Variations of the Sagittal Condylar Path Inclination

Methods: Fifty-one subjects with Angle's Class I occlusion (21-32 years of age, mean 25,1), with no previous orthodontic treatment and no signs and symptoms of TMD were included. Each participant gave written informed consent, which was approved by the Ethical Committee of the School of Dentistry, University of Zagreb. Recordings were obtained with the use of the electronic ultrasound measuring device (Arcus Digma II, Kavo, Germany), using kinematic axis as posterior reference point. Data were transferred to the computer, and processed and analyzed with device's software. For each subject movements of left and right condyles were divided into three equal segments. For each segment of the condyle movement, condyle path inclination was calculated.

Results:

For left joint mean condyle inclination values in 1st condylar movement segment demonstrated on the average 14,4% higher values compared to 2nd movement segment and 39,2% higher values than in 3rd movement segment. For the right joint 1st condylar movement segment demonstrated on the average 15,8% higher values compared to 2nd movement segment and 41,5% higher values than 3rd movement segment.

Conclusions: Movement of the condyle in temporomandibular joint in sagittal direction is not uniform. First segment of the movement, which in normal occlusion is the only one that affects occlusion, demonstrated steeper average inclination values (left 45.9°, right 46.8°) than recommended for average setting of articulators. The results suggest that the average values for semi-adjustable articulator setting need to be reconsidered.