Evaluation of Enamel and Dentinal Microleakage in Class II Silorane-Based and Methacrylate-Based Resin Composite Restorations Using Specific and Nonspecific Adhesives

The aim of this study was to evaluate enamel and dentinal microleakage in Class II cavities restored with silorane- and methacrylate-based resin composites using specific and nonspecific adhesives.
Thirty-six caries-free human premolars were used. Two Class II cavities were prepared on each tooth. The gingival floor was set at 1 mm above (on the mesial surface) and at 1 mm below (on the distal surface) the cementoenamel junction (CEJ). The samples were randomly divided into four groups, and the cavities were restored with a methacrylate-based composite (Filtek™ P60) and a silorane-based composite (Filtek™ P90) with specific and nonspecific adhesives. Microleakage was tested using a standardized dye penetration method. All samples were examined under a stereomicroscope, and microleakage scores were statistically analyzed using Kruskal-Wallis and Mann-Whitney-U tests. One sample from each group was examined under a scanning electron microscope (SEM) to determine the bonding area.
No significant difference was found between the groups in terms of the enamel microleakage (P=0.086). There was a significant difference between the groups with regard to dentinal microleakage (P=0.003). No significant reduction in microleakage was observed in groups restored with Filtek™ P90 composite using its specific adhesive compared to those restored with Filtek™ P60 composite using its specific adhesive (P=0.626).
The results indicated that the application of methacrylate- and silorane-based composites with specific or nonspecific adhesives had no impact on enamel microleakage, but it affected dentinal microleakage, and specific adhesives showed less microleakage. It seems that a phosphate-methacrylate-based intermediate resin is required to bond dimethacrylate adhesive to silorane-based composites.