Examination of the effect of aging process on marginal fit and fracture strength of temporary crowns prepared from different materials

Aim: This study was carried out to examine the effect of aging process on the marginal fit and fracture resistance of temporary crowns prepared from different materials. Materials and Method: The steel die representing the upper 1st premolar, from which the samples used in the study will be obtained, was prepared on a Computer Numerical Control (CNC) lathe with an anatomical occlusal surface, with a 6 mm crown length and a 1 mm chamfer step at 6° taper angle by standardization. 160 epoxy resin dies were obtained by impressing the prepared die using the conventional impression method. The prepared dies were randomly divided into four groups and the provisional crowns were prepared from different restorative materials (Vita CADTemp®, Dentalon Plus, Protemp 4, Imident). The prepared provisional crowns were cemented with temporary cement and kept in 37°C distiled water for 24 hours. Then half of the specimens (n=20) in each group (n=40) were randomly separated and the aging process was applied 5000 times in the device, which has two distilled water tanks at the temperature of 5 °C and 55 °C and has a mobile mechanism to transport specimens between these water tanks (by holding for 20 seconds in each tank). The marginal gap measurement of all specimens were made on epoxy resin dies with using a stereomicroscope. The fracture strength test of the specimens was performed by using the Instron Universal Test Device. Device. Jamovi 2,2,5 statistical program was used for statistical analysis. The normal distribution of comparisons was evaluated with the Kolmogorov-Smirnov test and the Q-Q plot. Covariance analysis was used to measure the relationship between variables because of the normal distribution. Tukey post-hoc test was applied for multiple comparisons. The significance level was taken as p < ,05 for statistical evaluations. Results: Independently from the aging process, poly acrylic resin (Vita CADTemp®) provisional crowns prepared with Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) showed significantly (p< ,001) lower marginal gap values than all other materials. Independently from the aging process, It has been determined that poly acrylic resin (Vita CADTemp ® ) provisional crowns showed significantly (p< ,001) higher fracture resistance values than provisional crowns prepared from all other materials (Protemp 4, Imident and Dentalon Plus). Also the provisional crowns prepared from PMMA (Imident) showed significantly (p< ,001) higher fracture resistance values than PEMA (Dentalon Plus) provisional crowns. It has been found that the aging process negatively affects the marginal fit and fracture resistance of all temporary crowns. Conclusion: It was found that the marginal gap measurement values and strength of all materials were within clinically acceptable limits. Keywords: Different provisional crown materials, Marginal fit, Fracture resistance