Creating Adequate Occlusal Reduction

With the minimum reduction numbers in mind for your occlusal reduction the next step is preparing the tooth. There are two critical steps during preparation that predictably create adequate reduction, knowing the dimension of the burs that you are using and  beginning with depth cuts to create a visual reference once the prep is underway. There are many different burs, both diamonds and carbides that will work to create depth cuts with adequate occlusal reduction. Find something that works for you, in your hands, but chose the bur with intention and have a consistent system for how you use it.

For years I did all of my occlusal reduction with a 330 carbide bur. The classic 330 is 1.5 mm from the tip to the end of the cutting surface. I  drop the bur the full extent of the cutting surface in all of the occlusal pits. Then I  play connect the dots, this assures that I have a depth cut running along the most common place we under reduce, the occlusal grooves. Next I move from the depth of the groove out over the cusps, through the buccal and lingual grooves and over the marginal ridges. This checkerboard pattern of occlusal depth cuts, makes the rest simple. Replacing the 330 with a parallel sided diamond, whose diameter is 1.5 mm or greater, I reduce the remaining tooth structure down until the depth grooves have been eliminated. This technique served me well and assured that I never had less than 1.5 mm of reduction on any of the occlusal surfaces of the prep.

When I began utilizing all porcelain restorations in the posterior, and my minimum reduction changed from 1.5 to 2mm, it was time for a new depth cutting bur. My favorite is the RW2 bur from Brasseler. Designed by Dr. Bob Winter, this bur is a depth cutting diamond and comes in two sizes, 2mm from the shank to the tip and 2.5mm from the shank to the tip. I follow the exact same process as before, dropping the bur into all the pits to its full depth to start and then creating my pattern of depth cuts. I finalize the occlusal reduction with a parallel sided diamond of 2mm in diameter.

Once I have smoothed and polished the prep, using this technique I rarely have to come back in and do additional preparation as a result of a thin provisional, or inadequate reduction when I do my reduction verification.