As a clinical instructor, one of the most frequent questions I get is, “How do you prepare a tooth for a crown faster?” My first response is usually, “it’s repetition that gets you faster” but what really helps most young doctors is to have a systematic approach to their preparation. In a broader sense, having a systematic approach to every procedure will help increase your speed for each of those procedures. As for crown preps, here is my approach:
1) Break contact with a small or thin bur. I use a 329 carbide but you could use a flame diamond bur as well. The thought here is to remove the risk of damaging the adjacent teeth and clear a path for your “shoulder” bur.
2) Reduce the occlusal or incisal portion of the tooth. I use the same bur that I am going to prep the shoulder with, a 847KR-016C. We are not checking for clearance just yet but rather shortening the tooth so we have less tooth to prepare.
3) Place your shoulder on all tooth structure that is in your direct vision. I like to use a coarse bur with a slight taper, the 847KR-016C. For instance, if I am prepping tooth #30 (as a right-handed operator) I can see all of the buccal surface as well as both interproximal areas, so this is what I prep first. I don’t make big sweeping motions but rather prep a small area and then move on. Once the buccal and interproximal shoulders are prepared, now extend the shoulder around the transitional line angles; still using direct vision. You want to make sure you have enough reduction on these line angles. Now that more than ¾ of the shoulder is prepared it’s time to move to indirect vision and prepare the lingual shoulder. At this point, the shoulder preparation on the lingual has been reduced to just connecting the mesial and distal line angles.
4) At this point there is a rough outline of the shoulder and the occlusal reduction. Now it’s time to finalize the dimensions you need for the specific material you have selected for the final restoration. For the occlusal reduction, I use a coarse 811.033. This bur mimics the contour of the occlusal table. Reduce to the depth you need. I will also smooth out the “third plane” which is usually a sharp edge on the immediate buccal and lingual of the occlusal table. Finally, I will use 847.016 finishing bur to smooth out the shoulder to the final dimensions as well as round any sharp areas of the prep.
This systematic process for a crown preparation should help you with reducing your speed while allowing you to refine your skills to prepare teeth the same each time.