| 摘要: | 氫氧基磷灰石(Hydroxyapatite)的晶體結構類似天然骨、具有骨引導功能且取得容易，因此被廣泛應用於骨科和牙科的臨床與研究發展。近年來，實驗得知能從珊瑚，蛋殼，牛骨和人骨加工來取得氫氧基磷灰石已獲得成功，然而研究證實氫氧基磷灰石具有緩慢的降解率和延遲骨癒合的缺點，因此依然須要發展或改良更好的氫氧基磷灰石骨填補材。再生醫學的研究中發現牙本質包含了骨基質蛋白，其對於骨形成是有效益的，但不同人間的移植則有免疫排斥與倫理上的問題。當人的牙齒經過熱處理後，牙本質粉可以用作骨移植；可是，牙本質粉填補材於醫學的應用上的了解卻相當缺乏。因此，本研究的目的是評估牙本質粉填補材的生物相容性與骨缺損的修復能力。
本實驗將比較不同顆粒大小的牙本質粉(250-500μm與500-1000μm)及市售骨填補材(HA/β-TCP, 250-500μm)對骨再生效果的差異，實驗進行時將骨填補材填入12隻紐西蘭白兔的前額葉顱骨的四個直徑6mm的人造骨缺損中，進行一周，二周，四周及八周之觀察。於觀察時間點取出填補處周邊骨的樣本，並且使用micro-computed tomography (micro-CT)來評估骨生成體積密度Bone volume density (BV/TV, %)的變化，接著再用組織切片來觀察骨組織的生長情形。本研究初步結果顯示，在四週時有骨填補材填入組別的骨體積密度(BV/TV, %)，當植入材料為250-500μm牙本質粉時為41.3±8.9％，當植入材料為500-1000μm牙本質粉時為45.9±5.8％和當植入材料為HA /β-TCP市售材料時為46.2±3.5％，均比對照組30.3±1.4％有顯著增加有顯著的差異(p<0.05)，此初步結果證明牙本質骨粉具有良好的生物相容性與骨引導功能可以早期促進骨癒合，是一個可利用且有發展性的骨填補材料。
Hydroxyapatite (HA) is widely used in the field of orthopaedics and dentistry due to their osteoconductive properties and their crystal structures similar to the natural bone. Recently, HA can be produced form coral, eggshells, bovine bone and deproteinized human bone. Furthermore, slow degradation rate and delayed bone healing after augmentation with bovine HA has been published.
The human dentin contains bone matrix proteins which is effective for the bone formation. Through heat treatment, the human dentin powders can be used as bone grafts. However, the medical application of dentin powders is rarely reported. Thus, the purpose of this study was to evaluate the bone regeneration ability of human dentin powder in rabbit calvarial defects.
Four bicortical calvarial bone defects with a diameter of 6 mm were created in each of twelve rabbits. The four defects were respectively grafted with dentin powder with particle size of 250-500μm and 500-1000μm, HA/β-TCP with particle size of 250-500μm and left empty were used as positive and negative control. After1,2, 4 and 8 weeks of healing, animals were sacrificed. The samples were harvested and fixed in 10% formalin. Before the preparation of histological sections, the samples were evaluated with a micro-computed tomography (micro-CT) for quantitative assays. Bone volume density (BV/TV, %) was determined through micro-CT images.
For the micro-CT analysis, the bone volume density increased significantly in all the grafted groups (41.3±8.9%, 45.9±5.8% and 46.2±3.5% for the dentin powder groups with small particles and with large particles, and HA/β-TCP groups respectively) in comparison to the control group (30.3±1.4%) at 4 weeks (P<0.05). However, the difference was not significant between the positive control and the dentin powder grafted groups at 8 weeks. Furthermore, similar new bone formation was found in both the particle size of dentin powder groups.
This study demonstrated that dentin powder could improve bone formation in the early stages of the healing process. In addition, our results revealed that human dentin powder may have potential for bone regeneration. |
