複合樹脂直接填補應用於根管治療後之牙齒: 鍵結強度與聚合收縮性質之分析

Abstract

複合樹脂在牙科的應用已行之有年亦獲致不錯的成效，然而對於複合樹脂在根管治療後牙齒根管內部填補之應用，則缺乏較深入的研究。因此本實驗的目的如下： (1) 以電子顯微鏡進行牙本質結構之觀察並比較不同部位間的差異，(2) 以推離鍵結測試 (push-out bonding test) 的方法，比較不同牙本質黏著劑應用在根管窩洞填補時，複合樹脂與根管部牙本質之間的鍵結效果。(3) 由於複合樹脂之後膠聚合收縮對於根管內填補時的牙本質鍵結有極大的影響，因此實驗的最後亦針對本研究團隊新研發的樹脂基質系統，以應變計測量法 (strain gauge method) 分析其後膠聚合時期所產生之收縮應力。 在牙本質的電子顯微鏡觀察中發現，各部位牙本質小管管徑與密度皆由內部牙本質往外部牙本質遞減，牙本質小管密度由牙冠牙本質往牙根牙本質遞減，而管周牙本質的厚度則由內部牙本質往外部牙本質遞增，由牙冠牙本質往牙根牙本質遞減。在鍵結強度的測試方面，使用total-etch technique所得到的平均鍵結強度為37 ± 12.4 MPa，較 self etch technique 的21 ± 6.8 MPa高 (p < 0.001)。而使用相同的牙本質黏著技術，在牙根冠部與牙根中段之鍵結強度則沒有統計學上的差異。在新研發樹脂基質的聚合收縮測量方面，在相同重量百分比下，實驗組之最終收縮量均較對照組 (BisGMA) 低，顯示新研發的樹脂基質確實可改善聚合收縮的現象，然而加入填料後的其他各種性質仍需進一步的實驗測試研究。

Composite resin has been used in dentistry for several decades and has achieved good results in clinical, in vivo, and in vitro studies. However, there are few thorough studies about the application of composite resin in intra-canal restoration of post-endodontically treated teeth. The purposes of our study were as follows: (1) Observing dentin microstructure using scanning electron microscope. (2) Determining the bond strength of composite resin to root canal dentin using different dentin bonding agents by means of push-out bonding test. (3) Because of the great influence of composite resin polymerization shrinkage on intra-canal dentin bonding, we also measured the post-gel polymerization shrinkage of a new developed low-shrinkage resin matrix system using strain gauge method. From the results of dentin microstructural study, we found that the diameter and density of dentinal tubules decreased from inner dentin to outer dentin, tubular density decreased from crown dentin to root dentin. Peritubular dentin thickness increased from inner dentin to outer dentin and decreased from crown dentin to root dentin. In the push-out bonding test, the average bond strength using total etch technique was 37 ± 12.7 MPa, higher than that of self etch technique (21 ± 6.8 MPa). Within each bonding agent, however, bond strength of composite resin to coronal or mid root dentin showed no significant differences. The results of polymerization shrinkage for the new developed resin matrix system showed that the new resin matrix system could improve resin polymerization shrinkage. However, other properties of the new resin system after adding fillers need further investigation.