Maxillary bar overdentures on four or six posterior implants: 10-year results from a randomized clinical trial

Objective To compare clinical and patient-reported outcomes when providing maxillary overdentures on four and six splinted implants placed in the posterior region during a 10-year follow-up period. Materials and Methods Sixty-six edentulous participants with functional maxillary denture complaints and insufficient bone volume to allow implant placement were scheduled for a bone augmentation procedure. After healing, participants were randomized to receive either four or six implants in the posterior maxilla. After 3 months of osseointegration, a bar overdenture was constructed. Implant survival, overdenture survival, clinical scores, peri-implant bone height changes, and patient satisfaction were assessed. Results Forty-six participants completed the 10-year follow-up. Implant survival was 100% in the 4-implant group and 96.7% in the 6-implant group. Seven new overdentures were made in the 4-implant group and 12 new overdentures were made in the 6-implant group due to excessive wear of the denture base and teeth. Clinical parameters did not differ significantly between groups. Mean marginal bone loss compared to baseline was 0.41 +/- 0.37 mm in the 4-implant group and 0.70 +/- 1.07 mm in the 6-implant group. Overall, patient satisfaction improved significantly, but did not differ between groups. Conclusion From this 10-year follow-up trial, it was concluded that bar maxillary overdentures on four or six implants in the posterior region of an augmented maxilla resulted in a comparable treatment outcome with high implant survival, limited loss of peri-implant marginal bone, and high patients' satisfaction. (Clinical trial registration number: NTR9729).