Aim. To investigate the effect of C factor on marginal adaptation of low-shrinking composite (Silorane).The null hypothesis was that the marginal adaptation of “Silorane” is not affected by the cavity configuration. Materials and Methods. A Silorane based and a methacrylate based composites, with their corresponding self-etch adhesive systems “Filtek Silorane/Silorane Adhesive Bond System and Filtek Z250/Prompt L-Pop” respectively were used. Standardized cavities were prepared on the buccal surfaces of 100 maxillary premolars. Teeth were grouped into 5 groups (n = 20), for the 5 C factors. Restored teeth were subjected to thermocycling. Microleakage testing was done and linear dye penetration was assessed using a stereomicroscope. Statistical analysis was done using the Student's t-test. Results. For the methacrylate based systems' overall leakage score was significantly higher than the Silorane-based one (P = 0.034). For the methacrylate-based, leakage was found in all tested teeth groups except group 1 (C factor 1/5). For the Silorane, One-way ANOVA revealed a statistically significant increase in dye penetration in the 5th group (P = 0.010). Conclusions. The null hypothesis was rejected. The Silorane-based resin although it resulted in a statistically significant good marginal adaptation, it showed tendency toward a high leakage score with C-factor of 5.

Reinforcement of ceramics by alumina for In-Ceram and leucite for Empress decreases color production. Level of acceptance between the different ceramic materials and thicknesses varied. DLFC showed the highest color matching at all thicknesses followed by ICS and IPSE in descending order. In general, increasing the thickness of fabricated crowns enhances color match.

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