Two or four implants for maxillary overdentures in edentulous patients: 1-year results of a randomized controlled trial.

INTRODUCTION: Maxillary implant overdenture therapy is a good treatment option for treating patients experiencing problems with their conventional maxillary denture. Retaining the overdenture with four implants and a bar attachment system serves as the current gold standard. However, there is a demand for less costly and less invasive treatment options. The aim of this randomized controlled trial was to compare marginal bone level change (MBLC), implant and overdenture survival, clinical, masticatory, and patient-related outcomes (PROMs) of maxillary implant overdentures with either two or four implants and a bar attachment system. MATERIALS AND METHODS: Forty edentulous participants were randomly allocated to two groups (n = 20), to receive either two or four implants in the maxilla. After healing, all the participants received an implant overdenture retained by a bar attachment system. All the participants were evaluated 1 and 12 months after overdenture placement. The primary outcome was MBLC. Secondary outcomes were implant and overdenture survival, clinical, masticatory, and PROMs. The outcomes were analyzed using parametric and non-parametric tests. RESULTS: MBLC was -0.03 mm in the 2-implant group and -0.16 mm in the 4-implant group (p = 0.21). Implant survival was 83.3% in the 2-implant group and 94.4% in the 4-implant group (p = 0.03). The median pocket depth change and clinical outcomes were low, and masticatory performance along with PROMs improved in both groups and did not differ significantly between them. CONCLUSION: Maxillary 4-implant overdentures perform better than maxillary 2-implant overdentures with a bar attachment system in terms of implant and overdenture survival and therefore remains the gold standard. However, both overdentures perform similarly in terms of MBLC, clinical, masticatory, and PROMs.