116 Chapter 7 Treatment protocol In the current study a standardized treatment protocol for treatment of the atrophied maxilla was used applying autologous bone grafts from the retromolar region, iliac crest or calvaria. In maxillary sinus floor augmentation surgery, a variety of grafts from different origins may be used. While different graft types may have an impact on healing times, long-term outcomes are comparable for both autologous grafts and bone substitutes27. However, in the current specific cases a large compromised bone defect needed to be reconstructed in both vertical and horizontal direction. In order to reconstruct such bone defects, autologous onlay bone blocks are the first choice. In addition, research on calvarial grafts used for reconstruction surgery shows results comparable to iliacal grafts and intra-oral grafts in clinical12,28,29,30, histological31 and patient related outcome measures12 and can be considered a viable alternative to the latter sites, without influencing treatment outcomes. Putters et al.12 therefore advises a patient centred decision when considering a donor site. Marginal bone level change The evaluated implants show a mean MBLC of -0.32 ± 0.46 mm after a mean evaluation period of 3.3 years, which is comparable to other retreatment studies5,7,18, although their prosthodontic procedures were different to the current study’s. Interestingly, the marginal bone level change in the present study is also similar to the study of Slot et al.27, comparing maxillary overdentures supported by four and six implants in pristine bone conditions. Patient related outcome measures The results on PROMs are similar to the outcomes of studies describing regular maxillary overdenture treatment32,33. This is quite surprising, since the patients in this study had gone through a prolonged treatment process, compared to a regular treatment procedure. This makes retreatment a sensible treatment choice from a patient satisfaction point of view. Number of implants The patients treated in this study received four or six implants. The choice for the number was based on the evidence available in the literature at the time of treatment34. Therefore, patients with the longest follow-up received six implants, while four implants were placed at a later point in time in comparable patients. Recent systematic reviews on this subject advise a minimum of four implants, but also state that the number of implants in overdenture therapy, as well as the type of anchorage, is still under debate35,36. Complications When considering maxillary implant retreatment, a few complications should be taken into account. The close proximity of the failing implants to the maxillary sinus often results in sinus membrane perforation during implant removal. Also, since the infected soft tissues are thin and of inferior quality, tension free wound closure after augmentation procedures might be challenging and post-operative wound dehiscence often occurs. Large dehiscenses can cause sequestra, which might necessitate a second augmentation procedure37. In the current study,
RkJQdWJsaXNoZXIy MTk4NDMw