Aims: The aim of this prospective study was to evaluate and compare the implant survival rate,

marginal bone levels and prostheses failure rate, of three-unit fixed dental prostheses (FDPs)

supported by three vs. two implants immediately loaded in the posterior area.

Material and Methods: Partially edentulous patients in need of a three-unit implant supported FDP

in the maxillary/mandibular posterior region were recruited and randomly split into two groups:

Group 1 with three-unit FDP supported by three implants (Control); Group 2 with three-unit FDP

supported by two implants (Test). Implants were inserted and immediately loaded with a temporary

FDP. Results: Sixty-three patients were included in the study. A total of 178 implants were placed

and immediately loaded (128 maxillary/50 mandibular) to support 74 immediate provisional fixed

prostheses (52 maxillary and 22 mandibular) delivered on the same day of implant

insertion/placement; 30 in Group 1 and 44 in Group 2. The comparison of three vs. two implants

resulted in comparable implant survival rate, marginal bone loss, and prostheses failure rate.

All implants healed uneventfully with no adverse clinical and radiographical signs or symptoms

except for one implant failure in Group 1 resulting in a cumulative success rate of 99,5%, 98,9% for

Group 1 and 100% for Group 2 with a follow-up of 6-to-10 (mean 7 years). Once loaded, the implants remained

in function from a minimum of 6 years to 10 years. Conclusions: Although more studies and larger sample sizes

are needed to validate this study, the results showed no difference between the two Groups, demonstrating the

potential viability of both clinical options.