title: Effect of ageing on healing of bilateral mandibular condyle fractures in a rat model.
abstract: To examine the hypothesis that conservative treatment is applicable to younger patients with bilateral mandibular condylar fractures, we studied the effect of ageing on the healing of bilateral mandibular condylar fractures in a rat model. Male Sprague-Dawley rats aged 3, 6, and 36 weeks (n=25/cohort, total n=75) were divided into a fracture group (n=12) and a sham control group (n=12); one rat from each cohort was used as a normal unoperated control. Cell proliferation was evaluated using the bromodeoxyuridine (BrdU) labelling index (LI). Osteochondrogenesis was assessed by the expression of Indian hedgehog (Ihh), type X collagen, and osteocalcin in the condylar head. Condylar fracture healing was found to be delayed by ageing. BrdU LI values in the fracture groups were higher in younger rats than in older rats at 8 weeks after fracture. The number of Ihh-positive cells in the fracture groups increased significantly up to 2 weeks after fracture, and then gradually decreased until 8 weeks after fracture. The findings of this study support the clinical concept of conservative treatment of bilateral condylar fractures in younger patients, but functional issues regarding ramus height and its consequences on occlusion have not been tested in this study.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tatsumi
authors.affiliation: Department of Oral and Maxillofacial Surgery, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hideshima
authors.affiliation: Department of Oral and Maxillofacial Surgery, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kanno
authors.affiliation: Department of Developmental Biology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Hashimoto
authors.affiliation: Department of Developmental Biology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Matsumoto
authors.affiliation: Department of Developmental Biology, Shimane University Faculty of Medicine, Izumo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Otani
authors.affiliation: Department of Oral and Maxillofacial Surgery, Shimane University Faculty of Medicine, Izumo, Japan. Electronic address: georges@med.shimane-u.ac.jp.
authors.forename: J
authors.initials: J
authors.lastname: Sekine
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001973:Bromodeoxyuridine; D049109:Cell Proliferation; D004195:Disease Models, Animal; D005593:Fracture Fixation, Internal / Q000379:methods*; D017102:Fracture Healing / Q000502:physiology*; D007124:Immunoenzyme Techniques; D008297:Male; D008335:Mandibular Condyle / Q000293:injuries*; D008337:Mandibular Fractures / Q000601:surgery*; D010012:Osteogenesis / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001973:Bromodeoxyuridine
keywords: ageing; cartilage; cell proliferation; condyle fracture