Treatment of caries affected dentin with different photosensitizers and its effect on adhesive bond integrity to resin composite.

Abstract

The aim of the present study was to evaluate the effect of different photosensitizers activated by photodynamic therapy (PDT) on shear bond strength (SBS) of composite resin on caries affected dentin compared to conventional cavity disinfectants. Forty carious mandibular teeth were collected through non-traumatic extraction. All samples were embedded in polyvinyl cross-sections to the cemento-enamel junction. The preparation of caries-affected dentin was performed by grinding the specimens using silicon carbide discs. All specimens were arbitrarily allocated in to four groups (n = 10). Group 1, affected dentin disinfected with methylene blue (MB) [100 mg/L]; Group 2, caries affected dentin disinfected using curcumin photosensitizer (CP) [500 mg/L]; Group 3, affected dentin disinfected with indocyanin green photosensitizer (ICGP) [0.5 mL] Group 4, affected dentin treated with 3 % H2O2. Two-step self-etch adhesives was smeared on all specimens for 15 s and photopolymerized for 10 s. All specimens were placed in an incubator with humid environment for 24 h at 37 °C followed by positioning in universal testing machine for SBS testing. Failure mode examination of debonded samples was performed by a stereomicroscope. Analysis of variance (ANOVA) was used for inter group comparison through mean and standard deviation of each group. For multiple group comparison Tukey HSD was employed. Level of significance was established at p < 0.05. In group 2 dentin disinfection using CP, displayed the highest SBS value (18.21 ± 1.39 MPa). Whereas, group 4 (3% H2O2 as cavity disinfectant) presented the lowest SBS values (13.39 ± 1.26 MPa). SBS in Group 3 (ICGP) (17.42 ± 0.55 MPa) specimens was comparable to group 2 (p > 0.05) samples. In group 1, samples disinfected with MB (15.18 ± 0.39 MPa) was found to be significantly lower compared to group 2 and group 3 (p < 0.05) respectively. Curcumin and Indocyanin green (ICGP) PS have the potential to be used as cavity disinfectant as it improves SBS of caries affected dentin to resin composite. Photodynamic therapy for disinfection of caries affected dentin will augment its bond strength, however its long-term effect on bond integrity still needs to be investigated.