The effects of different light sources on the bond strength of brackets bonded with indirect technique- a laboratory and clinic study

The aim of this study was to test the efficacy of light cured Transbond XT resin as an indirect bonding material. In the in vitro part of the study the effects of different light sources and curing times were investigated. The bond strength between the enamel bracket interfaces was measured and the amount of adhesive remaining on the tooth was evaluated. One hundred and twenty premolars were divided into 6 groups. In all groups, brackets were bonded on duplicate stone models with Transbond XT resin and transfer trays were prepared. In the first group, brackets were transferred to teeth using chemically cured Sondhi Rapid-Set. In all other groups, diluted Transbond XT resin was used. Following primer application on etched enamel surfaces, the trays were placed over the models. In Group 2, adhesive was cured for 5 s with Plasma light. In Groups 3, 4 and 5 curing times were 5, 10 and 20 s with LED, respectively. In Group 6, conventional halogen was used for 40 s. All teeth were placed in acrylic and were tested in shear mode. The lowest bond strength values were recorded with the Sondhi material and the highest with the 20 s LED. The Tamhane Post Hoc Test revealed that the bond strengths of Sondhi (p=0.01), LED 5 s (p=0.03) and LED 10 s (p=0.02) groups were statistically lower than LED 20 s group. No significant differences were found in ARI scores among the groups. In the in vivo study, randomly selected 2 segments were bonded indirectly with diluted Transbond XT resin cured with LED for 20 s on 20 patients. The remaining last 2 segments were bonded directly with Transbond XT resin cured with LED for 20 s. The failure rates of the brackets were observed for 6 months. The effects of these two bonding methods on the periodontal tissues were evaluated with `Gingival Index? and `Plaque Index?. At the end of the 6 month observation period, no significant differences were found between the effects of tested two bonding methods on the periodontal tissues.