Protective effect of resin coating on the microleakage of Class V restorations following treatment with carbamide peroxide in vitro

This in vitro study evaluated the effects of a resin coating on the microleakage of Class V restorations due to bleaching. One-hundred and sixty Class V cavities were randomly restored with one of four different restorative materials (n = 40): a compomer (Dyract AP), a conventional glass-ionomer cement (Ketac Molar Easymix), a resin modified glass-ionomer cement (Fuji II LC) and a resin composite (Filtek Z350). For each kind of material, 40 restorations were divided into four subgroups: bleached with resin coating (group BC), bleached without resin coating (group B), immersed in artificial saliva with resin coating (group SC), immersed in artificial saliva without resin coating (group S). In groups B and BC, the specimens were bleached with 10% carbamide peroxide gel for eight hours daily, while groups SC and S were stored in artificial saliva instead. After 28-day treatment, all the samples were subjected to a dye penetration test using the multiple-sectioning technique. In addition, one more test was performed to investigate the color difference between the coated and uncoated tooth surface after bleaching. There was a statistically significant increase in cervical microleakage in the group B specimens of Fuji II LC and Ketac Molar Easymix compared to their respective control specimen (group S). These effects on microleakage were not found in the bleached specimens with resin coating (group BC). There was also no visually-detectable color difference between the coated and uncoated tooth surface. In conclusion, resin coating is an effective method for avoiding the bleaching-induced microleakage of glass-ionomer cement.