Bonding strength of ceramic laminates to dental enamel after bleaching treatment

Abstract

Aim-This study evaluated the influence of bleaching agents on bond strength of ceramic laminates bonded to dental enamel, at different time periods. Material and methods-Eighty fragments of bovine incisors were divided into three groups: Group I-(control) without bleaching; Group II-At-home bleaching with 7.5% hydrogen peroxide (White Class, FGM) 1 hour-daily applications for 14 consecutive days; Group III-in-office bleaching with 35% hydrogen peroxide (Whiteness HP, FGM) (single session, 3 applications, 15 minutes). After bleaching, groups II and III were divided into 4 subgroups (n = 8), according to the cementation of the veneers. Specimens were subjected to shear bond strength testing after 24 hours, 7 days, 14 days and 28 days (EMIC, 20N load, 0.75mm/min cross-head speed). The specimens were analyzed in a magnifying glass (X20) for failure mode. The topography of the enamel surface of representative specimens was analyzed under SEM before and after bleaching. Results-The results were evaluated by ANOVA and Tukey's test (⍺ = .05). There was no statistically significant difference for the mean bond strengths of the tested groups. The results were similar to each other, except between the mean bond strengths of GII-24h and GII-28 days which presented a statistically significant difference. Conclusion-The bond strength values for home bleaching had a more efficient recovery when compared to in-office bleaching after a 28-day period. Most of the failures were of the adhesive type. Both types of bleaching caused changes in the enamel surface.