A total of 30 dentin discs were randomly assigned to five groups (n = 6/group) according to biofilm formation and surface treatment as follows:

Group C (control): no biofilm formation;

Group BF: biofilm formation and no surface treatment;

Group BF-E: biofilm formation and treatment with etching using 37% phosphoric acid (3M ESPE, St. Paul, MN, USA) gel for 15 s and rinsing with distilled water for 30 s;

Group BF-EC: biofilm formation and treatment with etching using 37% phosphoric acid gel for 15 s, soaking in chlorhexidine for 5 min after drying, and rinsing with distilled water for 30 s;

Group BF-RE: biofilm formation and prophylaxis using a rubber cup and plain pumice for 30 s, followed by etching using 37% phosphoric acid gel for 15 s, and rinsing with distilled water for 30 s.

Half of the samples in each group (n = 3) were observed with confocal laser scanning microscopy (LSM800, Carl Zeiss, Oberkochen, Germany) and scanning electron microscopy (SEM, S-4700, Hitachi, Tokyo, Japan) to quantitatively and qualitatively assess the biofilm, respectively.
Jeon B.K., Lee C.H., Kim A.R., Han S.H., Kim H.J., Antonson S.A, & Kim S.Y. (2020). Effect of Etching Procedures on the Adhesion of Biofilm-Coated Dentin. Materials, 13(12), 2762.
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