A Study on the Synthetic Hydroxyapatite Consolidation of Canine in Mandibular Bone Defects (Part 4) : Histopathological Observation of Porous Particles 9 Months Postoperatively

With the purpose of delaying regressive changes such as atrophy or osteoporotic change, which occur after tooth defects, synthetic hydroxyapatite (HAP) was applied to the lower canine jawbone. The HAP used in the present study was composed of porous particles 0.5 to 1.0 mm in size, several microns to 200 μm in pore diameter, and had an average porosity of 17.3%. Under local anesthesia, the first distomolar on the lower jaw bone of an adult mongrel dog was extracted, forming a bone groove of approximately 4 mm in width. HAP was formed. HAP was tightly packed into the groove, which was then sutured to achieve closure. After consolidation, the animals were kept for 2, 4, 13, 26, or 39 weeks. The lower jaw bones were cut in the buccolingual direction, and specimens for contact microradiography imaging and toluidine blue staining were prepared and examined. As a result, the formation of new bone tissue was noted around HAP from the early stage of consolidation, and good osteoconduction was found with apeak in the 13th week, while by the 39th week, displacement or scattering of HAP fractures was seen. Although external atrophy was somewhat delayed as compared with the control site, the newly formed bone tissues tended to disappear