Implant-supported Maxillary Overdentures; a 15-years Evaluation

• Introduction and rationale In patients who present persistent complaints with respect to their maxillary denture, providing implant support improves comfort, denture satisfaction and overall quality of life considerably and high implant survival rates are reported. Implant position, the number of implants and bone volume are all factors that presumably influence success of both the maxillary overdenture and the implants. Four- and 6-implant bar-supported maxillary overdenture studies report successful short and medium-term results, indicating that these treatment modalities are comparable and favourable. However, there is considerable heterogeneity with respect to patient and treatment variables within studies reporting on maxillary overdentures in general and four versus six implants in particular, with a lack of high quality long term data as well. The aim of the present study is to report long term results of bar-supported maxillary implant overdentures on four and six anterior implants for which various clinical surgical and prosthetic outcome measures and subjective, patient-reported parameters are described and compared. Evidence on maxillary IOD attachment systems has been mostly short to medium term, non-comparing or retrospective and therefore inconclusive. This underlines the need for studies comparing different attachment systems with a longer follow-up. The study design is an observational study to compare treatment outcomes of fully edentulous patients with maxillary IODs, supported by four or six implants. Patients were treated 15 years ago with dental implants and an overdenture in the maxilla because of problems with retention and stability with their conventional denture. Outcomes: primary outcome is the change in marginal peri-implant bone level 15 years after placing the overdenture. Secondary outcome measures will be implant and overdenture survival, peri-implant mucosa health and patients' satisfaction using a questionnaire.