Torque expression of a customized lingual appliance according to different elastomeric ligatures over time: an in vitro study

Abstract

Aim: Torque control in lingual orthodontics is essential to obtain optimal aesthetic results, nevertheless three dimensional control of anterior teeth depends on many factors and the role of ligatures in establishing the engagement of the wire into the slot is considered as a key point. The aim of this in vitro experimental study was to evaluate how different ligatures exposed to usage degradation perform in maintaining torque control in a customized lingual bracket appliance using two differently sized wires.

Materials and methods: A typodont with eight extracted human teeth was created and a set of customized lingual brackets was obtained. Lingual ligatures and ordinary ligatures were tested on the 0.016x0.022 NiTi and the 0.016x0.024 SS wires using a compression/traction machine to calculate the efficiency in torque control. For each wire and type of ligature, the typodont was stored in physiological saline Sodium- Chloride 0.9%, pH 5.5 to simulate the oral environment for one month and then the mechanical test was repeated. A statistical analysis was performed. Annali di Stomatologia 2018;VIII (2):59-64 59

Results: No significant differences were found in angle values between ligatures or timepoints when the complete set of data was tested (p>0.01).

Conclusions: The ligature type and stretching by use did not affect torque efficiency during the first month.