Tomographic evaluation of TMJ loading affected by occlusal pivots.
OBJECTIVE
The purpose of this study was to clarify the direction and magnitude of condyle displacement during clenching with occlusal pivots. Temporomandibular joint (TMJ) loading and flexibility and the clinical significance of orthopedic appliance therapy are also discussed.


METHODS
Participants were 16 volunteers with a mean age of 25.8 years. Maxillary and mandibular flat occlusal devices were fabricated. TMJ tomogram series were taken first with tripod support and then with maxillary clenched anterior pivot support and/or unilateral posterior pivot support. Condyle positions on the TMJ tomograms were analyzed using the digital subtraction technique.


RESULTS
When clenching with the anterior pivot, the anterior reference point (A) on the mandibular condyle was translated 0.1 mm posteriorly (P > 0.05) and 0.2 mm superiorly (P < 0.01) from the tripod-support reference point. In the case of the ipsilateral posterior pivot, point A was rotated 1.2 degrees (P < 0.01) and was translated 0.4 mm (P < 0.01) posteriorly and 0.18 mm superiorly (P > 0.05).


CONCLUSIONS
Condyle displacement during clenching with the anterior and posterior unilateral pivot was found, which supports previous findings. However, the direction and magnitude of the displacement differed from those of previous studies using jaw-tracking devices, and individual values differed greatly among subjects.
Sato
H
H
Department of Prosthodontics, Fukuoka Dental College, 2-15-I Tamura, Sawaraku, Fukuoka 814-0193, Japan. hsato@college.fdcnet.ac.jp
Ukon
S
S
Ishikawa
M
M
Ohki
M
M
Kitamori
H
H
D000328:Adult; D001732:Bite Force; D006801:Humans; D008297:Male; D008335:Mandibular Condyle / Q000000981:diagnostic imaging / Q000502:physiology*; D009119:Muscle Contraction; D017090:Occlusal Splints; D011859:Radiography; D013382:Subtraction Technique; D013704:Temporomandibular Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D014054:Tomography / Q000379:methods