A study was performed in two large hound dogs to evaluate the bone-induction potential of demineralized freeze-dried bone (DFDBA) placed into defects adjacent to implants that were placed into extraction sockets. Two implants were untreated controls, two implants received only Gore-Tex Augmentation Membrane (GTAM), two implants received GTAM and autologous bone, and six sites received GTAM and DFDBA. DFDBA was prepared from the long bones of a dog of the same breed as the experimental dogs. P2, P3, and P4 were extracted bilaterally, and buccal defects were created and measured. Twelve commercially pure titanium Brånemark implants were placed. At 12 weeks, clinical measurements were taken and the dogs were sacrificed. The untreated control defects had a mean clinical bone fill of 1.75 mm (37%). Sites treated with autologous bone had a mean of 5.0 mm (95%) of clinical bone fill within the original defects. Sites treated with DFDBA and barriers had 3.8 mm (75%) of bone fill, while sites treated with membranes alone had a mean of 4.2 mm (80%) of bone fill. Histologic evaluation revealed that DFDBA sites had retained nonviable bone chips in 45.4% of the bone matrix, and only 8.3% was lamellar bone. Autologous graft sites had 26.2% retained bone chips within the bone matrix, and 61% percent of the matrix consisted of lamellar bone. For GTAM-only sites, 70.2% of the matrix was lamellar bone and 29.8% was woven bone. Retained DFDBA bone chips were nonviable, occasionally surrounded by woven bone, and appeared to break up and then remineralize without the presence of osteoclastic or osteoblastic activity. Retained autologous bone chips were surrounded and incorporated by the host bone. The autologous bone grafts and DFDBA implants were considered to be osteoconductive. For the three treatment groups, within the defects there were sparse bone-implant contacts. The results indicate that GTAM barriers alone or with autologous bone grafts produced the best clinical and histologic results. DFDBA did not appear to induce bone formation in any of the evaluated specimens.

Alveolar Process↗

PubMedDate not supplied

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 volunteer 6 months after placement. Four test implants had been placed in immediate extraction sockets, while one implant was placed in a mature site and served as a control. The histologic analysis demonstrated that all five implants achieved osseointegration as demonstrated by light microscopy, whereas a varying degree of bone-implant contact was observed. The non-loaded control implant had the highest percentage of bone-implant contact, 72%, followed by the two implants placed in the canine sites presenting with a horizontal defect dimension of 1.5 nm or less. These implants were placed without a barrier membrane, but in a submerged fashion. The histometric analysis showed a mean bone-implant contact of 50% for these two implants. The lowest mean bone-implant contact (17%) was observed for the two molar implants, which had horizontal defect dimensions of 4 mm; these implants were placed in a non-submerged fashion with the implants perforating an expanded polytetrafluoroethylene membrane. The authors concluded that osseointegration may occur in immediate extraction sites in humans using titanium implants with a plasma-sprayed surface. The horizontal component of the peri-implant defect was apparently the most critical factor relating to the final amount of bone-implant contact.

Alveolar Process↗