Enamel Erosion by 15% and 18% Hydrochloric Acid Gels after Different Application Times

Background and Aim: Discolored teeth are among the most common reasons behind seeking esthetic dental treatments. Resin infiltration is a new technique for treatment of white spot lesions (WSLs). In this technique, 15% hydrochloric acid (HCl) is used to cause surface erosion. The aim of this study was to compare the enamel erosion caused by 15% and 18% HCl gels after different application times. Materials and Methods: In this experimental study, sixty sound enamel surfaces were randomly divided into six groups of 10 (G1-G6). G1 specimens were subjected to 15% HCl gel for 75 seconds. G2 and G3 samples were subjected to 15% HCl for 90 and 120 seconds, respectively. G4, G5, and G6 specimens were subjected to 18% HCl for 75, 90, and 120 seconds, respectively. The specimens were then evaluated under a scanning electron microscope (SEM), and the depth of erosion was recorded. Data were analyzed by using one-way analysis of variance (ANOVA) and Tukey&rsquo;s post-hoc test with a 95% confidence interval. Results: The depth of erosion in 18% HCl groups was greater than that in 15% HCl groups after the same application times (P<0.05). The depth of erosion was not significantly different between G3 and G4 samples (P>0.05). Conclusion: The results of this study showed that the application of 18% HCl for 75 seconds is a suitable alternative to the application of 15% HCl for 120 seconds in the resin infiltration technique.