The impact of oxidative mouthwash on microleakage of composite restorations: A stereomicroscopic study

Objective: Although oxidative mouthwashes have many antimicrobial benefits, it has been suggested that residual oxygen interferes with composite resin adhesion to dental structures. This study aimed to evaluate the effect of an oxidative mouthwash on the microleakage of composite restorations.Methods: Twenty-four extracted human third molars were randomly assigned into three groups: Group ۱: a ۰.۰۵% sodium fluoride mouthwash, Group ۲: an oxidative mouthwash, and Group ۳: distilled water. The teeth were immersed in the corresponding solution for ۱۰ minutes a day over ۱۴ days. Class V cavities were prepared in the buccal and lingual surfaces of the teeth (n=۱۵ per group) and restored with Filtek Z۲۵۰ composite. The teeth were thermocycled between ۵º C and ۵۵º C for ۱۰۰۰ cycles, then immersed in ۲% fuchsin solution for ۲۴ hours, followed by sectioning in the bucco-lingual direction. The gingival and occlusal microleakage were inspected using a stereomicroscope. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. The statistical significance level was considered at P ۰.۰۵.Results: The highest and lowest average microleakage scores were observed at the gingival and occlusal margin of cavities immersed in the sodium fluoride mouthwash, respectively. No statistical differences were observed in microleakage among the three groups either at the occlusal or at the gingival margin (P>۰.۰۵). The Mann-Whitney U test showed a statistically greater microleakage at the cervical (۱.۰۵±۱.۱) compared to the occlusal (۰.۶۹۴±۰.۵۳) margins, irrespective of the treatment groups (P=۰.۰۳۳).Conclusions: Using an oxidative mouthwash does not affect the microleakage of composite restorations