Temperature-influenced dimensional change of different molar anatomical areas

Objective To analyse the linear coefficient of thermal expansion (LCTE) of different tooth regions using thermal mechanical analysis (TMA). Methods Specimens (n = 12) were sectioned from different anatomical areas from recently extracted molars using a slow-speed diamond saw. During analysis the specimens were kept saturated with phosphate-buffered saline using a specially designed quartz container that was placed inside the TMA unit. Specimens were subjected to a 15-50 °C heating cycle as well as a 50-15 °C cooling cycle at a 5 °C/min rate. LCTE was determined using the slope of each respective cycle with each specimen being run three times with the mean representing the LCTE of each specimen. Mean results between heating and cooling for each sample were compared with paired t-test while results between regions were compared with ANOVA and Tukey post hoc (p = 0.05). Results Significant differences in LCTE were noted between tooth regions with caries-affected dentine, cervical, and root surfaces exhibited significantly lower LCTE. Furthermore, cooling LCTE was significantly greater than heating in all areas. Conclusions Under the conditions of this study, molar LCTE was found not to be uniform in all areas. Furthermore, cooling LCTE was found to be greater than heating.