In Vitro Comparison of Restoration Wear and Tensile Strength Following Extended Brushing with Sonicare® and a Manual Toothbrush

The purpose of this study was to compare the wear, cement margin breakdown and bond strength of restorations following 6 to 12 months of simulated use in vitro of the Sonicare® and a manual toothbrush. Extracted molar teeth with Class V hybrid composite resin restorations (n = 21) or with Class V gold inlays cemented with zinc phosphate cement were tested for wear and marginal integrity following brushing for a period that simulated 6 months of typical use. One-third of the molars in each group were brushed with the Sonicare and one-third were brushed with the manual brush. The remaining third served as non-treated controls. Toothbrushing was performed under a standardized load using a piston-action brushing machine. After brushing, the enamel, dentin/cementum and restorations were examined by light and scanning electron microscopy. There was no apparent wear of tooth structure or of restorative materials with either the Sonicare or the manual brush. There was a small loss of cement from the margins of the gold inlays following toothbrushing, which was similar and not significantly different between the sonic and manual brush. To test brushing effects on crown retention, four identical metal dies were prepared to simulate premolar crown preparations. Thirty cast copings, prepared to lit the dies, were cemented with zinc phosphate cement. Toothbrushing with Sonicare or the manual toothbrush was performed as before (n = 15 for each brush), but the simulated time was extended to the equivalent of 1 year of brushing. The dislodgernent force of cemented crowns was not significantly different (t-test, p > 0.10) between the manual (207 ± 69 N) and Sonicare (221 ± 61 N) groups. These results demonstrate that despite its high frequency bristle motion. Sonicare exerts no detrimental effects on cement margin integrity, crown bond strength or surface wear of den tal and restorative materials.