EFFECT OF INSERTION TECHNIQUES ON THE SHEAR BOND STRENGTH OF LOW-SHRINKAGE (Silorane) COMPOSITE RE-STORATIVE MATERIALS

Abstract

Objective: to evaluate the shear bond strength of low shrinkage (Silorane) based composite with different insertion techniques (layering and bulk) and storage conditions (wet, dry) and compare with conventional methacrylate composites. Materials and methods: 108 specimens were fabricated by used cylindrical shaped mould for SBS test, prepared from three types of composite materials, low shrinkage (Filtek Silorane), and two MBCs resins, Tetric EvoCeram, and Filtek Supreme resin composites, subdivided to 12 groups according to insertion technique (layering, bulk) and the storage condition (wet, dry at ±37℃ for one week) (n=9/groups). The SBS were measured with a crosshead speed of 0.5 mm/min. Ultimate shear strength data (MPa) from all tested groups were submitted to analysis of variance (one-way ANOVA) and the Tukey test (p = 0.05). The fractured surfaces of the test samples were visually evaluated by a light microscope at 20 and 40 times magnification. Fractures were classified as either adhesive or cohesive or mixed. Results: Filtek Supreme (MBCs) specimens inserted in bulk technique and stored dry showed the highest mean SBS (36.45 MPa) values. Silorane and Tetric Ceram (MBCs) were lower in their all groups (26.45, 26.78, 27.50 MPa for Silorane, 27.51, 27.02, 27.29, 28.21 MPa for Tetric Ceram resin specimens) except for Silorane specimens inserted in layers which was further decreased by wet storage (21.90 MPa), this was slightly similar to the result of Filtek Supreme specimens inserted in layers and stored dry, which showed the lowest (21.35 MPa) SBS among the groups. Conclusion: insertion technique type and storage condition didn’t significantly affect SBS of Silorane resin in compare with methacrylate resin, except for the specimens inserted in layers and wet condition, there was a significant decrease in SBS values. This finding support the clinical reliability of insertion the Silorane composite in bulk with a cavity deeper than 2 mm depth.