88 Chapter 4 Materials and methods This cross-sectional study was conducted at the University of Alberta, Edmonton, Canada and at Maastricht University Medical Centre (MUMC+), Maastricht, The Netherlands. The surgical reconstruction group consisted of patients treated at the University of Alberta Hospital and rehabilitated at the Institute for Reconstructive Sciences in Medicine (iRSM). Patients treated for benign tumours, or malignant tumours with a curative intent were included [12]. Eligible tumour locations were upper alveolar process, tuber maxillae, palate and maxillary sinus. Reconstruction was performed according to the Alberta Reconstructive Technique (ART) protocol [18, 19] for malignant tumours or the Rohner-protocol [20] for benign tumours. The Rohner prefabricated fibula technique allows for a two-stage approach. The primary surgery comprises prefabrication of the fibula with implant placement according to the surgical design and simulation (SDS) plan, followed by a healing period. Subsequently, the fibular flap is harvested in a second operation, and the reconstruction of the maxilla is carried out using cutting guides and the occlusion of the final prosthesis as a transfer template. In malignant tumours, the ART-technique, is based on 3D-printed surgical guides and positioning splints. Neck dissection, tumour resection, microsurgical reconstruction and implant placement are done in the first surgical stage, followed by exposing the implants in a second operation. In the obturator group, patients with edentulous upper jaws were included when maxillary defects were rehabilitated with an implant-supported obturator at Maastricht UMC+ [21]. Maastricht patients were treated according to the “surgical and prosthetic reconsiderations in patients with maxillectomy protocol” as defined by Lethaus et al. in 2010 [22]. Implant sites in the remaining facial skeleton or skull base were planned based on CT-data with the Simplant 3D® program (Dentsply Sirona, Charlotte, USA). When standard abutments did not comply with the required distances or angulation of our protocol, individual abutments were designed by hand or by using Cinema 4D® planning program (Design Express, Gouda, The Netherlands). If possible, a bar construction was made on the dental implants to support the obturator prosthesis. Magnet abutments were used as an alternative retention method, when the space between two implants was too wide. Exclusion criteria were cognitive impairment or the inability to understand English for the Canadian participants and an inability to understand Dutch for the Dutch participants.
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