A Study To Evaluate Tooth Preparation Of Teeth Prepared To Receive Fixed Bridges Using 3D Scanner, In Vitro Study.

Abstract

Background and Aim of study: The long term success of any fixed partial denture is related to the proper retention and resistance form of the abutment teeth. This study aimed to evaluate the abutment's taper and parallelism of some posterior abutment teeth prepared clinically to receive fixed partial dentures using a 3D scanner.

Materials and methods:  The final casts of twenty five posterior bridges each containing two abutments were the subject of this study.  A total of 50 dies were scanned using Ceramil Map 100 dental 3D scanner (Amann Girrbach, Vorarlberg, Austria). A 3D viewer software (MiniMagics2.0) was used to examine and measure the abutments on the computer screen. The wall taper of each abutment and the abutment's parallelism in both bucco-lingual and mesio-distal directions  were measured.

  Results: The abutments were not parallel in   mesio-distal direction by an average of  10.63°while in the bucco-lingual direction they were not parallel by an  average of  7.24°; this  difference was not statistically significant (P=0.137). The average taper of the anterior abutment of each bridge was 19.56° in mesio-distal direction and 21.32° in bucco-lingual direction.  In the posterior abutments the average taper in both directions was more than that on the anterior teeth, 25.14° and 28.44° respectively, and the difference was  statistically significant(P= 0.004).

Conclusion: The taper of the prepared teeth in this study were comparable to the values reported in earlier studies. However, the posterior abutments were mostly over tapered. In most cases, parallelism between the abutments was not achieved.

Recommendations: The dentist should attempt to decrease the taper of tooth preparations when the span is long and the abutments short.