Bond Integrity of Resin-modified Glass Ionomer to Dentin Conditioned Using Photodynamic Therapy and Low-level Laser Therapy: An In Vitro Study

Abstract

Aim: The aim of the study was to assess the conditioning efficacy of photodynamic therapy (PDT) and Er,Cr:YSGG laser (ECYL) to dentin compared with conventional regime bonded to resin-modified glass ionomer (RMGIC). Materials and methods: Forty mandibular teeth were cleaned, disinfected, and mounted vertically within the segments of polyvinyl pipes up to cementoenamel junction. The occlusal surfaces were flattened, and samples were divided into four groups according to conditioning protocols. Samples in groups I and II underwent PDT, samples in group III were conditioned with low-level laser therapy (LLLT) using Er,Cr:YSGG laser (ECYL), and samples in group IV were conditioned using polyacrylic acid (PAA). Fuji II LC was applied incrementally and light cured for 20 seconds. All samples were placed in universal testing machine for shear bond strength (SBS) testing. The fracture surface was analyzed using stereomicroscope at 50× magnification to determine mode of failure. Among different investigational groups Tukey test was used as post hoc along with analysis of variance (ANOVA). Significance level was established at p <0.05. Results: Maximum SBS values were observed in group IV dentin conditioned with PAA (19.55 ± 1.84 MPa), whereas minimum SBS values were shown by group I (methylene blue photosensitizer, MBP) activated by PDT (13.52 ± 1.22 MPa). In group III, dentin conditioned with ECYL (18.22 ± 2.07 MPa) and group IV (19.55 ± 1.84 MPa) surface treated with PAA exhibited comparable SBS values (p > 0.05). Fracture analysis revealed that in PDT group adhesive failure type was in majority. However, admixed failure type was commonly presented in groups III and IV. Conclusion: PDT of dentin using photosensitizers MBP and CP deteriorates bond values when bonded to RMGIC. The use of LLLT to condition dentin has the potential to improve SBS. Clinical significance: Dentin conditioning with LLLT using ECYL may improve, is of utmost importance for better treatment outcome, predictable prognosis, and improved bond integrity to RMGIC.