IN-VITRO COMPARISON OF RESTORATION WEAR AND TENSILE-STRENGTH FOLLOWING EXTENDED BRUSHING WITH SONICARE(R) AND A MANUAL TOOTHBRUSH

The purpose of this study was to compare the wear, cement margin break down and bond strength of restorations following 6 to 12 months of sim ulated use in vitro of the Sonicare(R) and a manual toothbrush. Extrac ted molar teeth with Class V hybrid composite resin restorations (n = 21) or with Class V gold inlays cemented with zinc phosphate cement we re tested for wear and marginal integrity following brushing for a per iod 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 contr ols. Toothbrushing was performed under a standardized load using a pis ton-action brushing machine. After brushing, the enamel, dentin/cement um and restorations were examined by light and scanning electron micro scopy. There was no apparent wear of tooth structure or of restorative materials with either the Sonicare or the manual brush. There was a s mall loss of cement from the margins of the gold inlays following toot hbrushing, which was similar and not significantly different between t he sonic and manual brush. To test brushing effects on crown retention , four identical metal dies were prepared to simulate premolar crown p reparations. Thirty cast copings, prepared to fit the dies, were cemen ted with zinc phosphate cement. Toothbrushing with Sonicare or the man ual toothbrush was performed as before (n = 15 for each brush), but th e simulated time was extended to the equivalent of 1 year of brushing. The dislodgement force of cemented crowns was not significantly diffe rent (t-test, p > 0.10) between the manual (207 +/- 69 N) and Sonicare (221 +/- 61 N) groups. These results demonstrate that despite its hig h frequency bristle motion, Sonicare exerts no detrimental effects on cement margin integrity, crown bond strength or surface wear of dental and restorative materials.