The aim of this study was to evaluate the effect of hyperbaric oxygen therapy (HBOT) on microvascular tissue and cell proliferation in the oral mucosa. Twenty patients, aged 51-78 years, were allocated randomly to a treatment or a control group. All had a history of radiotherapy (50-70 Gy) to the orofacial region 2-6 years previously. Tissue samples were taken from the irradiated buccal oral mucosa before HBOT and at 6 months after treatment. In the control group, tissue samples were taken on two occasions, 6 months apart. The samples were subjected to immunohistochemistry staining: double staining with CD31 and D2-40 for microvessels, or Ki-67 for the analysis of cell proliferation. Blood vessel density and area were significantly increased after HBOT (P=0.002-0.041). D2-40-positive lymphatic vessels were significantly increased in number and area in the sub-epithelial area (P=0.002 and P=0.019, respectively). No significant differences were observed in the control group. There were no significant differences in Ki-67-expressing epithelial cells between the two groups. It is concluded that the density and area of blood and lymphatic vessels in the irradiated mucosa are increased by HBOT 6 months after therapy. Epithelial cell proliferation is not affected by HBOT.
Keywords: angiogenesis; cell proliferation; immunohistochemistry; microvascular tissue; radiotherapy.
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