96 Chapter 4 Discussion The results of this study appear to demonstrate comparable masticatory performance and patient reported eating ability for patients with surgically reconstructed maxillae and patients with implant supported obturator prostheses. The mean MAI for both groups (18.20 ± 2.38 resp. 18.66 ± 1.37) are comparable with other compromised groups, like dentate obturator patients (18.4 ± 4.2) and healthy edentulous non-maxillectomy individuals with conventional maxillary dentures and implant-supported mandibular overdentures (18.5 ± 3.1) [25, 29]. Both maxillectomy groups remained below the MAI-level of the natural dentition group (15.8 ± 2.0), confirming previous research into chewing performance in maxillectomy patients [11, 25]. Several authors advocate for the benefits of surgical reconstruction over obturation of maxillary defects, especially for larger defects. Amongst them are authors mainly describing a personal preference solely based on experience [30, 31], or combining the best available literature with clinical experience [3, 17, 32]. Unfortunately, the best available literature is limited, and study populations are usually small. A recently published systematic review describes a risk of selection bias and heterogeneous measurements for studies comparing masticatory efficiency [7]. Additionally, the different methods of measuring masticatory performance: mixing ability test, colour changing chewing gum, and sieving method used in maxillectomy patients [11-13, 21, 25, 29, 33-36] complicate the comparison of the study results. Recent research confirms the benefits of implant-support to obturators [8, 21] and even suggests equivalent functional results as compared to surgical reconstruction [15, 16]. Our surgically reconstructed group has previously been compared with patients with an conventional obturator, most of them without implants [12, 37-39]. In contrast to our obturator group, the obturator group of this previous cross-sectional study had a significant lower mean MAI index (27.3 ± 0.5) which represents very limited masticatory performance. The retention method of these obturators might be a limiting factor, with only two obturators being implant-supported. Another possible explanation might be found in the feedingtube item of the EORTC-QLQH&N35. With eleven of the thirteen patients with an obturator scoring positive on the feeding-tube item, there is a possibility that those patients are not masticating at all and with that losing the physical fitness of the masticatory system to do so.
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