Immediate vs. delayed loading in the posterior mandible: a split-mouth study with up to 15 years of follow-up

The aim of this study was to evaluate the long-term clinical and radiographic outcomes of implants that were immediately loaded in a prospective, randomized, split-mouth clinical trial in the posterior mandible.

Patients with alveolar ridges that were bilaterally edentulous distal to the canines were enrolled to participate. On one randomly selected side of each patient's jaw, three implants (control group) with platform switching and a progressive thread design were placed, allowed to heal for 3 months, uncovered, and loaded occlusally using resin-splinted crowns, which then were replaced 6 weeks later by final prostheses. Three additional implants (test group) of the same size and design were placed on the contralateral side of each patient in symmetrical locations. The test implants were connected to their final abutments immediately after placement and immediately loaded. Periodontal indices and bone loss were evaluated at regular intervals.

After a mean loading period of 12.14 (±0.89) years for the test group and 12.40 (±0.89) years for controls, differences between the immediately and delayed loaded implants were not statistically significant (P > 0.05). The crestal bone loss was (mesial) 0.70 (±1.09) mm (test group) and 1.17 (±1.27) mm (control group) and the distal bone loss was 0.43 (±1.02) mm (test group) and 1.06 (±1.33) mm (control group) (P > 0.05). The maximum crestal bone loss was 3.12 mm for the test group and 3.78 mm for the controls after 10.125/10.397 years, respectively.

Immediate loading does not negatively influence the long-term prognosis of dental implants in the posterior mandible, improves the implant stability, and is associated with minimal crestal bone loss when platform switching and a one-abutment concept with a Morse-tapered connection are used.