The effect of At-home and In-office bleaching on microleakage of class V composite resin restorations using different types of universal adhesives in two modes of self-etch and etch-and-rinse: An in vitro study

Abstract

Introduction: Bleaching is the process of lightening the color of teeth that there are different materials and techniques to do it. Hydrogen peroxide and carbamide peroxide are the most commonly used " at-home" and "in-office" bleaching methods. When bleaching agents are in contact with dental structures, they also act on restorative materials and adhesive interfaces. The aim of this study was to investigate the effect of bleaching "at-home" and "in-office" on the microleakage of composite restorations performed with different universal adhesives in two methods of self-etch and etch-and-rinse. Materials and methods: Class 5 cavities were prepared in buccal and lingual surfaces of 132 healthy human premolars (264 cavities). Samples were divided into four groups (N = 33) based on the type and application of the adhesive system used. All Bond Universal adhesive was used in the first and third groups and G-Premio Bond adhesives was used in the third and fourth groups. In the first and third groups the etching method was total etch, and in the second and fourth groups, the cavities were prepared by self-etch method. After using the adhesive systems according to the manufacturer's instructions, curing was performed for 10 seconds. Then all the cavities were repaired with Spectrum composite, Incremental method and each layer was cured for 20 seconds. Finally, the samples of each group were divided into three subgroups (n = 11) based on the type of bleaching. In the first subgroups, home bleaching gel (15% carbamide peroxide) was used for 6 hours a day for 10 consecutive days. In the second subgroups, office bleaching was performed in two 15-minute periods on two different days. And the gel used was 40% hydrogen peroxide. The third subgroup was the control subgroup (bleaching was not performed). After 24 hours immersion in 2% methylene blue, the specimens were cut with a diamond disk in the bacolingual direction, in the direction of the longitudinal axis of the tooth, and examined by a 40-magnification observer under a stereomicroscope to compare the microleakage of Class five composite resin restorations, rank regression analysis was used (P-value <0.05). Results: The variables of adhesive type, application method (self-etch and etch-and-rinse) and margin type had a significant effect on microleakage (P-value <0.05). The amount of microleakage in All bond universal adhesive was significantly higher than G-Premio bond adhesive. The chance of being at a high level of microleakage in the self-etch mode was almost twice as high as in the etch-and-rinse mode. The Enamel margin had less microleakage than the cervical margin. The intervention variable or the same method of bleaching (at-home and in-office) by keeping the other factors constant, had no significant effect on the amount of microleakage (P-value> 0.05). Conclusions: Based on the results of microleakage test, a significant difference was observed between different adhesive systems and how they were used and the amount of microleakage in the cervical margin was higher than the enamel margin. Bleaching after composite restoration using adhesive had no significant effect on the microleakage of Class V restorations