Bond strength of composite materials after internal teeth bleaching using 30% carbamide peroxide

Introduction. Bond between composite materials and bleached teeth depends on the change of micro-morphological structure of enamel and dentin after the application of bleaching agent. Bleaching procedure can weaken adhesion of composite materials to hard tissues, where even just a presence of hydrogen peroxide may affect their polymerization. The aim of this study was to determine bond strength of composite materials after internal teeth bleaching using 30% carbamide peroxide. Material and Methods. The study was conducted on 20 extracted, endodontically treated human teeth. After internal teeth bleaching with 30% carbamide peroxide a class V cavity was prepared and restored with Tetric EvoCeram nanocomposite material. Microleakage was determined using dye method (silver nitrate) and measured on the incisal and gingival walls using stereoloupes. Results. Linear dye penetration on the incisal wall (7.25 μm) of bleached teeth was greater than on the incisal wall in non-bleached (control group) teeth (5.75 μm) but with no statistically significant difference. Dye penetration on the gingival wall of bleached teeth (20.00 μm) was greater than on the gingival wall of the control group (14.25 μm). This difference was statistically significant (p<0.05). Conclusion. Greater microleakage and inferior bond of composite material was observed in teeth bleached with internal bleaching technique (30% carbamide peroxide) compared to non-bleached teeth.