Method: Forty seven subjects with Angle Class I occlusion (age 21-31, mean 24,9), with no previous orthodontic treatment and no signs and symptoms of TMD were included. Recordings were obtained by an electronic ultrasound measuring device (Arcus Digma II, Kavo, Germany), using the kinematic axis as posterior reference point. Each subject had to make three protrusive, right and left lateral movements, from which the computer calculated left and right sagital condylar inclination and Bennett angle values.
Result:
Mean sagital condylar inclination was 41,7° for the left, and 42,5° for the right joint, relative to Camper's plane. Mean Bennett angle was 7,3° for left, and 9,0° for right joints. Intraindividual left-right side differences of posterior disclusive angles are shown in the following table.
|
Bennett angle |
Sagital Condylar Inclination |
Mean L-R difference (n=47) (degrees) |
4,2° |
5,1° |
No of participants with L-R difference < 3° |
23 |
18 |
No of participants with 3,1°-6,0° L-R difference |
12 |
12 |
No of participants with 6,1°-10,0° L-R difference |
8 |
12 |
No of participants with difference >10,1° |
4 |
5 |
Conclusion: The results of this study suggest that posterior disclusive angles differences greater than 5° can be considered normal (36% of participants for the sagital condylar inclination, and 26% for the Bennett angle showed L-R TMJ differences larger than 6°). Due to large intraindividual variations which can affect articulator setup values and thus the precision of removable and fixed prostheses fabrication, individual recording of articulator setup values can be recommended.