Evaluation of wear of occlusal splint materials produced at different heights using conventional, subtractive and additive manufacturing methods

SUMMARY The purpose of this study; It is the examination of the wear values of occlusal splint materials produced at different thickness by conventional, subtractive and additive manufacturing methods after thermal and mechanical aging in different time periods. Occlusal splint materials obtained from acrylic resin polymerized by heat with the conventional method, resin with 3D printing with the additive method, and PEEK and PMMA blocks with the subtractive method were used in 3 different thickness as 2 mm, 4 mm and 6 mm, 10 samples for each thickness group, 120 samples in total. It is produced in 20 mm diameter. The comparison of the wear values of the samples was compared as a result of applying thermal and mechanical aging for periods corresponding to the clinical time periods of 1 month, 3 months and 6 months after production. The samples were first subjected to a 5-55 oC thermal aging process for a period of 1 month. The thermally aged samples were mechanically aged in a chewing simulator for 20,000 cycles, equivalent to a period of 1 month. The wear of the samples after thermal and mechanical aging for a period of 1 month was transferred to the digital environment with a laboratory scanner. The obtained data was transferred to the Geomagic DesignX reverse engineering program and the volume loss was obtained in mm3 by applying the overlay method with the untreated sample data. The measurement of volume loss due to wear as a result of thermal and mechanical aging for 3 month and 6 month periods was carried out in the same way. Normality tests of the obtained data were checked with the Shapiro-Wilk test. Since the data were not normally distributed, comparisons between groups were made with the Kruskall-Wallis H test and within-group comparisons were made with the Mann-Whitney U test. Comparison of the samples before and after wear was made using the Wilcoxon test. 0.05 was used as the significance level, and if p<0.05 it was stated that there was a significant difference, and if p>0.05 it was stated that there was no significant difference. According to the results of the statistical analysis conducted in our study, in each sample group produced with different production methods, the wear rate in the 6 month period is statistically significantly highest (p<0.05), and the wear rate in the 1 month period is statistically significantly lowest (p<0, 05) was observed. There was no statistically significant difference in the thickness differences between the samples within a 1 month period (p>0.05). During the 3 and 6 month period, no statistically significant difference was observed within the thickness groups of the samples, except for the ProBase material, which was polymerized with heat using the conventional method (p>0.05). In the comparison of materials in the same thickness group in different time periods, the PEEK material produced by the subtractive method showed the statistically significantly lowest wear values (p<0.05), while the PMMA block produced by the subtractive method showed the statistically significantly highest (p<0.05) wear values. There was no statistically significant difference between the occlusal splint materials produced by the conventional method and the additive method (p>0.05).