Effect of Thermocycling, Teeth, and Polymerization Methods on Bond Strength Teeth-Denture Base

Abstract

Objective. To evaluate the shear bond strength between different artificial teeth and denture base polymerized by two polymerization methods submitted to thermocycling. Materials and Methods. Two acrylic resins were selected according to the polymerization method (water-bath and microwave), and four different artificial teeth (Biotone, Dentsply; Trilux, Vipi Dent; Premium 8, Heraeus Kulzer; Soluut PX, Yamahachi) were also tested. The polymerization of the acrylic resin was performed by using conventional cycle (8 h at 74°C) in water-bath and using two cycles (20 min at 270 W + 5 min at 360 W) by the microwave method. The shear bond strength was evaluated after 24 h of water storage at 37°C (immediately) and after the thermocycling test (5,000 cycles, 5–55°C). The shear bond strength (n=10) was performed using a universal testing machine (Instron 4411) at a crosshead speed of 1.0 mm/min. Modes of failures were classified as cohesive and adhesive. The data (MPa) were statistically analyzed by three-way ANOVA, and the mean values were compared by the Tukey test (α = 0.05). Results. In general, the polymerization by microwave showed the highest shear bond strength values, and Trilux artificial teeth had the lowest bond strength values (p<0.05). Thermocycling did not affect the shear bond strength (p<0.05). There was a predominance of cohesive failures for all groups. Conclusions. The chemical composition of the artificial teeth affects the bond strength, and the microwave method is preferable to perform the acrylic resin polymerization.