Torsional resistance of crowns cemented to composite cores involving three stainless steel endodontic post designs

Abstract

Statement of Problem: There are no studies analyzing the effects of a crown in relationship to torsional resistance for a titanium-reinforced core material supported by a post. Purpose: This study investigated the effects of post design on the torsional resistance of a crown supported by a titanium-reinforced composite core material (Ti-Core) and 3 endodontic posts (AccessPost, Flexi-Post, and ParaPost). Material and Method: Three groups of 10 specimens per group were studied. A total of 30 recently extracted human single-rooted (incisors) teeth with their crowns removed were used. Post holes preparations were created according to manufacturer’s instructions. All posts were cemented using Flexi-Flow with titanium cement. Scotchbond Multi-Purpose bonding system was used as the bonding system for all groups. All cores were fabricated with Ti-Core with titanium core material with hard copper bands as the matrix. The Ti-Core core material was allowed to set for 1 hour. Metal crowns were fabricated and cemented with zinc phosphate cement. Specimens were placed in a special jig and a clockwise torsional force was applied. Torsional force was measured on a Lebow 1102-200 torque transducer and recorded on a Hewlett Packard 7015B X-Y recorder in inch × ounce. A 1-way analysis of variance (ANOVA) was used to test for statistical significance (P <.00l). Results: The torsional values (inch × ounce) were AccessPost 77.2 ± 30.3, Flexi-Post 162.2 ± 51.2, and ParaPost 60.9 ± 28.4. SNK and Scheffé comparison tests revealed that the Flexi-Post group had significantly greater resistance to torque loading than the AccessPost and ParaPost groups, which were statistically similar to each other. Conclusion: Post design has an effect on torsional resistance of a crown supported by titanium-reinforced core build-up and post. The threaded split-shank design of the Flexi-Post dowel offers significantly greater resistance to torsional loading than the passive posts studied. (J Prosthet Dent 2000;84:38-42.)