Effect of Sandblasting on the Bond Strength between CAD–CAM Milled Metal Post and Direct Metal Laser-sintered Metal Post: A Comparative in Vitro Study

Abstract

Aim: To assess and compare the bond strength of Co–Cr metal posts fabricated with 2 different techniques: computer-aided design and computer-aided machining (CAD–CAM) and direct metal laser-sintering (DMLS). Materials and methods: Sixty extracted noncarious, human maxillary central incisor teeth with a similar morphology were decoronated 2 mm coronal to the cementoenamel junction (CEJ) and the roots were endodontically treated. Post space was prepared leaving 5 mm of gutta percha within the root canal. Co–Cr metal posts were fabricated according to CAD–CAM and direct metal laser-sintering (DMLS) techniques and were randomly divided into four study groups: group I, CAD–CAM milled metal post without sandblasting; group II, DMLS metal posts without sandblasting; group III, CAD–CAM milled metal post with sandblasting; and group IV, DMLS metal posts with sandblasting. After sandblasting posts were cemented with glass ionomer cement, pull-out bond strength test was performed using a universal testing machine. Using Kruskal–Wallis with post hoc (Mann–Whitney) tests statistical analysis of data was performed. Result: The highest pull-out bond strength was reported in group-IV (mean value = 6.65 ± 3.10 MPa). And the lowest was recorded for group-I (mean value = 4.38 ± 2.69 MPa). No significant difference in pull-out bond strength was found among the different groups (p > 0.05) due to smaller sample size. Conclusion: Within the limitations of this study, results suggest that surface treatment with sandblasting with 50 μm aluminum oxide particles was found to be an effective method for improving the bond between the DMLS and CAD–CAM milled metal posts.