Shear bond strength of provisional repair materials bonded to 3D printed resin

BACKGROUND/PURPOSE: There is limited literature on the materials of choice and their properties when repairing 3-D printed resin-based restorations. The objective of this in-vitro study is to determine the shear bond strength of various repair materials to 3D printed SLA (stereolithography) resin. MATERIALS AND METHODS: For Group A (control), fifteen cylinders of 3-D printing SLA resin were printed as one unit of a Ø6.8 × 8 mm (diameter and height) cylindrical block with a Ø3 × 5 mm cylindrical block at the center. For the test groups, forty-five specimen cylinders of 3-D printing SLA resin (Ø6.8 × 8 mm) were fabricated and the surfaces were treated with 3 different test materials: Group B: Poly-Methyl Methacrylate (PMMA); Group C: Bis-acrylic composite resin, and Group D: Bis-GMA composite All specimens were tested using an Instron machine at a crosshead speed of 0.5 mm/min. A Shapiro–Wilk test was used to assess normality within the data, then the data was statistically analyzed by a Mann–Whitney test. RESULTS: There were no statistically significant differences between testing groups, except Group A. Group B displayed mixed (87%) and adhesive (13%) failure at the fractured surface. Group C showed both mixed (60%) and adhesive failure at the fractured surface (40%). All Group D showed mixed fracture patterns, partly cohesive fractured surface within the base cylinder area and partly adhesive fractured surface at the bonded interface. CONCLUSION: No statistically significant differences in the shear bond strength of the different repair materials to 3D printed cylinders were observed. The 3D printed cylinder repaired with Bis-GMA composite demonstrated the most predictability from the fractography analysis.