全陶瓷材料用於固定式局部義齒已有數十年時間，雖然氧化鋯材料擁有絕佳的機械性質，但是在近幾年的臨床試驗卻發現全陶瓷固定式局部義齒的碎裂率比傳統金屬陶瓷義齒還要來的高，由於氧化鋯熱傳導係數比起金屬還要來的低，因此在製造過程中容易因為內外溫差而引起應力集中，造成結構上的缺陷，本研究透過最佳化不同材料介面間結構，以改善其應力集中的問題。
首先利用牙科設計軟體，取得傳統組的固定式局部義齒模型，將拓樸最佳化演算法導入有限元素分析軟體，進行固定式局部義齒介面形狀最佳化，利用有限元素節點連續性進行材料交界面的抓取，透過權重函數值得給定，以及置換材料門檻的設定，逐步的最佳化不同材料的幾何邊界，直到滿足收斂條件即停止，後續再針對最佳化後的結果進行後處理，得到最佳化後的完整模型。並且透過一個簡易直角試片進行實驗驗證，預設一個高度應力集中的模型，帶入最佳化法中進行最佳化，再針對改善後的試片形狀進行製作，並施以壓力實驗。
本研究期望以結構優化的方法針對不同材料的交界處進行幾何形狀的設計，以降低加工製造產生的殘留應力為目標，由模擬的結果來看，在優化前與優化後的陶瓷內部最大主應力分布較為平均，且傳統上氧化鋯頰側的最大主應力在經過優化後下降許多。而簡易的實驗驗證也取得初步的成功，最佳化後的結果徹底改善應力集中的區域。

All-ceramic fixed partial dentures (FPDs) have widely replaced metal-ceramic ones during the last few decades. Clinically, the substructure of the all-ceramic FPD was made by zirconia material and covered with a layer of veneering porcelain for esthetics. Although zirconia owned excellent mechanical property and biocompatibility, recent clinical trials reported that a high chipping rate appeared in veneered porcelain layers. The present study integrated the finite element method with optimization algorithm to find solution that lowers the risk of chipping. For validation, a simplified experiment was used to validate the optimization process. In all-ceramic FPD simulation results, the optimal model outperformed than the traditional model in terms of the peak values of maximum principal stress and stress concentration. In experimental results, the optimization process improved the cracking issue in fabrication process. The optimization approach presented in this study showed the potential to help clinicians achieve more robust all-ceramic FPDs and could also be applied to other biomechanical design processes.

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