Effect of universal adhesive systems on the enamel etching patterns, shear bond strength, adhesive remnant index and failure type of pit and fissure sealants applied to Er: YAG laser etched enamel: an in vitro study.

Abstract

To evaluate in vitro the effect of universal adhesive systems on the enamel etching patterns, shear bond strength, adhesive remnant index, and failure type of pit and fissure sealants applied to Er: YAG laser etched enamel. One hundred sixty-eight samples were included and randomly assigned to 8 study groups (n = 21 p/g) under specific enamel conditioning protocols. One representative sample per group was used to observe enamel etching patterns at 200x, 500x and 1500x by scanning electron microscopy (SEM). The shear bond strength (SBS) was carried out with a universal testing machine (Autograph AGS-X, Shimadzu, Kyoto, Japan); the adhesive remnant index (ARI) and adhesive failure type were evaluated with a stereomicroscope (Nikon, Tokyo, Japan). For data analysis SPSS v.25 program (SPSS IBM, New York, USA) was employed; ANOVA, Kruskal-Wallis and Mann-Whitney U tests were performed (p < 0.05). SEM analysis exhibited different etching patterns. The highest SBS values were found in group GV_CE_SBU_Clinpro (18.768 ± 3.188 MPa), followed by GVII_ErYAG_SBU_Clinpro (18.111 ± 3.939 MPa) and GVI_CE_FBM_Gseal (16.621 ± 2.931 MPa), p < 0.001; ARI showed the lowest adhesive index (0) for groups GIV_ErYAG_Gseal (75%) and GIII_ErYAG_Clinpro (55%), p < 0.05; adhesive failure was predominant followed by the mixed failure in all groups. The use of Er: YAG laser etching for the application of pit and fissure sealants (PFS) is recommended in conjunction with universal adhesives, as it surpasses conventional etching performance. The universal adhesive containing 10-MDP showed the best results in SBS, regardless of the type of pre-etching agent used.