Sprays

Not sporicidaI Not Sporicidal Inflammable Narrow spectrum Affected by organic matter

Compatible with most surfaces Benign for environment, silver plating Not compatible with brass, Copper zinc Non-corrosive

Very stable stored in dark container

No odour More expensive

Reference: 130,136

disinfection preventions to reduce the risk of infectious disease transmission.

The two main routes of transmission of SARS-CoV-2 is by airborne or direct contact.131 Respiratory droplets are generated when an infected person talks, coughs or sneezes, while contaminated aerosols are generated during AGPs on infected patients. Droplets and contaminated aerosols may also land on inanimate objects (equipment)

or environmental surfaces (fomites) where the SARS-CoV-2 virus can remain viable for up to 9 days.67 The immediate chairside environment of an infected or potentially infected patient can serve as a source of contact transmission.5,132-135 The ability of SARS-CoV-2 to persist on inanimate environmental surfaces (fomites),67 warrants thorough cleaning and disinfection to assure effective infection control and prevention.67,136,137 Environmental surfaces in the

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dental practice setting can be classified into two groups: (i) Highly-touched clinical contact surfaces including all clinical devices, (ii) house-keeping surfaces including working surfaces, door handles, floor, blinds, sinks, furniture and fixed items inside and outside patient rooms and bathrooms.130 Routine cleaning (i.e. using water and soap) as well as disinfection procedures to inactivate the virus, are appropriate for SARS-CoV-2 in the dental workplace setting. SARSCoV-2 viruses are enveloped by a phospholipid layer that is susceptible to soaps and detergents.138 It is also susceptible to other lipid solvents and can be efficiently inactivated within 1 minute contact time by surface disinfection procedures such as sodium hypochlorite (bleach) (0.1% or 0.5%), hydrogen peroxide (0.5%), alcohol (62-71% ethanol or isopropyl alcohol), benzalkonium chloride (BAC) and peroxyacetic acid.67 (Table 1)

•General principles of cleaning - The cleaning procedures must progress systematically from least soiled to the most soiled area, and conducted from top to bottom with the floor cleaned last.

- Detergent-impregnated wipes may be used but should not be used as a replacement for the physical cleaning process.130,139-141 •General principles of disinfection - Lack of hand hygiene and inadequate disinfection of environmental surface /devices between patients are the most important failures of infection control.25,142 - Bleach works on hard and non-porous surfaces, but requires pre-cleaning with a detergent.

- Most disinfectants used in health care are one-step products that clean and disinfect using the same product.143 - Cleaning of surfaces with common disinfectants such as ethanol and sodium hypochlorite inactivates the coronavirus within 1 minute of exposure.67 - Strength levels of common disinfectants are dependent upon concentration and contact time. Bleach (sodium hypochlorite) at 500ppm (0.05%) and 1000ppm (0.1%) solutions are both able to reduce the SARS virus.144,145 - Surface disinfectants should be sprayed directly onto surface and left on as directed before being wiped systematically and carefully.

- A short contact time (to kill microbes), of approximately 1-2 minutes, is desirable to ensure the disinfectant has killed the microorganisms before the disinfectant dries on the surface.140 - Pump spray bottles are an appropriate method of applying liquid germicides, with the exception of hypochlorite solutions.

An advantage of a pump spray is better penetration of the liquid germicide into crevices in the equipment where wipes may not effectively contact.130,146

•Criteria for selecting a safe and effective disinfectant The use of disinfectant wipes is becoming more widespread in the health care environment because these products are convenient to use, limits indiscriminate application of any chemical agent, decreases human contact and the amount of chemicals introduced into the environment.130 A disinfectant agent upon contact with the virus changes the virus protective coat, which loses is structure and aggregates, forming clumps with other viruses.147,148 Dental practitioners need to have an inexpensive, nontoxic, and practical disinfectant that is effective in disinfecting and sanitizing against viruses, specifically SARS-CoV-2. An ideal surface disinfectant must have low contact time with significant antiviral activity.

Several disinfectants have been recommended against SARS-CoV-2 and 5 major classes of surface disinfectants are identified for the dental practice setting: (Table1) 130,136,149-153 •Precautions and hazards with disinfectants Improper or excessive use of surface disinfectants poses potential health risks to users. Therefore, consistent and evidence-based recommendations are crucial to protect dental health care workers not only from SARS-CoV-2 but also accidental exposures to dangerous chemicals.

- Bleach disinfectants solutions should be prepared fresh each day.

- Avoid using sodium hypochlorite (bleach) on metals or acrylic resins because it has a strong corroding effect.154 - Hydrogen peroxide is explosive with heat.154 - Always wear gloves when cleaning and disinfecting.

- Because occupational diseases, such as asthma, among cleaning personnel have been associated with use of several disinfectants (e.g., chlorine, formaldehyde, glutaraldehyde), precautions should be used to minimize exposure to toxic chemicals(e.g., gloves, PPE, and proper ventilation).155-157 •Aerosolization, spraying and fogging Available studies show that SARS-CoV-2 can be detected in the air inside a room occupied by a confirmed COVID-19 patient for 3 hours after aerosolization.158 Fogging machines that rely on the dispersion of a fine mist of disinfectants in the air have proven their performance in the health care sector and food industry.159,160 Commercial fogging machines are also designed and based on the same

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flow physics of aerosolization, and their droplet size is below 10μ in order to facilitate extended airborne duration.161 It is suggested that using hypochlorous acid (HOCL) fogging daily in the dental practice setting is an inexpensive, non-toxic, easy to use procedure with high predictability and effectiveness against SARS-CoV-2.151 HOCL is a powerful disinfectant produced by a sterilized water generator and has a pH of 5-6.5 and a low effective chlorine concentration of 10-30ppm. Fogging with HOCL can achieve reduction of microbes and is safe for humans and the environment. Five minute fogging with H2O2 was sufficient to achieve inactivation of enveloped as well as non-enveloped viruses.162-165 The fogging process can alter the physical and chemical properties of the disinfectant, resulting in the reduction of available free chlorine concentration.166,167 Pre-adjustment of the concentration (200ppm) and pH (pH3-5) of the fogging solution to appropriate levels can produce reductions of all tested viruses on both vertical and horizontal surfaces, suggesting that it is an effective approach to reduce viruses on surfaces.168,169

•Surface disinfection - Best practice guidelines - Frequent hand washing or sanitizing and avoiding touching the face should be the primary prevention approach to reduce any potential transmission associated with animate surface contamination.170 - Cleaning with a neutral detergent and some form of mechanical action (brushing or scrubbing) helps to remove pathogens and is an essential first step in any disinfection process.171 - Spraying and fogging of bleach, formaldehyde, or quaternary ammonium compounds, is not recommended due to adverse health effects.172,173 Pillar 9: Ventilation, air conditioners, air cleaning, and airborne disinfection •Aerosols, airborne transmission and the significance of ventilation SARS-CoV-2 is transmitted via airborne transmission (aerosols).174,175 To date, the European Centre for Disease Prevention and Control176 as well as the Robert-Koch Institut177 have recognized aerosol transport. After initial denial, the WHO added aerosol transmission to their transmission mode brief.178,179 Given the persistence of SARS-CoV-2 viral loads in both the lower and upper respiratory tracts,180 as well as the persistence of the virus in the air 3 hours after

aerosolization in laboratory settings, airborne transmission is possible.158,181 An airborne virus is not naked but is contained inside expelled respiratory fluid droplets. Droplet desiccation is a fast process.182 Large droplets (>50µm) fall down on surfaces, but small droplets (<50µm) or droplet nuclei (<10µm) stay airborne and can travel long distances.182 Droplet nuclei distribution depends on the position of people, air change rate, the type of air distribution system and other air currents in the space.183 Analysis of superspreading events have shown that closed environments with minimal ventilation strongly contributed to a characteristically high number of secondary infections.184 Airborne transmission has made ventilation measures the most important engineering control in ICP. Mechanical ventilation can significantly increase the expulsion of air, and natural ventilation can be improved by active ventilation, creating a draft through the room.186

•Ventilation, airflow and air cleaning/disinfection One of the most overlooked aspects in air cleaning/ sterilization is controlled airflow aimed at killing harmful bacteria and viruses. Traditional air ventilation (air conditioning) systems are closed ventilation systems that pushes air back into the breathing zone, thus increasing the risk of cross-contamination with viruses trapped in the ventilation system. New air flow and air sterilization technologies have been developed to control air flow and air sterilization in indoor settings including, dental practices, operating theatres, waiting rooms and offices. Current technology is based on the use of HEPA (High efficiency particulate air) filters to scavenge small particles like viruses, combined with UV radiation and nano photocatalytic oxidation that kills respiratory viruses, including coronavirus on a single air exchange. HEPA filters are designed to trap or scavenge virus particles down to 0.3 microns.174,182 Forced airflow (with air filtering (HEPA) and UV light), uses a powerful fan that draws contaminated air away from the breathing zone (dentist–patient interface), removes or inactivates contaminated airborne particles, sterilizes the air and then sends it back into the breathing zone.128,186-189 It is possible that UV-C is safe for skin genotoxicity,190 however its effect to the naked eye that may cause impaired vision is not confirmed.191 Drawing contaminated air away from the dentist and the patient reduces the viral load in aerosols and surfaces by 80%.3,192 Increasing ventilation indoors (open windows) and preventing recirculation of air through closed air ventilation systems can go some way to ensure that infectious aerosols

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are diluted or flushed out of the air.

•Practical ventilation and airflow measures to reduce the risk of airborne transmission of SARS-CoV-2 - Dispersion of aerosols that have not been removed by HVS is primarily achieved by dilution of air changes. Effective heating, ventilation and air conditioning systems (HVAC) ventilation is a major factor in dissipating aerosols.

- HVAC systems may have a complimentary role in decreasing transmission in indoor spaces by increasing the rate of air exchange, decreasing the recirculation of air, and increasing the use of outdoor air.174,182 - HEPA filters must be used not only in clinical settings but also in outlet exhaustion tubes.193 - Open windows more to increase the amount of fresh air per square meter of floor area.

- Direct airflow should be diverted away from the individuals (e.g., the dentist, assistant and patient microenvironment).174,182 - AGPs should not be performed in a room that has no natural or mechanical ventilation.

- If air cleaners are used in larges spaces , they need to be placed close to people. Air cleaners are an easy to apply short term mitigation measure, but in the longer run, ventilation system improvements to achieve adequate outdoor ventilation rates are needed.174,182

Pillar 10: Immune boosting, designer antibodies and vaccines •Immune boosting It is important to boost your personal immunity and selfresistance by taking the following actions: (i) Get adequate sleep – sleep deprivation has an impact on the immune response.194 (ii) Moderate exercise seems to exert a protective effect, whereas bouts of strenuous exercise can result in immune dysfunction.195 (iii) Studies suggest proper supplementation with vitamin D may enhance one’s resistance to SARS-CoV-2.196 Vitamin D supplementation has an overall protective effect against acute respiratory infections.197,198 However, prospective clinical studies are required to address the association between vitamin D and COVID-19 severity.

Conclusion The COVID-19 pandemic is a stark reminder of the ongoing challenge of emerging and re-emerging infectious pathogens and the need for constant updating of standard ICP measures.

It is inevitable that every dentist will see asymptomatic patients or will be exposed to asymptomatic staff. The risk of transmission of SARS-CoV-2 by seemingly healthy individuals may account for 30-62% of potential infection exposure events. The disturbing reality is that we have no idea who among us is spreading the disease.

Even with the availability of vaccines, it remains important to apply a combination of protective measures, including screening for high risk patients, facial masking, hand sanitation, pre-procedural rinses, PPE, rubber dam and suppression of aerosolization. In addition, cleaning and disinfection, ventilation and air cleaning and paying adequate attention to healthy lifestyle and immune support are also important measures to prevent spread of infection.

No infection control measure can be practiced in isolation, nor is any one more important than the other.

DHCWs are obliged to follow the ethical principles of providing the best possible care that is in the patients’ best interest, while maintaining a balance in managing risks to optimally protect the patient and dental staff.

It seems acceptable to adopt the principle of ‘consider all patients as potentially infectious for air droplet /airborne disease and treat every case with equal and uniform precaution measures’ as a realistic, effective and safe approach towards infection prevention and control.

There are more research questions than answers to assist dentists in their infection control and prevention decisionmaking processes.

Educational Institutions should help in providing appropriate continuing professional education programs to develop DHCWs’ basic knowledge on appropriate respiratory virus infection and airborne control and prevention measures.

References References are available on request from: dentsa@iafrica.com

56 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 16, NO. 2

P R O D U C TS GC

ULTRADENT

G CEM ONE

OPALESCENCE FOR ALIGNERS

The ONE that simplifies all cementation procedures G-CEM ONE, the new self-adhesive resin cement from GC simplifies all cementation procedures. G-CEM ONE brings together high bond strength, effortless clean-up and long-lasting aesthetics as well as an excellent self-curing ability for a wide range of indications in ONE product solution.

G-CEM ONE is a truly universal, non-technique sensitive, versatile and reliable product that gives the flexibility of being effective in all cementation procedures for any type of restorations; from metal-based to resin and all-ceramic inlays, onlays, crowns, bridges, and posts.

G-CEM ONE offers a reduced inventory with less components for a reproducible workflow. It’s simply the ONE for peace of mind for all your adhesive requirements.

Opalescence PF Whitening for Aligners provides the benefits of the original Opalescence PF teeth whitening for those patients who want to both whiten and straighten their teeth. The #1 professional teeth whitening brand on the planet, Opalescence’s original formula is sticky and viscous, so it stays in the orthodontic aligner rather than migrating during treatment. This means that both the whitening and orthodontic treatments are more comfortable and effective for your patient. Opalescence PF Whitening for Aligners comes in a convenient, portable 4-syringe case so patients can take their whitening gel with them and whiten at their convenience.

NEW

DENTISAN RANGE

HENRY SCHEIN

DENTICHLOR TABLETS

HELIX TEST KIT

Water bottle disinfectant DentiChlor chlorine tablets provide rapid disinfection for dental chairs and equipment that have water bottles attached and dental impressions, provides effective management of blood spills and makes an effective disinfectant solution for water storage containers.

Key Points: o Easy to use o Rapid action

Class 2 Chemical Indicator Non Porous Load (helix) Helix steam test strips for autoclaves. Latex-free selfadhesive backing for storage on files. Kit includes Holder plus Sheets x 250.

Helix Test kit HS-900-8649 Includes device and 250 test strips

o Measured dose o 200 tablets per pack

Standards: Conforms EN 867-5, ISO 11140 - 1, Class 2.

ULTRADENT

UMBRELLA

The innovative Umbrella tongue, lip, and cheek retractor is a disposable retractor that provides clear access to all areas of the mouth while prioritizing patient comfort. Rather than pulling or

stretching the lips, it gently and naturally helps the patient hold their mouth open thanks to its durable, yet flexible, spring-like design.

The Umbrella cheek retractor prevents triggering the gag reflex for most patients and helps channel saliva for efficient evacuation.

Its innovative tongue guard also allows the tongue to comfortably remain away from the working area. It is easy to place and features anatomically positioned bumpers for you to rest a hand without causing discomfort to the patient. These benefits combine to make the procedure easier and provide a better overall experience for both clinician and patient.

All products available from: HENRY SCHEIN • Tel: 1300 65 88 22 • www.henryschein.com.au

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL.16, NO. 2 57

P R O D U C TS

NEW

DENTISAN RANGE

GC

BIOCLEAR KIT

G-CEM VENEER

Bottle shock treatment Ready-to-use biofilm remover for dental unit waterlines for regular weekly use or as a purge when also using a continuous DUWL maintenance product. Requires no mixing, Bioclear is a weekly treatment for cleaning dental unit waterlines (DUWLs) to prevent build-up of biofilm. Bioclear has proven efficacy removing biofilm, enabling waterlines to maintain water quality of <200 cfu/ml.

Light-curing resin cement for high aesthetic demands with ease of placement

Key Points: o Proven to remove biofilm o Ready to use – no mixing required o pH neutral o Weekly treatment for DUWL cleaning o Can also be used for quarterly purge of units with an in-line water treatment o Includes water test strips to ensure lines are free of bioclear before use

An aesthetic cement with simple application and high mechanical properties. G-CEM Veneer has all the ingredients to ensure the most stunning end result for a confident smile. The secret is in its optimally balanced formula with Full-coverage Silane Coating (FSC) technology. This innovative filler treatment allows a high filler rate to be achieved with homogeneous dispersion of fillers in the matrix. The result: unique handling without the need for pre-heating the composite and excellent physical properties. Combined with G-Multi PRIMER a universal primer, and G-Premio BOND, universal bonding agent, G-CEM Veneer ensures stable and durable adhesion to all types of substrates and preparations. Cementation of veneers, inlays & onlays become truly standardized.

NEW

HENRY SCHEIN

BOWIE & DICK TEST

DENTISAN RANGE

BIOCLEAR DIP SLIDES

Class 2 Chemical Indicator Porous Load

Continually monitor input and output water quality with dental dip slides. These easy-to-use biological dip slides identify microbial contamination of water. Simple, highly visual red spots indicate contamination and highlight where in your practice’s waterlines the contamination is most prominent.

Test set for steam penetration in the autoclave. Colour changes to green to confirm correct function.

Lead free and latex free.

Key Points: o Easy to use o Red spot system o 10 dip slides per pack o Test input and output water quality o Use to assess where contamination is most prominent in the water lines

Bowie & Dick test kit HS-9008646: Includes metal cassette, card and test sheets Standards: Conforms to ISO 11140-1

NEW

Key Points:

DENTISAN RANGE

BIOCLEAR DAILY Bioclear Daily is a disinfectant for continuous use in dental unit water lines (DUWLs). Used daily, it reduces the planktonic bacteria count in water flowing through the unit, minimising the potential for biofilm formation.

o For continuous use in dental unit water line feed bottles o Continuously controls water quality to reduce the potential formation of biofilm o Used at 1% concentration o Prepared solutions can be kept in suitable plastic containers for up to 10 days o Excellent material compatibility o Simple and easy to use

All products available from: HENRY SCHEIN • Tel: 1300 65 88 22 • www.henryschein.com.au

58 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL.16, NO.2