The purpose of this study was to evaluate effect of head posture change on initial occlusal contacts through measuring the distances between initial occlusal contacts and maximum intercuspal position at different head posture.
Two special devices were designed and constructed. Mandibular movement replicator was used to assess reliability of the K6 diagnostic system(MKG ; Myo-tronic Inc., Seattle, U.S.A.) and head posture calibrator was used to maintain the constant
head
posture during experiment. We measured difference of distance between initial occlusal contact and maximum intercuspal position with MKG in upright, supine, 45 degrees extension, 30 degrees flexion, 30 degrees right and left bending position of
the
head. The Frankfurt horizontal plane was used as a reference plane.
21 adults aged from 23 to 25 were selected, who have normal or class I molar relationship, and have no symptoms on TMJ and masticatory muscles, and have restorations less than 3 surfaces on each tooth, and have no other prosthetic restoration.
@ES The obtained results were as follows ;
@EN The mean absolute distances between intial occlusal contact and maximum intercuspal position were 0.39±0.18mm in the upright position, 0.65±0.37mm in the supine position, 0.65±0.37mm in the supine position, 0.59±0.33mm in the 45 degrees
extension, 0.70±0.53mm in the 30 degrees flexion, 1.12±1.10mm in the 30 degrees right bending and 1.94±0.67mm in the 30 degrees left bending of the head.
The positions of the initial occlusal contacts have a tenderly to locate anterior, left and inferior to maximal intercuspal position in upright position, posterior and inferior in supine position and 45 degrees extension, anterior and inferior in
30
degrees flexion, right and inferior in 30 degrees right bending, and left and inferior in 30 degrees left bending of the head.
There were significant differences among the initial occlusal contacts in each head postures(p<0.0001).
Therefore, we need to check initial occlusal contacts in the altered head posture during occlusal analysis and adjustment of occlusal appliance and dental occlusion for diagnosis and treatment of temporomandibular disorder.
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