Healing of marginal defects around implants

Abstract: The purpose of the present series of investigations was to study the healing of marginal defects around implants. The hard-tissue alterations following immediate implant placement in extrac-tion sites were analyzed in 18 patients (study I). In experimental studies in dogs (i) appositional bone formation in marginal defects at implants (studies II and III), the healing of marginal de-fects at implants with varying surface characteristics and installation techniques (study IV), as well as (iii) the healing of marginal defects that occurred at implants placed in a fully healed ridge or in a fresh extraction socket were evaluated. It was demonstrated that: - The marginal gap between the hard tissue walls and the metal body following implant installa-tion in fresh extraction sockets in humans was in most instances be resolved during the first 4 months of healing. In the process of healing 56% of the buccal and 27% of the lingual/palatal width of the hard tissue walls were lost. - Hard tissue formation started from the walls of the artificially prepared defect (appositional growth) in dogs and complete resolution of the defect including osseointegration was obtained after 4 months of healing. - The resolution of the experimentally produced defect was influenced by the surface characteris-tics but not by the positioning of the mucosa, i.e. if the implants were “submerged” or “non-submerged” during healing. - While almost complete osseointegration occurred at implants placed in artificially produced de-fects in dogs, the process of bone healing and osseointegration was compromised when implants were installed in fresh extraction sockets.