| Popis: |
AIM: The aim of this in vitro study was to investigate the differences in shear bond strength (SBS) of steel brackets bonded with two different bonding systems-one step and two steps, as well as to compare the Adhesive Remnant Index (ARI). MATERIALS AND METHOD: A total of 36 extracted intact permanent premolars (no cavities, no fillings, no white spot leasions) were randomly divided into two groups (n=16). Sample was stored in saline solution. The teeth were fixed in cubic plastic molds with cold-curing methacrylate resin. Before the bonding procedure in both groups the acid etching was performed using 37% phosphoric acid (Ultra-Etch, Ultradent Products Inc., South Jordan, UT, USA) for 15 s, rinsed for 20 s and then dried for 10 s. In Group I the brackets were bonded with Transbond XT Primer and Transbond XT Paste (3M Unitek, Monrovia, CA, USA). In Group II the brackets were bonded with GC Ortho connect (GC America, Alsip, Illinois, USA). In both groups the adhesive resin was polymerised for 20 s from two directions (mesial and occlusal) using a Bluephase light-curing unit (Ivoclar, Vivadent, Liechtenstein) with a power output of 1100 mW/cm². SBS was measured in MegaPascals (MPa) using Universal testing machine- crosshead speed of 1 mm/ min with an occlusal-gingival load applied parallel to the bracket's surface. Failure mode was assessed according to the Adhesive Remnant Index (ARI). T test was applied to analyze SBS data. Mann-Whitney U tests was used to compare the between-group differences in the ARI scores. In all the statistical tests the significance level was set at p≤ .05. RESULTS: No statistically significant difference was found among Groups 1 and 2 in SBS. ARI score was similar in both groups, (1.13 and 1.06 respectively). No statistically significant difference was observed for ARI scores, even though score 3 was registered only in some samples in group 1. CONCLUSION: One step bonding system demonstrated no reduction in SBS compared to two steps system. Both in one-step and two-steps bonding systems, breakage during debonding happened between enamel and bonding system. |
