Use of variable remineralization periods to improve the abrasion resistance of previously eroded enamel.

The objective of the study was to evaluate the period of remineralization needed to re-establish the resistance of eroded enamel against brushing abrasion. Enamel specimens were prepared from 84 polished bovine incisors. The samples were evenly distributed among 7 groups (A-G) and submitted to ten alternating de- and remineralization cycles which included abrasion by toothbrushing. Demineralization was accomplished by immersing the specimens in the erosive soft drink Sprite Light((R)) for 1 min. Remineralization was performed by storing the samples in artificial saliva for either 0 min (A), 10 min (B), 60 min (C) or 240 min (D). After each remineralization, the specimens were brushed in an automatic brushing machine. Group E (erosion and 240 min remineralization, but no brushing) group F (erosion, but no remineralization and no brushing), and group G (brushing, but no erosion and no remineralization) served as controls. After performing the cycles, loss of enamel was determined by profilometry. The following values (mean +/- SD) were obtained and statistically analyzed (p<0.05): group A (5.16+/-1.26 microm), B (2.47+/-0.68 microm), C (1.72+/-0.75 microm), D (1.11+/-0.42 microm), E (0.81+/-0. 23 microm), F (1.04+/-0.31 microm), G (0.22+/-0.15 microm). Only the differences between groups D, E, and F were statistically not significant. Under the chosen in vitro conditions, it is concluded that abrasion resistance of eroded enamel continuously increases with remineralization time. However, even after a period of 1 h of remineralization, abrasion of previously eroded enamel is increased