Evaluation of TMJ articular eminence morphology and disc patterns in patients with disc displacement in MRI Avaliação da morfologia da eminência e dos padrões do disco articular em pacientes com deslocamento de disco em IRM

The aim of this study was to assess the shape of the temporomandibular joint (TMJ) articular eminence and the articular disc configuration and position in patients with disc displacement. TMJ magnetic resonance images (MRI) of 14 patients with bilateral disc displacement without unilateral reduction were analyzed. Articular eminence morphology was characterized as box, sigmoid, flattened, or deformed. Articular disc configuration was divided into biconcave, biplanar, biconvex, hemiconvex or folded, and its position, as “a” (superior), “b” (anterosuperior), “c” (anterior) or “d” (anteroinferior). The images were divided and the sides with disc displacement with reduction (DDWR) and without reduction (DDWOR) were compared. Regarding articular eminence shape, the sigmoid form presented the greatest incidence, followed by the box form, in the DDWR side, although this was not statistically significant. In the DDWOR side, the flattened shape was the most frequent (p = 0.041). As to disc configuration, the biconcave shape was found in 79% of the DDWR cases (p = 0.001) and the folded type predominated in 43% of the DDWOR cases (p = 0.008). As to disc position, in the DDWR side, “b” (anterosuperior position) was the most frequent (p = 0.001), whereas in the DDWOR side, “d” (anteroinferior position) was the most often observed (p = 0.001). The side of the patient with altered disc configuration and smaller shape of TMJ articular eminence seems to be more likely to develop non-reducing disc displacement as compared to the contralateral side. Descriptors: Temporomandibular joint disorders; Temporomandibular joint disk; Temporomandibular joint dysfunction syndrome; Magnetic resonance imaging. Resumo: Objetivou-se avaliar a morfologia da eminência e a configuração e a posição do disco da articulação temporomandibular (ATM) em pacientes com deslocamento de disco. Foram analisadas imagens por ressonância magnética (IRM) da ATM de 14 pacientes com deslocamento de disco bilateral, sem redução unilateral. A morfologia da eminência articular foi caracterizada como caixa, sigmóide, aplainada e deformada. A configuração do disco articular foi dividida em bicôncava, biplanar, biconvexa, hemiconvexa e dobrada e a sua posição em “a” (superior), “b” (ântero-superior), “c” (anterior) e “d” (ântero-inferior). As imagens foram divididas e comparadas entre o lado com deslocamento de disco com redução (DDCR) e o lado sem redução (DDSR). Quanto à forma da eminência articular, a forma sigmóide foi a mais incidente, seguida da caixa, no lado com DDCR, embora esta diferença não tenha sido estatisticamente significante. No lado com DDSR, a forma aplainada foi a mais freqüente (p = 0,041). Na configuração do disco, a forma bicôncava foi observada em 79% dos casos de DDCR (p = 0,001) e a dobrada em 43% dos casos de DDSR (p = 0,008). Em relação à posição do disco, a posição “b” (ântero-superior) foi a mais freqüente no lado com DDCR (p = 0,001), enquanto que no lado com DDSR, foi a “d” (ântero-inferior) (p = 0,001). O lado do paciente com alteração na configuração do disco e uma forma menor da eminência articular da ATM parece ter mais chance de desenvolver o deslocamento do disco sem redução quando comparado ao outro lado. Descritores: Transtornos da articulação temporomandibular; Disco da articulação temporomandibular; Síndrome da disfunção da articulação temporomandibular; Imagem por ressonância magnética. Fabio Henrique Hirata(a) Antônio Sérgio Guimarães(a) Jefferson Xavier de Oliveira(b) Carla Ruffeil Moreira(c) Evangelo Tadeu Terra Ferreira(b) Marcelo Gusmão Paraiso Cavalcanti(b) (a) MScs, Department of Morphology, College of Medicine, Federal University of São Paulo. (b) PhDs, Department of Radiology, School of Dentistry, University of São Paulo. (c) MSc, Department of Stomatology, School of Dentistry of Bauru, University of São Paulo. Radiology Corresponding author: Marcelo Gusmão Paraiso Cavalcanti Disciplina de Radiologia, Departamento de Estomatologia Faculdade de Odontologia da Universidade de São Paulo (FOUSP) Av. Lineu Prestes, 2227, Cidade Universitária São Paulo SP Brazil CEP: 05508-000 E-mail: [email protected] Received for publication on Feb 07, 2006 Sent for alterations on Nov 29, 2006 Accepted for publication on Feb 11, 2007 Evaluation of TMJ articular eminence morphology and disc patterns in patients with disc displacement in MRI Braz Oral Res 2007;21(3):265-71 266 Introduction Magnetic resonance imaging (MRI) provides an excellent representation of soft tissues in anatomical and semi-functional relationships. The multisection images allow a tridimensional analysis of the temporomandibular joint (TMJ), providing the most complete assessment of the relationship of the mandibular head, articular disc, mandibular fossa and articular eminence.10 The TMJ is a bilateral articulation, connected to the mandible and interdependent, with its own movements in each side yet simultaneous, and could be considered as one sole joint.15 Several studies have assessed the TMJ as an individual or unilateral structure,2,3,12,18,20,22,23,24 not taking into account the contralateral side. Internal disorders of the TMJ have been defined as an abnormal positional relationship between the disc and the condyle, articular eminence, and/or articular fossa.18 It has been argued that the articular eminence morphology may be a factor in the etiology of internal TMJ disorders.8,9,11-14,19-21,25 Some authors have suggested that greater articular eminence inclination would be a predisposing factor for internal disorders,9,20,21 even though other studies did not support these results.8,11,13,14,19 Articular eminence flattening can be a result of internal disorders.5,12 The association of articular disc position and configuration in the TMJ with internal derangements,2,3,12,18,20,22,24 as well as temporomandibular disorders,1,4-7,16,17,23 has also been reported by many authors. The objective of this retrospective study was to assess the morphology of the articular eminence and articular disc on the side with disc displacement with reduction (DDWR) and on the side with disc displacement without reduction (DDWOR) in the same patient. Material and Methods The study protocol was submitted to and approved by the Research Ethics Committee, Federal University of São Paulo (CEP 1334/03). The investi-