Biocompatible. Chemically Inert Wear Resistant Esthetic

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1 What are the advantages of ceramics restorative dental procedures? Biocompatible Jeffrey Y. Thompson DENT Fixed Prosthodontics II February 10, 2004 Chemically Inert Wear Resistant Esthetic What are the disadvantages of ceramics restorative dental procedures? Hot-Pressed Leucite-Reinforced Porcelains Difficult to Fabricate Expensive (Fabrication Related) Abrasive to Natural Teeth High Clinical Failure rates IPS Empress FINESSE TM ALL-CERAMIC Traditional Feldspathic Porcelains vs. Leucite-Reinforced Porcelains Schematic of IPS Empress pressing furnace Traditional feldspathic porcelains contain vol% leucite crystals. Leucite-reinforced porcelains contain vol% leucite crystals. Leucite-reinforced porcelains are approximately 50% tougher (K IC = 1.5MPa. m 1/2 ) than traditional feldspathic porcelains.

2 Microstructure of IPS Empress Recommended preparation design and reduction for IPS Empress crowns Leucite crystals IPS Empress shading technique Structure of IPS Empress crown Empress core Empress layering porcelain Central incisors prior to restoration Central incisors after restoration with IPS Empress crowns

3 Hot-Pressed Glass-Ceramic Structure (Design) of IPS Empress 2 pressable ceramic crown Structure of IPS Empress 2 pressable ceramic crown Composition of IPS Empress 2 glass-ceramic core material and layering material Lithia disilicate glass-ceramic core material Fluoroapatite glass-ceramic layering material Lithia Disilicate (Li 2 O-2SiO 2 ) Framework (Core) Material Fluorapatite [Ca 10 (PO 4 ) 6 F 2 ] Layering Material Comparison of the translucency of a IPS Empress 2 FPD compared to a PFM FPD Recommended preparation dimensions for IPS Empress 2 posterior crowns

4 Alumina or Spinel-Based Coping Material Microstructure of InCeram Alumina In In-Ceram Alumina particles Laboratory fabricated In-Ceram Alumina crowns In-Ceram Spinel crowns display enhanced translucency Recommended preparation design and reduction for In-Ceram crowns Alumina-Based Coping Material

5 Structure of Alumina-Based Coping Materials Al 2 O 3 reinforced porcelain (Example: HiCeram ) Structure of Alumina-Based Coping Materials Glass-Infiltrated Al 2 O 3 (Example: In-Ceram ) Aluminum Oxide particles (white) in a matrix of porcelain (yellow) Glass powder with heat treatment fills in pores (red) in partially-sintered alumina (white) Structure of Alumina-Based Coping Materials Densely Sintered Al 2 O 3 (Example: Procera AllCeram) Microstructure of Procera Complete sintering creates non-porous, densely sintered alumina Al 2 O 3 particles Biaxial Flexure Strength of Dental Ceramics* A cast of the preparation is made and scanned in the Procera scanner ±116 σf σf (MPa) ±28 439± IPS Empress InCeram Procera Allceram *Odén,, 1994

6 The coping design is sent by modem to Procera/Sandvik in Stockholm for production (restorations now produced in US facilities) Computer controlled enlargement of the die compensates for sintering shrinkage Procera/Sandvik (Stockholm, Sweden) Procera Milling Machine Enlarged coping in green body stage and natural size coping after sintering Procera AllCeram crowns after application of layering porcelains Procera AllCeram Coping in Green-Body Stage Sintered Procera AllCeram Coping Semi-transparent Procera AllCeram copings prior to veneering Veneered Procera AllCeram crowns

7 Before and after restoration with Procera AllCeram crowns Zirconia-Based Coping Materials Before After Lava TM In In-Ceram Key Characteristics of Zirconia (ZrO 2 ) ZrO 2 (in partially stabilized form - PSZ) has the highest fracture toughness of any ceramic. High toughness (> 8MPa. m 1/2 ) is derived from a transformation toughening process. The high toughness of PSZ results in a material that is durable and fatigue resistant enough for high stress applications (i.e., posterior bridges). Fracture toughness of dental ceramics: Why is it so important? Toughness (K IC ) is constant for a given material. K IC = YσY f c 1/2 ( strength as flaw size ) Dental ceramics generally have low toughness. Because of low toughness, dental ceramics are susceptible to failure from processing damage. Toughness is usually the limiting property for ceramic materials. Phase Transformation in Partially Stabilized Zirconia (PSZ) Transformation Toughening in PSZ Tetragonal (T) crack Monoclinic (M) Phase transformation has associated volumetric expansion of 4.7%. Untransformed particle Transforming particle Transformed particle Process zone

8 Transformation Toughening in PSZ Transformation Toughening in PSZ crack crack Untransformed particle Transforming particle Transformed particle Process zone Untransformed particle Transforming particle Transformed particle Process zone Transformation Toughening in PSZ Transformation Toughening in PSZ crack crack Untransformed particle Transforming particle Transformed particle Process zone Untransformed particle Transforming particle Transformed particle Process zone Fracture Toughness of Dental Ceramics K IC (MPa m 1/2 ) Vita VMK 68 Dicor MGC IPS Empress Vitadur N 2.5 Empress 2 4 InCeram Alumina 4.5 Procera 6.5 InCeram Zirconia 8.5 Cercon The Cercon Laboratory Process: Framework + Veneering Porcelain Framework Start of Lab procedures Wax Model Sintering Scanning Milling

9 A wax pattern of the restoration is produced by a technician. The wax pattern is mounted and laser- scanned in the Cercon Brain. A Cercon blank is placed in the Cercon Brain and milled. A milled Cercon coping is placed in the Cercon Heat and sintered. A sintering process involves shrinkage. Microstructure of Cercon before and after sintering ZrO 2 particles milled sintered Pre-Sintered for milling Sintered after milling

10 Specific Cercon porcelains are applied and fired onto the coping for final esthetics.