Temporomandibular joint morphology and disc position in skeletal class III patients.
BACKGROUND
The purpose of this study was to investigate the relationship between temporomandibular joint (TMJ) morphology, including discal tissue and clinical symptoms in class III dentofacial deformity patients.


METHODS
Forty-four patients were examined with lateral, frontal and axial cephalograms. They were divided into two groups, consisting of a class III symmetry and a class III asymmetry group. By using magnetic resonance imaging the 88 joints could be classified into four types on the basis of disc position and shape: anteriorly displaced disc, anterior type, fully-covered type and posterior type. Furthermore, TMJ morphology was measured tomographically in the sagittal plane.


RESULTS
Anteriorly displaced discs in the asymmetry group (56.8%) occurred significantly more frequently than in the symmetry group (18.2%; p <0.05). TMJ symptoms (clicking, crepitus, closed lock, pain) were seen in 17/44 joints (38.6%) of the symmetry and 24/44 joints (54.5%) of the asymmetry group, for a total of 41/88 joints (46.6%). There were no differences in joint space ratio and condyle ratio. However, the fossa ratio on the deviation side was significantly higher than on the nondeviation side in the asymmetry group (p<0.05).


CONCLUSIONS
The incidence of internal derangement in asymmetrical class III patients is higher than in symmetrical mandibular prognathism, and this difference is associated with a difference in TMJ morphology of both sides.
Ueki
K
K
Department of Oral and Maxillofacial Surgery, School of Medicine, Kanazawa University, Japan. kueki@med.kanazawa-u.ac.jp
Nakagawa
K
K
Takatsuka
S
S
Shimada
M
M
Marukawa
K
K
Takazakura
D
D
Yamamoto
E
E
D000328:Adult; D019412:Anatomy, Cross-Sectional; D002508:Cephalometry; D016009:Chi-Square Distribution; D005146:Facial Asymmetry / Q000473:pathology; D005260:Female; D006801:Humans; D015994:Incidence; D004204:Joint Dislocations / Q000145:classification / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008313:Malocclusion, Angle Class III / Q000473:pathology*; D008335:Mandibular Condyle / Q000473:pathology; D011378:Prognathism / Q000473:pathology*; D018709:Statistics, Nonparametric; D013701:Temporal Bone / Q000473:pathology; D013704:Temporomandibular Joint / Q000473:pathology*; D019224:Temporomandibular Joint Disc / Q000473:pathology*; D013705:Temporomandibular Joint Disorders / Q000145:classification / Q000473:pathology; D014056:Tomography, X-Ray