Ideally the gingival floor should have a clearance from the adjacent tooth of
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1. Tooth preparation for class II amalgam restorations and its modifications
2. INTRODUCTION Amalgam although a brittle material, has been adequately serving as a restorative material since 175 years, understanding of its properties and judgment of the preparation design are the vital factors controlling its use. 2
3. 3 Class II Restorations. It is defined as a cavity that is present on the proximal surfaces of premolars and molars. ( G.V .BLACK ) DEFINITION
4. 4 INDICATIONS for using amalgam as restorative material Moderate-to-large restorations. Restorations that are not in highly esthetic areas of the mouth. Restorations that cannot be well isolated. Restorations that have heavy occlusal loads. Temporary and caries control restorations. Foundations. Restorations that extends onto root surface.
5. 5 Line angles and point angles 6 point angles 11 line angles Tooth preparation walls- Facial (proximal and occlusal portion) Lingual (proximal and occlusal portion) Gingival Pulpal Axial Distal / Mesial
6. INITIALCLINICAL PROCEDURES Marking the occlusal contacts with articulating paper . These contacts serve as guide in tooth preparation and restoration. Recontouring of any opposing “plunging cusp" or other pointed cusp to reduce the risk of fracture of the new restoration or the cusp from occlusal forces. For amalgam , the placement of rubber dam is generally recommended. 6
7. Burs used in class Ⅱtooth preparation 7 Width 0.8 mm & Length 3 mm
8. INITIAL TOOTH PREPARATION OUTLINE FORM Tooth preparation for caries on proximal surface should have occlusal outline such that it allow access to proximal lesion, remove demineralized enamel and dentin, and remove enamel not supported by sound dentin. If an occlusal carious lesion is present, it should be treated with a separated occlusal restoration. If the proximal and occlusal lesions are in close proximity so that there is minimal or no sound tooth structure separating the two preparations, they should be joined. 8
9. Mesio-occlusal class II preparation Occlusal outline form: Enter the pit nearest the involved proximal surface with a punch cut using a No. 245 bur. Viewed from the proximal and lingual aspects, the long axis of bur should be parallel to the long axis of tooth crown during cutting. 9 Bur position for entry;proximal view
10. 10 • Proper depth of the initial entry cut is 1.5-2mm.The pulpal depth is usually 0.1-0.2 mm in to the dentin. While maintaining the same depth and orientation ,bur is moved to extend the outline to include the central fissure and opposite pit ,if necessary. Completed occlusal step Occlusal view