Effects of precuring heating modalities on the shear bond strength and adhesive remnant index of orthodontic adhesive

Abstract

Aim: This study aimed to investigate precuring adhesive and bracket heating\cooling protocol on shear bond strength (SBS) and adhesive remnant index (ARI). Methods: 70 newly extracted lower premolars categorized randomly into 7 groups (n = 10 (ten teeth each)) according to adhesive and/or brackets temperatures. Pre-curing, the 3M Transbond PlusTM XT adhesive temperature was adjusted to 5, 22, 40, 70°C, while the brackets were stored at 5, 55°C before bonding. Also, adhesive and brackets were heated by tooth dryer before curing representing the seventh group. The samples were stored in deionized water for 24h at 37°C in dark incubator before debonding by universal testing machine. Analysis of variance (ANOVA) and post Hoc Tukey statistical tests were performed for SBS analysis, while Kruskal Wallis test analyzed ARI data (α=0.05). Results: Significant differences were found among the groups regarding SBS and ARI where p = 0.00, 0.024 respectively. SBS significantly increased when the adhesive temperature modified to 5°C and 70°C and brackets temperature adjusted to 5°C and 55°C. Also, heating the adhesive and brackets by tooth dryer generated peak SBS. While, heating the adhesive to 40°C declined SBS significantly. Conclusions: Lowering the temperature of the adhesive and/or brackets to 5°C and elevation their temperature above 55°C pre-curing has favorable effects on SBS. Storing the adhesive at 40°C before bonding showed reductions in SBS. Also, heating both the adhesive and brackets pre-curing formed all-out SBS with reduced ARI.