Instrumentation for solving abutment parallelism problems in fixed prosthodontics.

Casts from a number of preparations by dentists with a variety of fixed prosthodontic experience levels were surveyed, and the preparations were commonly found to contain undercuts, overtapered surfaces, and lack of a parallel path of insertion. A new instrumentation for preparing abutment teeth was examined, which eliminated the common inaccuracies caused by traditional techniques of using freely held handpieces and visually assessing the finished preparations. Three clinical preparation procedures were discussed. Each patient posed particularly demanding problems that required precise tooth preparation. Each completed prosthesis was readily inserted in the mouth due to the unobstructed uniform path of insertion. Keyways were not required in any of the prostheses.