Hamidreza Pakshir - DDS, MS Assoc. Prof. Dept. of Orthodontics, Dental School, Shiraz University of Medical Sciences, Shiraz, Iran
R Rostami - Orthodontist
AA Alavi - DDS, MS Assoc. Prof. Dept. of Restorative Dentistry, Dental School, Shiraz University of Medical Sciences, Shiraz, Iran

Background and aim: Different adhesives have been used for bonding orthodontic brackets to teeth. The aim of this study was to evaluate the possibility of using Core Max II in bracket bonding by comparing it's shear bond strength with the two commonly used orthodontic adhesives; Transbond XT and Unite. Subjects and Methods: In this interventional study, ۱۰۵ human premolars were divided into ۳ groups of ۳۵ each. After etching with ۳۷% phosphoric acid, Dyna-Lock stainless steel brackets (۳M Unitek, Monrovia, CA) with the average base surface area of ۱۲.۰۹ mm۲ were bonded with three different adhesives: Core Max II (Sankin, Tokyo, Japan) Transbond XT (۳M Unitek) and Unite (۳M Unitek). The shear bond strength of ۳ groups were measured by a universal testing machine (lnstron ۳۴۰۱, Canton, Mass) with cross- head speed of ۰.۵ mm/min. Adhesive Remnant Index (ARI) was determined under ۱۰x magnification. For data analysis, SPSS statistical package was used. Results: Mean shear bond strength of Core Max ۱۱ (۱۷.۲۴± ۳.۲ MPa) was significantly higher than Transbond XT (۱۵.۴۴ ± ۲.۲ MPa) (P=۰.۰۰۹) but had not statistically difference with Unite (۱۷.۱۶ ± ۳.۷ MPa) (P=۰.۹۳). Evaluation of ARI indicated that ۸۳% of Core Max II samples had score ۰ or ۱ and ۱۷% had score ۲ or ۳. These percentages were ۶۶% and ۳۴% for Transbond XT and ۷۷% and ۲۳% for Unite, respectively. Conclusion: In this study, it was concluded that: ۱) Core Max II had a shear bond strength higher that Transbond XT and equal to Unite. ۲) ARI of Core Max II showed a higher frequency of score ۰ and ۱, which indicated that after debonding, most of the adhesive remains on the bracket base. ۳) Core Max II has the potential of being a good orthodontic adhesive. (IJO ۲۰۰۶; ۱: ۴۲ - ۴۷) 

Shear Bond Strength, Core Max II, Transbond XT, Unite, Adhesive Remnant Index (ARI)