Restoration of carious dentin using diode irradiation on unmodified and chitosan nanoparticle-modified adhesive before LED polymerization: A SEM, FTIR, and μTBS evaluation.

AIM: To investigate the restoration of caries-affected dentin (CAD) using adhesive modification technique via diode laser (DL) irradiation of unmodified and modified adhesive with Chitosan nanoparticles (CHNP) before light emitting diode (LED) polymerization, and CHNPs modified adhesive+LED polymerization without DL on micro-tensile bond strength (μTBS), Degree of conversion (DC) and resin tag length (RTL).

MATERIAL AND

METHODS

Forty-four human mandibular molars were obtained, and CAD was exposed according to ICDAS criteria 5. Teeth were positioned vertically within the auto-cure acrylic resin and randomly distributed into four categories according to the adhesive modification (n = 11). Group1-Etch(E) + Bond(B) + LED,Group 2-E + B(CHNP) + LED, Group 3-E + B + DL + LED and Group 4-E + B(CHNPS) + DL + LED. All samples were restored using composite buildup followed by thermal aging. Surface characterization of CHNP with Energy-dispersive spectroscopy (EDS) was assessed along with RTL via scanning electron microscopy (SEM). μTBS and failure modes were analyzed utilizing a universal testing machine (UTM) and stereomicroscope, respectively. The DC was quantified using a Fourier Transform Infrared Spectroscopy (FTIR). A one-way analysis of variance, complemented by Tukey's post hoc test, was implemented for comparisons among the investigated groups (p < 0.05).

RESULTS

Group 4-E + B(CHNP) + DL + LED (107.43 ± 1.55 μm) presented the longest RTL with a score of grade 3 and the highest bond strength (11.54 ± 0.37 MPa). Whereas, Group 1 (E + B+ LED) displayed the shortest RTL (76.63 ± 0.82 μm) and lowest μTBS (9.31 ± 0.17 MPa). The adhesive irradiated with DL before LED polymerization in Groups 2 and 4 presented comparable DC (p˃0.05).

CONCLUSION

Pre-irradiating both unmodified and modified adhesives with chitosan nanoparticles using a diode laser before LED polymerization seems to be an effective approach. This technique enhances the material's mechanical properties by improving adhesive penetration, which in turn affects the length of resin tags,μTBS, and DC.