Comparison of heat transfer through various fixed prosthetic materials during grinding.

Abstract

To measure and compare the mean temperature values due to heat generated during the grinding of different prosthetic materials with diamond burs using a high-speed instrument with and without water cooling. In total, 120 disk-shaped specimens (10 × 2 mm), each with a smaller disk in the center (3 × 2 mm), were fabricated from yttrium-stabilized zirconia, monolithic zirconia, glass-ceramic, indirect composite, polyetheretherketone (PEEK), and cast metal (Ni-Cr alloy). The specimens were divided into six groups (n = 20) according to material type. The specimens in each group were ground continuously with a high-speed handpiece and diamond burs with (n = 10) and without (n = 10) water cooling until the smaller disks were removed. Two different methods (thermocouple and thermal camera) were used to measure the temperature during the grinding process. Results were analyzed using two-way ANOVA and paired samples t test (P < .05). PEEK had the lowest mean temperature values and metal had the highest values, both with and without water cooling, according to data measured with a thermocouple. Zirconia and monolithic zirconia samples without water cooling had the highest mean temperature values when measured with a thermal camera. Both with and without water cooling, composite samples had the lowest mean temperature value for thermal camera measurements. Water cooling is strongly recommended when grinding all prosthetic materials. The heat transferred to the supporting teeth may depend on the thermal conductivity of the material used.