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Maxillary Sinus Augmentation using TGF-β and Bone Grafting in Dogs

以轉化生長因子與骨移植促進上顎竇腔骨增進

摘要


牙科種植體已成功的被用來解決齒列缺損重建的問題,種植體可維持齒槽殘脊,可避免健康齒質之修形,提供義齒良好固位,支持及恢復咀嚼功能。然而在上顎後牙區因上顎竇及嚴重吸收之齒槽殘脊,在上顎竇底部至齒槽殘脊問,常常無法提供足夠高度和寬度之齒槽脊來種植植體。上顎竇底部增高術可增加齒槽脊之高度和寬度。許多骨移植材料被利用於上顎竇底部增高術,但是對上顎竇腔骨增進與骨整合的分子機轉乃不清楚。在骨癒合之過程中有兩個重要關鍵步驟,一為增加局部的骨先驅細胞之數目,另一為骨改造之速度。轉化生長因子可直接或間接加速骨先驅細胞之傳導或誘導,因而增進骨形成。在骨重塑階段,骨移植材料亦可用來誘導或傳導新骨形成。本研究的目的在上顎竇底部增高術時,植入轉化生長因子與骨移植材料,以期達到更理想上顎竇腔骨增進。本動物活體實驗是以十一隻臺灣土狗共二十二個上顎竇,分三組為對象。在上顎竇底部增高術時分別植入轉化生長因子混合OsteoGen(可吸收之氫氧磷灰石),自體骨混合OsteoGen及單獨OsteoGen之對照組,其樣本數分別為8, 10, 4。並分別於術後2, 4, 6個月後犧牲,取其標本進行研究。骨增生與癒合的結果用臨床,放射線攝影,電腦斷層攝影,組織,及掃瞄電子顯微鏡評估。電腦斷層攝影結果顯示上顎竇底部植入轉化生長因子混合OsteoGen或自體骨混合OsteoGen比單獨植入OsteoGen之對照組的骨密度較高。組織學檢查顯示轉化生長因子混合OsteoGen,自體骨混合OsteoGen及單獨植入OsteoGen之對照組均有新生血管與新骨形成,各組形成新骨的量似無明顯的差異。轉化生長因子混合OsteoGen這組似可見較多新生骨髓。形成之新骨多位於OsteoGen之間,OsteoGen雖有吸收現象,然而於移植後六個月仍可見殘餘之OsteoGen。移植時間較長者可見新生骨髓。本研究結果亦顯示因臺灣土狗之上顎竇大小比人類的小許多,骨癒合速度與類型也不盡相同,有待進一步施行人體研究,以期能達到實際應用於臨床病患。

關鍵字

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並列摘要


Dental implants may maintain residual alveolar ridge, avoid preparation of the healthy tooth, and provide better retention, support, and chewing functions. However, in the maxillary posterior areas the size and extension of the sinus cavities often jeopardized implantation of dental implants. The mechanisms involved in sinus augmentation and osseointegration are still not fully understood. The amount of new bone regenerated may not be adequate and the time for bone healing may take years to complete; therefore, the success rate of osseointegration in augmented sinus may be lower. Two critical processes for the enhancement of bone healing are to increase the number of local osteoprogenitor cells and to accelerate the rate of bone remodeling. TGF-β may directly or indirectly regulate cells of the bone marrow and re-establish the osteoblast phenotype and enhance new bone formation. During skeletal remodeling, bone grafting materials may also be used to induce or conduct new bone formation. The purpose of this investigation was to evaluate the potential use of TGF-β and / or bone grafting materials on sinus augmentation in vivo. Two, four and six months after sinus elevation and TGF-β and bone graft implantation, dogs were sacrificed. Results were assessed using clinical, histologic, and radiograghic techniques. SEM examination was also performed to evaluate the level of osseointegration ultrastructurally. Computed tomography (CT) showed an increase in mineralization over time for all study groups. CT showed that sinuses grafted with TGE-β /OsteoGen or autogenous bone/OsteoGen exhibited greater bone density than sites grafted with OsteoGen only. Histological results of the present study indicated that TGF-β/OsteoGen, autogenous bone/OsteoGen, and OsteoGen promoted similar amount of new blood vessels and new bone in grafted maxillary sinus. It appeared that TGF-β/OsteoGen formed more new bone marrow. New bone was formed primarily around OsteoGen. While OsteoGen was resorbed, there were still tremendous amounts of residual OsteoGen particles after 6 months of grafting. More new bone marrows were formed as graft time increased.

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