[Show abstract][Hide abstract] ABSTRACT: The aim of the present in situ study was to evaluate the effect of different periods of intraoral remineralization to decrease the susceptibility of previously demineralized enamel against toothbrushing abrasion. Six human enamel specimens (A-F) were recessed in the buccal aspects of each of eight intraoral appliances which were worn for 21 days by 8 panelists. Demineralization of the samples was performed twice a day extraorally in the acidic beverage Sprite Light for 90 s. Subsequently, the enamel specimens were brushed at different times. Specimen A was brushed immediately after the demineralization. The remaining samples B-E were brushed after the intraoral appliances had been worn for various periods of remineralization: specimen B, 10 min; C, 20 min; D, 30 min and E, 60 min, respectively. Specimen F was only demineralized and remineralized, but not brushed. After 21 days, enamel wear was measured with a laser profilometer. The following values (mean +/- standard deviation) were obtained: specimen A, 6.78+/-2.71 microm; B, 5.47+/-3.39 microm; C, 6.06+/-3.18 microm; D, 5.43+/-2.58 microm; E 4.78+/-2.57 microm, and F 0.66+/-1.11 micro;m. Analysis of variance revealed a significant influence of remineralization period on abrasive wear. However, even after a remineralization period of 60 min the wear was significantly increased as compared to the demineralized, but not brushed control. It is concluded that (1) abrasion resistance of softened enamel increases with remineralization period and (2) at least 60 min should elapse before toothbrushing after an erosive attack.