Abrasion of Human and Bovine Enamel After Erosive Challenge In-Vitro

Identification of alternative sources of enamel and dentine for tooth wear research is becoming more important due to increasingly limited availability of sound human teeth. Objectives: Characterise and compare the effects of abrasive wear on sound and dietary acid softened human and bovine enamel in terms of abrasion depth, surface roughness and gloss. Methods: Sixteen human and bovine enamel specimens were prepared to a flat polished (3μm diamond) finish. Eight of each were subjected to erosive challenge, (0.3% w/w citric acid, 3 mins, 20°C) before all specimens were brushed with Sident 9 silica abrasive slurries in 0.5% carboxymethylcellulose with 10% glycerol, for 10,000 double-strokes (ISO conditions) using a novel tooth-brushing simulator and defined brushing parameters. Before and after treatments, specimens were surface profiled using a Taylor-Hobson inductive-gauge profilometer to quantify abrasion depth and surface roughness. Gloss was measured using a Novo-Curve glossmeter. Results: The mean±SD for abrasion depth, roughness and gloss for human/bovine enamel after brushing were: Human: Abrasion=0.7851±0.2118μm, Ra=0.1322±0.0388μm, Gloss=67.9±12.9; Bovine: Abrasion=0.5252±0.1364μm, Ra=0.0616±0.0155μm, Gloss=88.1±7.8. Values for softened enamel after brushing were: Human: Abrasion=1.7239±0.2597μm, Ra=0.1188±0.0310μm, Gloss=54.2±9.3; Bovine: Abrasion=1.9441±0.2586μm, Ra=0.0891±0.0209μm, Gloss=64.0±7.6. Pre-softening caused abrasion of human and bovine enamel to increase 2.2 times and 3.7 times respectively compared to sound enamel. Roughness and Gloss for pre-softened enamel showed a similar trend to those for sound enamel after brushing, with bovine demonstrating glossier and less rough surfaces compared to human enamel. Statistical differences (p<0.05) were seen for roughness and gloss values for sound and pre-softened human and bovine enamel after abrasion. Conclusions: The susceptibility of human and bovine enamel to both erosion and abrasion was comparable, however bovine enamel was less rough with increased gloss compared to human following abrasive alone, or erosive and abrasive challenge. Bovine enamel may offer a suitable alternative substrate for tooth wear research.