Formation of a periodontal ligament around titanium implants.

The aim of this study was to examine wound healing events around titanium implants in the presence of retained root tips whose periodontium could serve as a source for cells which could participate in the healing process. Hollow cylinder implants with a titanium plasma-sprayed surface were placed in the mandible of monkeys where the apical portions of previously removed teeth were retained. After a healing period of 12 months, free of functional loading, the implants with surrounding tissues were removed and specimens analyzed in undecalcified sections. This report describes histologic findings of six such implants. Microscopic analysis revealed that in regions where implants were close to retained roots, a periodontal ligament had formed around large portions of the implant. Furthermore, there was a distinct layer of cementum on the implant surface and a periodontal ligament with collagen fibers perpendicularly oriented to the implant surface, implanted into the cementum on the implant surface as well as to the opposing bone. This initial observation suggests that it may be possible to achieve an anchorage of certain dental implants with a periodontium simulating that found surrounding the normal tooth. Furthermore, these findings provide the basis for further studies on regeneration of all components of the periodontal attachment apparatus including cementum, periodontal ligament, and bone.