Effect of Toothpastes with Different Abrasives on Eroded Human Enamel: An in situ/ex vivo Study

Abstract

The aim of the present study was to investigate the abrasive effect of CaCO₃ and SiO₂-based fluoride-free experimental toothpastes on eroded human permanent dental enamel and evaluate the effectiveness of waiting periods between acid exposure and tooth brushing. Twelve volunteers wore palatal appliances containing human enamel blocks for two periods of five days each. The appliances were immersed in a soft drink for five minutes four times a day (9:00 am, 11:00 am, 2:00 pm and 4:00 pm). On two occasions, two blocks were not submitted to additional treatment; two blocks were brushed (30 s) either with a CaCO₃ or SiO₂ toothpaste immediately after erosion and two blocks were brushed 1 h after erosion. Thus, the sample was divided into six groups: erosion alone (CaCO₃ and SiO₂ control); brushing with fluoride-free toothpaste (CaCO₃ immediate and 1 h after erosion; SiO₂ immediate and 1 h after erosion). Significant differences in wear depth were found between the enamel blocks in the CaCO₃ immediate and 1 h after erosion groups and the blocks in the CaCO₃ control group (p=0.001; p=0.022). No significant differences were found regarding the change in roughness and wear depth between blocks submitted to immediate abrasion and 1 h after erosion (CaCO₃ and SiO₂). The data revealed that surface roughness and wear depth is increased when erosion is combined with dental abrasion, regardless of the abrasive used. Waiting for 1 h to brush the eroded blocks offered no protective effect.