Prospective Pilot Study Evaluating Dental Side Effects of Radiotherapy on Subjects Treated for Head and Neck Cancer

Multi-centric, one arm phase II study. The first phase of the study will consist of an evaluation of the initial dental state of each subject based on a stomatological examination, an orthopantomogram, two bitewing radiographs (right and left sides) and an evaluation of all potential risks of caries and fractures. For all of subjects, a dental decalcification, dental care and/or avulsion if necessary, and afterwards, a dental splint will be performed before the start of RT treatment. Our previously developed predictive model for dental dose in function of the localisation of tumour and suspect lymph nodes based on the stomatological examination and on the pre-treatment imaging. An estimation of the intensity-modulated radiotherapy (IMRT) teeth dose will be made and translated into a colour based form of the pre-RT dental status. A contouring of the teeth will be performed and the planned dose for each tooth of each subject will be recorded by a dose volume histogram (DVH) curve based on the pre-treatment imaging. In the same way the mean dose and the V25 (the volume receiving 25 Gy) of the homo- and the heterolateral parotid gland will be calculated. Based on our predictive model, every tooth which potentially will receive more than 40 Gy and for which long term survival is compromised will be avulsed at least 2 weeks before the start of RT. After RT, the subject will have clinical follow-up with dental evaluation every 6 months for 36 months in order to identify possible dental events. At each consultation, a stomatological examination will be performed as well as two bitewing radiographs. An orthopantomogram will be done once a year. Furthermore, periapical X-rays will be performed if there is a dental complain or to refine a lesion visible on orthopantomogram.