A STEP-BY-STEP PROCEDURE FOR CLASS II INLAY CAVITY PREPARATION

Step 1. Anesthetic is administered and an extra heavy dam is placed.

Step 2. Removal of previous restorations and caries is accomplished. Check for oblique dentinal cracks under cusps. Leave undercuts.

Step 3. A film of calcium hydroxide is placed over the pulpal and axial walls with a small cotton pellet and then retention potholes are placed with a 34 inverted cone bur or 1/2 round bur, if needed to retain 'block-out' material.

Step 4. Composite 'block-out' material is placed in cavity preparation, if necessary. The use of an old bur to rough out the cavity preparation in composite is recommended because the composite will dull the bur quickly. The axial and pulpal walls depth may now be controlled.

Step 5. The occlusal outline and pulpal floor are established with a new straight fissure bur. An even taper of approximately 10 degrees is established with a #56 bur for bicuspids and a #57 bur for molars. Plane and smooth the pulpal floor with the end of the bur.

Step 6. A flat smooth gingival floor and a tapered axial wall of proper depth is established simultaneously with the same bur that was used in Step 5.

Step 7. The proximal wall draw and flare is established by uprighting the bur to parallel the long axis of tooth and then by leaning the bur and moving it diagonally pass the adjacent tooth. All walls must draw and the proximal flare must extend past the contact areas of the adjacent tooth both on the buccal and lingual for ease of finishing.

Step 8. The buccoaxial and linguoaxial line angles are placed in the distal proximal box of the tooth with a #42S off-angle chisel (15-10-16).

Step 9. The axial wall is smoothed and line angles are sharpened in the distal proximal box as well as smoothing the pulpal floor with the #42S chisel.

Step 10. The buccoaxial and linguoaxial line angles are placed in the mesial proximal box of the tooth with a #43S off-angle chisel (15-10-16).

Step 11. The axial wall is smoothed and line angles are sharpened in the mesial proximal box with the #43S chisel.

Step 12. The external gingival bevel is placed on the distal with a #232 Tucker gingival margin trimmer (10-98-10-16) forming a 60 degree bevel.

Step 13. The external gingival bevel is placed on the mesial with a #233 Tucker gingival margin trimmer (10-78-10-16) forming a 60 degree bevel.

Step 14. The occlusal bevel is placed with a straight fissure bur, (approximately 5 degrees more taper than the occlusal walls). The occlusal bevel is used to remove any irregularities and loose enamel rods at the cavosurface which will give the resultant restoration a nice flowing and more pleasing outline.

Step 15. Straighten the proximal walls and smooth the cavosurface margin, if space permits, with a 1/2 inch medium garnet disc. If the access is not sufficient for a disc, a #42S or #43S chisel also can be used.

Step 16. Use a sharp carbon G-5 explorer to sharpen and crisp all existing line and point angles of the preparation.

Note: An internal bevel is placed in most two surface Class II cavity preparations on bicuspids at the gingivoaxial line angle with a #232 gingival margin trimmer for a MO and a #233 gingival margin trimmer for a DO, prior to the planing and smoothing of the axial wall and the placement of the external gingival bevel. This bevel should be about 30 degrees. A preparation is defined with the bur; that is, the preparation meets all the requirements necessary for a precise casting to be fabricated - proper depth, smooth tapered walls and smooth floors and draw.

A preparation is refined with hand instruments; that is, those steps not able to be done with a bur. If each step of the preparation is done the best that it can be accomplished; then, when the steps are completed, the preparation is done.