Temperature rise during polymerization of three different provisional materials

The purpose of this study was to evaluate the temperature rise during polymerization of three different provisional materials by direct method on two different dentin disc thicknesses. Two autopolymerizing; bis-acrylic composite (Fill-in; Kerr), polymethyl methacrylate (Temdent; Weil Dental), and one light polymerizing composite (Revotek LC; GC) provisional restoration materials were used in this study. Sixty dentin discs were prepared from extracted molars (diameter, 5 mm; height, 1 or 2 mm). These dentin discs (1 or 2 mm) were placed on apparatus developed to measure temperature rise. The temperature rise during polymerization was measured under the dentin disc with a J-type thermocouple wire that was connected to a data logger. Statistical analysis was performed with two-way analysis of variance followed by Tukey HSD test (α = 0.05). Temperature rise values statistically varied according to the provisional restoration material used (light polymerized, auto polymerized; P  < 0.001) and the dentin thickness (1 and 2 mm; P < 0.001). The polymethyl methacrylate based provisional material induced significantly higher temperature rise than other provisional restoration materials at 2-mm dentin thickness (P < 0.01). At 1-mm dentin thickness, polymethyl methacrylate and composite induced significantly higher temperature increase than bis-acrylic composite provisional material (P < 0.05). The risk for heat-induced pulpal damage should be taken into consideration during polymerization of provisional materials in deep cavities in which dentin thickness is less than 1 mm.