Abstract:
This study aims to investigate torque expression in different types of esthetic
conventional and self-ligating brackets using a 0,019”x0,025” rectangular stainless
steel archwire. It was selected ten types of brackets from six different commercial
brands: four ceramic self-ligating brackets (In-Ovation C – GAC, Damon Clear –
Ormco, QuicKlear - Forestadent, Click-It - TP Orthodontics), one ceramic self-ligating
bracket with metal-reinforced slot (Clarity SL - 3M Unitek), three ceramic
conventional brackets (Inspire Ice – Ormco, InVu Ceramic - TP Orthodontics, Roth
Ceramic - Morelli) and one ceramic conventional bracket with metal-reinforced slot
(Clarity Metal-Reinforced Ceramic Bracket - 3M Unitek). As control it was used the
metallic Damon MX self-ligating bracket (Ormco). It was used 50 0,019”x0,025”
rectangular stainless steel archwire segments. Third-order moments were measures
at 12º, 24º e 36º by the use of an archwire torsion device associated with a Universal
Testing Machine (EMIC DL2000). For comparison of the third-order moment it was
used the Anova and Tukey tests. In all tested angulations the Damon Clear bracket
presented the highest third-order moment. It was followed by the Clarity, Clarity SL
and Damon Mx brackets, and with the worst torque expression was the InVu Ceramic
bracket. When it was observed the clinically effective torque this study showed that it
started in smaller torsion angles in that brackets that have smaller slot heights and
consequently smaller torque play between the archwire and the slot. Among them,
the Damon Clear was the one that firstly presented a clinically effective torque, and
the smallest slot height. The InVu Ceramic had the biggest slot height and was one
of the latest to express a clinically effective torque. Some brackets broke during the
tests not supporting all the torque applied. The QuicKlear bracket broke before 24°
and Ceramic Roth and Click-it broke before 36°.
