- 學位論文
自酸蝕牙科黏著劑經老化測試之奈米級斷層掃描非破壞性分析與剪切黏著強度檢測
Nondestructive Analysis on Dentin-adhesive-composite Interface by Nano-computed Tomography and Shear Bond Strength Evaluation of Self-etch Adhesives after Aging Tests
摘要
使用複合樹脂修復缺損的牙齒結構是當前牙科治療最常見的項目之一，如何讓牙齒和復形物得到良好的結合，牙科黏著劑在兩者之間扮演了相當重要的角色。目前，牙科牙本質黏著系統依照塗抹層處理方式，可以分為兩大類: 全酸蝕系統與自酸蝕系統，其中，自酸蝕系統具有降低牙本質被過度酸蝕破壞、減少全酸蝕複雜的步驟及防止治療後敏感等優點，是故廣受歡迎，然而其也存有許多缺點，如：黏著強度不高、長期穩定性較低、容易有水解性破壞及微滲漏(隙縫)的發生、產品化學成分穩定性不易維持等等。為了彌補自酸蝕黏著劑的缺陷，便有學者提出使用多層塗抹的方式來增強黏著強度，但是仍然缺乏這些做法的長期試驗與一致性的研究結論。 因此，本次研究目的為探討自酸蝕牙本質黏著劑於不同操作方式(一層塗抹1-coat、兩層塗抹2-coat、兩倍時間塗抹2-time)、加諸不同次數(0、1,000、10,000次)之冷熱循環老化後，其剪切黏著強度是否有所差異，並且藉由奈米級電腦斷層掃描(nano CT)將同一黏著樣品老化前後影像之重合比較，對牙本質-黏著劑-複合樹脂介面變化進行質化與量化分析。 本研究使用2種廠牌且不同pH值之自酸蝕黏著劑：Single bond universal (SBU, 3M Oral Care; Neuss, Germany)和G Premio bond (GPR, GC; Tokyo, Japan)，依前述不同方法進行操作，實驗設計分為兩大部分：第一部分為觀察各種操作方式下自酸蝕黏著劑對牙本質表面的處理差異，檢視牙本質表面之pH值變化、SEM影像與EDS分析。第二部分為測試各項操作方法與不同冷熱循環次數處理後之剪切黏著強度，以SEM觀察牙本質-黏著劑-複合樹脂介面影像，並使用奈米級電腦斷層掃描對樣品進行老化處理前後之非破壞分析。 結果顯示不同pH值自酸蝕黏著劑以各種方式操作後，牙本質表面pH值與酸蝕程度會有所不同，但是EDS分析則沒有顯著的Ca/P 比例變化，對於特定廠牌之自酸蝕黏著劑(GPR)使用不同操作方式會對剪切黏著強度有顯著性差異產生(兩層塗抹之強度顯著低於兩倍時間，p<0.05)，SEM和奈米電腦斷層掃描影像均可見明顯孔隙和裂縫生成，老化測試後各種操作方式之黏著強度不僅顯著降低，尤其以兩層塗抹組別其孔隙變化最為明顯，且其黏著強度也是最低(p<0.05)，反觀另一廠牌(SBU)則不易受到操作方式不同而有所差異(p>0.05)，但是不同次數之冷熱循環也會對其黏著強度產生統計上的顯著影響。 綜合以上研究結果可知，如果期望使用兩層塗抹、加倍塗抹時間等不同操作方法來增強黏著效果，對SBU來說各種操作方法間並不具有統計上顯著差異；若是對GPR而言，並不建議塗抹兩層的方式處理黏著牙本質，其兩層塗抹的操作方式不管是短時間或長時間老化後都會產生最差的鍵結效果。兩層塗抹的方法不僅失去了當初自酸蝕黏著劑因簡化步驟所產生的便利性優勢，在長時間老化後所測得之鍵結強度平均值還較一層操作方式低。最後，奈米等級電腦斷層掃描對牙本質-黏著劑-複合樹脂介面進行的質化與量化分析，也能夠支持前述研究結果，藉由這項非破壞性的技術，不但有利於觀察相同樣本經歷老化處理後的全面性變化，也可以避免因樣本不同而產生的個體差異。
並列摘要
Using composite resin to repair the damaged tooth structure is one of the most common work for dental treatments nowadays. Dental adhesives play an important role to make composite restorations bind to dental tissue well. Currently, dental adhesives can be categorized by the approach of the smear layer into two groups: etch-and-rinse and self-etch system. For self-etch adhesives, there are lots of benefits, such as reducing the dentinal destruction by over-etching, simplified steps and preventing post-operative sensitivity. Though above advantages result in popularity worldwide, it still exists some shortcomings, like: lower bond strength, poor long-term durability, increased possibility of hydrolytic degradation and microleakage, and difficult to maintain chemical stability of ingredients. To resolve these problems, thereby, some researchers claim that the application of multiple coats can improve bond strength of self-etch adhesives. However, it seems no identical conclusions among recent studies and different adhesives and less long-term evidences for different application strategies. Thus, the object of this study was to evaluate the influences of self-etch adhesives with three application strategies (single-coat, double-coat, double-time) on shear bond strength (SBS) under thermal cycling aging tests. Then, the nano-computed tomography (nano CT) before and after thermal cycling tests were obtained for images reconstruction and registration. The changes of dentin-adhesive-composite interface was analyzed qualitatively and quantitatively. Two self-etch adhesives (Single bond universal, SBU, 3M Oral Care; G Premio bond, GPR, GC) were used in the study. The study was carried out in two parts: Part I, to investigate the effects of different application strategies on pH values and texture changes of adhesives on the dentin surface. Part II, effects of different application strategies and thermal cycling on dentin-composite shear bond strength and dentin-adhesive-composite interface. Moreover, a nano CT was used to analyze the dentin-adhesive-composite interface before and after thermal cycling test. The results indicated that differences were detected on pH value and SEM images between three application methods but no significant changes of elements on EDS data. As for GPR, double-coat application caused significant lower SBS than double-time (p<0.05) and obvious voids and gaps could be observed with SEM and nano CT images. After aging tests, the SBS of all application strategies decreased significantly, especially for the group of double-coat in which the most vivid voids generated and the lowest SBS was noted (p<0.05). However, there were no significant differences for SBU with different application strategies (p>0.05) even the number of thermal cycling did reduce the SBS. From the given results, if we wanted to improve bond strength through different application strategies such as double-coat or double-time, there would be no statistically different for SBU. As to GPR, the double-coat application was not suggested because the SBS and dentin-adhesive interface would be worse no matter after short-time or long-time aging tests. The way to apply a double-coat not only caused inconvenience of self-etch adhesives but also decreased the bond strength especially after longer aging time. Lastly, nano CT could supply qualitative and quantitative analysis on the dentin-adhesive-composite interface which backed up the above findings. By means of this nondestructive analysis technique, we can investigate the comprehensive changes on the same sample under aging treatment and to prevent the individual discrepancy from different samples.