Class V. cavity preparation and restoration ONLAY

Class V. Cervical caries usually develops because the affected tooth surface is unclean Location: mainly vestibular, sometimes lingual surfaces Between the marginal gingiva and the largest convexity of the enamel

Poor oral hygene Poor brushing, wrong brushing technique cervicalPlaque accumulation

class V. cavity preparation The outline for the class V cavity preparation is primarily determined by the location and size of the carious area Round or tapered fissure bur of suitable size enter the carious lesion Mainly bean or kidney shape bur’s depth can be related to the original tooth contour Extend the preparation incisally, gingivally, mesially, and distally untill all external walls are positioned in sound tooth structure at pulpal depths ranging from 0,75 mm at the gingival wall to 1.25 mm at the incisal wall The axial wall follows mesiodistally the contour of the facial surface of the tooth

Class V. cavity preparation The axial wall will be convex mesiodistally The axial wall will be slightly shallower pulpally at the gingival wall with little or no enamel (approximately 0.75 to 1mm in depth) than at the occlusal wall with more enamel (1 to 1.25mm in depth)

Removal of any remaining dentin Round stainless steel bur Low speed

Pulp protection Apply appropriate base: axiopulpal wall should be covered Polycarboxilate cement Glass ionomer cement

Retention form The mesial,distal, gingival, and occlusal walls of the cavity preparation being perpendicular to external tooth surface, diverge outward, thus retention form must be provided Two retention grooves :mostly occlusally, and gingivally along the occlusoaxial, and gingivoaxial line Depth of the grooves should approximate 0.25mm Alternatively four retention coves may be prepared, one each in the four axialpoint angles of the preparation

Final procedures of cavity preparation Cleaning the cavity Inspecting Finishing external walls (suitable hand instruments: chisels or margin trimmers) Not to leave unsupported enamel

Insertion of amalgam Class V amalgam restorations are placed without the use af any type of matrix Using the amalgam carrier, insert the mixed amalgam into the preparation in small increments Condense first into the retention areas with an appropriately sized condenser Next condense against the mesial and distal walls of preparation Finally build the central portion to sufficient bulk to allow for carving

Carving and contouring restoration Removing excess immediately Carving should be done paralell to the margins, using the side of the explorer tine or the Hollenback carver Locate occlusal, mesial, distal finally the gingival margins and carve away the excess Facial contours may be increased only enough to prevent food impaction into gingival sulcus

Finishing and polishing the surface of the restoration Necessary to correct a mrginal discrepancy, or correct the contour Polishing of high copper amalgam s is unnecessary Not attempted within a 24 –hour period following insertion Should be perfect continuity of surface contour

Class VI. Class VI. cavity preparation is used to restorate: Incisal edge of anterior teeth Cusp tip regions of the posterior teeth Attritional wear has removed the enamel, and expose the underlaying dentin Hypoplastic cusp pit

Class VI. cavity preparation Enter the area with a small fissure bur Depth of 1.5mm is sufficient to provide bulk of material for srength Retention of restoration is ensured by the creation of small undercuts along the internal line angles Not to remove dentin supporting the enamel