生物活性替代性牙本質材料與複合樹脂鍵結機制之探討

Abstract

背景：Biodentine®為三矽酸鈣類基底材料，是現今越來越多案例用來作為牙髓保護的材料。但這高生物相容性的材料與樹脂的鍵結方面仍存在著一些挑戰。 目的：本篇的研究目的為（1）研究Biodentine的結晶過程與結構變化（2）探討Biodentine和複合樹脂填補材料之間的鍵結機制 材料與方法：我們預備了孔洞為直徑4 mm、厚度2 mm的中空壓克力樹脂來製作塊狀Biodentine。而這實驗可分成四個部分來進行。第一部分：生物性牙本質替代性材料結晶與結構變化分析，我們將Biodentine放置在37∘C、100%的相對濕度環境的dd water 或 Hank’s Balanced Salt Solution (HBSS) 當中，並透過XRD (2θ: 20∘-60∘)和SEM分析Biodentine在儲存不同時間點（第1, 2, 3, 7, 14和28天）時觀察不同階段的變化。同時我們也做了固化時間的測試。第二部分：剪切黏著強度（SBS）測試，藉著透過不同固化時間的Biodentine和複合樹脂做SBS測試。也透過三種黏著系統：Prime Bond™ NT (PNT), Single Bond Universal (SBU), Xeno V (Xeno) 和玻璃離子體 (GIC, Fuji II)加入做SBS 測試（每組12個），並在脫膠後利用SEM進行斷裂面分析。第三部分：酸蝕在Biodentine表面與鍵結強度帶來的效果（分組：不酸蝕、15秒、30秒、60秒）。表面粗糙度（每組15個）透過Profilometer (Surfcorder ET 200)來做測試，也在SEM觀察酸蝕過後的塊狀Biodentine表面。酸蝕後的Biodentine也利用先前提到的黏著系統和樹脂做SBS測試（每組12個），脫膠後也利用SEM進行斷裂面分析。第四部分：額外的起始劑對於Biodentine的效用。我們額外利用起始劑RelyX™ Ceramic Primer (RCP)或是Monobond™ Plus (MBP)處理Biodentine表面，並藉由SEM觀察各組鍵結的界面。此外，我們也做了SBS測試與脫膠後的斷裂面分析，也利用EDS和FTIR分析鍵結的界面。 結果與討論：Biodentine 的固化時間平均為21.6 ± 0.2 分，將用來作為本篇研究的其他測試中Biodentine的固化時間。在SEM以及XRD分析下，不論是dd water或HBSS的組別在Biodentine的生長方面並無明顯不同，而Biodentine的結晶至少要2週才會達到成熟。關於儲存不同時間下的Biodentine對SBS帶來的影響，使用自酸蝕黏著系統時，14d組會顯著高於22min組（Ｐ<0.05）。GI不論是在哪個時間點下做測試都得到最低的SBS（22min/GI: 3.5 ± 2.13 MPa; 1d/GI: 0.9 ± 0.83 MPa; 14d/GI: 0.1 ± 0.34 MPa）。此一測試中，一共只有約17%的樣本能超過10MPa。 結合表面粗糙度（Ra）與SEM檢驗可以看到過長的酸蝕時間（超過30s）處理Biodentine會損害表面的結構，損壞的表面則可能會損壞黏著的品質（0.07 ± 0.05~13.0 ± 4.2 MPa）。當使用monobond plus 預處理Biodentine時，MBP/SBU組能夠達到最高的剪切黏著強度（17.5 ± 3.6 MPa, p<0.05）。根據斷裂分析顯示大部分測試為混合型或內聚型破壞。這篇研究中只有一組可以達到合格的黏著強度（17 MPa）。結合EDS和FTIR分析的結果顯示MBP/SBU能增強鍵結可能是因為γ-MPTS和10-MDP功能性單體的幫忙導致。 結論：Biodentine不論在哪個環境下培養，結晶至少要2週才會達到完全固化。使用含γ-MPTS和10-MDP功能性單體的矽烷在Biodentine表面做預處理，能提供提升鍵結強度的效果。而玻璃離子體並不建議作為覆蓋Biodentine的修復材料。作為一個牙本質替代性材料提供樹脂材料來做鍵結，Biodentine的機械強度可能是不足的。

Background. Biodentine®, a tricalcium-silicate based material, has potential for dental pulp protection. However, the poor bonding ability of Biodentine to composite resin severely limits its application. Objective. The aims of this study include (1) the investigation of the crystallization process and microstructural changes of Biodentine, and (2) the elucidation of the bonding mechanism of Biodentine to composite resin restoration. Material and methods. A Biodentine block was fabricated from the hollow acrylic block (4 mm in diameter, 2 mm in thickness). This study was carried out in 4 parts: Part I included the characterization of bioactive dentin substitute materials, followed by the phase change analyses of Biodentine. X-ray diffraction was conducted on Biodentine specimens immersed in either DD water or HBSS at 37 °C and 100% relative humidity for various time intervals (1 d, 2 d, 3 d, 7 d, 14 d, and 28 d) at 2θ = 20°-60°. Furthermore, scanning electron microscopy (SEM) was performed on the obtained samples. Part II involved the shear bond strength (SBS) test of the composite resin with Biodentine under various setting times (22 min, 1 d, and 14 d). Three adhesive systems: Prime Bond™ NT (PNT), Single Bond Universal (SBU), Xeno V (Xeno), and glass ionomer cement (GIC, Fuji II) were used for the SBS test (n=12 for each group). The fractography was analyzed using SEM after debonding. Part III involved the investigation of the etching effect on Biodentine surface (Grouping: no-etch/ 15 s/ 30 s/ 60 s). In addition, the surface roughness (n=15 for each group) was tested using Surfcorder ET 200. The etched surfaces of the Biodentine blocks were examined using SEM. The SBS of the etched Biodentine to composite resin using the aforementioned adhesive systems was also evaluated (n=12 for each group). The fractography was also observed using SEM. Part IV involved the investigation of the effects of additional primers on Biodentine surface. Primers used for this study were RelyX™ Ceramic Primer (RCP) and Monobond™ Plus (MBP)\. The bonding interface of primer-Biodentine was observed using SEM. In addition, SBS test and fractographic analysis were performed. Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were performed to analyze the bonding interfaces. Results and discussion. The average setting time of Biodentine was tested as 21.6 ± 0.2 min, which was used as the setting time in this study for other tests. No evident difference in the Biodentine growth between the specimens immersed in DD water and those immersed in HBSS was observed during SEM and XRD. In addition, the crystal maturation of Biodentine was confirmed to take at least 2 weeks. For the effects of various time intervals of Biodentine on the SBS, a higher SBS value was observed in the 14-d group compared to that of the 22-min group using self-etch adhesive system (P<0.05). However, the lowest SBS value was observed in the GI group for all the time intervals (22 min/GI: 3.5 ± 2.13 MPa; 1 d/GI: 0.9 ± 0.83 MPa; 14 d/GI: 0.1 ± 0.34 MPa). In addition, only 17% of all the specimens achieved a bond strength above 10 MPa. The SEM examination of the surface roughness (Ra) confirmed that an increase in the etching time destroys the structure of Biodentine. The damaged surface may be detrimental to the adhesion quality (0.07 ± 0.05~13.0 ± 4.2 MPa). Furthermore, the highest SBS value was observed in the MBP/SBU group (17.5 ± 3.6 MPa, p<0.05). The fractographic analysis showed that most of the specimens tested in this study exhibited mixed failures. In addition, only one group in this study achieved the qualified bond strength (17 MPa). The EDS and FTIR analyses showed that the enhanced bonding of MBP/SBU group might be due to the presence of γ-MPTS and 10-MDP functional monomers in the silane primer. Conclusion. The Biodentine crystallization needs at least 2 weeks to achieve totally set regardless of the immersing solution. The Biodentine surface pretreated with silane containing of γ-MPTS and 10-MDP and further bonded with SBU exhibited an enhanced bond strength. In addition, GI is not recommended as a cover material on Biodentine. The mechanical strength of Biodentine may not be sufficient as a substitute for dentin and adhesion to composite resin.