由牙本質膠原蛋白和樹脂形成的混合層（hybrid layer）是牙本質黏著的關鍵。核黃素是一種光反應的膠原蛋白交聯劑，藉由光照產生活性氧物種 (reactive oxygen species)，進而促進膠原蛋白交聯，已被證實可以強化牙本質膠原蛋白並可增加牙本質黏著的耐久性。然而其最合適的處理濃度和時機尚未明瞭。此外，樹脂與氧氣接觸其聚合程度會被抑制，而形成氧化抑制層，於混合層中則可能降低樹脂的機械性質進而影響鍵結，故核黃素產生的活性氧物種被視為一項隱憂。本研究目標為，找出核黃素對牙本質黏著的最佳處理條件（光照時間/濃度/處理時機），以及驗證光反應產生的氧氣是否會影響黏著層的聚合程度。
本實驗第一部份擬找出核黃素的最適合濃度和光照時間，利用市售小牛膠原蛋白，以不同濃度核黃素(0.05%, 0.1%, 0.5%, 1%)和光照時間(30s、60s)處理，透過膠體電泳檢測和傅立葉轉換紅外線光譜儀檢測。再以此條件處理人類牙本質表面，利用拉曼光譜儀分析其交聯效果。第二部分先利用SOSG試劑檢測不同條件處理的核黃素所釋放的單態氧量。再使用拉曼光譜儀和奈米壓痕觀察經核黃素處理的牙本質黏著劑的聚合程度與奈米硬度。最後利用微張力試驗測試不同處理時間點組別對牙本質黏著強度短期和長期（六個月）的影響，並以掃描式電子顯微鏡觀察黏著層。
於第一部分實驗，膠體電泳檢測和拉曼光譜儀試驗中，0.05%核黃素可有效增加膠原蛋白交聯;在傅立葉轉換紅外線光譜儀實驗中，所有實驗組二級胺比例皆上升，以1%核黃素上升比例最高，但核黃素與二級胺吸收光譜類似，可能造成誤差。於第二部分實驗，核黃素處理不影響黏著劑的聚合程度，而0.05%與0.1%核黃素相比有較高的微硬度。第三部分中，0.05%核黃素組之微張力黏著強度高於0.1%核黃素，而處理次序上是酸蝕前處理有較好表現。掃描式電子顯微鏡觀測0.05%和0.1%核黃素在酸蝕前處理能降低維滲透發生。由目前實驗可知，在酸蝕前處理0.05%核黃素不會影響黏著劑聚合，且能有效促進膠原蛋白交聯，提升牙本質黏著強度，並減少微滲透的產生。

Dentin bonding is based on the hybrid layer which is made from dentin collagen and infiltrated resin. Riboflavin (RF) as a photoreactive collagen crosslinker generates reactive oxygen species after light irradiation, and which had been proven in increasing dentin-resin bonding. However, the specific concentration and the treatment protocol have not been discussed. Besides, oxygen inhibits free radical polymerization and yields uncured resin has been defined as “oxygen inhibition”. RF-generated singlet oxygen in resin polymerization was a concern and not surveyed yet. Therefore, the objects of this study were to investigate the optimal protocol of RF in dentin bonding treatment, and to examine the effect of RF-generated singlet oxygen on the polymerization of the adhesive layer.
In the first part, the crosslinking capability of different RF treating protocols was analyzed by SDS-PAGE, FTIR-ATR and Raman spectroscopy. In the second part, the appropriate protocols were then examined to determine their effects on resin polymerization by amounts of singlet oxygen, degree of conversion (DC) and nanohardness. Additionally, the microtensile bond strength (µTBS) and nanoleakage at the bond interfaces were investigated both immediately and after 6-month storage.
In SDS-PAGE and Raman spectroscopic analysis, 0.05% RF promoted collagen crosslinking, while a reverse result was found in FTIR-ATR which showed a higher amide II/I conversion in 1% RF. In the second part, no significant difference in DC was found, while 0.05% RF showed higher nanohardness than that of 1%. RF treatment before or immediately after acid-etching showed higher µTBS both immediately after bonding and after water storage, and no significant µTBS decrease after storage. SEM finding also showed a decrease in nanoleakage in these two groups.
With these results, RF concentration at 0.05% had better performance than 0.1% did overall. This study revealed that 0.05% RF treated before etching has higher collagen crosslinking, µTBS (immediately/ after storage) and less nanoleakage without jeopardizing resin polymerization.

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