Maxillary overdentures supported by four or six implants in the anterior region; 1-year results from a randomized controlled trial

Objective Comparing treatment outcome of four and six bar-connected implants in the anterior maxillary region to support an overdenture during a 1-year follow-up period. Material and methods Fifty edentulous patients with lack of retention and stability of the upper denture, but with sufficient bone volume to place implants in the anterior maxillary region, were selected. Randomization assigned patients to either four or six implants. Implant survival, overdenture survival, clinical scores, radiographic bone height changes, and patients' satisfaction were assessed. Results Forty-nine patients (one drop out) completed the 1-year follow-up. After 1year, implant survival was 100% in the four implants group and 99.3% in the six implants group (one implant lost). Overdenture survival was 100% in both groups. Mean clinical scores were low and did not differ between groups (independent Student's t-test). Mean marginal bone resorption was 0.24 +/- 0.32mm in the four implants group and 0.25 +/- 0.29mm in the six implants group. Patients' satisfaction had improved in both groups (paired Student's t-test). Conclusion Bar-supported overdentures on four implants in the anterior maxillary region are not inferior to overdentures supported by six bar-connected implants. Implant survival was high, peri-implant conditions were healthy and patients' satisfaction had increased significantly in both groups.