How Much Is .1mm?

I have a pet peeve. It has to do with prepping teeth. I still remember my operative instructor in junior clinic telling me to “drop that proximal box 1/4 mm.” I don't know about you, but 1/4 mm is very hard for me to see. It was hard when I was a 23-year-old dental student and is even harder now at 56, even with magnification.

I have been confused in recent years by all the new ceramics and the myriad of recommendations for tooth preparation for each of these materials. I am all for conservative tooth preparation. I am also all for keeping my life simple. I discuss materials with my ceramist and let him decide what will work best in the situation we are trying to solve, and then I cut the teeth. If the restoration is full coverage with glass, I cut a shoulder with a rounded internal line angle and I cut them all the same – about 1.5mm minimum reduction at the margin. If it is a veneer, I break contact unless under extreme duress.

Here is my thinking: if I can cut the tooth then I am cutting the tooth! I don't think saving 0.1 – 0.2mm or a contact will make much difference over the lifetime of the patient, but it will definitely make a difference in my ability to provide the best result possible.

Yes, my feldspathic veneer preps are more conservative than those for pressed. Yet I have seldom had my ceramist tell me I overprepped a tooth. Believe me, he loves having extra room for porcelain!

I want my work to be predictable and I like to use the fewest diamonds and burs I can. I don't want to make prepping any more difficult than it already is, so I just keep it simple. I will be criticized for my cavalier approach, but when I heard Bob Winter say a similar thing in our restorative design course I figure I am in pretty good company.