Influence of photodynamic therapy and different conventional methods on conditioning of lithium di silicate ceramics bonded to metallic brackets: An assessment of bond strength.

AIM: The aim of the current study was to assess the effect of different conditioning methods on Lithium di silicate (LDC) employing conventional and contemporary regimes bonded to metallic brackets. MATERIAL AND METHODS: 70 discs of LDC were prepared and polished to attain smooth surface. Samples were allocated into seven groups according to ceramic surface conditioning. Group 1 surface treated with Er-YAG laser and saline (S), Group 2 PDT using MBP + S, Group 3 H F + S (control), Group 3 HF (Hydrofluoric acid) + saline, Group 4 HF (Hydrofluoric acid) + ultrasonic bath (UB) + S, Group 5 sand blasting the glass ceramic surface with 120 um Al(2)O(3), Group 6 LDC surface conditioned with SECP(Etch and Prime) and Group 7 ECL(Laser) + S on was irradiated on LDC. Both chemical and mechanical surface treatments of LDC were followed by placement of metallic brackets. Samples were arranged in universal testing machine for shear bond strength (SBS) testing. Bond failure of brackets were assessed using ARI. To assess and compare the mean and standard deviations (SD) among experimental groups analysis of variance (ANOVA) was employed. All treatment combination means were compared using the post hoc Tukey's multiple comparison test at a significance level of (p </= 0.05). RESULTS: SBS values of Group 2 H F acid + S displayed highest bond durability (22.28 +/- 1.09 MPa). Whereas, specimens in Group 4 surface treated with 120 mum Al(2)O(3) displayed lowest SBS scores (11.81 +/- 0.55 MPa) and these bond scores were comparable to PDT using MBP + S (12.54 +/- 1.09 MPa) (p > 0.05). LDC surface treated by ECL + S (21.11 +/- 3.85 MPa), HF + UB + S (19.28 +/- 0.52 MPa) exhibited results comparable to HF acid + S (p > 0.05). CONCLUSION: LDC conditioned with HFS still remains as gold standard. Use of PDT for surface treatment of LDC and bonded to metallic bracket is not recommended as it results in decreased bond durability. Use of ECL-S and HF + UB + S has a potential to be used alternatively to HFS for LDC conditioning.