Susceptibility of Enamel to Initial Erosion in Relation to Tooth Type, Tooth Surface and Enamel Depth

摘要

This study aimed at assessing the susceptibility of different tooth types (molar/premolar), surfaces (buccal/lingual) and enamel depths (100, 200, 400 and 600 mu m) to initial erosion measured by surface microhardness loss (Delta SMH) and calcium (Ca) release. Twenty molars and 20 premolars were divided into experimental and control groups, cut into lingual/buccal halves, and ground/polished, removing 100 mu m of enamel. The initial surface microhardness (SMH0) was measured on all halves. The experimental group was subjected to 3 consecutive erosive challenges (30 ml/tooth of 1% citric acid, pH 3.6, 25 degrees C, 1 min). After each challenge, Delta SMH and Ca release were measured. The same teeth were consecutively ground to 200, 400 and 600 mu m depths, and the experimental group underwent 3 erosive challenges at each depth. No difference was found in SMH0 between experimental and control groups. Multivariate nonparametric ANOVA showed no significant differences between lingual and buccal surfaces in Delta SMH (p = 0.801) or Ca release (p = 0.370). Delta SMH was significantly greater in premolars than in molars (p < 0.05), but not different with respect to enamel depth. Ca release decreased significantly with increasing depth. Regression between Ca release and Delta SMH at 100 mu m depth showed lower slope and r(2) value, associated with greater Ca release values. At 200-600 mu m depths, moderately large r(2) values were observed (0.651-0.830). In conclusion, different teeth and enamel depths have different susceptibility to erosion, so when Ca release is used to measure erosion, the depth of the test facet in enamel should be standardized, whereas this is less important if Delta SMH is used. (C) 2015 S. Karger AG, Basel