Light-microscopic evaluation of the dimensions of peri-implant mucosa around immediately loaded and submerged titanium implants in monkeys.

Background: Immediate loading of dental implants is a successful treatment concept. The importance of healthy peri-implant soft tissues for the long-term success of dental implants has been widely recognized. The aim of this study was to evaluate the peri-implant soft tissues around immediately loaded and submerged implants in monkeys. Methods: A total of 48 implants were inserted in six Macaca fascicularis monkeys. For 24 implants (test implants), the prosthetic abutments were inserted immediately, and a custom-made metal superstructure was cemented after 3 days; the other 24 implants were left unloaded (control implants). Block sections of bone segments containing the implants were retrieved 9 months after surgical placement. A histomorphometric measurement of sulcular epithelium (SE), junctional epithelium (JE), and connective tissue (CT) contact percentage of the soft tissues around test and control implants was carried out. Results: In some specimens, the peri-implant epithelium was very similar to a pocket epithelium, whereas in others it was possible to observe an SE and a long junctional-like epithelium with a moderate amount of inflammatory cells. The supracrestal peri-implant CT was dense and organized in collagen fibrous bundles in an annular pattern around the implant. No statistically significant differences were present in the dimensions of SE, JE, and CT in test and control implants (P > 0.05). Conclusion: Immediate loading did not produce changes in the dimensions of the peri-implant soft tissues.