Peri-implant bone reactions at delayed and immediately loaded implants: an experimental study

ObjectiveThe aim of this study was to compare the peri-implant bone reactions of implants subjected to immediate loading with those subjected to delayed loading.Study designIn 6 mongrel dogs, bilateral edentulated flat alveolar ridges were created in the mandible. After 3 months of healing, 1 implant was placed in each side. On one side of the mandible, the implant was loaded immediately with a force of 20 N that was applied at a 120° angle from the tooth’s longitudinal axis at the labial surface of the crown for 1800 cycles per day for 10 weeks. On the opposite side, after a delay of 3 months to allow osseointegration to take place, the implant was loaded with the same force used for the immediately loaded implant. Ten weeks after loading, microscopic computerized tomography at the implantation site was performed. Osseointegration was calculated as the percentage of implant surface in contact with bone. Bone height was measured in the peri-implant bone.ResultsThe mean osseointegration was greater (65.5%) for the delayed-loading implants than for the immediately loaded implants (60.9%; P < .05). The mean peri-implant bone height was greater (10.6 mm) for the delayed-loading implants than for the immediately loaded implants (9.6 mm; P < .05).ConclusionThe results indicate that when implants are immediately loaded, the immediate loading may decrease both osseointegration of dental implants and bone height.