Radiographic evaluation of immediately loaded implants supporting 2-3 units fixed bridges in the posterior maxilla: a 3-year follow-up prospective randomized controlled multicenter clinical study

Objective To compare the survival rate and alveolar bone levels at implants installed in healed sites and functionally loaded within 1 h from installation or after 3 months. Material and methods A total of 30 patients (17 male and 13 female) were recruited and 71 implants with a SLA® surface, 4.1 mm in diameter and 8–12 mm long, were installed in a fully healed alveolar ridge, 36 as test and 35 as control implants. The test implants were immediately loaded with a temporary reconstruction in proper occlusion, while the randomly selected control sites received the final reconstruction after 3 months. Radiographic bone levels were determined after implant installation, prosthesis delivery, and at annual intervals thereafter. Results One patient of the control and one patient of the test were excluded from evaluation. No further losses of implants or patients were seen up to the 3‐year follow‐up. Hence, data from 28 patients were accounted for. A total of 37 and 36 metal–ceramic crowns were provided at the test and control sites, respectively. No biological and technical complications were observed during the 3‐year follow‐up. Bone levels at the time of implant installation were at 1.6 ± 0.8 and 1.7 ± 0.9 mm from the implant shoulder at the test and control sites, respectively. At prosthesis delivery, the bone levels were located at 2.4 ± 0.7 mm at the control sites 3 months after implant placement. After 1 year of function, similar bone levels were observed at both sites, displaying 2.4 ± 1.0 and 2.5 ± 0.8 mm at the test and control sites, respectively. No differences were found in the subsequent observation periods. Conclusion Survival rates and radiographic bone levels after 1, 2, and 3 years of observation did not differ between conventionally installed implants loaded immediately or delayed (after 3 months). Moreover, insertion torque values did not affect osseointegration.