Effect of water and saliva contamination on the shear bond strength of a new light-cured cyanoacrylate adhesive.

AIM The purpose of the study was to assess the effect of water and saliva contamination on the shear bond strength and site of bond failure of two different orthodontic adhesives (Transbond XT and cyanoacrylate Smartbond LC). MATERIALS AND METHODS 120 bovine permanent mandibular incisors were randomly divided into 6 groups, and each group consisted of 20 specimens. Each adhesive was tested under three different enamel surface conditions: 1) dry, 2) water contamination, 3) saliva contamination. 120 stainless steel brackets (0.018-inch slot DB, Leone) were bonded in each test group with the respective adhesive. After bonding, all samples were stored in distilled water for 24 hours and subsequently tested in a shear mode on an Instron Universal Testing Machine. Shear bond strength and site of bond failure were evaluated. Kruskal-Wallis and Fisher's exact tests were applied to determine significant differences in terms of bond strength among the 6 groups. The chi-square test was used to determine significant differences in the Adhesive Remnant Index (ARI) scores. RESULTS Transbond XT showed the highest bond strength values when it was applied onto dry enamel (P < 0.0002). No significant differences were reported when Transbond was used either on water- or saliva- contaminated enamel (P = 0.5), however the bond strength values were significantly low. For Smartbond LC no significant differences were found between dry and moist with water conditions (P = 0.3). Significantly higher bond strength values were reported when Smartbond LC was used on saliva contaminated enamel (P = 0.002). Significant differences in debond locations were found among the different groups. CONCLUSIONS The use of a cyanoacrylate adhesive is indicated under moist conditions (particularly saliva), and when a short setting time is required. This can be considered advantageous in clinical orthodontic bonding compared to conventional composites.