Análise da biomecânica no nivelamento da Curva de Spee: um estudo por meio de modelo de elemento finito

Abstract

Objectives: To evaluate the dental displacements and the periodontal ligament stress after the application of the reverse curve mechanics in the lower dental arch with deep Spee curve. Materials/Methods: A curve of Spee with a maximum depth of 4 mm was simulated in a finite element model, which had teeth, periodontal ligament (PL), trabecular bone, cortical bone, brackets edgewise (0.022’’x0.028’’). The curve of Spee levelling was simulated with continuous rectangular 0.016"x 0.022" wire with prefabricated reverse curve, with nickel-titanium and stainless-steel wires. Were analysed: Global and vertical displacement trend on canines and posterior teeth, maximum principal stress on PLs. Results: With the stainless-steel wire, the results presented the same pattern of displacement tendency observed with the nickel-titanium wire, but in greater magnitude. The maximum global displacement trend for the stainless-steel wire was 1.6 times greater than other, and it was concentrated mainly in the canines and premolars. The canine showed extrusion tendency on the vestibular face and intrusion on the lingual face, the PL was submitted to traction on the vestibular face and compressed on the lingual face. With nickel titanium wire, the first premolar had opposite movement of the canine. With stainless-steel wire, this tooth also presented stability in the mesio-lingual region. The second premolar showed a tendency of extrusion, traction the PL in the apex region. With the stainless-steel wire the first premolar showed an extrusion tendency in the mesial part of the vestibular face and intrusion in the distal part of the lingual face. Conclusions: The high modulus of elasticity of stainless-steel wire makes it to release larger forces than nickel-titanium. The canine presented a tendency of inclination to lingual and the second premolar presented tendency of extrusion, in both simulations. With the nickel-titanium wire, the first premolar had a tendency of inclination to vestibular and the molars presented stability. With the stainless-steel wire, in the first premolar there was a tendency of inclination to vestibular and distal and in the first molar, of verticalization.