Today: we will talk about all ceramic crown preparation.

DefinitionDefinition• Non metallic full coverage ceramic

restoration . Restoring the prepared ant. Teeth functionally & esthetically

• AdvantagesSuperior esthetic

Excellent translucency

Good tissue response

Conservative reduction of facial surface

Appearance of restoration influenced by color of luting agent

DisadvantagesDisadvantages Absence of metal substructure

Reduced strength of the restoration

Significant tooth reduction is necessary on proximal & lingual surface

Difficulty in obtaining well fitting margin

* Not effective as retainer for fixed prosthesis

* Wear observed on functional surface of natural tooth

* Wear may occur on functional surfaces of natural teeth that oppose porcelain restoration

•

IndicationsIndicationsin ant. Teethin ant. Teeth

* * Discolored tooth Discolored tooth

* * Tooth with enamel defectsTooth with enamel defects

* * Fracture teeth Fracture teeth

** Bilateral proximal decay with incisal Bilateral proximal decay with incisal angle involved (class 4 ).angle involved (class 4 ). ** Unilateral proximal decay Unilateral proximal decay

• * * Excessive attrition tooth Excessive attrition tooth

* * at rampant caries at rampant caries

* * malformed and rotated teethmalformed and rotated teeth*functions:*functions:**All ceramic is used as foundation All ceramic is used as foundation restorationrestoration

* * for endodontically treated teeth to for endodontically treated teeth to overcome esthetic problem associated overcome esthetic problem associated with metal post and core systemwith metal post and core system

• Contraindication Contraindication

* * With posterior teeth With posterior teeth * * young patients young patients → large pulp,high epithelium → large pulp,high epithelium attachment attachment

* * Deep or heavy bites Deep or heavy bites Bad habits ( ex. nail biting )Bad habits ( ex. nail biting )

* * If occlusal load is unfavorableIf occlusal load is unfavorable* * At long span bridge At long span bridge * * when other more conservative rest. is when other more conservative rest. is indicated indicated

PrecautionsPrecautions

• Over tapered prepared cingulum

→ ↓ Resistance & Retention → exert wedge like force thus ↑

stress causing fracture

•Horizontal surface at the junction of prepared fossa & lingual wall should be preserved → reduce stresses

• Lingual ridge of canine not completely reduced → ↑ rotational resistance

Facial reductionFacial reductionPlacing depth orientation groove

Depth of grooves should be 0.8 mmas at finishing become 1 mm

Reduce the areas between grooves Two planes in preparation to provide

adequate esthetics without affecting pulp. 1st plane is on incisal two third. 2nd plane is on one-third

* facial reduction should extend around the facial-proximal line angles & fade out on the lingual aspect of the proximal surface

* end of flat end diamond forms shoulder finishline

Incisal reduction Incisal reduction • reduction 1.5 : 2 mm clearance to provide

esthetic & adequate strength restoration

• 45 degrees towards lingual surface

• 3 depth grooves approximately 1.3 mm to allow additional loss during finishing

• tooth structure between the grooves should be reduced

• Incisal reduction should be perpendicular to the plane of incisal half of labial reduction

Lingual reductionLingual reduction

Cingulum reduction is done by Football Cingulum reduction is done by Football shaped diamond shaped diamond

care should be taken to prevent over at care should be taken to prevent over at the junction between cingulum & lingual the junction between cingulum & lingual walwall l

A short lingual wall reduces the retention A short lingual wall reduces the retention of the restoration of the restoration

Proximal reduction Proximal reduction

* The shoulder should be at least 1.0 mm wide

* care should be taken to avoid undercuts at the junction of axial walls & the shoulder finish line

Finishing the preparation Finishing the preparation * * All axial surfaces should be smoothed using All axial surfaces should be smoothed using finishing stones & bursfinishing stones & burs

* * Roundation of any remaining sharp line Roundation of any remaining sharp line angles to avoid porcelain fractureangles to avoid porcelain fracture * * Uniform width of shoulder finish line Uniform width of shoulder finish line (approximately 1mm ) to resist forces directed (approximately 1mm ) to resist forces directed from the incisal from the incisal

prepared by : prepared by : Moataz Abodief Moataz Abodief Mostafa El-Sadic Mostafa El-Sadic Nour Mohammed Nour Mohammed Waleed MohammedWaleed Mohammed

Dentistry College ; Assiut UniversityDentistry College ; Assiut University

thanksthanks