In vitro evaluation of giomers microleakage after exposure to 33% hydrogen peroxide: self-etch vs total-etch...

This study evaluated the microleakage of a giomer resin bonded with total-etch and self-etch adhesive systems after exposure to hydrogen peroxide. Thirty freshly extracted, caries-free human premolars and molars were used. The teeth were randomly divided into two groups: Group I was exposed to 33% hydrogen peroxide (Niveous-Shofu) for 30 minutes daily for five consecutive days; Group II received no treatment (control). A week later, Class V standardized preparations were performed on the facial and lingual surfaces, with the gingival margin placed 1 mm below the CEJ. Each group was then divided into two subgroups: in Groups IA and IIA, a self-etching adhesive system (FL Bond-Shofu) was applied, and in Groups IB and IIB, a total-etch adhesive system (Prime Bond NT-Dentsply/Caulk) was applied according to manufacturers' instructions. The teeth were restored using 2-mm increments of Beautifil A2 resin-based giomer material (Shofu). Each layer was cured using a Spectrum 800 curing light (Dentsply/Caulk) for 20 seconds at 600mW/cm2. The teeth were thermocycled 500x between 5 degrees C and 55 degrees C with a dwell of 30 seconds; they were then placed in a 0.5% methylene blue dye solution for 24 hours at 37 degrees C. Samples were sectioned longitudinally and evaluated for microleakage at the occlusal and gingival margin under a stereomicroscope at 20x magnification. Dye penetration was scored using the following scoring system 0 = no penetration; 1 = partial dye penetration along the occlusal or gingival wall; 2 = partial dye penetration along the occlusal or gingival wall but did not include the axial wall; 3 = dye penetration to and along the axial wall. A Mann-Whitney test revealed a statistically significant difference between subgroups at the occlusal level (p < 0.0001). Group IA yielded the most microleakage. No statistically significant difference was reported at the gingival level. Microleakage was affected by hydrogen peroxide exposure only at the enamel cavosurface margin when a self-etching primer adhesive system was used.