Erosion-protecting Effect on Root Dentin.

Objectives: This in vitro study evaluated the effect of different treatments on the prevention of root dentin wear.
Methods: One hundred and eighty slabs of bovine root dentin (4x3x2mm) were ground flat, polished and covered with composite resin except for two-thirds their outer surface (8mm²) to obtain a reference surface. The specimens were submitted to an initial erosive challenge with hydrochloric acid (HCl; pH=1.2; 0.1M, 20s, 3x). According to a randomized complete block design, the specimens were divided into three groups according to the following treatments (n=20): no treatment (C-control group), chitosan gel (CH), and TiF₄ varnish (TiF₄). Afterwards, all specimens were randomly submitted to erosive challenge with liquid (n=10) or gaseous (n=10) HCl (pH=1.2, 6x/day/20s for 6 days). After the third and sixth challenge of the day, half of the specimens were submitted to abrasion (20s, 2x/day), simulating the brushing stokes. The specimens were analyzed by confocal laser microscope for surface roughness (final-initial) and wear (step). The data were analyzed by ANOVA one (challenge) and 2-way (treatmentXabrasion) and Tukey test (α=0.05).
Results: For the erosive challenge, a higher wear value was observed for the liquid HCl (p<0.05), which differed statistically from the gaseous HCl. A similar result was observed for the treatments. The abrasion affected negatively the group eroded with liquid HCl and the lowest wear value was verified for TiF₄ (p<0.05). For gaseous HCl, all treatments showed similar values of wear and abrasion not affected (p>0.05)(Table). For the roughness, similar values were observed independent of abrasion (p>0.05) and only varnish was different (p<0.05).
Conclusions: In terms of wear, TiF₄ promoted the best protective effect of root dentin eroded with liquid HCl; however, it was affected by abrasion. In the gaseous erosive process, any treatment has the ability to reduce the dentin loss. Surface roughness was not affected by the different treatments.