IMPLANTS PLACED IN IMMEDIATE EXTRACTION SITES - A REPORT OF HISTOLOGIC AND HISTOMETRIC ANALYSES OF HUMAN BIOPSIES

Five titanium plasma-sprayed implants were biopsied from a human volun teer 6 months after placement. Four test implants had been placed in i mmediate extraction sockets, while one implant was placed in a mature site and served as a control. The histologic analysis demonstrated tha t all five implants achieved osseointegration as demonstrated by light microscopy, whereas a varying degree of bone-implant contact was obse rved. The non-loaded control implant had the highest percentage of bon e-implant contact, 72%, followed by the two implants placed in the can ine sites presenting with a horizontal defect dimension of 1.5 mm or l ess. These implants were placed without a barrier membrane, but in a s ubmerged fashion. The histometric analysis showed a mean bone-implant contact of 50% for these two implants. The lowest mean bone-implant co ntact (17%) was observed for the two molar implants, which had horizon tal defect dimensions of 4 mm; these implants were placed in a non-sub merged fashion with the implants perforating an expanded polytetrafluo roethylene membrane. The authors concluded that osseointegration may o ccur in immediate extraction sites in humans using titanium implants w ith a plasma-sprayed surface. The horizontal component of the peri-imp lant defect was apparently the most critical factor relating to the fi nal amount of bone-implant contact.