title: Dynamic changes in bone metabolism in the rat temporomandibular joint after molar extraction using bone scintigraphy.
abstract: Functional adaptation with reformation of bone tissue structure occurs after changes in mechanical stress distribution. To examine how occlusal changes affect the dynamics of bone metabolism in the mandibular condyle, bone scintigraphy of rat condyles was taken using (99m)technetium-methylene-diphosphonate (99mTc-MDP) after extraction of maxillary molars resulting in unilateral loss of occlusal support. Accumulation of 99mTc-MDP was significantly higher in the condyles on the extracted side than on the intact side 3 d after molar extraction. In addition, bone mineral density (BMD) and osteoprotegerin expression in extracted-side condyles were significantly increased while osteoclast numbers were significantly decreased when compared with intact-side condyles. These differences were not detected 28 d after molar extraction. These findings suggest that occlusal change transiently results in changes in the dynamics of bone metabolism at the mandibular condyles through the downregulation of osteoclastogenesis. These changes may be involved in functional adaptation of the temporomandibular joint.
authors.affiliation: Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan. m-yokoyama@mail.tains.tohoku.ac.jp
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Yokoyama
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Atsumi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tsuchiya
authors.forename: Shigeto
authors.initials: S
authors.lastname: Koyama
authors.forename: Keiichi
authors.initials: K
authors.lastname: Sasaki
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000222:Adaptation, Physiological / Q000502:physiology; D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D015519:Bone Density / Q000502:physiology; D002452:Cell Count; D002454:Cell Differentiation; D024042:Collagen Type I / Q000032:analysis; D015536:Down-Regulation; D007091:Image Processing, Computer-Assisted; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D008335:Mandibular Condyle / Q000000981:diagnostic imaging / Q000378:metabolism*; D023421:Models, Animal; D008963:Molar / Q000601:surgery*; D010010:Osteoclasts / Q000378:metabolism / Q000473:pathology; D053244:Osteoprotegerin / Q000032:analysis; D053245:RANK Ligand / Q000032:analysis; D011856:Radiographic Image Enhancement; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D000071681:Tartrate-Resistant Acid Phosphatase; D013669:Technetium Tc 99m Medronate; D013704:Temporomandibular Joint / Q000000981:diagnostic imaging / Q000378:metabolism*; D013997:Time Factors; D014081:Tooth Extraction
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D007527:Isoenzymes; D053244:Osteoprotegerin; D053245:RANK Ligand; D019275:Radiopharmaceuticals; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D013669:Technetium Tc 99m Medronate