Avaliação da estabilidade da cirurgia de avanço mandibular através da superposição de modelos tridimensionais

• Autor(a) principal: Carvalho, Felipe de Assis Ribeiro
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14103
• topic: Surgery; Mandibular advancement; Orthodontics; Cone beam computed tomography; Three dimensional imaging; Cirurgia; Avanço mandibular; Ortodontia; Tomografia computadorizada de feixe cônico; Imagem tridimensional; Boca - Cirurgia; Côndilo mandibular; CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA::ORTODONTIA

Although mandibular advancement surgery is considered a highly stable procedure, some clinical concerns have been raised regarding condylar and proximal segment changes that may lead to sagittal relapse and anterior bite opening. Assessment of surgical treatment outcomes using three-dimensional (3D) virtual models and superimposition tools allow the identification and quantification of bone displacement and remodeling that can help explain the interactions between the dental, skeletal and soft tissue components that underpin the response to treatment. This prospective observational study evaluated changes in the 3D position and remodeling of the mandibular rami, condyles and chin at splint-removal and 1 year after mandibular advancement surgery. For that, pre-surgery(T1), splint-removal(T2), and one year post-surgery(T3) cone-beam computed tomography (CBCT) scans of 27 subjects were used. An automatic technique of cranial base superimposition was used to assess changes in the anatomic regions of interest (ROI). Displacements were visually displayed and quantified in three-dimensional color maps by means of a contour line tool (ISOLINE). A paired t-test was used to compare changes between T1-T2 and T2-T3. Pearson correlation coefficients were used to check if displacements at the ROI were correlated within each other and along the evaluated times . The level of significance was set at 0.05. The mean mandibular advancement was 6.81±3.2mm at T2 and 6.36±3.41mm at T3 (p =0.13). Between T2 and T3, the chin position was further forward 2mm or more for 5 subjects and relapsed backwards ≥2mm for 7 subjects. 12% of patients showed relapses ≥4mm. For all other evaluated ROI, only the inferior rami (right 2.34±2.35mm and left 2.97±2.71mm) had mean displacements >2mm with surgery. In the long-term follow-up, those inferior rami lateral displacements were maintained (right 2.10±2.15mm, p=0.26 and left 2.76±2.80,p=0.46), as well as all other observed displacements (p>0.05). Post-surgical movement in the position of the chin was significantly correlated to changes in the posterior borders (left r=-0.73 and right r=-0.68) and condyles (left r=-0.53 and right r=-0.46). Mean displacements of the structures at the left side were slightly greater when comparing to the right side. Correlations of T1-T2 with T2-T3 displacements showed that the displacement of the left condyles with surgery were negatively correlated to its post-surgical adaptations (r=-0.51); and that superior portion of the left ramus surgery displacement was correlated to the post-surgical adaptation at the ramus posterior border (r=0.39) and condyle at the same side (r=0.39). It can be concluded that: (1) surgery changes were generally stable in one year follow up, but with a considerable individual variability; (2) post-surgical changes at the chin position are correlated to adaptations at condyles and rami posterior borders; and that (3) slightly greater displacements with surgery at the left side lead to greater post-surgical adaptations in the proximal segment at this side.