Effect of repeated firings on the marginal and internal adaptation of implant supported metal ceramic restorations fabricated with different thicknesses and fabrication method

Aim: The aim of this study was to compare the effects of repeated firing cycles on the marginal and internal adaptation of metal copings with different thicknesses fabricated using casting, LS, PYMF, PSMF, and TF methods. Materials and Methods: A total of 120 single-unit implant-supported copings were fabricated using casting, LS, PYMF, PSMF, and TF methods with 0.5 mm and 1.5 mm thicknesses for each group and porcelain was applied in accordance with the manufacturer's instructions (n=12). The marginal and internal adaptation of the metal copings were examined before the firing cycles and after the 4th and 7th firing cycles using a silicon replica technique with a stereomicroscope at x80. The results were analyzed using 3-way analysis of variance for repeated measurements on a single factor, 2-way analysis of variance and an independent samples t-test (p<0.05). Results: As a result of the repeated firing cycles, the changes in the KA and IA values ​​in the PYMF, PSMF, and TF groups and the change in the IA value in the casting group were statistically significant (p<0.05). The interaction of firing, method, and thickness difference on the KA and İA values was not statistically significant (p>0.05). Conclusion: After the firing cycles, the PYMF, LS, and TF groups were found to have better marginal and internal adaptation for both thicknesses than the casting and PSMF groups. Furthermore, the KA values of all the metal-ceramic restorations were found to be below the maximum clinical acceptability discrepancy (<120 μm).