3037 Condylar traces and TMJ fossa shape
D. GÖSSI, L.M. GALLO, and S. PALLA, University of Zurich, Switzerland

Objectives: In the literature on mandibular kinematics, traces of points moving solidarily to the condyle have been often proposed for an easy visualization of the fossa shape. However, these traces have never been related to real in vivo motion data applied to the real 3-D anatomy of the temporomandibular joint (TMJ). Aim of this study was therefore to investigate whether the points whose traces best approximate the fossa are in a systematic geometric relationship to the condyle. Methods: Magnetic resonance imaging and jaw tracking were combined for the reconstruction and animation of the TMJ. We analyzed 20 TMJs from 10 asymptomatic subjects performing jaw opening as well as protrusive movements at deliberate rate. The trajectories were calculated for every point in a portion of space surrounding the condyle and moving solidarily to it in a 3-D grid with 0.5 mm spacing. The point maximizing the cross-correlation function between trace and its projection onto the fossa was defined as "best approximating" the fossa shape (BA). Results: During jaw opening, in 75% of the joints the BAs were within a sphere with 5.2 mm mean radius, centered 0.8 mm dorsally, 2.7 mm caudally and 0.7 mm internally to the medial condylar pole (remaining joints: radius 3.1 mm, center 2.5 mm dorsally, 3.4 mm caudally and 2 mm internally to the lateral pole). During protrusion, the BAs were even more dispersed, 50% being closer to the medial pole (radius 10.1 mm, center 0.9 mm ventrally, 3.9 mm caudally, 2 mm internally) and 50% closer to the lateral pole (radius 10.2 mm, center 2.2 mm dorsally, 2.5 mm caudally and 2.6 mm internally). Conclusions: Given the great dispersion found, the use of traces of a univocal condylar point appears questionable for an optimal approximation of the fossa shape.

Seq #275 - TMJ - Structure and Function II
3:45 PM-5:00 PM, Friday, 8 March 2002 San Diego Convention Center Exhibit Hall C

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