Microleakage around zirconia crown margins after ultrasonic scaling

Objectives: To measure microleakage around zirconia crown margins cemented with self-adhesive resin or resin modified glass ionomer (RMGI) cements after ultrasonic scaling.
Methods: 24 molars were prepared for crowns (margin 0.5mm coronal of cementum-enamel junction). Preparations were digitally scanned and zirconia crowns milled. Specimens were divided into three groups (n=8): RMGI (RelyX Luting Plus), self-adhesive resin cement (Rely X Unicem 2), and a self-etch resin cement (Prelude One, Cem EZ). After cementation, specimens were ultrasonic scaled with a piezoelectric device (60sec, hand pressure). After thermocycling (20,000 cycles/5-55°), specimens were immersed in 5wt% fuchsine dye before sectioning bucco-lingually. Microleakage was examined under 40X light magnification. Statistical comparisons were made using a 3-way ANOVA, paired t-test, and Tukey post-hoc analysis (α=0.05).
Results: Ultrasonic scaling did not alter microleakage at the margins of crowns (p=0.36). There were significant differences in microleakage between cements on both scaled (p=0.003) and untreated margins (p<0.000). The self-adhesive resin cement produced less microleakage than the RMGI cement when ultrasonic scaled (p=0.002) and untreated (p<0.0001).
Conclusions: Piezoelectric ultrasonic scaling did not increase microleakage at the margin of zirconia crowns cemented with resin or RMGI cements.