The aim of this study was to assess the amount of mineral loss from enamel surfaces that were subjected to extended simulated tongue abrasion (STA) cycles performed after various demineralisation periods.
Methods:
Windows of 12x3mm were created across the labial surfaces of twenty bovine incisors then randomly assigned into two equal (n=10) experimental groups; group 1 had a fixed hour erosion, group 2 had a fixed STA period of 1 minute. Group1 (G1) were eroded for 1hr then subjected to TSA forces (117 strokes, load 172g) over 1,2,3,4, and 5 min cycles. Group2 (G2) specimens were eroded for 0 min, 1hr, 6hr, 12hrs and 24hrs, then abraded for 1min after each erosion cycle. Mineral loss was quantified using quantitative laser fluorescence (QLF), non-contact profilometry (NCP) and transverse microradiography (TMR).
Results:
A significant difference in fluorescence loss (QLF) between the original/lesion (O) and the reconstructed/sound (R) enamel surfaces of both groups was found (p>0.05), with DF values ranging from 1573% ± 193 to 1689% ± 190 (G1), and 1497% ± 281 to 1764 % ± 119 (G2), respectively. NCP demonstrated the greatest step-height with surface depth range from 133.6µm ± 26.4 after 24hr erosion (G2) as compared with 87.5µm ± 37.9 after 5min abrasion (G1). One min abrasion (G2) created more surface loss 37.1µm ± 13.9 than abrading non-eroded surfaces 25.9µm ± 4.5. At the end of 24hr erosion DZ (TMR) showed mineral loss of 532µm ±60 (G2) as compared with 443±63 (control) whereas G1 had a lower Ld of 121±133 to 202±180 (control).
Conclusion:
Exposing enamel surfaces to extended erosion periods can be aggravated by abrasion forces applied for as short as 1min.