Avaliação do disco articular de pacientes submetidos à cirurgia ortognática: estudo retrospectivo com RNM

Abstract

Maxillofacial skeletal deformities affect a large part of the world population and they are characterized by structural morphological changes, which is determined from unfavorable genetics and diagnosed during craniofacial growth. These deformities impair aesthetic and function, such as difficulties in chewing, swallowing, diction and breathing. Orthognathic surgery (OS) is a procedure to establish the anatomical and functional balance of the bones on the face, as from maxillary and mandibular osteotomies, to correct the dentofacial disharmony and restoring the functional balance of the individual’s jaws, to normalize breath, the chewing and to improve self-esteem. Patients with dento-skeletal deformities are more susceptible to internal disorders in the temporomandibular joint. In the scientific literature there is considerable distrust regarding the incidence of joint disc displacement in patients with facial deformities and a possible alteration in this positioning after orthognathic surgeries. Then, the objective of this work was to evaluate, by means of nuclear magnetic resonance (NMR), the shape and position of the articular disc in relation to the mandibular condyle before and after orthognathic surgery in patients with Pattern II and Pattern III facial submitted to bimaxillar orthognathic surgery. For the analysis, records and images of MRI from a private clinic located in the city of Salvador, BA, Brazil were available. MRI scans were performed on the 1.5-T (Signa, General Electric, Milwaukee, WI) with 3-inch coil receivers bilaterally, according to the routine sequence and the image acquisition protocol advocated by Zhang, SY Et al., (2009) and Cai, XY et al., (2011). The images were evaluated using diagnostic search criteria for adapted temporomandibular disorders (RDC / TMD) described in 2009 by Ahmad, M et al., Diagnostic criteria for temporomandibular disorders (RDC / TMD). The same team that used the same surgical technique operated all patients. In the evaluation of joint disc positioning, the study showed that Standard II and Standard II long face patients had the highest incidence of internal disturbances in the postoperative period of orthognathic surgery with counterclockwise rotation of the occlusal plane. The opposite was observed in Standard III patients, because it was the facial pattern that presented greater stability in the position and shape of the articular disc in the pre and postoperative period of orthognathic surgery with counterclockwise rotation of the occlusal plane. Therefore, Orthognathic surgery seems to modify meaningly the position and shape of the articular disc, with different behaviors associated with different facial patterns.