Effect of radiotherapy on the artificial acrylic resin tooth bond to the acrylic resin denture base.

This study aimed to evaluate the fracture resistance of the bond between an artificial acrylic resin tooth and its acrylic resin denture base after radiotherapy with maximum therapeutic doses of 40 and 70 Gy. Sixty wax blocks were fabricated with heights of 4.0 cm and bases with dimensions of 1.0 cm2 and 1.8 cm2. A posterior acrylic resin tooth was placed on each wax block on the base with the smallest area. Thirty of the blocks were thermopolymerized using the conventional technique and 30 using the microwave technique, and the blocks were divided into 6 groups (n = 10): 1 (control, conventional) and 2 (control, microwave) did not receive radiation; 3 (conventional) and 4 (microwave) received a total dose of 40-Gy radiation; and 5 (conventional) and 6 (microwave) received a total dose of 70 Gy. The groups of 40 and 70 Gy received fractional doses of 2 Gy per day, 5 days per week, until their respective total dose was completed. During the study, all specimens were stored in ballistic gel at a temperature of 37ºC. After the radiotherapy treatments, the bonds between teeth and bases in all groups were submitted to a fracture resistance test. Analysis of variance and Tukey test (P < 0.05) verified no statistically significant differences between groups 1 and 3 (P = 0.727), 2 and 4 (P = 0.537), or 4 and 6 (P = 0.727). However, there were statistically significant differences between groups 3 and 5 (P < 0.001), 5 and 1 (P = 0.006), and 6 and 2 (P = 0.034). Therefore, for both polymerization techniques, the maximum radiation dose of 70 Gy weakened the bond between the acrylic resin tooth and its acrylic resin base.