Oral cancer is an increasing global problem. The annual estimated incidence is around 275,000 with a wide geographical variation. Two-thirds of these cases occur in developing countries (South and Southeast Asia). In the Netherlands the incidence of squamous cell carcinoma of the oral cavity is 4.1 per 100,000 in the male population and 2.7 per 100,000 in the female population. These numbers have increased over the past few decades and this trend is continuing. This trend is also seen in the UK. The increasing incidence is mostly attributed to excessive use of alcohol and smoking, but also to the proportional rise in the ageing population.

Surgery, on indication followed by radiotherapy, is the curative treatment of choice. Ablative surgery for oral cancer results in altered anatomical relations and physiology. Besides being permanently disfigured, patients suffer from diminished or lost essential oral functions, such as speech, chewing and swallowing. Because oral tumours are mainly located on the tongue and the floor of the mouth postoperative radiation with or without chemotherapy results in significant additional side effects such as diminished tongue mobility, tongue sensation and xerostomia. This has a considerable impact on the patients’ emotional and social well being and consequently a significant adverse effect on the quality of life (QOL).

Improvement of oral functions may be achieved by implant-supported prosthetic rehabilitation. The timing of oral rehabilitation is still subject to debate. To date, implant survival in oncological patients is thought to be less than in non-oncological patients. Up to 35% of the implants placed in irradiated bone were reported to be lost. Thereby, the survival of implants in grafted bone was lower compared to those in non-grafted bone.

In general, two methods are being proposed for implant placement in the edentulous symphyseal region: direct placement during ablative surgery (DAS implants) or postponed (P implants) placement ( Fig. 1 ). Postponed means more than 6–12 months after initial oncological treatment. DAS implants have the advantage that the implantation site has not been compromised as a result of radiotherapy, thereby bypassing, for example, the need for preventive antibiotics and hyperbaric oxygen therapy prior to implantation to reduce the risk of osteoradionecrosis. The main disadvantage of primary implantation is that proper positioning of the implants is more difficult, especially if the tumour is located near the interforaminal region. In those cases, the soft tissue contour is often unpredictable, sometimes resulting in an improper implant position and frustrating oral rehabilitation as a consequence. In addition, DAS implants may have to be removed in case of tumour recurrence, the incidence of which is highest during the first postoperative year.

Definition of implant survival.

In two large Dutch head and neck oncology centres, different protocols for implant placement were used. In the Radboud University Nijmegen Medical Centre (RUNMC) implants were placed, if possible and feasible, in the original non-reconstructed mandible during ablative surgery (DAS protocol). In the University Medical Centre Utrecht (UMCU) all edentulous patients were seen after oncological treatment during a multidisciplinary consultation to evaluate the opportunities for prosthetic rehabilitation with or without the use of dental implants. As such, implants were placed during the post-therapy phase provided that no recurrence had occurred in the meantime and depending on tumour-treatment related sequelae (postponed (P) protocol).

The authors’ hypothesis is that, for implants placed in the edentulous symphyseal area in patients with a primary squamous cell carcinoma (SCC) in the oral cavity, the DAS protocol will result in faster prosthetic rehabilitation than postponed installed implants, without increase in the complication rate.