Evaluation of bond strength of silorane and methacrylate based restorative systems to dentin using different cavity models

Objectives: the aim of this in vitro study was to evaluate the microtensile bond strength (μtbs) to dentin of two different restorative systems: silorane-based (p90),and methacrylate-based (p60),using two cavity models. material and methods: occlusal enamel of 40 human third molars was removed to expose flat dentin surface. class i cavities with 4 mm mesial-distal width,3 mm buccal-lingual width and 3 mm depth (c-factor=4.5) were prepared in 20 teeth,which were divided into two groups (n=10) restored with p60 and p90,bulk-filled after dentin treatment according to manufacturer's instructions. flat buccal dentin surfaces were prepared in the 20 remaining teeth (c-factor=0.2) and restored with resin blocks measuring 4×3×3 mm using the two restorative systems (n=10). the teeth were sectioned into samples with area between 0.85 and 1.25 mm2 that were submitted to μtbs testing,using a universal testing machine (emic) at speed of 0.5 mm/min. fractured specimens were analyzed under stereomicroscope and categorized according to fracture pattern. data were analyzed using anova and tukey kramer tests. results: for flat surfaces,p60 obtained higher bond strength values compared with p90. however,for class i cavities,p60 showed significant reduction in bond strength (p<0.05). no statistical difference between restorative systems was shown for class i cavity model (p>0.05),or between class i cavity and flat surface group,considering p90 restorative system (p>0.05). regarding fracture pattern,there was no statistical difference among groups (p=0.0713) and 56.3% of the fractures were adhesive. conclusion: it was concluded that methacrylate-based composite μtbs was influenced by cavity models,and the use of silorane-based composite led to similar bond strength values compared to the methacrylatebased composite in cavities with high c-factor.