Methods: Sixty provisional bridges were made (n=15 each group) using: Group 1-Protemp™ Plus (3M ESPE), Group 2-Luxatemp® Solar (DMG), Group 3-Integrity® (Dentsply Caulk), Group 4-Visalys® Temp (Kettenbach). Teeth #19 and #21 were prepared as abutments for the 3-unit bridge on Typodont (Columbia, NY). Approximate reduction amount was 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. A metal cast duplicate was made from the Typodont as a template for provisional bridge restorations.
Polyvinyl-siloxane impression material was used as a template for fabricating the provisional bridge. The pontic design for missing tooth #20 was a modified ridge lap. All samples were polished with pumice and cemented using TempBond® (Kerr) on a metal template prior to testing.
The modified 3-point bending test was carried out using a universal testing machine (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. Data was recorded in Newtons. Statistical analysis was conducted using a one-way analysis of variance (ANOVA) with post hoc Tukey HSD Test for pairwise comparison. Statistical difference was predetermined at p<.05.
Results:
Group (n=15) |
Mean Flexural Loading Strength (N) |
Standard Deviation |
1 |
573.94 |
198.11 |
2 |
296.22 |
92.13 |
3 |
307.38 |
106.79 |
4 |
458.35 |
132.71 |
Groups 2 and 3 were statistically lower than Groups 1 and 4. There was no statistical difference between Group 2 and 3 (p= 1), nor between group 1 and 4 (p= 0.11).
Conclusion: Strength testing resulted in Group 1 being comparable to group 4. Both groups 1 and 4 were significantly higher than groups 2 and 3. Initial mode of failure was observed on the junctions between abutment crowns and pontics. Fracture resistance in provisional bridges may have clinical implications in the success of final restorations.