Effect of home bleaching on the vickers micro-hardness of resin based dental materials

Abstract

Introduction: ‘Whiter teeth’ have become a common cosmetic need for patients and therefore, in an effort to improve the appearance of natural teeth, home whitening agents have gained popularity. This in-vitro study investigates the effect of 6% carbamide peroxide on the Vickers micro-hardness of five aesthetic resin-based restorative materials.

Material and Methods: Eighteen specimens (5x2 mm) for each material including micro-hybrid (Filtek Z250), nanofilled composite (Filtek Z350), packable composite (Quixfil), flowable composite (Surefil SDR), and compomer (dyract) were fabricated and polished. Afterwards, the specimens were sonicated and stored in distilled water at 37°C for 24 hours. Baseline Vicker’s Hardness was recorded. The specimens were then subjected to 14 days bleaching treatment and surface hardness of the composite resins was re-evaluated. Paired t-test and one-way ANOVA with Tukey's post-hoc test (α = 0.05) were used for analysis of data.

Results: Surface hardness was significantly reduced for Dyract XP and Surefil SDR, increased for Quixfil and least effected the Filtek Z350 and Filtek Z250 following application of 6% Carbamide peroxide. However, maximum variation in hardness values was observed for Surefil SDR. Statistically similar hardness values were observed among five tested materials except for Surefil SDR before the bleaching procedure, though post-bleaching, substantial difference (p≤0.001) in the hardness values was detected for most of the tested materials.

Conclusions: Indiscriminate use of home bleaching kits for tooth whitening should be discouraged as it can variably affect the physicochemical properties of existing aesthetic resin based restorations.