•ALL CERAMIC ALL CERAMIC RESTORATIONSRESTORATIONS

Complete ceramic crownComplete ceramic crown

Should have relatively even Should have relatively even thickness circumferentially thickness circumferentially

About 1 to 1.5mm thickness needed About 1 to 1.5mm thickness needed to create esthetically pleasing to create esthetically pleasing restorationrestoration

• AdvantageSuperior estheticExcellent translucencyGood tissue responseConservative reduction

of facial surfaceAppearance of

restoration influenced by color of luting agent

• Disadvantage Reduced strength of

restoration Significant tooth reduction Difficulty in obtaining well

fitting margin Not effective as retainer

for fixed prosthesis Wear observed on

functional surface of natural tooth

IndicationIndicationAreas with high esthetic Areas with high esthetic

requirementrequirementTooth should be relatively Tooth should be relatively

intact with sufficient intact with sufficient coronal structure to coronal structure to support the restoration support the restoration particularly incisal area particularly incisal area

Centric contact must be Centric contact must be in an area where in an area where porcelain is supported by porcelain is supported by tooth structuretooth structure

• contraindicationcontraindication

• When more When more concervative concervative restoration can be restoration can be usedused

• If occlusal load is If occlusal load is unfavourableunfavourable

ContraContra

PreparationPreparation

ArmamentariumArmamentarium Narrow round tipped tapered Narrow round tipped tapered

diamonddiamond Football shaped diamondFootball shaped diamond Finishing stones and carbideFinishing stones and carbide Mirrors and periodontal probeMirrors and periodontal probe Explorer chisels hatchetsExplorer chisels hatchets handpiecehandpiece

Facial reductionFacial reduction

Placing depth orientation groove One depth groove in middle of facial wall

and one each in the mesiofacial and distofacial trancitional line angle

Depth is 0.8mm to allow finishing Cervical component parallel to path of

placement and incisal component parallel to original contour of the tooth

Reduction is performed on half at a time

Lingual reductionLingual reduction

Football shaped diamondFootball shaped diamondSelected path of placement has been Selected path of placement has been

transferred from cervical wall of facial transferred from cervical wall of facial preparation preparation

Place depth groove in middle of Place depth groove in middle of cingulum wallcingulum wall

Margin should follow free gingival crestMargin should follow free gingival crestShould not extent too far subgingivallyShould not extent too far subgingivally

Chamfer preparation and Chamfer preparation and finishingfinishing

1mm wide smooth continuous and free of 1mm wide smooth continuous and free of any irregularityany irregularity

A 90 degee cavosurface angle is optimalA 90 degee cavosurface angle is optimal Objective is to direct stress parallel to path Objective is to direct stress parallel to path

of placementof placement A sloping shoulder result unfavourable A sloping shoulder result unfavourable

loading of porcelain loading of porcelain Round any remaining sharp line angle to Round any remaining sharp line angle to

prevent wedging actionprevent wedging action

Strengthening mechanism of dental Strengthening mechanism of dental ceramicceramic

• Fabrication defect

Created during processing

Consist of voids porosity microcrackSurface crack

Induced by machining

Flaw effectively determines the fracture resistance of restoration

Crystalline reinforcementIntroduction of high proportion of crystalline phase A crystalline phase with greater thermal expansion coefficient produce tangential compressive stress near crystal matrix interphaseSuch tangential stress tends to divert the crack around particle

Chemical strengtheningChemical strengthening Relies on the exchange of small alkali Relies on the exchange of small alkali ions for larger ion bellow the strain point ions for larger ion bellow the strain point of ceramicof ceramicThis techniqe is diffusion driven and its This techniqe is diffusion driven and its kinetic are limited by time temperature kinetic are limited by time temperature and ionic radius of exchanging ions and ionic radius of exchanging ions

• Stress induced transformation Zirconia is monoclinic at room

temperature and tetragonal at 1170 degree

Stress triggers transformation from tetragonal to monoclinic zirconia

This leads to strengthening as a result of increase in grain volume in the vicinity of the crack up

GlazingGlazingAddition of surface glaze Addition of surface glaze The principle is formation of low expansion The principle is formation of low expansion surface layer at a high temperaturesurface layer at a high temperatureSelf glazing consist of an additional firing in air Self glazing consist of an additional firing in air after original firing without application of a low after original firing without application of a low expansion glazeexpansion glaze

Prevention of stress corrosionPrevention of stress corrosion Baked on metal foil may reduce fracture Baked on metal foil may reduce fracture incidence by reducing moisture exposure to incidence by reducing moisture exposure to internal surface of ceramicinternal surface of ceramicCoating are used also used to reduce stress Coating are used also used to reduce stress corrosion of glass ceramiccorrosion of glass ceramic

SelSelection of all ceramic ection of all ceramic systemsystem

• Fracture resistanceFracture resistance

• Promising result if the restoration are Promising result if the restoration are confined to lower stress anterior teethconfined to lower stress anterior teeth

• EstheticEsthetic

• A knowledge of available ceramic system is A knowledge of available ceramic system is neededneeded

• Marginal adaptation of system is importantMarginal adaptation of system is important

• Translucency of adjacent teeth and Translucency of adjacent teeth and discoloration must considereddiscoloration must considered

• A more opaque high strength core A more opaque high strength core ceramic system like inceram or procera ceramic system like inceram or procera are not good choice for highly translucent are not good choice for highly translucent teethteeth

• AbrasivenessAbrasiveness• Potential for abration of opposing tooth Potential for abration of opposing tooth

particularly in patient with parafunctional particularly in patient with parafunctional habithabit

• Low abration material should be Low abration material should be concideredconcidered

All ceramic partial fixed prosthesis

• Inceram alumina for anterior fdp• Lithium disilicate heatpressed

ceramic empress 2 cad cam procera system are also suitable for anterior fdp

All ceramic foundation restoration

• All ceramic is used as foundation restoration for endodontically treated teeth to overcome esthetic problem associated with metal post and core system

Resin bonded ceramicResin bonded ceramic

Performance of all ceramic restoration has Performance of all ceramic restoration has been enhanced by use of resin bondingbeen enhanced by use of resin bonding

Half moon fracture of crown is common form of failure it occure in

Teeth with edge to edge occlusion

When opposing tooth occlude cervical fifth of lingual surface

Teeth with short crown

Teeth with overshortened preparation