The incidence of salivary gland tumors, both benign and malignant, is increased in patients treated with irradiation for diseases of the head and neck and in Japanese atomic bomb survivors.Most of the tumors were benign, with Warthin tumor being the most frequent. Among the malignant tumors, the frequency of mucoepidermoid tumor was highest.An association between tumors of the salivary glands and dental radiography has been shown, although this association is likely a consequence of more dental radiographs made to investigate the symptoms of an existing tumor, rather than the dental radiation doses inducing tumors.   Reference: White and Pharoah, Oral radiology, Ed 8th, pg-91, 92