CAVITY PREPARATIONS. Cl ™ : - Pits and fissure caries - Upper anterior teeth palatal pits -...

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Transcript of CAVITY PREPARATIONS. Cl ™ : - Pits and fissure caries - Upper anterior teeth palatal pits -...

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CAVITY PREPARATIONS Slide 2 Cl : - Pits and fissure caries - Upper anterior teeth palatal pits - Posterior teeth occlusal surface Cl : Posterior teeth proximal surface Cl : Anterior teeth proximal surface ( not involving the incisal angle ) Cl V: Anterior teeth proximal surface involving the incisal angle Cl V: All teeth cervical 1/3 Slide 3 Slide 4 Slide 5 Cavity preparation stages and steps: Initial stage steps: 1. Out line form and initial depth 2. Primary resistance form 3. Primary retention form 4. Convenience form Final stage steps: 5. Removal of infected dentin and old restoration 6. Pulp protection 7. Secondary resistance and retention form 8. Finishing extrenaal walls 9. Final cleaning,inspecting,varnishing and conditioning. Slide 6 Step 1:( Out line form) - Mental image 1 st depth rough out line alter by seeing hidden problems. - Remove weakened enamel - Preserve cusp and marginal ridge strength - faciolingual extention - Connect two close cavities - dentin depth.2 -.8 mm - Care for D.C extension, esthetic, occlusion and cavosurface margin. Slide 7 Slide 8 Slide 9 Slide 10 Slide 11 Slide 12 Step 2:( Primary resistance form) - Flat floor - extension - Rounding internal line angels - Cap weak cusps - Provide enough thickness for restorative material - Box shape - Preserve cusps and marginal ridge - Care for occlusion, remaining tooth structure amount and restorative material type. Slide 13 Slide 14 Step 3: (Primary retention form) - Occlusal dove tail ( Cl ) - Composite mechanical bond with tooth. - Amalgam: * Cl walls converge occlusally *Cl and Cl V retention grooves *Adhesive systems Slide 15 Step 4: (Convenience form) - Observation - Accessibility - Ease prepare and restore Slide 16 Step 7: ( Secondary resistance and retention form ) - Cavity wall conditioning by etch enamel and dentin bonding agents - Mechanically: * Retention grooves and locks * Pins, slots and steps * Bevel enamel margins Slide 17 Step 8: (Finishing extrenal walls ) - Create: * Good marginal seal between tooth and the filling material *Smooth marginal junction * Maximum strength to tooth and the filling material - Care for * Enamel rod direction and support ADJ and laterally. * Margin location * Filling material type cavo surface angel: a. Amalgam: 90 maximum strength of tooth and Amalgam b. Gold: bevel provide marginal metal ease burnishing and adaptation Slide 18 Step 9: (Final cleaning,inspecting,varnishing and conditioning). Cleaning by remove debris and smear by citric or polycarboxilic acid Slide 19 New modified cavity preparation techniques: Slide 20 Box only preparation - Small D.C - Facial a lingual proximawalls occlusal convergence - Locks 0.5 mm depth in gingival point angels then decrease occlusally - ( retention ) Slide 21 Tunnel preparation - Proximal D.C - Marginal ridge intact - access and visibility Slide 22 Slot preparation: - At root - Approach facial and lingual - High speed bur 2, 4 - Out line form : limited pulpal depth 0.75 1 mm gingivally and 1 1.25 mm occlusaly ( enamel ) - In facial approach : * Lingual wall face facially as much as possible * Provide access, visibility and convenience * Help in Amalgam condensation - Remove remaining D.C by bur 2, 4 - External walls 90 cavosurface angel - Retention grooves by bur 1/4 in occlusal and gingival walls at axial line angels, with 0.25 mm depth Slide 23 Slide 24 Sandwich technique: - G.I.C under composite - G.I.C bond to tooth and composite retention and seal. - F D.C Slide 25 Bonded amalgam: - Same preparation - Retain weakened remaining tooth structure - Need special adhesive materials Slide 26 Adjoining restorations: - Can repair or replace existing Amalgam filling defective part if the remaining Amalgam filling is good - Adjoining restoration on occlusal surface coz new restoration dove tail can be prepare without eliminating existing restoration dove tail - May prepare Amalgam filling in two or more phases ( eg. Cl lesion continued with Cl V, so 1 st prepare and restore Cl before Cl V ) Slide 27 Slide 28 Composite cavity preparation Slide 29 cavity preparation designs: - Conventional - Beveled conventional - Modified - Combination of the above three Slide 30 Conventional : - Past design - Out line form : * Extend external walls to initial limited uniform dentin depth * External walls follow enamel rod direction * External walls on root meet root surface at right angel - Dentin retention grooves - For materials like ( Amalgam, silica, porcelain ) ( brittle and edge strength ) - Not preferred for composite - For composite if lesion at root ( non enamel areas ) Slide 31