In vitro evaluation of different remineralization periods in improving the resistance of previously eroded bovine dentine against tooth-brushing abrasion

One dentine specimen was prepared from each of 90 bovine incisors. The samples were then evenly distributed among nine groups (A–I) and submitted to 10 alternating de- and re-mineralization cycles, including abrasion by tooth brushing. Each cycle started with a demineralization using the erosive soft drink Sprite Light® for 1 min, followed by storing the samples in pooled human saliva for a total of 240 min. The specimens were removed from the saliva at different intervals (group A, 0 min; B, 15 min; C, 30 min; D, 45 min; E, 60 min; F, 90 min; G, 120 min) and brushed in an automatic brushing machine. Groups H (erosion, but no brushing) and I (no erosion, but brushing), which were also stored in saliva for 240 min, served as controls. After these cycles, loss of dentine was determined by profilometry, producing the following values (mean±S.D.), which were analysed statistically (P⩽0.05): group A (5.03±1.49 μm), B (4.44±1.09 μm), C (4.91±0.95 μm), D (5.47±1.52 μm), E (5.29±1.45 μm), F (4.76±0.74 μm), G (5.16±0.71 μm), H (2.61±1.31), I (1.11±0.39). Groups A–G had no significant differences, but they showed a significantly greater loss of dentine than groups H and I. It is concluded that the abrasion resistance of eroded bovine dentine is still decreased after a remineralization period of 120 min.