Abstract :Purpose: Different procedures and materials have been introduced for fabrication of prostheses. The present study aimed at comparing the retention of implant-supported frameworks casted from two different types of patterns (wax and acrylic resin).
Materials and Methods: Twenty-four implant analogues were mounted in acrylic blocks, a solid abutment were secured on each analogue, and the samples were divided into two groups (N = 12). Die spacer was applied with specified thickness of 30 microns, up to 0.5 mm from the finish line. Frame patterns were fabricated using wax or acrylic resin material with a loop formed on the occlusal surfaces. The samples were casted, and adjusted for complete seating on the abutments. The numbers of adjustment times were recorded and analyzed through Mann-Whitney test. After cementation with zinc phosphate cement, the specimens were thermo cycled (between 5ºC and 55ºC, 5000 cycles), and the retention was measured using universal testing machine connected to the occlusal loop (0.5 mm/min). The results were analyzed using independent sample t-test.
Results: The mean retention (standard deviation) value was 407.234 (67.485) N for wax group, and 576.187 (98.673) N for acrylic formed group. There was significant statistical difference between the frameworks retention in two groups (P< 0.05). Furthermore, significant difference was noted in the quantity of adjustment times between the groups (P< 0.05).
Conclusion: Considering the limitations of the present study, although acrylic specimens required significantly more adjustment time compared to the wax-formed patterns, the retention quantity was significantly more in the former.