134 Appendices SUMMARY Patients experiencing problems with their conventional maxillary denture can benefit from an implant-retained overdenture (IOD). Four-implants with a bar-clip attachment is currently the favourable treatment option. However, treating patients with a maxillary IOD can be challenging, especially in case of severe atrophy of the alveolar process, in which reconstructive surgery using bone augmentation is needed. However, when reconstructive surgery can be avoided, for instance by using 3D virtual surgical planning and a surgical template, the morbidity, the treatment costs, the invasiveness, and the treatment-time can be reduced. Besides the optimization of the surgical part of the treatment, there may also be room for optimization on the prosthetic part of the treatment. As an alternative to bar-clip retention, the overdenture could also be retained by using solitary attachments. Another optimization might be using less than four implants to retain the overdenture. Even though implant surgery has become a safe and predictable treatment for replacing teeth, biological complications such as peri-implant diseases and the loss of implants does occur. Especially for the implant retained maxillary overdenture these complications and following treatment are hardly mentioned in current literature. Therefore, the general aim of the research described in this thesis was to assess the treatment outcomes of a number of maxillary implant overdenture treatment modalities for the edentulous maxilla. In chapter 2 the aim of the study was to compare the 5-year follow-up outcomes of maxillary overdentures retained by bars or solitary attachments. For this study, fifty consecutively selected fully edentulous patients experiencing problems with their conventional denture received four implants and were randomly allocated to receive a maxillary overdenture with either bar- or solitary attachment retention. After 5 years, the mean marginal bone level change was higher in the solitary attachment group (-1.41±1.38mm, p=0.024) than in the bar group (-0.99±0.96mm). Also, fewer implants survived in the solitary attachment group (89.5%, p=0.027) than in the bar group (96.3%). The overdenture survival rate was 95.0% and 91.3% in the bar and solitary attachment group, respectively. Although the clinical and patient related outcomes were favourable and did not differ significantly between the groups, the peri-implantitis incidence was 25.8% in the solitary attachment group and 5.1% in the bar group. Therefore, it was concluded that in maxillary 4-implant overdenture therapy, the marginal bone level, implant survival rate, and the number of complications are better with bar attachments than with solitary attachments. Both groups’ clinical and patient related outcome measure scores were equal throughout the entire follow-up period. Templates aim to facilitate implant placement in the prosthetically preferred position. Mucosa-supported and bone-supported templates are commonly used in the edentulous maxilla. In the atrophic maxilla (Cawood V and VI), however, these templates can be easily displaced due to a lack of supportive tissues, even in cases where anterior sites offer sufficient bone for implant placement. To assist in positioning and stabilisation, we designed a template that utilises the nasal aperture as a fulcrum to create a forced and exclusive fit. The aim of chapter 3
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