Flexural Loading Strength of Provisional Restorative Material

Objective: To compare in-vitro five different provisional restorative materials under flexural loading conditions. 

Methods: Teeth #19 and #21 were prepared as abutment teeth for the 3-unit bridge on Typodont (Columbia, NY).  The amount of reduction was approximately 2 mm on the occlusal, 2-2.5 mm on buccal, lingual, and proximal walls, 1-1.5 mm full deep chamfer margin and 15-20 degrees total occlusal convergence.  All line angles were rounded and no undercuts were present on prepared teeth.  A metal cast duplicate was then made from the Typodont as a template in preparation for the provisional bridge restorations. Total of fifty provisional bridges were made with ten samples for each group. Clear acrylic sheet was used as a template for replicating the provisional bridge using a suck-down air-vacuum technique.  The pontic design for the missing tooth #20 was a modified ridge lap.  All samples were then polished with pumice and cemented using TempBond on a metal template prior to testing.  The modified 3 point bending test was carried out using a universal testing machine with 10K (Instron 5566A, crosshead speed 1.0 mm/min).  The initial crack was recorded and testing stopped when it hit a catastrophic failure of the bridge. All the data was recorded in Newtons and analyzed using a one-way analysis of variance (ANOVA). Statistical difference was predetermined at p<.05.

Results: There was a statistical difference within the groups. A Neuman-Keuls pos-hoc showed that Groups 1,2,4 and 5 were significantly higher when compared with Group 3. There was no significant difference between Groups 1,2,4 and 5.

Conclusion: There was no significant difference between Groups 1,2,4 and 5. Group 3 yielded a value that was significantly lower compared to other groups.