Bone Reaction to Bovine Hydroxyapatite in the Mandibular Defects

Objectives:The purpose of this study was to evaluate the bone reaction to new bovine hydroxyapatite grafted in surgically created mandibular defects of beagle dogs.

Methods:Four beagle dogs were used in this study. The 2nd/4th premolars on both sides of the mandible were carefully extracted. In the extraction sockets, the defects sized 8mm x 6mm x 5mm were made and the flaps were closed.

After 4 weeks of healing, buccal-lingual full thickness flaps were elevated. Each defect was randomly assigned to 3 different group : Defects of 'G' group were grafted with OCS-B® and secured with interrupted sutures. Defects of 'GM' group were filled with OCS-B® and covered with Bio-Gide®. In 'NG' group, the flaps were replaced and sutured without any graft materialor membrane.

Results:The graft materials were in direct contact with the newly formed bone as well as with connective tissue. The osseous tissue around the grafted particles presented numerous osteocytes, typical to a woven bone pattern. At 6 week, the bridging of new bone tissue around graft particle was observed.

After 6 weeks, the grafted group regardless of the barrier membrane showed the good ridge morphology compared with the non-grafted group. The non-graft site revealed the severe bony defect. The recovered defect area of 'G' and 'GM' goup was significantly larger than that of 'NG' group. Average bone area fraction of 'G' and 'GM' group was also higher than that of 'NG' group and the difference was significant. But, no statistically significant difference was noted between 'G' group and 'GM' group in bone area fraction.

Conclusions:New bovine hydroxyapatite(OCS-B®) was demonstrated to have a biocompatibility and osteoconductivity in dog model. Further studies are necessary to verify its long term tissue reaction in human.