Methods: In this pilot study, some extracted human anterior teeth were selected to provide sound enamel surface. Samples were randomly divided into the following groups of 3 as follows; Group1: 15%HCL (Icon, DMG, Germany) – 120 s (control). Group2: 18%HCL (Kimia, Iran) – 60 s. Group3: 18%HCL (Kimia, Iran) – 90 s. Group4: 18%HCL (Kimia, Iran) – 120 s. The samples were prepared for SEM evaluation. The etching pattern and line scanning were evaluated and compared with significance of 0.05.
Results: SEM evaluation indicated that Group2 resulted in partial etching pattern on enamel in comparison to control group; no homogenous patterns in the surface erosion were observed. 90 s application of this acid was more aggressive than 120 s of 15%HCL with demineralization of interprismatic parts more than control group. In Group4 the mean demineralization depth was 19 micron.
Conclusions: Results of this pilot study revealed that 60 s application time of 18%HCL (made in Iran), caused partial etching of enamel which will be not appropriate for diffusion of resin in next step. It seems that a research should be conducted on evaluating a time between 60-90s for acceptable etching pattern of enamel for resin diffusion.