Passive self-ligating metal brackets: evaluation of torque and slot measurements

New orthodontic bracket designs have been regularly developed. Their clinical performance depends on reliability of measures, among other factors. Objective: The aim of this study was to evaluate slot measures and torque angle of different passive self-ligating metal brackets, while comparing them with measures provided by manufacturers. Material and methods: Five different passive self-ligating metal bracket brands were selected (n = 10 each): Tellus EX, Tellus EX New, Damon Q, Easy Clip and ID-Logical. Bracket slots images were obtained with the aid of Starrett, MV300 Galileo Vision System. For slot digital measurement, Software M3 Metrology Reabout IV was used. Slot measures were evaluated in cervico-occlusal direction (slot height), buccolingual depth (in-out), and bottom-slot inclination (torque angle). Difference between obtained and provided measures was estimated and expressed as a percentage. Data were subjected to descriptive statistical analysis. Results: Most brackets evaluated by the present study revealed variation in both torque angle and slot measures which were confirmed to be greater than those provided by the manufacturer (Easy Clip, Damon Q and Tellus EX), except for two brackets (Tellus EX New and ID-Logical). The latter presented variation within normality with values accepted by ISO standards (± 1 degree and ± 1 mm variation). Conclusion: Most brackets assessed herein (Easy Clip, Damon Q and Tellus EX) presented variation in torque angle and slot measures. Tellus EX New and ID-Logical brackets remained within standards. Better standardization and control should be assumed by manufacturers in order to promote more reliability and predictability of the orthodontic treatment results.