不同厚度與顏色的陶瓷材料對於樹脂黏合劑光聚合表現之影響

Abstract

近年來，牙科陶瓷已被廣泛地應用於牙體復形治療，加上各類樹脂材料的問世，使得在臨床治療上有更多選擇。二矽酸鋰（lithium disilicate）與氧化鋯（zirconia dioxide）為目前市面上以及臨床端最常用的陶瓷材料，二矽酸鋰其良好的透光性以及與牙釉質相近的物理性質，常做局部復形的材料，但仍有機械強度不足的問題，而氧化鋯同樣為牙科陶瓷，透光性較差但有較良好的機械強度。

這兩類材料均需要利用以樹脂為基底的黏合劑進行黏著，臨床上常用的選項包含樹脂黏合劑（resin cement）、流動性複合樹脂（flowable composite resin）與預加熱複合樹脂（preheated composite resin），並利用光照射使其固化，然而不同陶瓷的厚度與顏色搭配不同的黏合劑顏色都有可能影響光照效率進而導致黏合劑聚合不全、黏著效果不佳，進而導致成黏著介面變質並對牙髓細胞產生影響。

因此本研究將測試二矽酸鋰與氧化鋯在不同厚度與顏色的條件下對於光照的影響與對不同種類黏合劑聚合度的改變，並延伸探討各類黏合劑的聚合度改變對於牙髓細胞的影響。

本研究中使用厚度分別為0.5 mm、1.0 mm與2.0 mm，顏色為A1及A3的二矽酸鋰與氧化鋯試片，其中氧化鋯組別又分為3Y-TZP與ML，測試各種材料與厚度及顏色的組合對於光照效率的影響，後續搭配三種黏合劑（RelyX U200 self-adhesive resin cement、Grandio-So heavy flow、Viscalor bulk），測試黏合劑聚合度及其對細胞的影響；實驗方法包含光照效率的測試、FT-IR聚合度測試、酸鹼值測試、Alamar blue細胞活性測試、活性氧檢測以及流式細胞儀。

由以上的的實驗得知，二矽酸鋰的透光率優於氧化鋯，同時顏色與厚度也皆會影響材料透光度，同時也反映在黏合劑聚合度上，在相同的照光時間下，二矽酸鋰組別的聚合度優於氧化鋯，再以二矽酸鋰搭配各種黏合劑進行細胞實驗，會發現樹脂黏合劑組（resin cement）的酸鹼值最低，影響細胞的生長最明顯，並且在24小時內就會造成大部分細胞死亡。

綜合以上實驗結果，材料的種類、厚度與顏色皆會影響透光度與黏合劑聚合度，但在光照時間足夠的情形之下，相同種類的材料所呈現的黏合劑聚合度則不受厚度與顏色影響，而在各類的黏合劑中，其中又以樹脂黏合劑呈現出來的細胞毒性最明顯，所以在臨床上使用的時候應綜合考量實際狀況，選擇最理想的材料與黏合劑組合。

In recent years, dental ceramics have been widely used in restorative treatment, and the advent of various resin materials has provided more options for clinical treatment. Lithium disilicate and zirconia dioxide are currently the most used dental ceramic materials on the market and clinically. Lithium disilicate has good light transmission and physical properties like tooth enamel, so it is often used as a partial restoration. But it still has the problem of insufficient mechanical strength, and zirconia dioxided is also a kind of dental ceramic, which has poor light transmission but good mechanical strength.

These two types of materials need to be adhered with resin-based luting cement. The commonly used clinical options include resin cement, flowable composite resin and preheated composite resin., and use light cure unit to cure it. However, different thicknesses and colors of ceramics and different cement colors may affect the light intensity, resulting in incomplete polymerization of the cement, poor adhesion, and easy to cause deterioration of the adhesive interface and damage to the pulp tissue.

Therefore, this study will test the influence of lithium disilicate and zirconia dioxide on the light intensity and the changes in the degree of conversion of different types of cement under the conditions of different thicknesses and colors and extend to explore the effect of changes in the degree of conversion of various cements on dental pulp cells.

In this study, lithium disilicate and zirconia dioxide specimens with thicknesses of 0.5 mm, 1.0 mm and 2.0 mm and colors of A1 and A3 were used. The zirconia group was further divided into 3Y-TZP and ML. The effect of the combination of thickness and color on the light intensity, followed by matching with three cements (RelyX U200 self-adhesive resin cement, Grandio-So heavy flow, Viscalor bulk) to test the degree of polymerization of the cement and its effect on dental pulp cells. The experimental method includes lighting intensity test, test of degree of conversion by FT-IR, pH value test, Alamar blue cell viability assay, ROS detection assay and flow cytometry.

According to the above experiments, the light transmittance of lithium disilicate is better than that of zirconia. At the same time, the color and thickness will also affect the light transmittance of the material, and it is also reflected in the degree of polymerization of the cement. Under the same lighting time, the degree of the lithium disilicate group is better than that of zirconia, and then the cell experiment is carried out with lithium disilicate and various cemenet. It will be found that the pH value of the resin cement group (resin cement) is the lowest, which affects the growth of the cells the most. significantly, and causes most of the cell death within 24 hours.

Based on the above experimental results, the type, thickness, and color of the material will all affect the light transmittance and the degree of conversion of the cement. Among all kinds of adhesives, the cytotoxicity of resin cement is the most obvious. Therefore, when using clinically, the actual situation should be considered comprehensively, and the most ideal combination of materials and adhesives should be selected.