Sialadenitis and xerostomia are the most frequent adverse events of high-dose radioiodine therapy. Saliva has vital functions in maintaining periodontal and oral health. Therefore, xerostomia not only impairs quality of life permanently, but may also increase the risk of caries and tooth extractions. Nevertheless, despite more than 6 decades of radioiodine therapy for thyroid cancer, large studies on long-term oral adverse events are still lacking. In the present study, we investigate the influence of high-dose radioiodine therapy on the long-term oral health.