title: Influence of altered occlusal plane on rabbit temporomandibular joint cartilage.
abstract: BACKGROUND
  There is limited knowledge relating to the influence of mechanical stress on the temporomandibular joint (TMJ) and the degree of damage this stress can induce in the case of an altered occlusal plane on the extracellular matrix cartilage and chondrocytes. The aim of this study was to examine the histopathological influence of an altered occlusal plane on rabbit TMJ cartilage.
  
  
  METHODS
  Fifteen male Japanese white rabbits were used in this study. In 12 cases, the upper right and lower left teeth were ground to their cervical level so that the occlusal plane was tilted right side up. Their temporomandibular joints (TMJs) harvested at 3 days, 1, 2 and 4 weeks were analyzed immunocytochemically and immunohistochemically. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick endlabeling (TUNEL) method was used for immunocytochemical study to detect DNA fragmentation in chondrocytes. An immunohistochemical study was also performed to evaluate the metabolism of type 2 collagen in the extracellular matrix in the TMJ cartilage.
  
  
  RESULTS
  The number of apoptotic cells increased in all experimental animals. More apoptotic cells were observed in the articular eminences than in the condyles. The type 2 collagen-positive area in the condyles was reduced at the beginning but recovered within 4 weeks, and remained small throughout this experimental period in the articular eminences.
  
  
  CONCLUSIONS
  These findings suggest that histopathological changes occurred in response to alteration of the occlusal plane. The influence decreased as the occlusal plane recovered in the condyles, but the immunocytochemical and immunohistochemical influence continued in the articular eminences.
authors.affiliation: Division of Orofacial Functions and Orthodontics, Kyushu Dental College, Manazuru, Kitakyushu, Japan.
authors.forename: Sakiko
authors.initials: S
authors.lastname: Yoshikawa
authors.forename: Etsuo
authors.initials: E
authors.lastname: Nodai
authors.forename: Manabu
authors.initials: M
authors.lastname: Habu
authors.forename: Norihiko
authors.initials: N
authors.lastname: Furuta
authors.forename: Jinichi
authors.initials: J
authors.lastname: Fukuda
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yamaguchi
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis; D002358:Cartilage, Articular / Q000378:metabolism / Q000473:pathology*; D019902:Chondrocytes / Q000473:pathology; D024043:Collagen Type II / Q000378:metabolism*; D003769:Dental Occlusion, Traumatic / Q000503:physiopathology*; D003799:Dental Stress Analysis; D005109:Extracellular Matrix / Q000473:pathology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D008335:Mandibular Condyle / Q000473:pathology; D011817:Rabbits; D013314:Stress, Mechanical; D013704:Temporomandibular Joint / Q000378:metabolism / Q000473:pathology*; D014716:Vertical Dimension
chemical_list: D024043:Collagen Type II