放疗是治疗头颈部恶性肿瘤的三大方法之一。但放射线在杀死肿瘤细胞的同时对机体的正常组织也造成一定程度的损害 ,并导致一系列并发症状的出现 ,口腔微生态系变化就是其中之一 ,已为越来越多学者重视。口腔微生物及其口腔环境构成口腔微生态系。一般情况下 ,口腔环境中的天然 Radiotherapy is one of the three major ways to treat head and neck cancer. Radiation, on the other hand, kills tumor cells and also damages the normal tissues of the body to a certain extent, resulting in a series of complications. The change of oral micro-ecosystem is one of them, which has attracted more and more scholars’ attention. Oral microorganisms and their oral environment constitute the oral micro-ecosystem. Under normal circumstances, the natural environment in the mouth