How successful are maxillary implant-retained overdentures on two or four implants?

Area of Science:

• Dental Implantology
• Prosthodontics
• Oral Rehabilitation

Background:

• Edentulism affects the maxilla, often necessitating implant-supported prostheses.
• Two-implant mandibular overdentures are a common treatment, but maxillary rehabilitation requires further investigation.
• Asynchronous loading protocols for multiple implants are being explored for improved outcomes.

Purpose of the Study:

• To evaluate the survival and success rates of four-implant overdentures in the edentulous maxilla.
• To assess prosthetic complications associated with this treatment modality.
• To compare outcomes in patients with pre-existing two-implant mandibular overdentures.

Main Methods:

• A randomized crossover clinical trial involving 24 participants with edentulous maxillae.
• Four maxillary implants (two anterior, two posterior) were placed and loaded asynchronously, followed by full arch loading.
• Kaplan-Meier survival analysis and assessment of prosthetic complications over a mean follow-up of 2.2 years.

Main Results:

• Implant survival rate was 93.8% after a mean of 3.1 years, with all losses occurring in anterior positions.
• A total of 27 prosthetic complications were recorded, generally manageable.
• Denture success rate was high at 95.8% after a mean follow-up of 2.2 years.

Conclusions:

• Four-implant overdentures in the maxilla demonstrate good implant survival and are a recommendable option for patients with two-implant mandibular overdentures.
• While prosthetic complications are frequent, they are typically manageable, and patient preference favors the four-implant solution.
• Posterior implants did not show superiority over anterior implants in this study, but overall patient satisfaction was high.