Toothbrush abrasion of erosively altered enamel after intraoral exposure to saliva: an in situ study.

The aim of this in situ study was to test the effect of toothbrush abrasion on enamel previously exposed to a standardized artificial erosive agent. To generate moderate erosive lesions, slabs of the buccal surface of human premolars were immersed in a solution of citric acid for 3 min. Then they were attached to intraoral appliances and each one was exposed for 0 min (= toothbrushing immediately after intraoral exposure), 30 or 60 min to the oral milieu of 1 of 7 female subjects with a mean age of 22 years. Immediately thereafter the volunteers brushed the slabs for 30 s with toothpaste using their preferred brushing technique. For each test person the secretion rate of resting and paraffin-stimulated saliva, buffering capacity and pH were measured. The following mean losses of substance at the surface were registered: 0.258+/-0.141 microm (toothbrushing immediately after intraoral exposure), 0. 224+/-0.087 microm (toothbrushing after intraoral exposure of 30 min) and 0.195+/-0.075 microm (toothbrushing after intraoral exposure of 60 min). Toothbrush abrasion in situ was significantly lower after 60-min exposure to the oral environment than after 0-min (p<0.001). Also, the 30- and 60-min values were significantly different from each other (p<0.001). Multiple linear regression analyses revealed that in this model toothbrush abrasion was associated with the intraoral exposure to saliva (p = 0.026), the severity of the erosive attack (p<0.001) and the secretion rate of resting saliva (p = 0.029). If no other preventive measures are taken we suggest that individuals at risk for erosive tooth wear wait at least 1 h before brushing their teeth after consuming erosive foodstuffs or beverages.