Histopathological changes in collagen and matrix metalloproteinase levels in articular condyle of experimental model rats with jaw deformity.
OBJECTIVE
To investigate the dynamics of the cartilage matrix in the articular condyle after removal of a side shift plate; Emergence of type I, II, and III collagen in the matrix as well as changes in levels of matrix metalloproteinase (MMP)-1, -8, and -13 that degrade collagen were studied histopathologically and immunohistochemically.


METHODS
Lateral displacement of the mandible was achieved by attaching a side shift plate to the anterior teeth of the maxilla in male rats at 6 weeks. The wearing period of the side shift plate was 8 weeks. Observations were made at 0, 1, 2, 4 and 8 weeks after removal.


RESULTS
In histopathological findings, the timing of proliferation of the layer of hypertrophy varied between the bilateral sides. In immunohistochemical findings a significant decline in the expression of type II collagen in the displacement side was observed immediately after removal. Moreover, the expressions of MMPs were elevated in both sides on 0 weeks. At 1 week after removal, a significant elevated in the expression of type II collagen, MMPs was decline in both sides.


CONCLUSIONS
After removal, the levels of MMP-1, -8, and 13 were reduced and the emergence of type II collagen increased. Thus, cellular outgrowth was initiated to trigger intracartilaginous ossification to restore the cartilage matrix.
Watanabe
A
A
Department of Orthodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan. watanabe.aya40@nihon-u.ac.jp
Yamaguchi
M
M
Utsunomiya
T
T
Yamamoto
H
H
Kasai
K
K
D000818:Animals; D001862:Bone Resorption / Q000473:pathology; D002358:Cartilage, Articular / Q000473:pathology; D002454:Cell Differentiation; D049109:Cell Proliferation; D003094:Collagen / Q000032:analysis*; D024042:Collagen Type I / Q000032:analysis; D024043:Collagen Type II / Q000032:analysis; D024061:Collagen Type III / Q000032:analysis; D003238:Connective Tissue / Q000473:pathology; D006984:Hypertrophy; D008297:Male; D008310:Malocclusion / Q000473:pathology*; D008335:Mandibular Condyle / Q000473:pathology*; D020781:Matrix Metalloproteinase 1 / Q000032:analysis; D053509:Matrix Metalloproteinase 13 / Q000032:analysis; D020784:Matrix Metalloproteinase 8 / Q000032:analysis; D020782:Matrix Metalloproteinases / Q000032:analysis*; D010012:Osteogenesis / Q000502:physiology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D024042:Collagen Type I; D024043:Collagen Type II; D024061:Collagen Type III; D003094:Collagen; D053509:Matrix Metalloproteinase 13; D020782:Matrix Metalloproteinases; C507083:Mmp13 protein, rat; D020784:Matrix Metalloproteinase 8; D020781:Matrix Metalloproteinase 1