Biomechanical effects of a new crimpable gate spring combined with conventional rectangular archwires for torque adjustment of individual anterior teeth : A comparative finite element study.

Objective: Precise root torque adjustment of anterior teeth is indispensable for optimizing dental esthetics and occlusal stability in orthodontics. The efficiency of traditional rectangular archwire manipulation within bracket slots seems to be limited. The crimpable gate spring, a novel device, has emerged as a promising alternative. Yet, there is a paucity of guidelines for its optimal clinical application. This study used finite element analysis (FEA) to investigate the biomechanical impact of the gate spring on torque adjustment of individual anterior teeth and to elucidate the most effective application strategy.

Methods: A FEA model was constructed by a maxillary central incisor affixed with an edgewise bracket featuring a 0.022 × 0.028 inch (in) slot. A range of stainless steel rectangular archwires, in conjunction with a gate spring, were modeled and simulated within the bracket slots. A control group utilized a conventional rectangular wire devoid of a gate spring. Palatal root moments were standardized to 9, 18, and 36 Nmm for both experimental and control groups.

Results: The gate spring significantly amplified palatal root movement, notably with the 0.019 × 0.025 in archwire. However, this was accompanied by an increase in stress on the tooth and periodontal ligament, particularly in the cervical regions. The synergistic use of a 0.019 × 0.025 in rectangular archwire with a gate spring in a 0.022 × 0.028 in bracket slot was identified as most efficacious for torque control of individual anterior teeth.

Conclusions: The gate spring is a viable auxiliary device for enhancing torque adjustment on individual teeth. However, caution is advised as excessive initial stress may concentrate in the cervical and apical regions of the periodontal ligament and tooth.