Zirconia Fundamentals

Scientific Update February 2009

Material Update •e.max CAD/e.max Press – Lithium Disilicate

Material Properties

Indications •Inlays •Onlays •Veneers •Thin Veneers (press) •Crowns •Anterior Bridges (press)

IPS e.max Press and CAD Clinical Studies

IPS e.max Press Crowns (3 to 5 years) •Böning, Dresden, D •Esquivel, San Antonio, USA •Stappert, Freiburg, D •Watson, London, USA •Dumfahrt, Innsbruck, A •Sorensen, Portland, USA •Edelhoff, Aachen, D

40 Crowns 36 Crowns 30 Crowns 30 Crowns 24 Crowns 16 Crowns 121 Crowns

IPS e.max Press Bridges (3 to 5 years) •Böning, Dresden, D •Anusavice, Gainesville, USA •Kern, Kiel, D •Sorensen, Portland, USA

14 30 37 56

Inlay-retained bridges •Kern, Kiel, D •Göring, Zurich, CH

45 16

Adhesive bridges •Ries, Würzburg, D

80

IPS e.max CAD - MO Crowns (MO) • Mörmann, Zurich, CH (3year) • Kelly, UConn, USA • Nathanson, Boston, USA • Sorensen, Portland, USA

60 51 30 20

IPS e.max CAD LT Crowns •Reich, Leipzig: e.max CAD LT for CEREC – 41 posterior crowns

•Beuer, München: e.max CAD LT for Everest – 30 crowns (mainly anterior)

•Bindl, Zürich: e.max CAD LT for CEREC – 30 crowns

•Fasbinder, Ann Arbor: e.max CAD LT for CEREC – 61 crowns

IPS e.max Press and CAD Esthetics

IPS e.max Translucency Overview

e.max CAD

e.max CAD

e.max CAD

MO

LT

HT

Empress CAD Empress CAD LT

HT

•Higher edge strength vs. traditional glass ceramic materials (can be finished thinner without chipping) •Low viscosity of heated ingot enables pressing to very thin dimension (minimal prep or noprep veneers) •Chameleon effect due to higher translucency

•Please observe the following procedure for the fabrication of thin veneers: – Apply the spacer to the preparation or tooth to be treated according to the veneer preparation guidelines – For thin veneers without preparation, locate the restoration margins in the proximal area as well as along the gingival margin.

– Observe the minimum thickness of the veneer.

– Sprue, invest, press, divest and remove the reaction layer according to the stipulations – It is possible to apply IPS e.max Ceram Incisal or Transpa.

– Conduct the Stain and Glaze firing with IPS e.max Ceram.

– Thin veneers have to be adhesively cemented.

Material Thickness Requirements The following material thicknesses must be observed to produce the desired tooth color and provide adequate strength:

IPS e.max Press Thin Veneer •IPS e.max Press can be used for the fabrication of very thin veneers (minimal Prep). If sufficient space is available, e.g. retrusion of a tooth, no preparation is required.

•The following minimum thicknesses for fabricating thin veneers have to be observed: labial

incisal

0.3 mm

0.4 mm

Factors affecting strength •Crystallization procedure •Bulk of material •Bonding vs. cementation

Effect of Heat Treatment on Strength of Dental GlassCeramic Discs

Question asked •What happens if the firing parameters of the standard crystallization program are changed?

Objective •To examine the effect on biaxial flexure strength by altering the heat treatment of the e.max CAD by changing the closing time, heating rate and long term cooling

Common shortcuts •Four groups were used for this study: – (1) Control – manufacturer’s instructions – (2) Rapid Closing - manufacturer’s instructions but the closing time is reduced from 6 min to 18 s – (3) Increased Heating Rate - manufacturer’s instructions except the initial heating rate is changed from 30ºC/min to 90ºC/min and – (4) No long term cooling - manufacturer’s instructions except no long term cooling is used.

Strength was studied •An ISO 6782 sized disc (1.2 mm in thickness and 15.5 mm in diameter) was scanned using the Cerec InLab (Sirona).

•Twenty specimens were milled for each group in four shades (five in each of A3, A3.5, B1 and BL2) using standard milling.

•The specimens were fired and glazed in one firing according to the firing parameters of each group in a P500 Programat oven (Ivoclar Vivadent).

•Specimens were tested using a universal testing machine (Instron Corporation) at a crosshead speed of 0.5 mm/min using a pin on three ball configuration.

Effect of Treatments Strength Versus Treatment 400.0 380.0 360.0 340.0 320.0 300.0 280.0 260.0 240.0 220.0 200.0 Control

Rapid Closing

Increased Heating Rate

No Long Term Cooling

Question asked How does cementation affect the failure load for e.max CAD and zirconia core restorations?

Objective To measure the fracture load of CAD/CAM lithium disilicate glass-ceramic crowns (e.maxCAD, Ivoclar Vivadent, Inc.) and zirconia core (Lava core, Lave Ceram 3M/ESPE) cemented either conventionally (Zinc Phosphate, Fleck’s) or adhesively (Multilink Automix, Ivoclar Vivadent, Inc.).

Thickness and Cementation Groups Four groups were used for this study: (1) e.max CAD LT full contour and conventional cementation (2) zirconia core/veneered and conventional cementation (3) e.max CAD LT full contour and adhesive cementation (4) zirconia core/veneered and adhesive cementation.

Load to Failure was measured Ten specimens were produced for each group. A standardized molar crown was scanned using the Cerec InLab (Sirona).

Twenty crowns were designed with recommended dimensions for lithiumdisilicate material. The specimens were fired and glazed according to the manufacturer’s instructions in a P500 Programat oven (Ivoclar Vivadent, Inc.).

Twenty copings with proper support were milled in zirconia using the Lava system.

These copings were layered in a matrix to full anatomy. The occlusal morphology was the same for all the crowns in the study. All crowns were cemented to composite (Heliomolar, Ivoclar Vivadent) preparations which were formed from the internal surface of each crown using either conventional cementation (Fleck’s Zinc Phosphate) or adhesive cementation (Multilink Automix) and stored in water for 24 h at 37°C. The crowns were loaded using a 15 mm diameter steel ball at a crosshead speed of 0.5 mm/min with an Instron Universal Testing machine.

Mean breaking load [N]

crown crunch test 3500 3000 2500 2000 1500 1000 500 0 Multilink Automix

Fleck's Cement

lava zirconia lava zirconia

Multilink Automix

Fleck's Cement

e.max CAD

e.max CAD

Zirconia Restorations

Conclusion Within this study, adhesive cementation increased the failure load of CAD/CAM crowns, though no statistical difference was found between the crown materials.

Lithium Biocompatibility

Summary •……..tended towards increasing cytotoxicity, however were less cytotoxic than several commonly used composites and comparable to several alloys and glass ionomers.

Scientific Update July 2008