We often encounter bone defects in patients who underwent surgery for diseases in the oral and maxillofacial region. Large bone defects need to be restored. These defects can usually be reconstructed well with fresh bone autografts. A second surgery has to be performed to extract donor bone. For patients, an operation to retrieve fresh bone autografts is quite stressful. In recent years, calcium phosphate-based materials have been used for bone regeneration. Many clinical studies have reported the use of hydroxyapatite (HAP) for bone reconstruction. Two forms of HAP, namely blocks and granules, are available. However, the handling and molding characteristics, as well as the form-maintaining property of granular HAP, are not satisfactory.
Hiruma added a viscoelastic binding agent to HAP to improve its characteristics. HApG was prepared by adding gelatin to granular HAP. The addition of gelatin improved the handling and molding characteristics, in addition to the form-maintaining property. A dried specimen of this material was produced in this study. When this dried specimen was soaked in body fluid
in vivo,the viscosity of the binding agent was reduced. As a result, granular HAP might gradually become scattered. Therefore, we assumed that better healing of the bone defects would occur as a result of increased new bone volume, when granular HAP is gradually scattered.
In this study, we used a dried specimen of HApG which was prepared by adding gelatin to granular HAP, and soft X-ray and histological analyses were conducted.
The results were as follows:
1. The density of the dried specimen increased in the order of HAp200G1 and HAp100G1, when we mixed them with purified water at a powder and liquid ratio of 1.5.
2. When analyzed with soft X-rays, both HAp100G1 and HAp200G1 appeared radiodense.
3. We measured the bone mineral density using soft X-ray photography. The bone mineral density of both HAp100G1 and HAp200G1 increased with time.
4. HAp100G1 and HAp200G1 showed similar histological findings. New bone formation occurred inwards from the defect border;bone appeared to grow towards the defect center as time passed.
A dried specimen of HApG demonstrated improved handling and molding characteristics as well as form-maintaining property, and the osteoconduction was good.
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