International Dentistry Australasian Edition Vol.18 No.2

VO L. 18 N O. 2 I N T H I S I SS U E Falk Schwendicke Amalgam: Gone for good?

Alessandro Martini ‘Unbleachable’ discolourations: truth versus myth Josette Camilleri Hydraulic cements in endodontics

The clear choice for a beautiful smile

Masterclass in Oral Diseases Andre W van Zyl and Wynand P Dreyer Oral biopsies, an essential part of dental practice Hendrik Zellerhoff Single-visit, all-ceramic anterior tooth restorations in the dental practice Adam Nulty A literature review of current 3D printing materials in dentistry Clarence P. Tam Premolar case with a nano-hybrid, intuitive universal composite Marco Simonetti, Benedetta Gori, Dario Marzocco, Marco Broglio and Giuseppe Teani Post-endodontic hybrid ceramic restoration Katherine Losada A simplified approach to Class IV restorations using the press-mould technique

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Contents Volume 18 No. 2

04 Clinical

4

Amalgam: Gone for good?

Falk Schwendicke

14 Clinical

‘Unbleachable’ discolourations: truth versus myth

Alessandro Martini

20 Clinical

Hydraulic cements in endodontics Josette Camilleri

26 Masterclass in Oral Diseases 14

Oral biopsies, an essential part of dental practice Dr Andre W van Zyl and Prof Wynand P Dreyer

34 Clinical

Single-visit, all-ceramic anterior tooth restorations in the dental practice Hendrik Zellerhoff

40 Clinical

A literature review of current 3D printing materials in dentistry Adam Nulty

50 User Report

20

Premolar case with a nano-hybrid, intuitive universal composite Clarence P. Tam

54 Clinical

Post-endodontic hybrid ceramic restoration Marco Simonetti, Benedetta Gori, Dario Marzocco, Marco Broglio and Giuseppe Teani

60 Clinical

A simplified approach to Class IV restorations using the press-mould technique Katherine Losada

26

64 Products

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 1

Vol. 18 No. 2 ISSN 2071-7962 PUBLISHING EDITOR Ursula Jenkins EDITOR Dr Andre W van Zyl

Henry Schein goes Pink

ASSOCIATE EDITORS Prof Cecilia Goracci Prof Simone Grandini EDITOR-IN-CHIEF EMERITUS Prof Dr Marco Ferrari

Practice Pink is an initiative of Henry Schein Cares, the Company’s global corporate social responsibility program.

Through Practice Pink, Henry Schein, together with nongovernmental organizations and supplier partners across North America and Europe, is helping dental and medical health care professionals raise awareness and support for a cure for breast cancer and other cancers.

“At Henry Schein, we strongly believe in the potential of public-private partnerships to contribute to a healthier world, and the Henry Schein Cares Practice Pink program exemplifies this belief,” said Maureen Knott, Vice President U.S. Supplier Initiatives, Henry Schein and President, Henry Schein Cares Foundation. “Through the combined dedication and generosity of our supplier partners and customers, we will persist in our commitment to advancing cancer research and prevention, all while striving together for a world where cancer is no longer a threat About Henry Schein Cares Henry Schein Cares stands on five pillars: empowering team Schein to reach their potential, advancing health equity and expanding access to care for underserved communities, accelerating environmental sustainability, strengthening, and diversifying our supply chain, and maintaining strong ethical governance. Health care activities supported by Henry Schein Cares focus on four main areas: (1) wellness, treatment, prevention, and education; (2) capacity building; (3) emergency preparedness and disaster response; and (4) health system strengthening.

Rooted in a deep commitment to social responsibility and the philosophy of enlightened self-interest championed by Benjamin Franklin, the purpose-driven vision of Henry Schein Cares is “doing well by doing good.” Our commitment to sustained, long-term economic success while also creating shared value for society is achieved through the work of Henry Schein Cares and our stakeholder model that engages all five constituents of our Mosaic of Success.

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 Martin Vorster Prof Peet van der Vyver Prof Laurence Walsh Prof Fernando Zarone

If you have any questions about Henry Schein Cares and other projects we are involved in, please email scheincares@henryschein.com.au

Published in association with

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

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CLINICAL

Amalgam: Gone for good?

Falk Schwendicke1 Introduction For about a century, dental amalgam has been the standard restorative material for posterior caries lesions. Given the ease of placement, particularly its moisture tolerance, but also its relatively high resistance against masticatory forces and secondary caries, amalgam remains the restorative standard in most statutory or public health insurances until today. Whilst concerns towards its biocompatibility and wider health effects repeatedly entered the public debate, a number of studies were able to refute such assumptions and to showcase the general safety of amalgam, if properly placed.

Notably, the usage of amalgam will likely cease in many countries in the world over the next years – grounded in the so-called Minamata treaty. Emanating from the spoilage of mercury used in an industrial process in the city of Minamata in Japan and a series of widespread health effects due to subsequent mercury uptake, the vast majority of nations worldwide have signed the Minamata treaty, binding the signees to reduce and eventually stop the usage of mercury in any industrial process. In that sense, dentistry is an outlier; only for dentistry, the treaty did not mandate a complete “phaseout” of the material, but a “phase-down”. Signing nations promised to undertake measures to reduce the usage of dental amalgam, for example via the reinforcement of prevention or the development and adoption of alternative restorative strategies.

In many countries in the world, including all countries of the European Union, policy makers have indeed decided to overachieve this promise and phase-out the usage of dental amalgam completely. For some groups, i.e. pregnant or lactating women, this phase-out has already become reality. Within this reality, dentists are now faced with an important question: Which alternative material to use?

Restorative options in the post-amalgam era In the course of the last 60 years, a range of amalgam alternative materials have been introduced.

Broadly, they fall into three categories; 1. Resin-based composite materials, placed in increments to compensate for polymerization shrinkage and to allow safe polymerization, 2. Glass-based materials, i.e. glass ionomers and glass hybrids, 3. Materials combining the properties of both material classes (for the latter, terminology is not consistent and the clinical evidence often limited).

Resin composites, especially, have a long tradition of being used as an alternative to amalgam, in particular for posterior load-bearing restorations extending into the proximal surface. Micro- and nano-hybrid resin composites have shown excellent physical properties, such as high resistance against abrasion and erosion, high flexural 1 Prof. Dr Falk Schwendicke, strength, polishability and aesthetics. Moreover, these materials can be placed Head of the Department of Oral adhesively and therefore do not rely on macroretentive cavity preparation, allowing Diagnostics, Digital Health and Health Services Research Charité in for minimally invasive dentistry. Notably, the placement of resin composites comes with a number of prerequisites like strict moisture control, stepwise preparation and Berlin (Germany).

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

CLINICAL

1a

1b

1c

Fig. 1. A: Multiple cervical non-carious lesions, prior to treatment; B: cervical lesions restored with the glass ionomer EQUIA Forte from GC; C: Glass hybrid restorations at follow-up after 6.5 years (Courtesy of Prof. Matteo Basso, Italy).

conditioning of the cavities, e.g. involving acid-etching and adhesive placement. In recent years the trend towards simplifying these application steps has been one focus of manufacturers, for example by combining the etching and the adhesive steps or by reducing the need for increment placement when using “bulk fill” composites instead.

Nevertheless, the placement of resin composites – especially in equigingival or subgingival situations - is technically demanding. Moreover, the material itself is relatively costly when compared to dental amalgam.

Hence, resin composites can safely be regarded as one of the contemporary amalgam alternatives, but nevertheless does not “check all the boxes”.

Glass ionomers and glass hybrids For several decades, glass ionomers have not been considered a fully fletched amalgam alternative, mainly because of their limited stability against abrasion and erosion and their low flexural strength, which resulted in limited longevity in occlusal-proximal posterior cavities.

More recent generations of this material glass have been developed to specifically address the discussed main weaknesses. A more advanced category of glass-based materials, called glass hybrids, claims to have overcome the most limitations around abrasion and erosion stability, and also to come with significantly improved flexural strength.

This has been achieved by alterations in the chemical composition of the material: mainly the introduction of an additional, smaller and highly reactive glass particle and longer acrylic-acid chains. Moreover, the introduction of an additional coating step for the occlusal or other accessible surfaces, with a nano-resin material being placed onto the rougher glass surface protects the porous glass body against acid and abrasion. This coating has also been found

to significantly improve the aesthetics of this formerly poorly polishable material. When the coat wears off, the glass hybrid undergoes a unique second maturation, substantially increasing the restoration’s hardness.1 In the range of laboratory studies, it was confirmed that indeed the glass hybrids come with significantly superior properties compared with their predecessors, while retaining the advantages of this material class, namely the option to place it in bulk, the ease of placement and its high bioactivity (especially the known release of fluoride). Notably, laboratory studies are not necessarily perfect surrogates for clinical behaviour. Only clinical studies can demonstrate the true effects of any material alterations and the potential suitability of a restorative material as an amalgam alternative.

Glass hybrids: Clinical data as hard currency As with most scientific advances, the development of the glass hybrids was not a revolution but an evolution. A number of studies – some of them even practice-based – investigated the direct predecessors of glass hybrids and confirmed the advances of this material class over the last one and a half decade, refuting the notion of glass-based materials being merely a temporary material 2-4. The current generation of glass hybrids has been assessed in several studies that are presented in more detail in the subsequent paragraphs. Reassuringly, these studies were not all related to manufacturers and were conducted by a range of groups from all over the world. Moreover, they dealt with different clinical indications and employed robust clinical designs, such as randomized control trials, to compare the glass hybrid material against an accepted standard of care like a resin composite. Two main application fields have been explored, i.e. cervical and posterior, loadbearing lesions.

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 5

SCHWENDICKE

2a

2b

2c

Fig. 2 A: Class I restoration on tooth 47 with marginal discoloration and recurrent caries, prior to treatment; 2B: Class I glass hybrid restoration with EQUIA Forte, right after placement; 2C: Glass hybrid restoration at follow-up, 3 years after placement (Courtesy of Prof.

Matteo Basso, Italy).

3a

3b

3c

Fig. 3A: Class II restoration on tooth 26 with secondary caries; 3B: Class II glass hybrid restoration with EQUIA Forte on tooth 26, right after treatment; 3C: Class II glass hybrid restoration, 5 years after treatment (Courtesy of Prof. Matteo Basso, Italy).

Cervical lesions (Fig. 1) The cervical placement of glass ionomers, especially resin-modified glass ionomers, has a long tradition and is backed by a wealth of clinical studies demonstrating the usefulness of this material for this purpose. Resin-modified glass ionomers have consistently outperformed alternative materials when it comes to survival and success of cervical restorations 5. For glass hybrids, two randomized trials were identified comparing this material against resin composites.

The first study 6 included a small sample of 25 patients with non-carious cervical lesions and bruxism, i.e., a very specific group. In these (overall rather young) patients, a total of 148 lesions were randomly restored (indicating a massive clustering of the lesions per patient) with either a glass hybrid (Equia Forte, GC, Tokyo, Japan) or a resin composite (Ceram.X One Universal, Dentsply, Konstanz, Germany).

After 6, 12 and 24 months follow-up, the restorations were re-evaluated using the modified USPHS criteria. When assessing the 126 remaining restorations (in 22 patients) at the 24-months recall, it was apparent that both materials performed similar. Only for marginal adaptation, a significant

difference was found, with glass hybrids showing slightly reduced adaptation. Secondary caries was not observed on any of the restorations.

Another study 7, with a follow-up of 36 months, assessed the survival, quality and costs of glass hybrid (Equia Forte) and resin composite restorations (Filtek Supreme XTE, 3M, St. Paul, USA) for managing cervical lesions; more specifically, sclerotic non-carious cervical lesions. In 88 patients (50–70 years) with 175 lesions, restorations were directly placed without any mechanical preparation (which eventually resulted in high annual failure rates for both groups, see below). Restoration quality was assessed at 1-, 18- and 36 months using FDI-criteria. Costs were evaluated using a so-called micro-costing approach (accounting for the time used for placing the material) and, during follow-up, fee items of the statutory insurance in Germany. Of the 88 patients, 43 received glass hybrids (83 restorations) and 45 resin composites (92 restorations); cluster randomization had been applied. At 36 months, 17 glass hybrids and 19 resin composites showed total retention loss, 5 glass hybrids were partially lost (no significant difference between materials).

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

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4a

4b

Fig. 4A: Class I cavity prior to treatment; B: Glass hybrid EQUIA Forte HT (GC) restoration (Courtesy of Dr. Zeynep Bilge Kütük, Turkey).

FDI ratings were not significantly different for any domain except surface lustre (here, composites were superior to glass hybrids – while it should be noticed that the latest generation of glass hybrids addressed such aesthetic effects specifically) (Fig. 4). Costs were significantly lower for glass hybrids, both initially (glass hybrids: 32.57; SD 16.36 € versus resin composites: 44.25; SD 21.40 €) and over the full observational period (glass hybrids: 41.72; SD 25.08 €, resin composites: 51.60; 26.17 €).

In summary, both studies – randomized trials of a robust design – indicate the suitability of glass hybrids for restoring cervical lesions. Moreover, they demonstrate that the material is not only showing similar survival, but also flag the advantageous cost-effectiveness of this material. Notably, and as mentioned above, the fact that glass ionomer materials work well in this indication is not necessarily new. However, aspects around the economic differences between composites and glass hybrids for managing cervical lesions have not been assessed in detail before.

The fact that regardless of the used restorative material, a preparation of sclerotic surfaces is likely beneficial, should also be highlighted.

Occlusal-proximal lesions (Figs. 2 and 3) In contrast to cervical lesions, glass ionomers were not considered to restore posterior, load-bearing and proximally extended cavities in the past. As mentioned, their limited flexural strength and abrasion/erosion resistance have often compromised the success and survival of glass ionomer restorations for this indication. On the contrary, with the glass hybrid materials, a number of clinical studies have

now refuted that notion. Two recent randomized trials are particularly noteworthy: In the first trial 8, a glass hybrid (Equia Forte), a bulk-fill composite resin (Filtek Bulk Fill Posterior Restorative, 3M) and a micro-hybrid composite resin placed incrementally (Charisma Smart, Heraeus Kulzer, Hanau, Germany) were compared. 109 teeth in 54 rather young patients (31 female, 23 male, mean age 22 years) with two-surfaced (mesialocclusal, occlusal-distal) cavities in permanent teeth were randomly restored. The restorations did not extend towards cusps and all cervical margins were placed in sound enamel (i.e. not subgingivally). After caries removal and minimal invasive preparation, the materials were placed. After up to 24 months, 84 restorations were re-evaluated using the modified USPHS criteria. Composite restorations showed better anatomic form, contact point, colour match, surface texture and overall survival compared to the glass hybrid restorations.

In contrast, another, multinational randomized controlled split-mouth trial 9, 10 in four university hospital centres in Zagreb (Croatia), Belgrade (Serbia), Milan (Italy) and Izmir (Turkey) compared a glass hybrid (Equia Forte) against a nano-hybrid composite (TetricEvoCeram, IvoclarVivadent, Schaan, Liechtenstein) for a similar indication. The study included occlusal-proximal two-surfaced restorations in the molar region in adults with a permanent dentition; each individual needed to have two similar cavities in vital (positive response to ethyl chloride) molars of the same jaw to allow for the split-mouth design. A total of 360 restorations (in 180 patients) were placed. Per patient, one tooth was randomly selected to be restored with glass hybrid and the other was

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

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Table 1: Costs and survival of glass hybrids and composites in different countries (mean, SD)

Parameter

Croatia

Italy

Serbia

Turkey

Age (years)

26.5 (7.4)

44.6 (15.8)

31.7 (11.4)

30.6 (11.2)

Gender (female/male)

44/16

16/16

16/12

40/20

Glass hybrids costs (USD)

92.7 (7.4)

146.1 (12.9)

44.0 (3.3)

66.2 (11.9)

Composites costs (USD)

126.42 (16.3)

146.2 (19.3)

61.0 (3.5)

128.6 (3.8)

Glass hybrids survival (months)

35.1 (3.4)

35.3 (2.3)

34.1 (6.2)

35.0 (3.0)

Composites survival (months)

34.3 (5.1)

35.0 (4.0)

34.9 (4.6)

35.8 (1.0)

restored with composite material. Pre-contoured sectional matrices (Palodent Plus, Dentsply) were employed and cavities conditioned according to manufacturer’s instructions prior to placing the material. For the composite, a two-step self-etch adhesive (AdheSE, IvoclarVivadent) was employed.

Patients were followed up after one week, 1 year, 2 years and 3 years and restorations assessed using FDI-2 criteria.10 Additionally, the costs of each restoration from the patient’s perspective were calculated in US Dollar (USD), accounting for direct medical costs. To assess cost-effectiveness, incremental-cost-effectiveness ratios were used, expressing the cost difference per gained or lost effectiveness.

In that trial, patients in Italy were older than in the other centres, and overall, more patients were female than male.

32 patients dropped out over the 3-years period, and 21 received re-treatments (on 27 restorations). The mean survival time of the restorations was high across all centres and did not differ significantly between the two materials (Table 1). In three of the four countries, composite was more expensive both initially (e.g. for its placement) and on the long term (over the 3 years follow-up and accounting for managing complications, too). When assessing the costeffectiveness (USD and survival in months), composite was usually more costly than glass hybrids in three of the four counties, and overall, composite was more expensive at limited clinical benefit (costing additional 268.5 USD per additional month without complications).

The emerging body of evidence displays that the glass hybrids are also promising for posterior, proximally extended cavities. While there are some inconsistencies around the comparative longevity of glass hybrids versus composites for this purpose between the two described studies, especially the large multinational trial is assuring: In four independent

centres, concordant results were generated, confirming that both composites and glass hybrids are suitable materials over the 3-year observational period for load-bearing cavities.

Notably, the cost-effectiveness of glass hybrids was once more confirmed, deeming it a particular amalgam alternative when cost considerations are important, for example in lowand middle-income countries but also in most statutory or social insurance settings in high-income areas. Using an extrapolation model,11 it was further demonstrated that this cost-effectiveness was likely to be retained on the long term; a recent study found the added effectiveness of composites minimal (tooth retention for a mean (SD) 54.4 (1.7) years) but also more costly (694 (54) Euro) than glass hybrids. In sensitivity analyses, and under certain assumptions, glass hybrids were even more effective and still less costly than composite.

Glass ionomers as essential medicines Given the advantages of glass ionomers and glass hybrids and the recent advancements, a WHO expert committee, in 2021, declared that “glass ionomer cement has cariespreventive properties due to continued capture and release of fluoride ions, which remineralise carious tooth structures, and have a bacteriostatic effect. Glass ionomer cement results in lower rates of recurring caries compared to composite or amalgam restorations, and also reduces the incidence of new cavities on other teeth. The simplicity of application makes glass ionomer cement suitable for primary health care and field settings, including for “people with special needs”.12 As a result, glass ionomers were, as one of few dental materials, defined as “essential medicines”,13 i.e. materials needed for a basic healthcare system. Essential medicines are usually the most efficacious, safe and cost-effective materials for

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 9

SCHWENDICKE

a certain condition (in this case dental caries).

In 2019, glass hybrids were recognized by the FDI as a class of restorative materials for permanent teeth, suitable for single-surface restorations and Class II restorations. 14, 15

Conclusions The era of dental amalgam is slowly coming to an end – and it can be expected that in the future, the usage of amalgam will fully cease in most healthcare systems. There is not a single material fulfilling all requirements towards an amalgam replacement; instead, a range of materials with different properties are available and dentists will need to make informed choices which material fits which indication best. Glass ionomers and glass hybrids are among the potential amalgam replacements, and have shown a considerable evolution over the last two decades.

Evidence supports the usage of glass hybrids for both cervical and posterior load-bearing restorations. The costeffectiveness and applicability of these materials is likely superior to that of other materials, while improvements in further material characteristics (specifically flexural strength) would be welcome to establish this material as truly universal amalgam replacement material. For most healthcare systems worldwide, though, glass ionomers and glass hybrids are already “essential medicines” according to WHO. References 1. Shimada Y, Hokii Y, Yamamoto K, et al. Evaluation of hardness increase of GIC restorative surface in saliva. Clin Oral Invest (2015) 19:1701–1754.

2. Gurgan S, Kutuk ZB, Ergin E, Oztas SS, Cakir FY. Clinical performance of a glass ionomer restorative system: a 6-year evaluation. Clin Oral Investig. 2017;21(7):2335-43.

3. Klinke T, Daboul A, Turek A, Frankenberger R, Hickel R, Biffar R. Clinical performance during 48 months of two current glass ionomer restorative systems with coatings: a randomized clinical trial in the field. Trials. 2016;17(1):239.

4. Friedl K, Hiller KA, Friedl KH. Clinical performance of a new glass ionomer based restoration system: a retrospective cohort study. Dent Mater. 2011;27(10):1031-7.

5. Schwendicke F, Gostemeyer G, Blunck U, Paris S, Hsu LY, Tu YK. Directly Placed Restorative Materials: Review and

Network Meta-analysis. J Dent Res. 2016;95(6):613-22.

6. Koc Vural U, Meral E, Ergin E, Gurgan S. Twenty-four-month clinical performance of a glass hybrid restorative in non-carious cervical lesions of patients with bruxism: a split-mouth, randomized clinical trial. Clin Oral Investig. 2020;24(3):1229-1238.

7. Schwendicke F, Müller A, Seifert T, Jeggle-Engbert LM, Paris S, Göstemeyer G. Glass hybrid versus composite for non-carious cervical lesions: Survival, restoration quality and costs in randomized controlled trial after 3 years. J Dent. 2021; 110:103689.

8. Balkaya H, Arslan S. A Two-year Clinical Comparison of Three Different Restorative Materials in Class II Cavities. Oper Dent. 2020;45(1):e32-e42.

9. Schwendicke F, Rossi JG, Krois J, Basso M, Peric T, Turkun LS, et al. Cost-effectiveness of glass hybrid versus composite in a multi-country randomized trial. J Dent. 2021;107:103614.

10. Miletić I, Baraba A, Basso M, Pulcini MG, Marković D, Perić T, et al. Clinical Performance of a Glass-Hybrid System Compared with a Resin Composite in the Posterior Region: Results of a 2-year Multicenter Study. J Adhes Dent.

2020;22(3):235-47.

11. Schwendicke F, Basso M, Markovic D, Turkun LS, Miletić I. Long-term cost- effectiveness of glass hybrid versus composite in permanent molars. J Dent. 2021;112:103751.

12. Expert Committee on Selection and Use of Essential Medicines. Glass ionomer cement – dental caries https://cdn. who. int/media/docs/default-source/essential-medicines/2021e m l - ex p e r t - c o m m i t t e e / ex p e r t - r ev i e w s / a 16 _ g i c _ r ev 1. pdf?sfvrsn=660f8835_82021 (Accessed Sept 16, 2022).

13. WHO. Expert Committee on Selection and Use of Essential Medicines https:// HYPERLINK http://www/ www. who.int/groups/expert-committee-on-selection-and-use-ofessential-medicines (Accessed Sept 16, 2022) 14. FDI World Dental Federation. 2019; Carious Lesions and First Restorative Treatment. https:// HYPERLINK http:// www. fdiworlddental.org/ www.fdiworlddental. org/ cariouslesions-and-first-restorative- treatment. (Accessed Sept 14, 2022).

15. FDI World Dental Federation. Carious lesions and first restorative treatment: Adopted by the General Assembly: September 2019, San Francisco, United States of America. Int Dent J. 2020; 70: 5–6.

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CLINICAL

‘Unbleachable’ discolourations: truth versus myth Alessandro Martini1

Treating tetracycline stains is one of the biggest challenges for a dentist who deals with aesthetics.

The main side effect of taking antibiotics during pregnancy is a deposition in the dentine of a developing tooth as calcification of a fluorescent pigment. At the time of the eruption, the dentine of these teeth shows a brown to grey discolouration, and, consequently, aesthetic discomfort of the patients suffering from it.

Looking to the past, the traditional approach was based on ‘subtractive’ techniques aimed at covering the most severe discolourations after removing the overlying enamel.

However, we should think conservatively for many reasons, but mainly as, although veneers are a simple and efficient solution, satisfactory results are only achieved with adequate thickness, meaning too prominent veneers, or preparations deep in dentine.

So, the question is… do we really need to touch sound enamel?

Case report In 2020, a patient came to the practice asking to improve the appearance of the severe tetracycline-induced dyschromia she suffered from.

I first took a picture using a Vita shade guide (Figure 1). According to Jordan and Boksman’s (1984) classification, prognosis of bleaching was poor. However, I chose this procedure as the safest, cheapest and less invasive one.

In addition, if the bleaching did not show significant success, it would still be preparatory to a rehabilitation with indirect restorations in order to have a lighter substrate.

Alessandro Martini Private Practice, Studio Dentistico Martini, Verona, Italy

1

Figure 1: Severe tetracycline-related discolouration

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

CLINICAL

Figure 2: Polarised picture of discoloured teeth

Figure 3: Model trimming for the fabrication of bleaching trays

Figure 4: Discoloured teeth before bleaching

Figure 5: One month of bleaching of discoloured teeth

Figure 6: Two months’ bleaching. discolouration during bleaching

Antibiotics-induced

I find that taking a polarised photo can be of great help from a diagnostic point of view to better frame the issue (Figure 2).

First of all, alginate impressions were taken. Models were

Figure 7: Four months’ bleaching

created using a surgical blade to deepen the sulcus, to better follow the contour of the gingiva and avoid contact of the material with soft tissues.

A 1mm soft tray material was used to fabricate a custom-

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MARTINI

Figure 8: Five months’ bleaching

Figure 9: Seven months and two weeks (after two months of lockdown) with 10% carbamide peroxide. Whitening teeth suffering from severe dyschromia

Figure 10: Dark teeth after bleaching for eight months (of which two weeks with 16% carbamide peroxide, White Dental Beauty)

Figure 11: Final result

fit tray without placing any reservoir (Figure 3). The tray has to cover almost 3mm of keratinised tissue. The particular consistency of this bleaching gel and a perfect customtray fit allow to avoid dilution of the material in the cervical area by saliva or bleaching gel leakage that could cause hypersensitivity.

The patient was instructed to put a drop of bleaching gel the size of half a rice grain for each tooth in the tray.

In this case, a 10% carbamide peroxide gel (White Dental Beauty) was chosen to be applied overnight, six days a week for five months.

A monthly appointment was arranged and a 3ml syringe of bleach delivered to the patient.

Figure 4 shows the initial situation and Figures 5 to 10 show the situation after each month of bleaching.

Figure 11 highlights the final result after eight months and

two weeks (and oral hygiene).

To boost the bleaching effect, 16% carbamide peroxide gel was applied for the last 30 days (Figure 12).

Reflection An evident aesthetic improvement was achieved without preparing teeth for veneers.

Could we have done better? Absolutely. Yet, when treating patients, the aim is to satisfy them completely, which means in this case we reached our goal.

Figure 13 shows the details from the polarised picture after finishing treatment.

Conclusions No sensitivity has been reported by the patient. As demonstrated by the before and after polarised photographs

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

MARTINI

Figure 12: Final result after whitening teeth with severe dyschromia

Figure 13: Polarised picture of bleached teeth

14: Before and after bleaching severely discoloured teeth

(Figure 14), a deep bleaching effect has been achieved with a very small amount of low concentration product placed in contact with enamel surfaces for a long time.

White Dental Beauty whitening gels are powered by Novon technology.

Novon is a whitening compound that contains hydrogen peroxide, urea and sodium tripolyphosphate and produces a pH jump into the alkaline pH range upon application, reducing the risk of sensitivity.

Be careful when you choose your bleaching system: the lower the pH of the product, the higher the sensitivity.

In addition, patient selection is very important – be sure to choose the right patient for treatment. A nine-month treatment needs a high level of compliance.

In the case presented in this article, a mild relapse of the tooth shade at nine months was observed compared with the immediate post-bleaching result.

I find it helpful to tell your patient that nothing is forever in dentistry (except extraction, obviously).

References 1. Jordan RE, Boksman L. Conservative vital bleaching treatment of discoloured dentition. Compend Contin Educ Dent. 1984;5(10):803-807.

2. Haywood VB, Leonard RH, Dickinson GL. Efficacy of six months of nightguard vital bleaching of tetracyclinestained teeth. J Esthet Dent. 1997;9(1):13-19.

3. Management of tetracycline discolored teeth. PR Newsome, H Linda – Aes Dent Today, 2008.

4. Vano M, Derchi G, Barone A, Genovesi A, Covani U. Tooth bleaching with hydrogen peroxide and nanohydroxyapatite: a 9-month follow-up randomized clinical trial. Int J Dent Hyg. 2015; 13(4):301-307.

5. Manauta J, Salat A. Layers, An atlas of composite resin stratification. Chapter 4 and 5, Quintessence Books, 2012.

This article first appeared in Clinical Dentistry and has been reprinted with permission.

Martini A (2023) ‘Unbleachable’ discolourations: truth versus myth. Clinical Dentistry 3(4): 33-35

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

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CLINICAL

Hydraulic cements in endodontics Josette Camilleri 1

Endodontic procedures are divided into pulp therapy, non-surgical root canal treatment and surgical treatment. The materials that are most indicated for the following procedures are hydraulic cements. They are: •Vital pulp therapy •Regenerative endodontics •Root canal obturation using the gutta percha point and root canal sealer •The management of immature apices, either by apical plugs or apical surgery •Perforation repair.

The aim of this article is to provide an overview of the properties and uses of hydraulic cements in endodontics.

Hydraulic cements The main features of hydraulic cements are the need of water to set and also environmental moisture to allow the materials to develop their properties.

This has clinical implications because, when performing endodontic procedures, the environment changes with the use other materials and irrigating solutions. There is also the presence of blood and tissue fluids that effect the material properties.

A classification for these materials has been proposed based on the material chemistry (Camilleri, 2020), helping clinicians to understand the differences in the types of material, as this has clinical implications.

Furthermore, the classification also subdivides the materials according to use, which is coronal, intraradicular and extraradicular.

Josette Camilleri, Professor of Endodontics and Applied Materials, Honorary Specialty Dentist, University of Birmingham, UK. Visiting Professor, KU Leuven, Belgium and University of Oslo, Norway 1

Material composition and presentation Most of the hydraulic cements are composed of a powder and liquid.

The powder comprises a cement and radiopacifier and may contain additives, depending on the material clinical use.

The liquid is water, which may also contain additives to enhance the material properties.

Some materials use non-aqueous vehicles, and these can be delivered in syringes, facilitating delivery. There are three types of presentations, namely: 1. Powder and liquid (Figure 1a) 2. Automix syringes (Figure 1b) 3. Single syringe/container systems, which can be of different consistencies (Figure 1c).

The automix syringes use resins as vehicles and as such cannot be classified as hydraulic cements as the primary reaction is the resin reaction.

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

CLINICAL

1a

1d

1c

Figure 1A: Powder and liquid systems – such as Proroot MTA and Biodentine.

Figure 1B: Automix syringes – such as MTA Fillapex.

Figure 1C: Single syringe/container systems of different consistencies – such as the Totalfill BC that have a range of sealer, paste and putty.

Hydraulic cements can have different chemistries. The tricalcium and dicalcium silicate chemistry is the one that is most investigated in dentistry. The materials used for endodontic procedures have a tricalcium silicate chemistry.

This means, when mixed with water (as in the powder/liquid) or absorbs moisture from the environment in the single syringe system, it will hydrate and form calcium silicate hydrate and calcium hydroxide (Camilleri et al, 2005; Camilleri, 2007; Camilleri, 2008).

Clinicians need to be careful to ensure that the materials they choose for the procedures have the tricalcium silicate chemistry.

Materials containing bismuth oxide should not be used for any endodontic procedure. This is due to the reactivity of bismuth oxide with endodontic irrigation solutions (Camilleri et al, 2020), particularly sodium hypochlorite (Camilleri et al, 2020; Camilleri, 2014) and also in contact with collagen in the tooth structure (Marciano et al, 2014).

Clinical use Intracoronal use The application of hydraulic calcium silicate cements intracoronally includes their use for vital pulp therapy and regenerative endodontic procedures.

The use of hydraulic cement for vital pulp therapy requires a specific clinical protocol (Al Ali and Camilleri, 2022).

•Dentine cleansing with sodium hypochlorite and ethylene diamine tetracetic acid (Hadis et al, 2020) •Management of the dental pulp, if necessary. Use of sodium hypochlorite reduces bacterial load •Placement of a fast setting, bismuth oxide free hydraulic calcium silicate cement. If Biodentine is used, five drops of liquid need to be placed with the powder in the capsule and mixed in Septodont mixer for 30s (Domingos Pires et al, 2021) •Selective etching with a five-second etch of the hydraulic calcium silicate pulp preservation material and a total etch of the dentine and enamel (Meraji and Camilleri, 2017; Camilleri, 2013). The enamel etch can be undertaken prior to the placement of the hydraulic cement to avoid the washing out of the material •Application of a dentine bonding agent or use of a resin-modified glass ionomer over hydraulic cement and placement of a composite resin restoration.

If the restoration cannot be undertaken on the first visit the tooth can be restored fully with Biodentine (Hashem et al, 2014). It is not recommended to use a zinc oxide eugenol or a glass ionomer temporary restorative material over the Biodentine, as it interferes with the material setting (Camilleri, 2011).

For regenerative endodontic procedures, the clinical guidance from the European Society of Endodontology is

2a

2c

2b

2d

Figures 2A, 2B, 2C and 2D: Vital pulp therapy in molar showing the total removal of caries and previous restoration, placement of Biodentine and restoration with composite resin on the same visit.

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 21

CAMILLERI

3a

3b

3c

3d

Figures 3A, 3B, 3C and 3D: Management of UR1 with a flared apical terminus. After root canal preparation and working length determination, the master cone is placed to length and radiograph taken to check the fit. The spaces not filled with gutta percha were filled with sealer taking extra care not to extrude the sealer past the root apex.

recommended (Galler et al, 2016).

The hydraulic cements are used as barriers and the same principles as those outlined for vital pulp therapy are recommended.

Intraradicular use The intraradicular use of the hydraulic cements is for root canal obturation, where they are recommended to be used in single cone obturation technique.

In addition, they are recommended as an apical plug for management of immature apices.

The material features for such procedures are: •Adequate flow •Radiopacity •Antimicrobial characteristics.

The presentation of root canal sealers varies from powderliquid to single syringe devices.

Heat carriers used for warm vertical compaction techniques cause desiccation of hydraulic sealers that are in powder to liquid format (Camilleri, 2015) with the single syringe ones being more resistant to heat (Hadis and Camilleri, 2020).

The clinical procedure and tooth preparation are similar for both procedures. The following steps are recommended: •Root canal debridement with copious irrigation with sodium hypochlorite •Use of ethylene diamine tetracetic acid to remove smear layer. This is specifically important when using single syringe sealers, as the removal of smear layer allows the dentine fluid to re-enter the root canal, enabling the sealer to hydrate. Unless the sealer hydrates, the antimicrobial

properties are compromised (Zancan et al, 2021) •Final irrigation with sterile water. This is done to avoid leaving chemicals that may interfere with the hydration in situ. Since the hydraulic cements are susceptible to environmental changes, the obturation and choice of sealers needs to be matched with the irrigation protocol (Fernandes Zancan et al, 2021) •For single cone obturation, a cone fit radiograph is taken to check how the cone adapts to the space in the root canal. The sealer is placed at mid-root level. Since the hydraulic cements are water-based, there is a tendency for overfill, which should be avoided. A typical single cone obturation clinical case is shown in Figures 3a to 3d •For apical plugs in management of immature permanent teeth, the hydraulic cement is packed with a long shank plugger without pressure. Biodentine has adequate handling properties so it can be placed at the canal orifice and the pushed downwards with the pre-measured long shank pluggers. MTA is more difficult to place and necessitates the use of a carrier to place the material.

A plug of approximately 4-5mm should be placed. The rest of the root canal can be obturated with syringable thermoplasticised gutta percha. A clinical case is shown in Figures 4a to 4d.

Extraradicular use Although hydraulic cements were developed for blocking the communication between the root canal and the periodontal ligament space in reparative procedures, such as root-end surgery and perforation repair, there is no research on an

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

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4a

4b

4c

4d

Figures 4A, 4B, 4C and 4D: Dens invaginatus in UR2 leading to immature apex, which was managed by an apical plug of Biodentine. Recall after one and two years is shown after the postoperative radiograph.

optimised clinical protocol.

A collection of a few failed cases indicates that the hydraulic cements used for such procedures tend to be very sensitive to the environment and may not set or be washed out with time, leading to case failure (Camilleri and Aznar Portoles, 2020).

Conclusions Hydraulic cements are unique materials used in endodontic practice. As they are susceptible to the environmental moisture, an appropriate clinical protocol is necessary to optimise the material properties and avoid case failure.

Not all hydraulic cements have the same chemistry, therefore the interactions may differ (Camilleri et al, 2022).

References

AAE (2021) Position Statement on Vital Pulp Therapy. J Endod 47(9): 1340-4 Al-Ali M, Camilleri J (2022) The scientific management of deep carious lesions in vital teeth using contemporary materials. A narrative review. Front Dent Med Sec Dental Materials 3: 1048137 Camilleri J (2007) Hydration mechanisms of mineral trioxide aggregate. Int Endod J 40(6): 462-70 Camilleri J (2008) Characterization of hydration products of mineral trioxide aggregate. Int Endod J 41(5): 408-17 Camilleri J (2011) Scanning electron microscopic evaluation of the material interface of adjacent layers of dental materials. Dent Mater 27(9): 870-8 Camilleri J (2013) Investigation of Biodentine as dentine replacement material. J Dent 41(7): 600-10 Camilleri J (2014) Color stability of white mineral trioxide aggregate in contact with hypochlorite solution. J Endod 40(3): 436-40 Camilleri J (2015) Sealers and warm gutta-percha obturation techniques. J Endod (1): 72-8 Camilleri J (2020) Classification of hydraulic cements used in dentistry. Front Dent Med Sec Dental Materials 1: 9 Camilleri J, Atmeh A, Li X, Meschi N (2022) Present status and future directions: Hydraulic materials for endodontic use. Int Endod J 55 Suppl 3: 710-77 Camilleri J, Aznar Portoles C (2020) Clinical perspective of hydraulic

materials developed for root-end surgery. Special edition: endodontics in the era of hydraulic cements. ENDO 14(3): 205-216 Camilleri J, Borg J, Damidot D, Salvadori E, Pilecki P, Zaslansky P, Darvell BW (2020) Colour and chemical stability of bismuth oxide in dental materials with solutions used in routine clinical practice. PLoS One 15(11): 0240634 Camilleri J, Montesin FE, Brady K, Sweeney R, Curtis RV, Ford TR (2005) The constitution of mineral trioxide aggregate. Dent Mater 21(4): 297-303 Domingos Pires M, Cordeiro J, Vasconcelos I, Alves M, Quaresma SA, Ginjeira A, Camilleri J (2021) Effect of different manipulations on the physical, chemical and microstructural characteristics of Biodentine. Dent Mater 37(7): e399-e406 Fernandes Zancan R, Hadis M, Burgess D, Zhang ZJ, Di Maio A, Tomson P, Hungaro Duarte MA, Camilleri J (2021) A matched irrigation and obturation strategy for root canal therapy. Sci Rep 11(1): 4666 Galler KM, Krastl G, Simon S, Van Gorp G, Meschi N, Vahedi B, Lambrechts P (2016) European Society of Endodontology position statement: Revitalization procedures. Int Endod J 49(8): 717-23 Hadis M, Camilleri J (2020) Characterization of heat resistant hydraulic sealer for warm vertical obturation. Dent Mater 36(9): 1183-1189 Hadis M, Wang J, Zhang ZJ, Di MA, Camilleri J (2020) Interaction of hydraulic calcium silicate and glass ionomer cements with dentine. Materialia 9: 100515 Hashem DF, Foxton R, Manoharan A, Watson TF, Banerjee A (2014) The physical characteristics of resin composite-calcium silicate interface as part of a layered/laminate adhesive restoration. Dent Mater 30(3): 343-9 Marciano MA, Costa RM, Camilleri J, Mondelli RF, Guimarães BM, Duarte MA (2014) Assessment of color stability of white mineral trioxide aggregate angelus and bismuth oxide in contact with tooth structure. J Endod 40(8): 123540 Meraji N, Camilleri J (2017) Bonding over Dentin Replacement Materials. J Endod 43(8): 1343-9 Ricucci D, Siqueira JF Jr, Li Y, Tay FR (2019) Vital pulp therapy: histopathology and histobacteriology-based guidelines to treat teeth with deep caries and pulp exposure. J Dent 86: 41-52 Zancan RF, Di Maio A, Tomson PL, Duarte MAH, Camilleri J (2021) The presence of smear layer affects the antimicrobial action of root canal sealers.

Int Endod J 54(8): 1369-1382

This article first appeared in Clinical Dentistry and has been reprinted with permission. Camilleri J (2023) Hydraulic cements in endodontics. Clinical Dentistry 3(6): 63-66

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

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Masterclass in Oral Diseases Oral Biopsies

with Dr Andre W van Zyl1 Prof Wynand P Dreyer2

Oral biopsies, an essential part of dental practice

Scan to see video Andre W. van Zyl MChD (Oral Medicine & Periodontics) Private Practice, Hermanus, South Africa

1

Wynand P. Dreyer Professor Emeritus, Oral Medicine and Periodontics, Stellenbosch University Specialist in Oral Medicine and Periodontics BDS (Wits), HDD (Wits), PhD (Stellenbosch), FCD(SA)OMP

2

Introduction A definitive diagnosis for oral diseases/ lesions usually requires a tissue biopsy supported by a histological report from an oral pathologist. This is the gold standard for diagnosing oral diseases/ lesions, however, a diagnosis may be possible based on clinical appearance and a detailed history. In general, a biopsy should be avoided if there is no clear referral plan for a definitive diagnosis and relevant treatment after the removal of the tissue. It is unacceptable to put a patient through a surgical procedure that may have a high-cost impact (when pathology fees are added) and then have no outcome to the process.

This does not imply that, as a clinician, you are required to treat the disease. It just means there must be a prior identified process whereby the patient will be treated for the diagnosed disease/lesion. This may require that the patient needs to travel long distances, and frequently, should the diagnosis be oral cancer. The expertise required to treat an oral disease/lesion, should be identified beforehand and a relationship must be established with a competent referral clinician.

Although cancer treatment centres are found in most larger towns/ cities, the surgeons required to perform the final excision biopsy may not be available outside larger metropoles.

In order to understand the histological report and to choose the most appropriate area for biopsy, one must have a thorough knowledge of the histological differences of oral mucosae and the distribution of the different types within the oral cavity. Most biopsies in the oral cavity that are intended to obtain a diagnosis of oral mucosal disease, requires a biopsy with a surgical depth of not more than 3-4mm. This is within the scope of practice of all dentists and all that is needed is to recognise abnormal from normal when examining the oral mucosa.

This Masterclass will have the following learning objectives: • examination of the oral cavity • know the different types of oral mucosae • learn biopsy techniques • understanding suturing materials and techniques for wound closure.

A video is presented to illustrate the surgical biopsy and suturing techniques (scan QR code).

Examination of the oral cavity The oral cavity is anteriorly bounded by the lips, posteriorly by the faucial pillars whilst the hard palate is the superior boundary and anterior two thirds of the tongue and floor of mouth inferior boundary.

The oral cavity can be examined by direct vision and palpation and are both actions that are important to detect lesions, lumps, and changes in colour. The clinician must ensure the full extent of the oral cavity is examined, in detail, by vision and palpation. This should be done using the dental light or other source of good illumination.

To examine the oral cavity properly, one must pull the tongue forward and sideways by holding the tip of tongue with gauze (Figure 1).

Using a dental mirror while at same time asking patient to relax the tongue, the tongue can be moved away from teeth to inspect the posterior floor of the mouth (Figure 2).

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

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Figure 1: Tongue pulled out with a gauze swab to give a good grip and the lateral aspect inspected all the way to the foliate papillae at the back (arrow)

Figure 2: Tongue moved away from teeth for visual inspection of posterior floor of mouth.

Oral cancer found in these two areas are often diagnosed late since it is not regularly examined properly as described above. The buccal and lip mucosa are easy to examine, and the complete surface should be inspected and palpated. The tongue can be depressed with the dental mirror to inspect the faucial arches and oro-pharynx as far back as the tonsillar folds- especially if the patient is asked to say “Aah”.

Different types of oral mucosae The mucous membrane lining the inside of the oral cavity is called the Oral Mucosa and consists of 3 layers, namely, the oral epithelium, lamina propria and oral submucosa. In certain areas the submucosa may be absent and the lamina propria attached directly to underlying muscle or bone.

The oral submucosa contains minor salivary glands which are quite numerous, especially in lip mucosa, and can be problematic when taking a biopsy in the latter site.1 The oral cavity has three different mucosal surfaces, namely: •Oral (lining) mucosa, consisting of non-keratinized stratified squamous epithelium. This is found on the movable surfaces inside of lips, cheeks, floor of mouth and ventral surface of tongue. The vermillion or “lip-red” links the labial mucosa with skin at the lips.

•Masticatory mucosa is made up of gingiva and the soft tissue of the hard palate, consisting of keratinized or parakeratinized stratified squamous epithelium tightly bound to underlying bone.

•Specialized mucosa (keratinized or non-keratinized) is found on the dorsal and upper lateral surfaces of the tongue. This is modified for taste and sensory perception and the dorsal surface of tongue is covered in papillae (hairlike filiform and slightly more rounded fungiform papillae) and taste buds. The fungiform papillae may appear as red dots if their surfaces are not keratinized.

The posterior border of the oral cavity is formed by the circumvallate papillae on the dorsal surface of tongue.1 Oral mucosal epithelium has a high turnover rate and is replaced every 2-3 weeks, with the buccal mucosa

Figure 3: Basic biopsy kit includes Plastic suction with small tip, needle holder, a fine tipped tissue forceps, suture scissors and scalpel handle.

being the fastest at 2 weeks and hard palate the slowest at 24 days.1 This may explain why white/red lesions may sometimes disappear within weeks if the cause is removed, such as a sharp tooth edge. It also explains the fast healing of oral wounds.

Due to the nature of masticatory mucosa being attached to underlying bone, it is often not possible to close a biopsy wound in attached gingiva/hard palate.

Biopsy techniques A biopsy sample of the oral mucosa must be fixed in formalin, as soon as possible, and forwarded to an oral pathologist for a histological evaluation. As a clinician you will almost always ask for the histology to be stained with H&E (haematoxylin and eosin). It is important for clinicians to realise that oral mucosal lesions may be due to a local disease but may also be a manifestation of skin diseases or systemic conditions. This is why it is almost always indicated to take a biopsy of any lesion that does not disappear 2-3 weeks after removing an obvious irritating factor such as a sharp tooth/denture.

The techniques that oral clinicians must master are surgical and punch biopsies. Both are invasive procedures which will lead to bleeding and may need to be closed with sutures.

Most oral biopsies are however surgical biopsies that sample a larger area than punch biopsies and will include a normal adjacent tissue field with the abnormal lesion.

Surgical biopsy (see video for procedure) Surgical biopsy remains the gold standard for analysis of oral mucosal pathology, and especially for oral cancer.2 To perform a biopsy, a small surgical instrument set is required (Figure 3), consisting of a fine-toothed tissue forceps (so as not to damage the tissue), a scalpel handle for 15 or 15C scalpel blades, suction with a small 2-3mm tip which can be plastic or metal, needle forceps for suturing and suture scissors (which can also be used for removing pedunculated lesions or extending an incision).

Surgical biopsies can be excisional where the whole

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4a

4b

Figure 4a: Pedunculated lesion which can be easily excised using scissors or scalpel.

Figure 4b: Lesion excised and closed with 6/0 sutures.

lesion is removed, if small enough, or incisional where a sample of a large lesion is taken.

Incisional biopsy Incisional biopsies should ideally include part of the abnormal lesion and cross the border of the lesion to include some normal tissue as well.

Incisional biopsies are indicated when: •The lesion is too large to remove by complete excision.

•A diagnosis is required before a decision is made on the most appropriate treatment, especially if the patient has no symptoms or is not convinced anything is wrong.

•A malignancy is suspected.

Excisional biopsy Excisional biopsies (Figure 4a, b) are therapeutic by removing the abnormality and for diagnostic purposes.

Each clinician will have to know their limitations in removing a lesion completely. Novices may want to remove lesions not exceeding 5mm in diameter whereas experienced specialists may remove lesions exceeding 10mm in size or even larger.

As surgical biopsies are invasive, the clinician must plan the closure of the wound before removing the sample/ lesion. The buccal mucosa may be much easier to close than the floor of mouth and the lip may require careful planning as the aesthetic demands or risks for creating a surgically

induced defect are high.

Once the size of the incision and the outline is planned, a scalpel blade is used to “draw” the outline by piercing just through the epithelium. This will leave a shallow bleeding line showing the biopsy outline before removing the lesion (Figure 5a-c).

If satisfied with the biopsy size, the incision can be taken 3-4mm deep in a wedge format that will allow easy closure of the wound. The biopsy tissue to be removed can be stabilised by holding it with a fine tissue forceps or by looping a suture through the sample to be removed (This is demonstrated in the video).

If the clinician suspects a malignancy, an excision biopsy should never be attempted, as this will leave no remaining lesion for the surgeon to plan the excisional treatment.

Should a clinician be confident that the lesion is malignant, the patient may be directly referred to the surgeon who will perform the biopsy and excision surgery.

When a vascular lesion is to be biopsied, care should be taken as excessive bleeding may result. Excision in such cases would be better as the lesion can be removed without perforation into the vascular part of the lesion (Figures 6a, b).

Punch biopsy A punch biopsy is performed with a circular blade on a thin pencil-like handle (Figures 7a, b). The is used in a circular motion to punch through the mucosa into the lamina propria as deep as is deemed necessary.

5a

5b

Figure 5a: White lesion on lip that needs to be excised.

Figure 5b: Biopsy area outlined before Figure 5c: Lesion closed with minimum distortion cutting deeper to remove the specimen. using a 6/0 suture.

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

5c

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6a

6b

Figure 6a: Vascular lesion that needed to be removed on vermillion part of lip. This type of lesion should be approached with caution to prevent excessive bleeding.

7a

Figure 6b: Vascular lesion excised widely to prevent excessive bleeding and closed with 6/0 suture.

Figure 7a: Biopsy punch with a 4mm diameter which can take a core up to 10mm deep.

10a

Figure 8: Specimen marked with an orientation suture to indicate anterior aspect and placed on blotting paper to prevent distortion in the formalin.

Figure 9: Labelled specimen Figure 10a: Biopsy wound bottle with formalin obtained lateral aspect of tongue. from a pathology laboratory.

A punch biopsy is a very simple procedure and is literally a “Point, push and twist” (see video). It may need a single suture to close if there is profuse bleeding. It is also suitable for multiple biopsies of a large lesion, which may be more representative of the disease than a single surgical biopsy.

This is of course much easier than performing a surgical biopsy but has its limitations, namely: •It harvests a small sample and may not render enough tissue for the pathologist if it is a complex disease or histology. It may be enough for oral cancer though, if taken from the tumour itself and is deep enough.

•Not suitable if the tissue is very soft and mobile.

•Not of value for a pedunculated lesion •Leaves an open wound in firm tissue that may heal slower and with a scar due to healing by secondary intention.

Removing and placing sample in biopsy bottle Once the specimen tissue is removed, it should be placed on a small piece of blotting paper (use any rigid paper if no blotting paper is available) with the bleeding surface on the paper (Figure 8). This will stabilise the specimen and prevent it from rolling up, making it easier for the pathology lab to orientate the specimen correctly. Leave the specimen on the

7b

Figure 7b: Speak to your local pathology lab about supplying a biopsy punch.

10b

Figure 10b: Wound closed with a continuous suture with one knot either side of incision. This will be less irritating than individual sutures with multiple knots and is also easier to remove if needed.

paper while closing the wound to enable attachment to the paper, before placing it in the formalin, still on the paper. If the specimen needs to be marked with a suture to orientate the pathologist as to which part is anterior/superior, the assistant can hold a gauze on the biopsy wound if it bleeds profusely while the clinician marks the specimen with the suture before placing it on the paper (Figure 8).

Specimen bottles can be obtained from a pathology laboratory or ask your local pharmacist (figure 9).

If multiple specimens are taken, one specimen should be placed per bottle and each clearly marked with the following information: •Patient’s full name •Site of biopsy (i.e., left lateral tongue) •Clinician’s name The biopsy sample should be accompanied with a histology request form which can be obtained from the pathology lab you will send it to. This form will contain the full detail of patient, medical insurance details and what should be done with the sample (in all oral biopsies transported in formalin the request will be for “H&E histology”). In addition, you should supply the following information on the request form:

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•Clinical appearance of lesions •Duration of lesion and /or symptoms •Relevant medical history and risk factors- and here of great importance is tobacco use (cigarettes per day for how many years?) and alcohol - how many units per week.

•Clinical differential diagnosis if you have any ideas (i.e. for any ulcer it may be “traumatic ulcer, oral cancer”).

Sutures and suturing techniques Most biopsies are done in soft mobile tissue which will make the removal of sutures difficult after 7-14 days, since tissue may be swollen and sutures not visible.

It is advisable therefore to use absorbable sutures in case the patient may not be able to return for removal or sutures are too difficult to remove. Absorbable sutures may vary greatly in the time it takes to be absorbed. Chromic gut sutures are fast absorbing and are good alternatives to braided sutures that may take too long to absorb and may cause suture granulomas to form after a few weeks. Rapid absorbing braided sutures are a good alternative and have good knot security but are more expensive.

As suture knots will be irritating to the patient, it is worth utilizing a continuous suture to reduce the number of knots to one on either side of incision. This is demonstrated in the

video and can be seen in Figures 10a, b on the tongue, where knots may be an extra irritation to the patient.

As a rule of thumb, a 4/0 size suture on a reverse cutting needle of 19mm will work for most situations. On the lip vermillion it is better to use a small needle of 11-13mm and 6/0 suture (Figures 5c and 6b). This will be less visible and leave a smaller scar than a 4/0 suture.

Conclusion Oral diseases are an important part of dental practice and especially so if referral specialists are not close at hand. The more you involve yourself with oral diseases, the easier it will become to identify abnormalities, perform biopsies, and formulate differential diagnoses. To perform a biopsy is less invasive than removing a tooth and is within the scope of all dentists.

References 1. Brizuela M, Winters R. Histology, Oral Mucosa. StatPearls.

Treasure Island (FL)2023.

2. Yang G, Wei L, Thong BKS, Fu Y, Cheong IH, Kozlakidis Z, et al. A Systematic Review of Oral Biopsies, Sample Types, and Detection Techniques Applied in Relation to Oral Cancer Detection. BioTech (Basel). 2022;11(1).

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 31

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Single-visit, all-ceramic anterior tooth restorations in the dental practice Hendrik Zellerhoff 1

Hendrik Zellerhoff, Private Practice, Laer, Germany.

ISCD-certified International Cerec trainer. Member DDA Berlin and DGCZ board 1

The patient’s desire for “fast” and aesthetic restorations is increasing in everyday practice. Many patients are well informed and aware of the possibilities of digital dentistry or chairside treatment. There are various materials for the production of a single-visit restoration (short process time). The new, fully crystallized CAD/CAM block made of lithium disilicate, Initial LiSi Block has recently been added to our options.

The ceramic has optimal physical and aesthetic properties without the need for an additional crystallization firing. In this article, the potential of the material is shown by means of an anterior tooth restoration.

The production of indirect restorations in the dental practice has established itself for single elements. Here, the digital workflow offers clear advantages over the conventional method. Often, the preferred option is a single-visit restoration when possible because of the resulting time savings for the patient. The potential is high.

Nevertheless, the choice of materials plays an important role. In order to meet the requirements for a single-visit treatment (short procedure time) without having to expect the patient to spend long times in the practice, materials that only need to be polished and not additionally crystallized are advantageous. A crystallization fire in the dental practice takes time. In addition, inaccuracies in peripheral areas could influence the quality of the results.

In case crystallization firing is to be avoided, the choice of materials has so far been limited to hybrid ceramics and glass-ceramics. Alternatives were high-performance composites, so-called hybrid ceramics. New in this environment is now the first fully crystallized lithium disilicate ceramic Initial LiSi Block (GC). This CAD/CAM ceramic block is based on the proven HDM technology (High Density Micronization). The ultrafine crystals simplify the milling of the ceramic, so that Initial LiSi Block is milled in the fully crystallized stage. The crystallization firing step is eliminated and time is saved. But not only the time advantage speaks for this material. Due to the fact that no crystallization firing is necessary, restorations made of Initial LiSi Block impress with their very good fit and edge stability. Even fine-tapered edges remain precisely fitting.

Thanks to its high accuracy of fit and aesthetic results, Initial LiSi Block is the ideal, timesaving solution for single-visit restorations. Even in the anterior tooth area, all-ceramic restorations can be made as a harmonious counterpart to the neighboring tooth.

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

CLINICAL

Fig. 1 Tooth 21 is to be supplied with an all-ceramic crown – single-visit.

Fig. 2 Material of choice: the fully crystallized lithium disilicate CAD/CAM block ‘Initial LiSi Block’ (GC).

3a

3b Fig. 3a and b Pretreatment of tooth 21 and core build-up (GRADIA CORE, GC)

Patient case Initial situation and choice of material

The patient consulted the dental practice with an endodontically pre-treated tooth 21. The tooth built up with composite showed strong discoloration and partially carious lesions. The patient wanted an aesthetic restoration of the tooth and emphasized that this had to be implemented as quickly as possible – in just one appointment. This request, frequently asked by patients, can be granted in case of single tooth restorations using CAD/CAM chairside technology. It was decided to make a single-visit restoration.

When choosing a material, the focus is on the time-effective workflow. Nevertheless, the aesthetic demands should be met as well. The aesthetic challenge in this case was the manifold color variance of the neighboring teeth (Fig. 1).

Imitating such a tooth shade – especially in the anterior tooth area – requires a material that absorbs the light-optical

properties of natural teeth. The choice fell on Initial LiSi Block (Fig. 2). This ceramic has remarkable aesthetic properties and convinces – in addition to the time-saving production – with natural opalescence and a harmonious shade effect.

Making the crown in the dental practice Under local anesthesia, the conservative measures were carried out on tooth 21. The old composite fillings were removed, carious areas eliminated and the tooth was built up (Fig. 3). After the follow-up preparation, the situation could be digitized using an intraoral scanner and the data were imported into the CAD software. The construction of the fully anatomical crown 21 was based on the automatic design proposal (Fig. 4). In the software, fine adaptations of shape, surface and texture as well as the control of the functional conditions were carried out. Then the crown was milled from Initial LiSi Block. The ceramic can be milled quickly.

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 35

ZELLERHOFF

Fig. 4 CAD construction of the crown in the software based on an automatic design proposal.

Within a short time, the crown was ready. And while with a conventional lithium disilicate the final material properties are achieved by the additional crystallization firing, Initial LiSi Block is already industrially completely crystallized. Hence, an additional crystallization fire is omitted.

The preparation of the crown and build-up were followed by a try-in inside the patient’s mouth (Fig. 5). The fit was excellent. It turns out that the milling of Initial LiSi Block creates very smooth and precisely fitting edges. Edge areas could be thinned out to the maximum due to the material properties. The surfaces of the crown were homogeneous.

This resulted in a shorter post-processing time. In addition, the smooth surface reduces wear on the antagonist in the occlusal contact area.

Finalizing the crown and seating Thanks to the aesthetic properties of the ceramic, natural opalescence was already present; high gloss could be achieved in a few minutes by simple polishing. In the present case, the anterior crown also needed to match the neighboring teeth. The three-dimensional paintable ceramics Initial Lustre Pastes (GC) were used for individualisation. With a few different colors, the crown was optically adapted to the

neighboring teeth, fired and completed within a short time.

After etching (20 seconds with 5-9% HF) and conditioning (GC Multi PRIMER) the crown’s inner surfaces as well as preparing the tooth surface, the adhesive cementation (GC G-CEM ONE, translucent shade) took place. The result reflected the potential of Initial LiSi Block. The ceramic crown looked alive and natural from within. The color-varying structure of the neighboring teeth was imitated well. It showed a natural surface structure. Within one appointment, the patient was provided with an all-ceramic crown that was more than satisfactory in its aesthetics (Fig. 6).

Result For single-visit restorations, the choice of material is crucial.

High-strength silicate ceramics as CAD/CAM blocks have proven their worth. However, with conventional lithium disilicate ceramics, an additional crystallization firing is necessary to achieve the final physical properties. GC Initial LiSi Block is industrially fully crystallized. A crystallization firing in the dental practice is therefore not necessary. Despite the fact that the material already has its final hardness (408 MPa, biaxially), it can be easily and quickly milled due to the fine crystals in the material’s structure (HDM technology).

At the same time, the aesthetic properties impress with their remarkable opalescence. In many cases, polishing is enough to finish a crown. The high gloss is achieved within a few seconds. The production time in this case is about 30 minutes.

In challenging cases (e.g. anterior crowns), additional characterization (painting or micro-layering) is possible. This takes only a few minutes. Initial LiSi Block is ideally suited for

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

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Fig. 5 Try-in of the crown directly after milling (crystallization firing was not required)

single-visit high-strength ceramic restorations. For the dental practice, this means a great added value: time savings, cost-effectiveness, patient satisfaction as well as an efficient workflow and reduced use of materials.

Reprinted with permission from GC get connected

Fig. 6 Single-visit treatment: crown made of GC Initial LiSi Block.

The difficult color structure of the neighboring teeth could be optimally reproduced. The before and after pictures show the potential: Within a very short time and in just one appointment, the patient could be taken care of.

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

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A literature review of current 3D printing materials in dentistry Adam Nulty1

Introduction The current generation of 3D printers are lighter, cheaper, and smaller, making them more accessible to the chairside digital dentist than ever before. 3D printers in general in the industrial and chairside setting can work with various types of materials including ceramics, polymers as well as metals.

Evidence presented in many studies show that an ideal material used for dental restorations is characterised by several properties related to durability, cost-effectiveness, and high performance (Rayyan et al, 2015). The range of materials used for provisional dental restorations should be non-toxic, biocompatible, inert, reasonably inexpensive, and aesthetic with change in colour or appearance after fabrication and complete resin polymerisation through curing (Balkenhol et al, 2009).

Furthermore, the material for dental restoration should be easy to manipulate, dimensionally stable under all conditions through sufficient strength and resilience, and easy to polish and repair. The material also needs to be chemically stable in the oral cavity by being insensitive to water sorption and dehydration; hence lead to a lack of expansion, shrinkage, or cracking (Vaidyanathan, Vaidyanathan and Arghavani, 2016).

Current materials There is currently a wide range of materials used in the dental sector of 3D printing.

These are summarised in Table 1, with a more in-depth description below of the most widely used materials specifically used in dentistry.

Professor Adam Nulty BCHD MJDF RCS ENG PGCERT MSC He is president of the International Digital Dental Academy.

1

Current long-term 3D printed ceramics and current restorative resins Considering the requirements for a non-toxic, biocompatible, and inert material, the range of materials available for use in 3D printed dental restorations are limited. On the other hand, the fabrication process of CAM milling manufacture requires high temperatures to convert ceramic materials into restorations suitable for placement in the mouth.

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

CLINICAL

Figure 1: A variety of dental resin materials

Figure 2: Surgical guides are an example of the use of biocompatible resins used in dentistry

Ceramic 3D object is currently extremely limited in dentistry as it is manufactured by binding fine ceramic powder to a binder where a traditional process of ceramic restorations such as lithium dislocate is ground from ceramic blocks in chairside setting (Elizabeth, 2014).

Ceramic materials have several ideal properties for use in long term dental restorations such as lead-free, non-toxic and watertight; however, ceramic is a complex material to design a 3D object as it requires a number of considerations in design due to the different structural changes the object may undergo during the finishing process.

The current 3D printers developed for dental applications are limited in their use of metals and ceramic materials to produce provisional dental restorations and are variable in the effect of print direction and accuracy (Brenes et al, 2020).

Most of the 3D printing materials used in dental restorations are polymers. Unlike the ceramics and metals, the chemical and physical properties of polymers are characterised by elasticity and tensile strength, which potentially provide highperformance and durability features required for use as a dental restorative material (Vaidyanathan, Vaidyanathan and Arghavani, 2016).

In orthodontic practice, 3D printing technologies have produced a wide array of prosthetics for dental restorations using polymer materials such as denture bases, artificial teeth, temporary crowns, bridge and crown facings, and implants (Oberoi et al, 2018; Stewart and Bagby, 2018).

Studies have reported the use of polymers in 3D printing technologies for dental applications, including implant fixture construction and intervention, maxillofacial reconstruction (Fernandes et al, 2016), metal bridges (Gebhardt et al, 2010). Other studies have reported the application of 3D printing in manufacturing dental prosthetics used in dentistry as orthodontic appliances (Al Mortadi et al, 2015) as well as the fitting surfaces and the frameworks of removable partial dentures (Carter et al, 2016).

The majority of polymers used as dental restorative materials such as resins are prepared using the methods of addition polymerisation, and in particular SLA and DLP technologies.

In dentistry, most dental resins are based on methacryrates due to relatively easy processing, costs, and aesthetics.

Denture base materials are often supplied in either gel or powder-liquid form (Vaidyanathan, Vaidyanathan and Arghavani, 2016). The powder consists of acrylic or copolymer heads, an initiator like benzoyl peroxide, pigments (mercuric sulphide, cadmium sulphide, or dyes), and opacifiers where one the most effective being titanium dioxide. They also contain dyed synthetic fibres to stimulate the blood vessels underlying the oral mucosa, plasticisers, and inorganic particles such as glass fibres and beads or zirconium silicate (Abdulmohsen et al, 2016). Conversely, the liquid is composed of a monomer particularly methyl methacrylate, an accelerator, inhibitor, plasticiser, and a cross-linking agent.

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Table 1: A list of materials used with 3D printing in dentistry grouped by manufacturing technology Printing technology

Materials available

Polyjet printing

Photopolymers

Multi-jet printing

Plastics, ceramics and metals

Fused deposition modelling (FDM)

ABS, polypropylene, polycarbonates, polyesters

Selective laser sintering (SLS)

Plastics, ceramics and metals

Selective laser melting (SLM)

Metals

SLA / DLP

Photopolymers, plastics and ceramics

For the gel form of denture base materials, it basically contains all the components of particle-liquid form but lacks chemical accelerators. The dental materials in gel form are commonly stored in the refrigerators since the material’s shelf life is significantly affected by the amount of inhibitor present and its storage temperature (Hayden, 2015).

The current dental restorative materials applied in dentistry encompass photosensitive resins, as a polymer or particlereinforced composite. Biocompatible polymers are widely used in dentistry for general restorative procedures and the most common 3D printers available to use chair side accommodate similar polymer-based 3D printing resins.

3D printed indirect dental restorations may involve either particle-reinforced composites, which are similar to the direct restorative composites, or fibre-reinforced composites (Hayden, 2015). The particle-reinforced composites are typically produced in the dental laboratories to improve the materials physical and mechanical properties such as density, elasticity, and strength using polymerisation process through heat and pressure.

For the fibre-reinforced fibreglass composites, they are produced using the same technology of making fibreglass sports equipment where fibre mesh is embedded in polymers (Peñate et al, 2015).

Dental resin-based composites are structures comprising a highly cross-linked matrix reinforced by a dispersion of glass ceramics and resin filter particles and/or short fibres (Vaidyanathan, Vaidyanathan, and Arghavani, 2016; Hayden, 2015). Many of these resin-based composites are now highly aesthetic with excellent translucency; hence, becoming the most popular of the aesthetic or tooth-coloured filling materials for use in dental clinics (Nayar, Bhuminathan and Bhat, 2015).

The resin materials can also be made in various consistencies by altering the glass particle size and consistency as well as the filler content, which allows easily manipulation and moulding to a tooth shape that is long lasting and durable once polymerised and full cured (Anusavice et al, 2013).

Polymeric resins are increasingly being used in dentistry for dental restorations, replacing tooth structure and missing tooth. One advantage of these polymeric resins is their ability to bond with other resins, directly to the tooth structure or to other restorative materials such as amalgam. For example, a denture base with attached denture could be used to restore chewing ability when all teeth are missing. Most of these restorative and prosthetic applications are based on photopolymerisable methacrylate resins (Balkenhol et al, 2009; Peñate et al, 2015).

Several manufacturers are working on 3D printed resin versions of these same polymers for use in orthodontic clear aligners, denture bases, artificial teeth, surgical guides etc. As one of the largest vendors of 3D printing materials, Stratasys has been reported to have developed various types of dental 3D printing materials such as wax deposition modelling (WDM) and polyjet materials (Hayden, 2015).

The WDM are used to manufacture extremely accurate diagnostic wax-ups, paired with a removable wax-blend materials, referred as Truesupport, which can be removed at relatively low temperatures. It has been reported that Stratasys 3D printers using WDM produce the most accurate wax-ups in the dental industry.

Additionally, other 3D printing benefits of WDM include the ability to directly produce from digital files, no waste disposal issues, high-quality casting with minimal postprocessing procedures, and TSCA-registered for safety.

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

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Metals A material commonly used in dentistry is metal which is popular for the use in strengthening restorations or incorporation into frameworks. This has led to these materials to be researched and developed for additive manufacture, mainly via selective laser sintering (SLS). Due to favourable levels of strength, cobalt-chromium and titanium metals have seen the most developments (Khaing, Fuh and Lu, 2001).

PEEK and nylon A 3D printing material of recent development for use in dentistry has been the polyether materials such as polyether ether ketone (PEEK) and nylons for use in frameworks, to strengthen other materials and in 3D printed flexible dentures. These materials have a higher melting point and as such require a fused deposition modelling (FDM) printer with a high temperature, high precision nozzle tip (Dizon et al, 2018).

Like most 3D printing applications, the benefits of using 3D printed metals, peeks and nylons are many, including faster processing, less wasteful additive rather than subtractive manufacture as well as less manual labour and labour intensive processes.

However, there are limitations to the fabrication of restorations and frameworks using additive manufacturing.

Rather than a homogenous structure, fabrication of these materials with 3D printing may result in porous structures that are inherently susceptible to staining, fracture and cracking (Dizon et al, 2018; Turner, Strong and Gold, 2014).

Proposed materials for exploration Reinforced composites The most popular and commonly used polymeric denture base material within dentistry is known as polymethylmethacrylate (PMMA). It is an extremely stable, transparent thermoplastic that does not decolour in the presence of UV light, and exhibits remarkable ageing properties (Anusavice et al, 2013).

PMMA is a resin-based material that has been used in 3D printing technologies to fabricate dental provisional restorations to protect oral structures such as pulpal tissue from thermal sensitivity, physio-mechanical pain, and bacterial contamination (Balkenhol et al, 2009). For the purposes of implant treatment, larger framework restorations and dentures, these PMMA 3D printed prostheses require high tensile and flexural strengths to be adequate for long term use. This underscores the importance of using materials

with sufficient wear resistance and mechanical strength in orthodontic clinical practice (Abdulmohsen et al, 2016).

Conventional self-polymerising PMMA-based resin materials have been shown with a number of limitations, including high polymerisation shrinkage, water sorption and heat generation, and thus there are concerns that these limitations may pass over to 3D printed PMMA restorations (Patras et al, 2012).

Conventional fabrication using PMMA with a mixture of self-polymerising powder and liquid requires longer cure times than would be practical for a chairside setting (Patras et al, 2012). Considering one of the advantages of digital manufacturing is speed and efficiency, the use of 3D printed resin materials need to be both a viable alternative to conventional resin materials to support long-term dental applications in orthodontic practice (Peñate et al, 2015).

In particular, the recent advancements in routine dental practices with chairside CAD/CAM dentistry – such as 3D printed prosthodontic treatments – have been driven by the introduction of new processing technologies and dental materials.

A number of dental laboratory processes can be used to fabricate either fixed or removable dental prostheses such as crowns using a variety of dental materials (Chen et al, 2018). The advancement of both casting gold alloys and the associated accuracy in dental casting technologies has contributed to the persisting use of these prostheses (Bajraktarova-Valjakova et al, 2018).

New dental ceramic materials, such as glass ceramics as well as lithium silicates/disilicates and zirconia-based ceramics, have been successfully used by CAD/CAM enabled dental clinics, with several studies showing excellent long term success rates over 10 years (Miyazaki et al, 2013).

Therefore, any new 3D printing material must be equal to or show alternate benefits to these well studied materials as well as biosafety and excellent aesthetics (Guess et al, 2011).

Zirconia-based materials Among all dental ceramics, zirconia is the most popular biomaterial of choice in contemporary dental restorations in dentistry, particularly as a structural material for crowns, bridges, inserts, and implants (Miyazaki et al, 2013).

Zirconia (zirconium dioxide) provides optimum properties of a material for dental use, including tensile strength, fatigue resistance, and outstanding wear properties and biocompatibility (Della Bona, Pecho and Alessandretti, 2015).

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

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Figure 3: Temporary 3D printed teeth for use in a 3D printed denture

Figure 4: SLS 3D printed metal partial denture framework in CoCr

Zirconium (Zr) has similar biochemical properties to titanium (Ti) metal, in which both are commonly used in implant dentistry as they lack the capacity to hinder the bone forming cells (osteoblasts) to facilitate osseointegration (Grandin, Berner and Dard, 2012).

Although zircornia is characterised as useful dental biomaterial, zirconia-based materials present several challenges in its dental practice applications as they are difficult to adhere to compared to other glass ceramics and composite materials (Della Bona, Pecho and Alessandretti, 2015).

The adhesive bond between ceramics and resin-based materials comes is through a combined micro mechanical and chemical interaction across the contact interface.

The overall bond strength is highly dependent on the surface treatment and surface energy through silination of the glass ceramic to increase its wettability (Della Bona, Pecho and Alessandretti, 2015; Della Bona et al, 2014).

It has been reported that of all types of acid-resistant bonding for ceramic dental restorations like glass ionomer (GI) and hydrophobic phosphate monomers containing 10-methacryloyloxydecyl-dihydrogen-phosphate(MDP) monomer, resin-based composite systems are the most popular and effective for high bond strength between a wide range of materials (Della Bona et al, 2014; Matinlinna, 2014).

Several studies have shown that quality and the durability of the micro-mechanical and/or chemical bond between glass ceramic and resin-based materials has a high impact on the long-term success rates of the prosthesis placed (Della

Bona and Kelly, 2008; Della Bona et al, 2007).

The non-reactive or acid-resistant surface of zirconia often poses a major concern related to poor adhesion or reduction of bond strength to other substrates (Della Bona et al, 2007).

Furthermore, chemically polymerised materials available for provisional dental restorations using either PMMA or resin-based composites have unique properties, which depend on the composition of the chemical monomer (Oba et al, 2014).

It has been demonstrated that different monomers vary in their chemical effects such as polymerisation shrinkage, exothermic reactions, marginal fit, colour stability, periodontal responses and fracture strength (Della Bona, Pecho and Alessandretti, 2015). The fracture strength of the provisional restorative materials relates to the mechanical properties (Kim and Watts, 2007).

In terms of mechanical strength and physical properties, the superiority of zirconia has largely been utilised for aesthetic dental restoratives, including crowns and bridges (Karaokutan, Sayin and Kara, 2015). Zirconia is typically veneered with feldspathic porcelain due to its insufficient translucency; nevertheless, the strength of the veneering porcelain has been indicated as inadequate in its function as a dental restorative (Miyazaki et al, 2013). The main clinical feature of failed zirconia-based restorations has been reported to be due to the wear and fracture of the laminated porcelain layer (Alp, Murat and Yilmaz, 2019).

However, ‘full contour’ zirconia-based restorations without a porcelain layer have been shown to be problematic in some

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cases with wear of the opposing teeth causing gross fracture and ultimate total failure of the prosthesis (Della Bona, Pecho and Alessandretti, 2015; Cha et al, 2017).

In a study by Park and colleagues (2018), wear resistance of the 3D printed resin material was compared to the milled and the conventional self-cured resin materials opposing zirconia and metal antagonists (CoCr alloy). The basic component of all the three resin materials was similar but the study found differences in wear patterns between the materials and the casted cobalt-chromium (CoCr) alloy denture abraders.

This study suggested that the properties of PMMA-based resin materials could vary according to the fabrication methods used. When CoCr alloy metal abrader was applied in the 3D printed resins, cracks occurred as well as separation of the inter-layer bonds between layers of resin.

This occurs as the bond that occurs between layers is weaker than the bond formed between each consecutive 3D printed layer (Park et al, 2018).

The results of the study by Park and colleagues (2018) indicated that the clinical use of 3D printing technologies presents a more convenient and promising technique fabricating provisional dental restorations and increase productivity in dentistry.

Limitations Another limitation of 3D printed materials occurs as the surface of these materials are vulnerable to oxygen inhibition.

As these prostheses could then be subject to immediate exposure to saliva through direct patient contact, the longterm mechanical strength and long-term colour stability could be reduced (Balkenhol et al, 2009). Conversely, blocks used in CAD/CAM systems are constructed with the optimum polymerisation conditions in place for complete and uniform polymerisation without inhibition.

Studies have shown that provisional dental restorations fabricated from materials in CAD blocks (monomethacrylate or dimethacrylate) have superior mechanical properties compared to those fabricated by both conventional and 3D printing technologies (Rayyan et al, 2014; Peñate et al, 2015).

A meta-analysis study by Astudillo-Rubio and colleagues (2018) found no significant difference between monomethacrylates (PMMA) and dimethacrylates (PEMA) in regard to their fracture strength, the ability to prevent the propagation of cracks. However, both groups vary according to the way they interrupt the cracks propagation where dimethacrylate materials are less susceptible to crack

propagation in the presence of water (Abdulmohsen et al, 2016; Astudillo-Rubio et al, 2018).

PEMA may therefore be a potential avenue for increased strength in future 3D printing materials, which are less brittle than PMMA based materials (Rayyan et al, 2014; Peñate et al, 2015).

Over time, water absorption by non-cross-linked polymers subsequently weakens the material, which gradually diminishes the plasticising effect and the associated fracture toughness (Balkenhol et al, 2009).

Polymethylmethacylate (PMMA) resin remains one of the most commonly used materials for provisional dental restorations within dentistry due to greater flexural strength compared to PEMA. It has been reported that provisional dental restorations based on PMMA have many advantages, including: • Colour stability • Aesthetics • Marginal fit • Tensile • Strength.

Furthermore, a number of PMMA dental models can be easily fabricated, polished, and repaired using the 3D printers, which not only reduces the production time but also allows multiple 3D copies to be produced without altering the dental anatomy (Alp, Murat and Yilmaz, 2019; Cha et al, 2017; Park et al, 2018).

However, as the studies above have shown, the flexural strength of PMMA decreases gradually over time, meaning current formulations may be inadequate for use as long-term restorations.

Studies have reported that the use of PMMA resin materials in dental restoration cause irritation of oral tissues, have low wear resistance, and high volume shrinkage due to leaching of the free monomer (Patras et al, 2012; Park et al, 2018).

Future developments with graphene and fibreglass reinforcement Based on evidence presented in meta-analysis by AstudilloRubio and colleagues (2018), several studies reported that the structure of the provisional dental restorations could be reinforced with fibreglass or graphene to improve their flexural strength and fracture toughness, and this could be a possible route for 3D printer materials to provide more suitable long term restorations (Kim and Watts, 2004; Hamza, Johnston and Schricker, 2014).

These strengtheners may not make the material completely

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immune to fracture, but may simply change the fracture path to allow easy repair of chips rather than a full catastrophic fracture leading to ultimate failure of the prosthesis (Astudillo-Rubio et al, 2018). Therefore, if 3D printing resin can incorporate graphene or polyethylene fibres into the polymer matrix, this should result in a stronger restoration (Nayar, Ganesh and Santhosh, 2015; Gopichander, Halini Kumarai and Vasanthakumar, 2015).

Hamza, Johnston and Schricker (2014) assessed this reinforcement effect following the addition of 1% of the polyhedral oligomeric silsesquioxane (POSS). The results indicated that ‘the reinforcement effect of POSS on flexural strength depended on the brand’, suggesting that particular chemical composition of the provisional materials determines the ability of POSS to improve their mechanical properties, which may mean that some 3D printer resin brands may perform better than others even if based on similar material technology.

Conclusion Current materials in 3D printing provide a wide range of possibilities for providing more predictable workflows as well as improving efficiency through less wasteful additive manufacturing in CAD/CAM procedures.

Incorporating a 3D printer and a digital workflow into a dental practice is challenging but the wide range of manufacturing options and materials available mean that the dentist should be well prepared to treat patients with a more predictable and cost effective treatment pathway.

As 3D printing continues to become a commonplace addition to chairside dental clinics, the evolution of these materials, in particular reinforced PMMA, resin incorporating zirconia and glass reinforced polymers offer increased speed and improved aesthetics that will likely replace subtractive manufacturing milling machines for most procedures (Nayar, Ganesh and Santhosh, 2015; Gopichander, Halini Kumarai and Vasanthakumar, 2015).

References The full list of references is available from on request from: ursula@moderndentistrymedia.com This article first appeared in Clinical Dentistry and has been reprinted with permission.

Nulty A (2022) A literature review of 3D printing materials in dentistry: part four. Clinical Dentistry 2(3): 44-49

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

E4

CHAIRSIDE PRODUCTION IS SO EASY The new E4 makes it so easy for you to get started with chairside production of dental restorations, and gives you maximum freedom. Combine the E4 with your preferred intraoral scanner, any CAD software and materials that are appropriate for your individual patients. The E4 is the heart of your workflow and produces the perfect restoration for you. The integrated CAM software enables you to get started right away!

THE ALL-ROUNDER FOR BLOCKS The E4 has many talents. Wet grind glass ceramics or composites with ceramic content and dry mill materials such as zirconia and PMMA

A small change with a big effect Benefit from easy switching: Insert the tank for wet processing or the optional container for machining dust and start processing high-quality restorations.

A special filter mat in the liquid tank ensures that the tank is free of chippings.

Wet grinding The PUREWATER Technology ensures thatthe closed liquid circuit in the machine requires no grinding additives. For you, this means easy disposal and even lower running costs.

Dry milling The optional dry container enables you to mill materials such as zirconia, PMMA and various composites with your E4 with no cooling water or compressed air.

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USER REPORT

Premolar case with a nano-hybrid, intuitive universal composite Clarence P. Tam1

Case background A stable ASA 2 65-year old female presented to the practice for restorative dentistry with a medical history significant for a non-descript immunoglobulin deficiency, for which she receives regular infusions. She reports no known drug allergies. Clinically, she was diagnosed with an occlusal peripheral rim fracture leaving a food trap on tooth 1.4 (FDI notation). Tooth 15 featured an extensive amalgam with extreme proximity to the distal marginal ridge, which exhibited distal vertical axial fractures as a result of cyclic expansion-contraction over time.

The restorative goal of minimally invasive direct dentistry would be complicated by the undoubtedly dark dentin substrate under the amalgam. A material was sought that featured both an excellent chameleon mechanism as well as physical properties to maximize the prognosis of direct restorations in this area.

Dr Clarence P. Tam, HBSc, DDS, AAACD, FIADFE Private Practice limited to Cosmetic and Restorative Dentistry, Auckland, New Zealand

1

www.clarencetam.co.nz

Restorative procedure The patient was subjected to topical anesthetic prior to buccal infiltration using 1 carpule of 2% Lignocaine with 1:100,000 epinephrine. A rubber dam was affixed prior to preparation of tooth 15MO with dissection of the distal vertical marginal ridge fracture. The margins of tooth 14O and 15MOD were refined before bevelling as the ends of enamel rods facilitate better bonding relative to the sides of enamel rods. A 27 micron aluminum oxide micro air abrasion treatment was completed prior to affixing, wedge and matrix to reconstruct the mesial marginal ridge of tooth 15. A matrix-inmatrix solution was used to recreate the proximoaxial contour of 15D This provided hermetic closure at the proximogingival cavosurface margin as well as an ideal contour for the missing axial wall.

Following a total etch technique, a 2% Chlorhexidine scrub was completed for 30 seconds and the dentin blot dried to a moist state. A 5th generation bond was applied, air thinned and cured as per manufacturer instructions. Microlayers are important during the delicate first 5 minutes of hybrid layer formation, and were completed using 0.25mm increments of CLEARFIL MAJESTY™ Flow (Kuraray Noritake Dental Inc.). This technique can be expected to increase significantly the shear bond strength to dentin1,2.

This was completed both in the proximal box floor area as well as mid-occlusally. The marginal ridge was completed using CLEARFIL MAJESTY™ ES-2 Universal (Kuraray Noritake Dental Inc.). Since the dentin base was heavily stained, CLEARFIL MAJESTY™ Flow was used before utilizing CLEARFIL MAJESTY™ ES-2 Universal in a lobe-by-lobe creation of occlusal anatomy. Post-operative occlusal checks verify that the restoration is conformative to occlusion and esthetically excellent with no visible marginal show.

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

USER REPORT

1

2

3

4

Rationale for material choice The marginal ridges were micro-layered horizontally as was the floor of the resulting Class I preparation as per a reduced layer thickness-technique modification of Nikolaenko et al,3 whereas the highest shear bond strengths were found when a 1mm horizontal layering technique was used.

CLEARFIL MAJESTY™ ES-2 Universal is at the forefront of a simplified restorative armamentarium for the modern practice. It takes cloud-shading one step further by offering a “Universal” shaded composite featuring Light Diffusion Technology (LDT) with simultaneous ideal sculptability, optical metamerism and physical properties for use in any restorative situation in the mouth. Featuring barium glass nano fillers and proprietary pre-polymerized nanoparticle fillers, the latter boasts a high refractive matrix that is able to disperse light and fool the eye with even the thinnest of layers, obviating the need for opaquer composites in cases like the one featured. When paired with CLEARFIL MAJESTY™ Flow in a conservative layered technique, the 81% filled flowable produces a radiographically well-demarcated layer, and the superficial CLEARFIL MAJESTY™ ES-2 Universal boasts

an easy-to-polish robust single shade restorative solution that will virtually fulfil all of your restorative needs for nonbleaching patients.

Physically, with compressive strength is rated at 348 MPa and flexural strength at 116 MPa, CLEARFIL MAJESTY™ ES-2 Universal is in the range of natural enamel and dentin.

The built-in fluorescence is very enamelomimetic, which is excellent for nightclub social situations.

References 1. Bertschinger C, Paul SJ, Luthy H, Scharer P. Dual application of dentin bonding agents: effect on bond strength. Am J Dent. 1996;9(3):115-119 2. Magne P, Kim TH, Cassione D, Donovan TE. Immediate dentin sealing improves bond strengths of indirect restorations. J Prosthet Dent. 2005;94(6):511-519 3. Nikolaenko SA, Lohbauer U, Roggendorf M, Petschelt A, Dasch W, Franenberberger R. Influence of C-Factor and layering technique on microtensile bond strength to dentin.

Dental Mater. 2004;20(6):579-585

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 51

CLINICAL

Post-endodontic hybrid ceramic restoration Marco Simonetti,1 Benedetta Gori,2 Dario Marzocco,3 Marco Broglio4 and Giuseppe Teani5

Introduction Today, the use of the latest generation of ceramic materials and modern CAD/CAM systems gives us the opportunity to reconstruct damage to the hard tooth substance and to benefit from the enormous advantages of this technology in terms of: • Precision • Maximum accuracy • Shorter, more comfortable patient treatment.

The aim of this article is to demonstrate the prosthetic restoration of an endodontically, restoratively and aesthetically compromised tooth in the digital workflow. The previous restoration with an old, functionally and aesthetically insufficient amalgam filling played a decisive role.

Marco Simonetti Specialist in restorative dentistry, Endodontics, aesthetics, prostheses and paedodontics. Private Practice, Porcari, Italy

1

Benedetta Gori Postgraduate degree in endodontics and restorative dentistry, University of Siena, Italy

2

Dario Marzocco Private Practice, Porcari, Italy

3

Marco Broglio Dental Technician, Porcari, Italy

4

Giuseppe Teani Dental Technician, Porcari, Italy

5

Case study A 57-year-old male patient came to the dental practice for a check-up because he found the old restoration on his lower right first molar (LR6) unsightly. The clinical examination revealed a large amalgam filling that was about 20 years old.

Radiological diagnostics showed an insufficient endodontic treatment in the periapical region. After appropriate revision treatment, the tooth should be stabilised with glass fibre pins and a build-up filling with flowable composite.

A prosthetic restoration with a crown was then planned to restore the tooth’s aesthetics, as well as resistance to chewing forces.

Endodontic revision and stabilisation At the first treatment appointment, the amalgam filling was removed under a rubber dam and the root canals were completely revised and filled. In the same session, two glass fibre posts with dual-cure composite cements were adhesively placed in the distal and mesio-vestibular canals.

A build-up filling with flowable composite was then placed and the tooth crown was prepared with diamond instruments.

At the end of the session, a temporary restoration fabricated intraorally was finished, polished and cemented.

In the second session, the tooth shade was determined digitally using the Vita Easyshade V spectrophotometer, which proceeded precisely and simply by hand. This was followed by the digital impression with an intraoral scanner to produce a more precise temporary restoration that enabled optimal gingival shaping.

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

CLINICAL

Long-term temporary composite The virtual data set was sent to the dental technician, who designed the new long-term temporary restoration using CAD/CAM. The restoration was manufactured from the Vita CAD-Temp composite block (Vita Zahnfabrik) in the determined tooth shade. The newly fabricated long-term temporary restoration was temporarily cemented.

After about three weeks, the gum tissue around the second temporary restoration had healed perfectly and formed, which is why a second optical impression could be taken with the intraoral scanner for the fabrication of the final crown.

The corresponding STL file of the crown preparation on LR6 was sent to the dental laboratory so that the CAD/ CAM-supported fabrication could be implemented on this basis.

Final hybrid ceramic For the fabrication of the final restoration, the clinical and dental technician team decided on the easy-to-process Vita Enamic HT Multicolor in shade 2M2. The hybrid ceramic consists of a porous, pre-sintered feldspar ceramic block (86% by weight), which is then infiltrated with polymer (14% by weight) under pressure and heat (He, Purton and Swain, 2011).

The result is a dual ceramic-polymer network that exhibits toothlike material properties, where microcracks in the ceramic are stopped at the polymer-interface (Coldea, Swain and Thiel, 2013).

The CAD/CAM material is not fired and can be characterised after production with the light-curing stains Vita Akzent LC. In this case, the surface was sandblasted, silanised, painted and then finished with the light-curing glaze Vita Akzent LC Glaze.

Fully adhesive seating After the try-in, the fully adhesive integration was carried out with the tailored, fully adhesive Vita Adiva F-Cem bonding system.

After the composite cement had cured, the occlusion was checked. Any grinding measures should always be carried out after final bonding.

This was followed by final finishing and polishing with the two-stage Vita Enamic Polishing Set Clinical, which enabled quick smoothing of the ground areas.

The excellent aesthetic result of the restoration was perfectly integrated into the adjacent teeth and the adjacent gingival anatomy.

Fig. 1: Initial situation with the amalgam-filled and highly discoloured tooth LR6

Discussion The treatment and the success of the clinical case were made possible through the use of modern materials and digital workflows, which offer numerous advantages for users (clinical and technical) and patients.

The main advantages lie in the material properties, which became clear in the different treatment stages.

The long-term temporary material Vita CAD-Temp is a composite that is characterised by excellent aesthetics and high strength.

The decision in favour of a final restoration with the hybrid ceramic Vita Enamic Multicolor was made because of the natural aesthetics, but also because of the toothlike flexural modulus, which is a real advantage in terms of the long-term stability of the restoration.

The glass fibre post and the composite cement should also have a toothlike flexural modulus in order to be able to react to chewing forces with the same deformation as the residual tooth substance. This avoids stress peaks between the different restorative materials and the remaining hard tooth substance and prevents fractures between them.

A clinical long-term assessment of the success of the therapy is not yet possible in this particular case.

However, in countless studies, the hybrid ceramic has already shown its potential for long-term clinical success in teeth treated with root canals in terms of precision (Saglam, Cengiz and Karacaer, 2020; Elashmawy and Elshahawy, 2022) and resilience (Elashmawy et al, 2021; El-Refaay, Hassan and Mohammed, 2020; Elashmawy, Aboushelib and Elshahawy, 2021), in comparison to other materials,

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 55

SIMONETTI ET AL

Fig. 2: View into the pulp cavity after revision treatment and root canal filling with gutta percha

Fig. 3: Situation after inserting glass fibre pins and building up with flowable composite

Fig. 4: Radiological view of LR6 after endodontic treatment and crown build-up

Fig. 5: Clinical situation after preparation and before the intraoral scan

such as lithium disilicate and zirconia.

At the same time, the fabrication costs for hybrid ceramic restorations are significantly lower.

The integrated shade gradient is the basis for a natural aesthetic. The right shade is essential from a prosthetic point of view, which is why the Vita Easyshade V spectrophotometer can be described as indispensable for tooth shade determination.

Numerous clinical studies have shown that digital tooth shade determination with the Vita Easyshade V is more precise than visual shade comparison with the human eye

(Hampé-Kautz et al, 2020; Lehmann et al, 2017; Igiel et al, 2017).

The Vita Adiva bonding system is very comprehensive and offers simple and reproducible handling for adhesive bonding for every user.

All steps are described in a comprehensible manner and broken down according to the type of restoration and substrate surface. Following the procedure is the basis for successful cementing.

After integration, the crown looked natural, and it reliably masked the severely discoloured stump.

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

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SIMONETTI ET AL

Fig. 6: Construction of the second temporary restoration of Vita CAD-Temp in the Exocad software

Summary A functional and aesthetic treatment result was achieved, thanks to new material properties in combination with reproducible digital technology.

It is advantageous to be able to work with increasingly powerful, modern materials. They enable clinicians and patients to receive treatment more quickly. Fabrication is easier than with the classic restoration forms, and the work for the practice team is made easier.

The patient immediately felt comfortable with his new hybrid ceramic restoration.

The first follow-up appointment was made for six months.

References

Coldea A, Swain MV, Thiel N (2013) Mechanical properties of polymer- infiltrated-ceramic-network materials. Dent Mater 29(4): 419-26 El-Refaay AY, Hassan MR, Mohammed RM (2020) Assessment of the fracture resistance of endodontically treated premolars restored with endocrowns constructed of two different materials. Egyptian Dental Journal for Researchers 533(4): 42 Elashmawy Y, Aboushelib M, Elshahawy W (2021) Retention of different CAD/CAM endocrowns bonded to severely damaged endodontically treated teeth: an in vitro study. J Indian Prosthodont Soc 21(3): 269-275 Elashmawy Y, Elshahawy W (2022) Effect of thermomechanical fatigue loading on the internal and marginal adaptation of endocrowns utilizing different CAD/CAM restorative materials. Int J Prosthodont doi: 10.11607/ijp.7771. Epub ahead of print Elashmawy Y, Elshahawy W, Seddik M, Aboushelib M (2021) Influence of fatigue loading on fracture resistance of endodontically treated teeth restored with endocrowns. J Prosthodont Res 65(1): 78-85

Fig. 7: The final crown made of the polychromatic hybrid ceramic Vita Enamic Multicolor

Fig. 8: The final crown made of Vita Enamic Multicolor and integrated with Vita Adiva F-Cem

Hampé-Kautz V, Salehi A, Senger B, Etienne O (2020) A comparative in vivo study of new shade matching procedures. Int J Comput Dent 23(4): 317-323 He LH, Purton D, Swain M (2011) A novel polymer infiltrated ceramic for dental simulation. J Mater Sci Mater Med 22(7): 1639-43 Igiel C, Lehmann KM, Ghinea R, Weyhrauch M, Hangx Y, Scheller H, Paravina RD (2017) Reliability of visual and instrumental color matching. J Esthet Restor Dent 29(5): 303-308 Lehmann K, Devigus A, Wentaschek S, Igiel C, Scheller H, Paravina R (2017) Comparison of visual shade matching and electronic color measurement device. Int J Esthet Dent 12(3): 396-404 Saglam G, Cengiz S, Karacaer O (2020) Marginal adaptation and fracture resistance of feldspathic and polymer-infiltrated ceramic network CAD/CAM endocrowns for maxillary premolars. Niger J Clin Pract 23(1): 1-6 This article first appeared in Clinical Dentistry and has been reprinted with permission. Simonetti M, Gori B, Marzocco D, Broglio M, Teani G (2023) Post-endodontic hybrid ceramic restoration. Clinical Dentistry 3(7): 23-25

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

E5

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CLINICAL

A simplified approach to Class IV restorations using the press-mould technique Katherine Losada1

Introduction Upper central incisors are the teeth that fracture most frequently in the early years of life. To restore these Class IV lesions can be stressful for the practitioner as they are in the direct view whenever the patient speaks or smiles. Any mistake in shade, shape or contour is easily noticed and may bother the patient in his daily life. Materials and methods that lead to a predictable end result are very valuable to any dentist and all the more for starting dentists.

Katherine Losada, DDS Private Practice, Zürich, Switzerland

1

Case Report A 32-year-old male patient came to the dental office complaining of being dissatisfied with the appearance of his upper central incisors. Both teeth were several times restored in the last 15 years due to a skateboard accident. He did not want any alterations to the shape of the teeth, but he wanted to have the colour of the restorations adjusted to his original shade (Figs. 1-2). At the moment of consultation, tooth 21 had already undergone endodontic treatment.

Teeth 11 and 21 had shade A2 as base color and were not very translucent. The core shade A2 of the G-ænial A’CHORD™ composite system (GC) had sufficient translucency for this purpose and was selected for the final layer. This universal composite with simplified unishade system and natural fluorescence excellently mimics the tooth shade and makes shade selection less complicated, even when you are using this system for the first time. To obtain a lively result, it was decided to use JE (junior enamel) and AO1 at the back portion to create a subtle gradient in the translucency (Fig. 3).

To copy the existing tooth shape, an impression was taken with a non-perforated metal tray filled with vinyl polysiloxane (EXACLEAR, GC). This material is flexible yet firm enough to use for the press-mould technique and enables visual control and lightcuring through the mould due to its translucency (Fig. 4).

A second impression was taken with a silicone putty material (Optosil comfort Putty, Kulzer) to create a firm key to shape the palatal side (Fig. 5). Instead of using the palatal portion only, a window was cut out of the key, exposing the central incisors with slight extension towards the distal sides. This way allows more support for a stable, better controlled repositioning of the silicone key in the arch.

The edges of the transparent silicone as well as the putty key were trimmed ensuring that the keys were supported by teeth only after repositioning them in the mouth and

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

CLINICAL

1a

1b

Figure 1: Situation before treatment. Two old Class IV restorations were present on the Figure 2: Palatal view before treatment. upper incisors.

Figure 3: The selected shades of G-ænial Figure 4: The original shape was copied A’CHORD (GC) composite (JE: Junior with a transparent mould (EXACLEAR).

Enamel).

could be seated correctly in the presence of a rubber dam.

These pre-treatment procedures take less than 10’ and ensure control over the pre-existing tooth shape. Next, local anaesthesia was given and the tooth surfaces were cleaned to remove any remaining plaque and/or dental calculus.

The teeth were isolated with rubber dam and the clamps were placed on the premolars to avoid interference with the silicone key. Both keys were tried in to check interference with the rubber dam. Tooth 11 needed the largest restoration and was built up first. The old composite was removed, all sharp edges were rounded and a 2 mm bevel was created with a diamond bur (Fig. 6).

The neighbouring teeth were isolated with Teflon tape.

Then, the tooth was etched with phosphoric acid gel and a universal adhesive (G-Premio BOND™, GC) was applied according to the manufacturer’s instructions.

The palatal silicone key, separated with a small amount of Modeling Liquid (GC), was seated in the mouth (Fig. 7) to build up the palatal portion of the tooth in shade JE (Fig. 8).

Thereafter, because of the thickness of the build-up (approximately 1.5 mm), the core was built up with AO1 to

Figure 5: Silicone putty key to create the palatal portion.

block out the incident light in the middle of the tooth. At the incisal edge, 1 mm of JE remained uncovered so this would give some extra translucency in this region.

For the final layer, the A2 composite was preheated in order to have a smooth spreadable texture (desired for this technique) and placed into the transparent EXACLEAR mould at the vestibular side of tooth 11. Then, the mould pressed over the upper front teeth (Fig. 9). Gentle pressure was applied to avoid overfilling and the composite was lightcured through the mould. Depending on the shade, G-ænial A’CHORD can be cured in 10 (output >1200 mW/cm²) to 20 seconds (output >700 mW/cm²) in layers up to 2-2.5 mm. EXACLEAR has a high transparency, so curing through the mould can occur efficiently because there is little light attenuation. After removal, the restoration margins were finished to remove any possibly present overhang. The same procedure was repeated to restore tooth 21. The whole appointment including the polish time did not last longer than 90 minutes.

The patient was pleased with the immediate postoperative result; because of the fast procedure, there was

INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL. 18, NO. 2 61

LOSADA

Figure 6: Removal of the old composite and isolation.

Figure 7: Silicone key in situ.

Figure 8: After build-up of the palatal shield.

Figure 9: Press-mould technique.

little dehydration (Fig. 10). He was still pleased after one year (Fig. 11).

This case is an example of how quite large anterior build-ups can be done in a fast manner without having to compromise on the aesthetic result. Using the press mould technique and the simplified shading system of G-ænial

A’CHORD is not only efficient in terms of saving time but also cost-effective. And because of the excellent colour stability and wear resistance of G-ænial A’CHORD, the patient can enjoy his restored smile for a long time.

10a

10b

First published in GC get connected

Figure 10: Post-operative result.

Figure 11: At follow-up after one year.

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

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All products available from: HENRY SCHEIN • Tel: 1300 65 88 22 • www.henryschein.com.au 64 INTERNATIONAL DENTISTRY – AUSTRALASIAN EDITION VOL.18, NO. 2