In vitro evaluation of shear bond strength of new and rebonded brackets reconditioned with grinding: Effect of ARI index

Abstract

The aim of the current study was to compare the rebond strength of the high ARI index brackets with that of the low ARI index and also with the new brackets. Initially, 150 new brackets were gathered and underwent a bonding/rebonding procedure on human premolar teeth to achieve various ARI indices. The brackets were then rebonded (on 3 sets of 20 new human premolar teeth) as group A: brackets with ARI score above IV (i.e., IV+-); group B: brackets with ARI score below II (i.e., II-); group C: brackets with ARI score III. Group D (control group) included another twenty premolar teeth which were bonded with new brackets. The bond strengths were evaluated using ANOVA analysis and Tukey follow up test under SPSS. Statistical significance was set at p<0.05. The ANOVA analysis indicated that ARI score IV+ brackets (group A) and also new brackets (group D) had significantly a higher rebond strength (13.98 and 15.67 Mpa, respectively) than those of ARI score II- (8.05 Mpa) and score III (9 Mpa) brackets (p<0.05). However, no statistically significant difference existed between control and ARI score IV+ group (p>0.05). The findings indicated that score IV and V brackets had a higher rebond strength than score I-III brackets. Furthermore, score IV and V brackets had a comparable rebond strength with new brackets. However, as with any laboratory study, caution should be taken in extrapolating these findings to oral environment. é Medwell Journals, 2014.