RESUMEN
Class V cavities are mostly filled with tooth colored restorations. Microleakage is an important problem with tooth colored restorations. Some studies show that ultrasonic scalers could cause microleakage. The aim of this study was to examine the effects of ultrasonic scaling on three different tooth colored restorations; namely, composite resin, glass-ionomer and comboglass. In this in-vitro study, sixty extracted premolars were randomly divided into three groups of 20 teeth. In all the teeth the same size class V cavity was prepared. First, second and third group teeth were filled with composite, gloss inomer and compoglass, respectively. After thermocycling, half of the teeth in each group were scaled with ultrasonic [test group]; whereas, the other half were used as control. Then, all the specimens were kept in 2% fuchsin for dye penetration testing for approximately 24 hours. After sectioning, the specimens' microleakage was quantified with steriomicroscope. The data were analyzed statistically by Kruskal-Wallis analysis and Mann-Whitney U-tests with Bonferroni's correction. In the first [composite] and third [compoglass] groups ultrasonic scaling had no effect on microleakage [P>0.05]; whereas, in the second group [glass-ionomer] ultrasonic scaling caused more microleakage than the control group. The difference was statistically significant [P<0.001]. The ultrasonic scaler should be used with caution around class V cavities filled with tooth colored restorations because of the possible microleakage effect