Influence of phototherapy on adhesive strength and microleakage of bleached enamel bonded to orthodontic brackets: An in-vitro study.

Aim: The aim of the present in-vitro study was to explore bleached enamel reversal with phototherapy (Er,Cr:YSGG) when using two dissimilar bonding system to bond brackets on microleakage and shear bond strength.
Material and Methods: Amongst one twenty samples, ninety samples were bleached using 35% hydrogen peroxide. After the bleaching procedure, the teeth were randomly divided into three groups according to surface conditioning treatment (n = 30 each). Group 1: treated with Er,Cr:YSGG (ECL) Group 2: 10% sodium ascorbate (SA) and Group 3: Bleached only (BO). Based on the type of adhesive, specimens were further classified into eight subgroups. In subgroup 1,2,3 and no treatment (NT) (n = 15) adhesive Transbond XT was applied on already etched surface and these subgroups were named as NT-TEP, BO-TEP, ECL-TEP and SA-TEP. Similarly, in subgroup 5,6,7 and NT specimens (n = 15) were conditioned with Transbond Plus self-etching primer and these subgroups were named as NT-SEP, BO-SEP, ECL-SEP and SA-SEP. Samples from each subgroup were exposed to increasing load for evaluation of shear bond strength. Microleakage among subgroups were tested by immersing samples in Methylene blue prior one day. Analysis of variance and Tukey multiple comparisons test was used to assess data.
Results: The maximum and minimum bond strength was observed in group NT-TEP [17.14(2.54)] and BO-SEP [6.14(0.215)] respectively. Samples conditioned with phototherapy ECL-TEP [16.14(1.231)] exhibited comparable bond strength to specimens conditioned with sodium ascorbate (SA-TEP) [16.72(1.298)]. Similarly, bond strength values of ECL-SEP [13.43(0.921)] and SA-SEP were comparable. The highest microleakage score was demonstrated in BO-SEP [83.21(38.21)] whereas, the lowest microleakage scores were displayed in NT-TEP [23.73(13.45)].
Conclusion: Er,Cr:YSGG phototherapy reversal on bleached enamel with etch and rinse adhesives has a potential to be used in clinical settings alternate to conventional sodium ascorbate when bonding orthodontic brackets.
(Copyright © 2019 Elsevier B.V. All rights reserved.)