Construction of an In Vivo Debonding Device and Comparison of Bracket Failure Rate and Debonding Force for Indirect Orthodontic Bonding

Abstract

A major limitation of indirect bonding is incomplete penetration of the curing light through transfer trays, leading to inadequate curing of light-cure adhesive resin, causing bracket bond failure. Dual-cure adhesive resin is both light and chemically cured, which reduces the requirement of light for curing of the composite. Comparative evaluation of bracket failure rate and bond strength between dual-cure composite and light-cure composite for indirect orthodontic bonding of brackets. A split-mouth randomized clinical study was carried out in 51 patients (30 females and 21 males). Indirect orthodontic bonding using Erkogum as adhesive to attach the bracket to cast and glue gun material was utilized to form a transfer tray. Conventional light-cure and dual-cure adhesive resins were compared with regard to their bracket failure rate, adhesive remnant index score, and in vivo clinical bond strength. Kolmogorov-Smirnov test was employed to test the normality of data. Mann-Whitney U test and Chi-square test were performed for the quantitative variables and it was observed that both the groups showed similar results for the parameters being measured. The mandibular arch showed more bracket failure, the dual-cure composite group showed more bracket failure, however, the adhesive remnant index (ARI) score for both the groups was similar. No statistically significant difference was seen concerning the clinical bond strength between the two adhesive resins. Dual-cure adhesive system can be used for indirect bonding in orthodontics. The mandibular arch had a higher bond failure in the second premolar region. The sequence of bond failure was concordant among both the adhesive groups. However, dual-cure adhesive invariably showed more bracket failure. The highest bond strength was observed for the maxillary canine brackets in the light-cure group, and mandibular canine brackets in the dual-cure group. Whereas, the weakest bond strength in the light-cure group was observed for the mandibular second premolar brackets and for maxillary second premolar brackets in the dual-cure group. There was no significant difference between the in vivo clinical bond strength between the two adhesive systems. On debonding, majority of the adhesive was observed to be on the tooth surface. This study signifies that both light-cure and dual-cure resins can be used for indirect bonding procedures but light-cure composite resin shows a lower bracket failure rate as compared to dual-cure composite resin.