[Immunohistochemical study of type I and type II collagen in the remodelling of the supraosseous tissue of mandibular condyle].
OBJECTIVE
Previous studies focused on the pathological changes of the supraosseous tissue of mandibular condyle (STMC), but little is known about extracellular matrix during the remodelling activity of temporomandibular joint (TMJ). This study will examine the characteristics of type I and type II collagen during this process.


METHODS
The animal model was established by extracting the left lower molars of adult rabbits. Temporomandibular joints of two sides were taken after 2 weeks, 1 month and 3 months respectively, and embedded in paraffin. Then 5 microns-thick sections were cut and processed for immunohistochemistry and haematoxylin-eosin staining. An immunohistochemical ABC method was used to determine the local changes of type I and type II collagen. The positive cells were counted in order to analyze quantitative changes.


RESULTS
After loss of teeth from 2 weeks to 3 months, the number and arrangement of chondrocytes changed. Some chondrocyte clusters were also observed in the non-extraction side of TMJ. Most STMC cells stained positively with anti-type I collagen, but weakly in chondrocytes and hypertrophic chondrocytes. On the other hand, type II collagen only existed in chondrocytes and some hypertrophic chondrocytes. The expression of type I collagen decreased after 2 weeks and became stronger after 1 and 3 months, furthermore distributed unevenly in STMC. Some hypertrophic chondrocytes in the non-extraction side showed strong positive staining with anti-type I collagen. Type II collagen in two sides decreased after 2 weeks, then became stronger after 1 and 3 month, but the whole level was less than that of the control group. Expressions of two kinds of collagen were compared between two sides. Type I collagen in the non-extraction side was stronger than that in the extraction side, while type II collagen had an opposite result.


CONCLUSIONS
Adult rabbits have a limited remodelling ability, and the synthesis and secretion of type I and type II collagen will change when the remodelling is beyond a proper extent, which will lead to impaired resistance and elasticity of fibrocartilage.
Duan
X
X
Department of Oral Biology, Stomatological College, Fourth Military University.
Mao
Y
Y
Wang
H
H
D000818:Animals; D016723:Bone Remodeling; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism*; D024043:Collagen Type II / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D008335:Mandibular Condyle / Q000166:cytology / Q000378:metabolism*; D008963:Molar; D010012:Osteogenesis; D011817:Rabbits; D011897:Random Allocation; D013704:Temporomandibular Joint / Q000166:cytology / Q000378:metabolism; D014081:Tooth Extraction; D016388:Tooth Loss / Q000503:physiopathology
D024042:Collagen Type I; D024043:Collagen Type II