The aim of the present study was to monitor genotoxic and cytotoxic effect of X-ray on exfoliated buccal mucosa cells and investigate the association between the effects and the accumulated absorbed doses of oral mucosa. 98 participants' buccal mucosa cells were collected before and 10 days after different series of dental radiographs performed. Cytological preparations were successively dyed with the methods of Feulgen and fast-green, and analyzed under a light microscope. Micronuclei (MN)and other cells were scored. Accumulated absorbed dose of buccal mucosa was estimated with the method of anthropomorphic phantom and dosimeter chips. The dose rang was 0.18-3.54 mGy. A significant difference in the rate of MN cell was found before and after X-ray examinations (P = 0.008) as well as in the rates of Pyknotic (p < 0.001) and Karyolytic cell (p = 0.0021). When only the patients whose mucosa absorbed dose is lower than 1 mGy was analyzed, significant differences were not found except for Karyolytic cells (p = 0.0313). There was a correlation between the accumulated does and the change rate (ρ = 0.25, p = 0.0118). The frequency of micronuclei cells in buccal mucosa may be increased when a series of dental radiographs including a CBCT examination was performed.