A theoretical and clinical investigation into the taper achieved on crown and inlay preparations

The minimum angles of taper that can in theory be formed to various preparations were established for representative dental preparations and operating distances. These values were compared with the taper of dental preparations formed both under laboratory conditions and in clinical practice, the latter by measurement of taper on the dies of clinically successful crowns and inlays. A possible explanation for the discrepancy noted between recommended degrees of taper and the tapers produced under clinical conditions was considered to be due to the requirement by a dental surgeon to avoid forming undercuts to the line of withdrawal of a cast intracoronal or extracoronal retainer.