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ABSTRACT
The aim of this study was to investigate the pathological changes of the lateral pterygoid muscle (LPM) using magnetic resonance imaging (MRI) in patients with anterior disk displacement with nonreduction (ADDnr) of the temporomandibular joint (TMJ) and to compare the abnormal findings of the LPM with the clinical symptoms and other pathological MRI alterations of the TMJ. Bilateral or unilateral ADDnr was demonstrated in 142 patients by MRI (176 TMJs; 106 females; 36 males; range 19 to 72 years; mean 43.9 years). In 123 TMJs, the LPMs were clearly observed in MRIs and analyzed in this study. Pathological changes of the LPM were found in 92 TMJs (74.8%) in MRI. Hypertrophy, atrophy and/or contracture were detected in the superior belly of the LPM (SBLPM) (35.8%, 44/123) or in the inferior belly of the LPM (IBLPM) (9.8%, 12/123) or in both bellies (29.3%, 36/123). The pathological changes of the LPM in MRI presented a significant association with the main clinical symptoms of TMJs with ADDnr, i.e. pain on jaw movement (P<0.01), pain in the LPM (P<0.01), pain in TMJ (P<0.05) and restricted jaw opening (P<0.05). The proportion of the abnormalities in LPM was significantly lower in TMJs with condylar limitation (63.6%) than in TMJs with condylar hypermobility (83.3%) and normal motion (88.9%)(P=0.008). Osteoarthritis was found to be correlated with condylar limitation (P<0.01). The results of this study indicate that the pathological changes of the LPM in TMJs with ADDnr could be detected by MRI and have a significant association with the main clinical symptoms of the patients. When condylar limitation happened, on the contrary, the pathological changes of the LPM in MRI were reduced. The alteration of the clinical symptoms in the patients with ADDnr might be associated with the pathological situations and symptoms of the LPM.
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Notes on contributors
Xiaojiang Yang
Dr. Xiaojiang Yang received his D.D.S. degree from the West China University of Medical Science in 1985 and his Master's degree as a specialist in maxillofacial surgery from the Chinese General Military Postgraduate Institute in 1990. In 1991 he was a visiting scholar at the Department of Maxillofacial Surgery Leuven University Hospital, Belgium. Currently, Dr. Yang is a researcher at the Institute of Dentistry, Oulu University, Finland.
Hannu Pernu
Dr. Hannu Pernu received his D.D.S. degree from the Institute of Dentistry, University of Turku, Finland in 1972 and his M.D. degree at the same university in 1979. He became a specialist in oral surgery in 1983 and in maxillofacial surgery in 1995 at the University of Oulu, Finland. He works as senior lecturer and maxillofacial surgeon at the Department of Maxillofacial Surgery, Oulu University Central Hospital.
Juhani Pyhtinen
Dr. Juhani Pyhtinen received his M.D. degree in 1971 from the University of Oulu, Finland where he also received a Ph.D. degree in 1977. He became a specialist in radiology in 1978 and a subspecialist in neuroradiology in 1981. He is currently a professor at the Department of Neuroradiology, Oulu University Central Hospital.
Petri A. Tiilikainen
Dr. Petri A. Tiilikainen received his D.D.S. degree in 1999 from the Institute of Dentistry, University of Oulu, Finland. He is a research assistant in the Department of Prosthetic Dentistry and Stomatognathic Physiology at the Institute of Dentistry, University of Oulu, Finland.
Kyösti S. Oikarinen
Dr. Kyösti S. Oikarinen received his D.D.S. degree from the Institute of Dentistry, University of Turku, Finland in 1978 and his Ph.D. degree in 1987 at the University of Oulu, Finland. He received a D.M.D. degree in 1988 at Hamburg University, Germany. He is a professor and head of the Department of Oral and Maxillofacial Surgery, Institute of Dentistry, University of Oulu, and chief dentist in the Oral and Maxillofacial Department of Oulu University Hospital. Currently, he is a professor at the Department of Oral and Maxillofacial Surgery in the Faculty of Dentistry, Kuwait University.
Aune M. Raustia
Dr. Aune M. Raustia received her D.D.S. degree in 1974 at the Institute of Dentistry, University of Helsinki, Finland. She obtained her Ph.D. degree in 1986 at the University of Oulu, Finland. Dr. Raustia is a professor at the Department of Prosthetic Dentistry and Stomatognathic Physiology at the Institute of Dentistry, and Dean of the Institute of Dentistry, University of Oulu, Finland.