[In vitro effect of an air-powder abrasive system on the susceptibility of dental tissues to artificial caries].

An air-powder jet abrasive system has recently been introduced for stain removal from teeth. The purpose of this study was to investigate whether its abrasive effect on enamel and on the root renders these surfaces more caries prone. The AIR-FLOW (EMS SA) abrasive was directed for 30 seconds on predetermined (test) sites of the crown and the root of each of 10 teeth, under controlled conditions. These and adjacent (control) sites in the form of windows, were then exposed to an acid gel for caries-like lesion formation. The central sections of each window were examined under the polarizing microscope. The enamel treated with the abrasive appeared somewhat roughened while the root showed crater-like abrasion defects averaging 303 mm (+/- 140) in depth. The mean depth of enamel test lesions was 253 mm (+/- 77) and that of control lesions 98 mm (+/- 77), the difference being statistically significant (p less than 0.001). The corresponding values for the root lesions were 695 mm (+/- 103) and 695 mm (+/- 120) respectively. Consequently, enamel surface modification by AIR-FLOW decreased the resistance of enamel to caries-like lesions in vitro and it is postulated that this may also happen at "susceptible sites" in vivo. Loss of cementum and superficial dentine abraded by AIR-FLOW was significant but did not lead to increased root susceptibility to caries-like lesions in vitro.