Effects of occlusion on mandibular morphology and architecture in rats

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• 作者：Jia Liu ; MD^a ; Shi-Yu Liu ; PhD^b ; Ya-Juan Zhao ; PhD^c ; Xu Gu ; MD^d ; Qiang Li ; PhD^e ; ^{lqaq726@163.com" class="auth_mail" title="E-mail the corresponding author} ; Zuo-Lin Jin ; PhD^a ; ^{zuolinj@fmmu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Yong-Jin Chen ; PhD^e ; ^{cyj1229@fmmu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Rat ; Occlusal hypofunction ; Mandible ; Bone mineral density ; Micro-CT ; Bone marker
• 刊名：Journal of Surgical Research
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：200
• 期：2
• 页码：533-543
• 全文大小：2917 K

文摘

A rodent occlusal hypofunction model has been widely established in jawbone-related studies. However, the effects of occlusal stimuli, with total elimination of molar contacts, and its rehabilitation on mandibular remodeling remain unclear.

Materials and methods

Forty-eight 5-wk-old Sprague–Dawley male rats were used. Twenty-four experimental rats underwent occlusal hypofunction by insertion of a bite-raising appliance. Twenty-four rats received no treatment (control group). Two weeks later, half the experimental rats (occlusal hypofunction group) were killed; the appliance was removed from the remaining experimental rats (recovery group) for two additional weeks before killing. Control animals were killed biweekly. Body weight and masseter muscle weight were measured, and the mandibles were subjected to micro-computed tomography to evaluate the mandibular morphology and cortical bone characteristics. The expressions of osteoblast- and osteoclast-related genes were evaluated with quantitative polymerase chain reaction.

Results

No significant body weight differences were observed between the experimental and control rats. However, lighter masseter muscle, shorter mandibular incisor crown, mandibular body and ramus, and higher mandibular alveolar process and first molar fossae were observed in the occlusal hypofunction group. Moreover, the cortical bone characteristics associated with the expression of osteoblast- and osteoclast-related genes were remarkably different in the central and posterior mandible in the occlusal hypofunction group. At the 2-wk recovery time point after occlusal stimuli, the altered parameters in the masseter and mandible returned to normal levels.

Conclusions

Mandibular remodeling via bone turnover is region specific for altered occlusal stimuli. Normal occlusion is an important determinant of the mandibular morphology and architecture.