The Effect of Diode Laser and Resin Infiltration on the Shear Bond Strength of Orthodontic Brackets Bonded to Demineralized Enamel

Background: The purpose of this study was to compare the effect of diode laser and resin infiltration on the shear bond strength (SBS) of orthodontic brackets bonded to demineralized enamel surfaces.Methods and Materials: Thirty six sound extracted maxillary premolars were collected for this in-vitro study. Samples were demineralized at 37ºC over the course of 48 hours. Specimens were randomly divided into three equal groups (n=12), namely: Group 1 (control group): no surface treatment was applied. Group 2: resin infiltration (DMG, Hamburg, Germany) was preformed prior to bonding. Group 3: enamel surfaces were irradiated with diode laser (970 nm, 2 W) for 15 seconds with continuous scanning. Orthodontic brackets were bonded to the prepared surfaces of all specimens. The SBS values were recorded using a Universal Testing machine. ANOVA was used to compare SBS values between different study groups followed by Tukey’s post hoc test for pairwise comparison. P-value <0.05 was considered statistically significant.Results: Group 2 demonstrated the highest mean SBS values (6.62 ± 0.75 MPa), followed by group 1 (6.24 ± 0.76 MPa) and group 3 (4.80 ± 0.68 MPa), in descending order. According to ANOVA, there was a statistically significant difference between the average SBS values among the three study groups (P=0.001). Pairwise comparison revealed that the mean SBS value recorded for the laser-treated group, was significantly lower than that of the resin infiltration and control groups (P=0.001 for both). However, the difference between the SBS of the resin infiltration group and the control group was not statistically significant (P=0.423).Conclusion: Surface pretreatment with diode laser irradiation resulted in low SBS values, indicating a weak bond strength between the orthodontic brackets and demineralized enamel surfaces. These findings suggest that diode laser surface treatment is not effective for bonding orthodontic brackets to teeth with white spot lesions.