We describe the long-term complications six years after chemoradiotherapy in a 20-year old woman with nasopharyngeal carcinoma. We wanted to know whether the radiation dose was constant throughout the oral cavity, and thus uniformly affecting the corresponding dental and skeletal structures. Clinical and radiologic findings are described six years after chemoradiotherapy based on a two-dimensional computerized treatment planning system. This revealed radiation caries limited only to posterior teeth, proximal caries in the anterior teeth, limited but continuous salivary flow, mild periodontal infection, mild xerostomia, and a regenerative capacity of bones and the developmental process. The quantitative assessment of radiation delivered to the mandible revealed a high radiation dose in the posterior area and a minimal dose in the anterior area. This explains the differences in caries manifestation between the anterior and posterior teeth. According to the present study, individualized radiation fields, using a two-dimensional treatment planning system, result in restriction of severe damage of the dental and skeletal structures, which usually follows chemoradiotherapy. Orthodontic treatment could be initiated according to individual patient needs.