Radiotherapy for head and neck cancers has long been known to complicate the dental and oral health of patients. The objective of the present study was to investigate oral health status of patients with head and neck cancers in northern Thai patients who were undergoing the radiotherapy. Seventy-six patients with head and neck cancers undergoing the radiotherapy with or without chemotherapy were recruited for oral examinations including DMFT, periodontal, mucosal, and oral hygiene conditions. In addition, candida infection, salivary flow rate, and maximum jaw opening were evaluated. The results showed that
the mean DMFT and mean plaque index were 3.0 and 1.38, respectively. Of all patients, 48.7% had mucositis, 23.7% had xerostomia, 32.9% had restricted mouth opening and 36.8% had oral candidiasis. C. albicans was the most common species isolated. Concerning dental treatment required, 45.6 % of the patients needed fillings at least one or more teeth, 38.2% needed extraction of at least one or more teeth, and 51.5% needed periodontal treatment. In conclusion, these findings indicate that dental and periodontal prophylaxis prior to radiotherapy in this group of patients was inadequate.