In this paper, we reported a case of ORN arising around dental implants placed before radiotherapy. This is the third such case report to be published. Granström et al. reported three cases of ORN developing around dental implants previously placed for skin-penetrating prosthesis [8]. Slama et al. reported a case of mandibular ORN in post-implant radiation [9]. In these cases, the presence of dental implants in the radiation field was thought to play a possible role in the development of ORN. In our case, although the patients had dental implants in both sides of the mandible, ORN occurred only in the left side, which was included in the field of radiotherapy applied for the treatment of oropharyngeal cancer arising in the left side. This fact suggested a possible causal relationship between the presence of dental implants and the development of ORN.

The presence of a dental implant may affect the development of ORN by two mechanisms. Firstly, the presence of the implant may cause a change in the radiation dose distribution around the dental implant [4, 10, 11]. Radiation scatter and electronic disequilibrium from implant materials are thought to cause both soft and hard tissue complications in the oral cavity. Friedrich et al. [10] reported on titanium dental implants in the field of ORN. Ozen et al. [4] examined the dose enhancement from scattered radiation at bone-dental implant interfaces. They reported that there is a 21 % maximum increase in the dose to alveolar mandibular bone in close proximity to the titanium. The increase in dose enhancement fell off rapidly and become insignificant at 2 mm from the interface. They suggested that it is not clear whether a local overdose of the order of 15 to 21 % will cause a significant increase in the incidence of bone necrosis around osteointegrated titanium implants. Beyzadeoglu et al. [11] also reported that irradiation, with different radiation beams and different irradiation angles, did not sufficiently affect the total dose to lead to ORN of the mandible. From the results of these studies, it could be said that the bone-implant interface is exposed to possible dose enhancement from scattering by the dental implants if the dental implants are included in the radiation field.