A dose distribution map was generated based on the estimated doses received, which could allow prediction of the areas most affected by radiation and facilitate further correlations with dental complications after radiotherapy. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1708-1716, 2016.

Oral positioning radiotherapy stents are devices that protect healthy structures adjacent to the target volume of head and neck radiotherapy treatment, leading to reduced acute and chronic side effects. This study describes a digital workflow to produce an oral positioning radiotherapy stent and analyze its efficacy by measuring dosimetric variations with and without this stent. An oral positioning radiotherapy stent was created according to a digital workflow that included intraoral scanning, digital design, and 3D printing for a patient with squamous cell carcinoma of the tongue. The patient underwent computed tomography to evaluate radiotherapy treatment by intensity‐modulated radiation therapy with and without the use of the 3D‐printed oral stent. The use of a 3D‐printed oral positioning radiotherapy stent is a feasible and reproducible technique that reduced the planning target volume and radiation doses delivered to the hard palate, right parotid gland, and left parotid gland by 42%, 21%, and 8.5%, respectively.

BackgroundRadiotherapy (RT) is frequently used in the treatment of head and neck cancer, but different side-effects are frequently reported, including a higher frequency of radiation-related caries, what may be consequence of direct radiation to dental tissue. The intensity-modulated radiotherapy (IMRT) was developed to improve tumor control and decrease patient’s morbidity by delivering radiation beams only to tumor shapes and sparing normal tissue. However, teeth are usually not included in IMRT plannings and the real efficacy of IMRT in the dental context has not been addressed. Therefore, the aim of this study is to assess whether IMRT delivers lower radiation doses to dental structures than conformal 3D radiotherapy (3DRT).Material and methodsRadiation dose delivery to dental structures of 80 patients treated for head and neck cancers (oral cavity, tongue, nasopharynx and oropharynx) with IMRT (40 patients) and 3DRT (40 patients) were assessed by individually contouring tooth crowns on patients’ treatment plans. Clinicopathological data were retrieved from patients’ medical files.ResultsThe average dose of radiation to teeth delivered by IMRT was significantly lower than with 3DRT (p = 0.007); however, only patients affected by nasopharynx and oral cavity cancers demonstrated significantly lower doses with IMRT (p = 0.012 and p = 0.011, respectively). Molars received more radiation with both 3DRT and IMRT, but the latter delivered significantly lower radiation in this group of teeth (p < 0.001), whereas no significant difference was found for the other dental groups. Maxillary teeth received lower doses than mandibular teeth, but only IMRT delivered significantly lower doses (p = 0.011 and p = 0.003). Ipsilateral teeth received higher doses than contralateral teeth with both techniques and IMRT delivered significantly lower radiation than 3DRT for contralateral dental structures (p < 0.001).ConclusionIMRT delivered lower radiation doses to teeth than 3DRT, but only for some groups of patients and teeth, suggesting that this decrease was more likely due to the protection of other high risk organs, and was not enough to remove teeth from the zone of high risk for radiogenic disturbance (>30Gy).

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