title: Effects of bisphosphonates on mandibular condyle of ovariectomized osteoporotic rats using micro-ct and histomorphometric analysis.
abstract: OBJECTIVE
  To evaluate microarchitectural changes in condylar cartilage and associated subchondral bone after bisphosphonates treatment using an ovariectomized (OVX) osteoporosis rat model.
  
  
  METHODS
  Thirty six-month-old female Sprague-Dawley rats were randomly divided into sham, OVX, and risedronate (RIS)-treated groups. Both OVX and RIS groups received bilateral ovariectomy. OVX group was treated subcutaneously with saline, whereas RIS group received risedronate treatment (2.4 μg/kg) subcutaneously for 3 months. At the end of 3 months, animals were sacrificed and the entire condyles were harvested for micro-CT and histological analyses. Immunohistochemistry (IHC) was performed to assess the expression of type I/II collagen protein by semiquantitative imaging analysis.
  
  
  RESULTS
  Micro-CT analysis showed OVX group had significant condylar subchondral bone loss compared to sham as shown by significant decrease in bone volume fraction (P = 0.028), trabecular thickness (P = 0.041), and significant increase in trabecular spacing (P = 0.003). In RIS group, partial inhibition of OVX-induced bone loss was detected. HE staining showed proliferative layer of condylar cartilage reduced, while hypertrophic chondrocyte layer increased significantly in RIS group compared to sham and OVX groups. IHC showed reduced expression of Col I in both the OVX and RIS groups, whereas expression of Col II was reduced in the OVX group but increased in the RIS group.
  
  
  CONCLUSIONS
  Our findings suggest that systemic bisphosphonate treatment influences the structure and ossification of condylar cartilage and it has a dual action on condyle in a postmenopausal osteoporosis rat model which raises the concerns for the potential side effects of BPs on condyle to elder patients.
authors.affiliation: Department of Stomatology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai, China.|Department of Prosthodontics, Ninth People's Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors.forename: Liting
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Shanghai Institute of Traumatology and Orthopaedics, Shanghai, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Shen
authors.affiliation: Shanghai Institute of Traumatology and Orthopaedics, Shanghai, China.
authors.forename: Li
authors.initials: L
authors.lastname: Wei
authors.affiliation: Shanghai Institute of Traumatology and Orthopaedics, Shanghai, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Department of Stomatology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai, China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Gao
mesh_terms: D000818:Animals; D059266:Bisphosphonate-Associated Osteonecrosis of the Jaw / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D004164:Diphosphonates / Q000009:adverse effects*; D005260:Female; D008335:Mandibular Condyle / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology; D010024:Osteoporosis / Q000000981:diagnostic imaging / Q000473:pathology*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D000068296:Risedronic Acid / Q000009:adverse effects; D055114:X-Ray Microtomography
chemical_list: D004164:Diphosphonates; D000068296:Risedronic Acid
keywords: bisphosphonate-induced osteonecrosis of the jaws; collagen; mandibular condyle; osteoporosis; ovariectomy