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Similaire à 汞齊的窩洞修形 0
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汞齊的窩洞修形 0
- 2. Instrument of cavity preparation • High speed small round bur,fissure bur,inverted cone bur.(carbide or diamond) • Low speed round bur.(carbide) • Hand cutting instrument
- 3. Step of amalgam cavity preparation • In shallow cavity,outline form design should be considered first. • In deep cavity,convinience form and remove of deepest part of carious dentin must perform before any other step of cavity prepared.
- 4. Cavity preparation(I) • Cavity depth 1.5 mm or beneath DEJ 0.2 mm. • Isthmus width equal 1/3-1/4 B-L cusp width. • Cavity width should less than ½ of B-L cusp width. • Buccal-lingual converge and mesial-distal diverge. • Marginal ridge should preserve of 1.6 mm. • Pulpal wall parallel to occlusal plane. • Not involved oblique and transverse ridge, if it is unnecessary.
- 13. Criteria of carious dentin removed • Remove unminerized dentin with excavater or low speed round bur. • Tiny white powder without stagnation on bur surface. • Light reflect over dentin surface.
- 22. Cavity preparation(II) • Trunket cone in proximal box. • In Class II cavity , proximal clearance 0.2 mm, gingival clearance 0.5 mm. Reverse curve in buccal surface. • Axiopulpal line angle should be rounded or bevel, gingival line angle beveled. • Gingival wall width should be 0.8-1.2 mm.