不同光照模式對於複合樹脂之應力作用、聚合反應及細胞毒性之影響

Abstract

複合樹脂是目前臨床上常用的填補材料之一，並且因其價格低廉，操作簡易，以及顏色美觀，使得其應用範圍越來越廣泛。然而，在聚合過程中，樹脂具有收縮的現象，常常造成術後敏感、二度齲齒、填補物邊緣變色、甚至牙髓發炎。為了改進複合樹脂的性質，許多人研發出新的聚合模式和光聚機。因此，本實驗的目的，在於使用不同的聚合模式和光聚機，測量臨床上常用的不同複合樹脂其收縮時的微應變和單體聚合程度之變化，並探討其對於細胞毒性反應之相關性。 實驗的三種複合樹脂包括微粒型、混成型、以及流動型三種。聚合使用的光聚機為鹵素光及發光二極體兩種光源，並依照不同模式進行光照。三種受試的光聚機為XL3000（3M公司），Optilux501 (Kerr 公司)，和LEDemetron （Kerr公司）。 單體聚合的動態過程變化由FTIR光譜分析儀測量。單體測試的樣本厚度，以及照射方法，均和微應變測試相同。另外，並測試了最高聚合速率、最高聚合速率發生之時間、最高聚合速率時的單體聚合程度、以及在300秒後的最終聚合程度等因子。 實驗亦比較不同光聚模式對於不同複合樹脂應力作用及聚合度與細胞毒性的反應。結果顯示，當照射能量越強，單體聚合程度也越高，直至達到平衡。在同樣的能量下，微粒型聚合樹脂的單體聚合程度是三種複合樹脂中最低的。 以三種複合樹脂來說，微應變和單體聚合程度都具有二次方程式的關係。除了boost 模式以外，當微應變越高，單體聚合程度也越佳。 在細胞毒性反應測試中，實驗組和對照組（不加入樹脂樣品單獨培養者）未見有意義的差別，顯示此聚合程度並未造成細胞之毒性。

Resin composites are widely used in modern dentistry. However, the unpolymerized monomer and shrinkage in polymerization procedure caused severe problems, such as post-operative sensitivity, recurrent caries, marginal discoloration, and even pulpitis. In order to improve the properties of resin composites, some new curing machines with different modes were developed. However, there was no correlated investigation of the relationship between curing modes, curing units as well as physical properties and cytotoxicity of resin composites. Therefore, the aims of this study were to setup a mode of investigation for understanding the relationship between curing modes of curing units as well as physical properties and cytotoxicity of resin composites. Three kinds of resin composites including microfilled, all-purposed, and flowable types were investigated. Halogen light and light emitting diode curing units with different curing modes were compared. Properties of resin composites including microstrain, monomer conversion and cytotoxicity were investigated. The hypotheses of the study were: 5. When the total applied energy was increased, the microstrain and degree of conversion were also increased. 6. The relationships between total energy and microstrain or degree of conversion for three resin composites were predictable. 7. The soft-start method could provide a good method to cure resin composite with similar degree of conversion and less microstrain. 8. With lower monomer conversion, the cytotoxic effects would be more obvious. In this serial studies, the results indicated that when the applied energy was increased, the monomer conversion value was increased, and then reached a plateau. Under the same energy level, the monomer conversion of microfilled resin composite (Heliomolar) was the lowest among the three resin composites. There is a predicted quadratic equation manner relationship between microstrain and monomer conversion value of each composite cured with each curing machine. When the microstrain was increased, the monomer conversion value was increased with all curing modes except boost mode. In cytotoxicity test, there was no significant difference between the experimental groups and control group (cells cultured without resin samples immersed). The hypothesis 1 and 2 were confirmed. However, the hypothesis 3 and 4 was partially confirmed. The results indicated that the soft-start method could offer less or equal microstrain of resin composites with the same degree of conversion.For clinical application, soft-start method is suitable for high-matrix-content resin composites and better for shallow cavity restorations.