Evaluation of bond strengths of metal frameworks prepared by different techniques with dental porcelains

Aim: The aim of this study was to evaluate the bond strength of metal frameworks produced by casting, milling, direct metal laser sintering (DMLS), selective laser melting (SLM) techniques with three porcelain. Material and Method: In order to evaluate the bond strength, a total of 240 Co-Cr based metal frameworks were produced by casting, milling, DMLS and SLM techniques according to ISO standards and then three different superstructure porcelains were built on the prepared specimens. Thermal aging was applied to half of the specimens (120 specimens). The three point bending test was applied to evaluate bond strengths of all specimens. All data were evaluated by variance analysis and Tukey multiple comparison test (p<0.05). Results: It was seen that metal frameworks prepared by casting technique had the highest bond strength with porcelain, and there was a statistically highly significant difference between framework production techniques (p<0.001). It was determined that the bond strengths of the specimens prepared by Vita VMK Master and G-Ceram MF porcelain were not statistically different (p>0.05), while the specimens prepared by Vita VM 13 porcelain showed significantly lower bonding values (p<0.001). It was determined that the bond strength values of all specimens were negatively affected by thermal aging (p<0.001). Conclusion: As a result of the study; the best bond strength values were obtained in the casting/Vita VMK Master group in the non-aging specimens and in the casting/G-Ceram MF group in the aged samples. Keywords: Framework preparation techniques, bond strength, porcelain, aging process