BONE APPOSITION ONTO ORAL IMPLANTS IN THE SINUS AREA FILLED WITH DIFFERENT GRAFTING MATERIALS - A HISTOLOGICAL STUDY IN BEAGLE DOGS

The placement of oral implants into jaw bone has a high predictability provided an adequate bone volume surrounding the implant is present t o ensure primary stability and resistance to functional loading forces after completion of osseointegration. In the distal area of the maxil la, an adequate bone volume is often lacking because of the proximity of the sinus cavities. The aim of this study was to evaluate histologi cally the simultaneous placement of endosseous implants into the sinus cavity and the surgical elevation of the sinus floor including fillin g the cavity with different grafting materials. In 9 sinus areas of 5 beagle dogs, 9 titanium implants (ITI(R) Dental Implant System) were p laced, and the void space of the sinus cavity was filled simultaneousl y with either demineralized freeze-dried human cortical bone (Musculos keletal Transplant Foundation), resorbable hydroxyapatite (Osteogen(R) ) or natural cancelleous bovine bone mineral (Bio-Oss(R)). To study bo ne formation, fluorochrome markers (tetracycline HCl and calcein green ) were used at 2 and 8 weeks. Clinically, all implants healed uneventf ully, and 5 months after implant placement the dogs were killed for hi stologic evaluation. All implants exhibited osseointegration within th e pre-existing cortical bone of the sinus floor. The implants surround ed by freeze-dried bone xenografts yielded no formation of new bone, w hereas the sites with hydroxyapatite or natural bovine bone mineral de monstrated newly formed bone with direct contact at the implant surfac e. The average extent of bone to implant contact was 25% (SD=10.6%) an d 27% (SD=8.8%), respectively in relation to the length of the origina lly denuded implant surface. In addition, the bone markers revealed a rapid bone formation and remodeling, especially around natural bovine bone mineral particles. This study yields new bone formation with dire ct contact to the implants surfaces in the sinus cavity into which sui table grafting materials were placed simultaneously. Resorbable hydrox yapatite (Osteogen(R)) and natural cancellous bovine bone mineral (Bio -Oss(R)) were osteoconductive and hence were suitable for bone formati on around endosseous implants.