Evaluation of using a self-etching primer during indirect bonding under dry and contaminated conditions.

Abstract

Self-etching primers (SEPs) and indirect bonding have both been used separately to bond brackets with clinical success, and both have advantages over more traditional bonding methods. Thus, the purpose of this study was to determine if SEPs used with an indirect bonding technique can provide acceptable bracket strengths under both dry and contaminated conditions. Sixty-four human maxillary premolars were cleaned, mounted, and randomly divided into four groups of sixteen. In group 1 (control), 16 orthodontic brackets were bonded to dry teeth using a traditional phosphoric acid etchant/primer; in group 2 (control), the same etchant/primer was used but saliva contamination occurred after the primer was applied; in group 3, a SEP was used on dry enamel surfaces; in group 4, the SEP was used, and saliva contamination occurred after SEP application. In all groups, the bonding adhesive and indirect bonding method were the same. The teeth were debonded ~36 hours following initial bonding using a universal testing machine. After debonding, the amount of residual adhesive remaining on each tooth was evaluated. Analysis of Variance was used to compare the shear bond strength of the four groups, and the Pearson exact test was used to compare the Adhesive Remnant Index (ARI) scores for the four groups. The Analysis of Variance (F=1.94) indicated that there were no significant differences (p = 0.133) in bond strength between the groups. The comparisons of the ARI scores indicated that bracket failure mode was not significantly different (p = 0.11). The present findings indicated that using an SEP with indirect bonding can provide acceptable bond strengths when bonding orthodontic brackets. Saliva contamination occurring after the placement of the primer or SEP had no negative effect on the shear bond strength; thus, the SEP provided no substantial benefit when bonding under contaminated conditions. For all groups, the ARI scores showed that the majority of the adhesive stayed on the teeth after debonding, providing evidence that contamination occurring after the primer/SEP application does not negatively affect the bond strength to enamel.