Implant-retained mandibular overdentures with Branemark system MKII implants: A prospective comparative study between delayed and immediate loading

This study was designed to compare the results of immediate and delayed loa ding of implants with implant-retained mandibular overdentures. Ten patient s (test group) received 40 Branemark System MKII implants (4 per patient) p laced in the interforaminal area of the mandible. Standard abutments were i mmediately screwed to the implants, rigidly connected with a bar, and immed iately loaded with an overdenture. Ten patients (control group) received th e same type and number of implants in the same area, but the implants were left to heal submerged. Four to 8 months later, standard abutments were scr ewed to the implants and the same prosthetic procedure was applied. Each im plant was evaluated at the time of prosthetic loading and at 6, 12, and 24 months after the initial prosthetic load with the following parameters: mod ified Plaque Index (MPI), modified Bleeding Index (MBI), probing depth (PD) , and Periotest. Peri-implant bone resorption was evaluated on panoramic ra diographs taken 12 and 24 months after initial prosthetic loading. No signi ficant differences were found between the 2 groups regarding MPI, MBI, Peri otest, peri-implant bone resorption, and PD at 6 and 24 months (P >.05). Th e only difference was found regarding PD values on the mesial and lingual s ites at 12 months (P <.05). The cumulative success rate of implants was 97. 5% in both groups. Results from this study showed that immediate loading of endosseous implants rigidly connected with a U-shaped bar does not seem to have any detrimental effect on osseointegration. Conversely, this method s ignificantly shortens the duration of treatment with relevant satisfaction for the patients.