Effect of Photodynamic therapy and Er,Cr: YSGG laser on bond strength of bleached enamel to composite resin

Objective: The purpose of the present study was bleached enamel reversal using conventional ascorbic acid (AA) and contemporary methods including Photodynamic therapy (PDT), Er, Cr: YSGG (ECL) on bond integrity to composite resin. Material and method: Forty sound permanent mandibular premolars were collected from a dental clinical setting and disinfected. All forty samples were mounted vertically in a rubber mold exposing only the clinical crown. All samples were bleached using Opalescence Boost Professional Teeth Whitening. After the bleaching procedure, each sample was randomly allocated into four groups according to surface treatment. Samples in group 1 were treated with methylene blue photosensitizer (MBP). Samples in group 2 were exposed to 10% sodium ascorbate. Samples in group 3 were treated with Er, Cr: YSGG laser (ECL). Samples in group 4 were not treated (control). All Samples were treated with 37% phosphoric acid and a bonding agent was applied. A bulk-fill composite was cured to all specimens and all samples were treated in a thermocycler. Specimens were placed in a universal testing machine for shear bond strength (SBS) testing. Descriptive statistics were associated by analysis of variance (ANOVA) and Tukey's post hoc test maintaining level of significance (p 0.05) Results: The lowest SBS scores were achieved in the bleached enamel (BE) group (15.25 +/- 1.745 MPa). Whereas, the highest bond integrity was attained by AA group (32.23 +/- 1.854 MPa). Samples treated with ECL (31.87 +/- 1.659 MPa) and AA (32.23 +/- 1.854) were comparable (p 0.05). Samples treated with PDT exhibited significantly different SBS (22.41 +/- 1.258) compared to other experimental groups Conclusion: ECL showed a reversal effect of BE compared to AA and has the potential to be used in clinical settings. BE reversal using MBP needs further investigation.