Resistance to sliding [RS] was investigated for 3 passive self-ligating brackets (Damon 3MX [DA]–SDS Ormco; Vision LP [VLP]–American Orthodontics; SmartClip [SC]-3M Unitek), 3 interactive self-ligating brackets (In-Ovation R [IN]–GAC, Time 3 [TI]–American Orthodontics, Speed [SP]–Strite industries) and a conventional bracket tied with elastomeric module (Ovation [OV]–GAC). For all cases, a 0.018" x 0.025" stainless steel archwire was drawn through each bracket (n=4) at a rate of 10 mm/min over a distance of 2.5 mm at 34°C. The RS was measured at second-order angulations, ranging from -9° to +9°. The theoretical critical contact angles for binding θc were calculated and ranged from 2.9° to 4.9°. Linear regression lines of RS against θ were determined, for each bracket, below and above their θc. From the intersection of the 2 lines, the experimental θc was defined. The experimental θc and RS values at experimental θc were submitted to 1-way ANOVA. Both were statistically significant. TI presented θc (5.1°) significantly higher than IN (3.5°) and OV (3.3°). The smallest RSs were presented by the passive self-ligating brackets, VLP (17.8 cN), DA (30.9 cN) and SC (48.9 cN); which were significantly lower than the RSs of IN (101.7 cN) and SP (129.1 cN). It was concluded that an interactive clip design is not necessarily associated with low θc or high RS as TI presented the highest θc with intermediary values of RS. The best θc-RS combinations were observed for the passive self-ligating brackets, especially for VLP. (Grants: FAPESP 08/51280-5).