Histologic evaluation of the effects of irradiation on mandibular bone in minipigs – preliminary results

Background: Radiation therapy is often part of treatment of head and neck malignancies. After radiotherapy patients are at risk to develop osteoradionecrosis. The development of osteoradionecrosis is unpredictable and has a major impact on quality of life.

Objectives: The radiation induced histologic changes were investigated in minipigs in order to find an experimental model of radiogenic bone damage.

Methods: Sixteen Göttingen minipigs were divided into four groups to receive irradiation at an equivalent dose of 0, 25, 50 and 70 Gray. Thirteen weeks after irradiation, three implants were placed on the left side of the mandible. Twenty-six weeks after irradiation the minipigs were sacrificed and histologic assessment of left and right mandible was done on Masson Goldner trichrome colored coupes.

Results: Two minipigs developed osteoradionecrosis (one with 50 Gray and one with 70 Gray). We present here the histology of two controls, two 50 Gray and two 70 Gray minipigs. Both cases of osteoradionecrosis were included. We show that depending upon the radiation dose, the shape of the mandibular canal varies due to reactive bone apposition. In all irradiated minipigs bone remodeling is seen, both inside and outside the external cortical layer. Nerve fibers show a decrease in color-intensity in the 70 Gray group and fibrosis of the intima is seen in the irradiated arteries.

Conclusions: Bone remodeling with the formation of subperiosteal and reactive bone, intimal fibrosis and trombosis in the inferior alveolar artery, as seen in our experimental model, is also described in human studies. We propose therefore that this is a successful animal model for radiogenic bone damage.

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Jan 21, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Histologic evaluation of the effects of irradiation on mandibular bone in minipigs – preliminary results
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