Comparison of biomechanics and clinical validation of torsion and swing tooth extraction methods

Background: Adolescents often require extractions of premolar teeth with single flat or curved roots for orthodontic treatment of malocclusions. The torsion method is typically considered unsuitable for these teeth due to the risk of root fractures. However, clinical experience suggests that moderate torsion can safely and efficiently dislocate these teeth, particularly in younger patients with developing dental structures. Despite the widespread use of torsion and swing methods, comparative studies on their biomechanics and efficacy are lacking. Methods: Three-dimensional finite element analysis was used to compare biomechanical behaviors of the tooth-PDL (periodontal ligament)-alveolar bone complex during torsion and swinging loading. Clinical trials focused on the symmetrical extraction of premolar teeth required for orthodontic treatment in adolescents, comparing the two methods in terms of extraction time, alveolar socket expansion, surgical difficulty and patient satisfaction. Results: The torsion method exerted less stress on the single-rooted tooth and surrounding alveolar bone, proving superior to the swinging method in tearing the PDL. Clinical validation showed that the torsion method significantly reduced extraction time (averaging 12.10 ± 5.36 s, p < 0.001), buccolingual expansion of the alveolar socket (0.53 ± 0.20 mm, p < 0.001), and volume expansion of the alveolar socket (1.22 ± 0.05 mm3, p < 0.001). It also resulted in lower surgical difficulty and great postoperative patient evaluations. Conclusions: Both methods resulted in safe extraction, but the torsion method proved more advantageous by reducing the risk of root fracture, preserving the alveolar socket, and improving extraction efficiency. Clinical Trial registration: ChiCTR2400086715.

Tooth extraction; Biomechanics; Tooth socket; Oral surgery; Minimally invasive; Finite element analysis

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