含超分枝聚氨酯丙烯酸酯的新型3D列印義齒基底樹脂材料泡水之六個月期間材料機械性質評估

Abstract

實驗目的： 義齒基底材料須具備良好的機械強度與耐磨性，以承受咬合力並確保長期配戴的穩定性。隨著數位牙科發展，3D列印成為製作義齒的新方式，具有效率高、材料利用率佳等優勢，但其樹脂義齒基底在臨床使用中仍易斷裂，顯示長期耐久性不足。為改善此問題，本研究開發一種新型超分支聚氨酯丙烯酸酯混合樹脂，並透過體外實驗，比較其在長時間潮濕環境下的機械性質，評估其與另外兩款市售列印樹脂的性能差異。 材料與方法： 本研究所開發之超分支聚氨酯丙烯酸酯（HBPUA）樹脂，編號為TIH4，其合成程序首先以三甲醇丙烷（1, 1, 1-tris(hydroxymethyl)propane, 98%, TMP）、二異氰酸異佛爾酮（isophorone diisocyanate, 98%, IPDI）與丙烯酸－2-羥基乙酯（2-hydroxyethyl acrylate, HEA）依最佳比例，單體莫爾比1:3:3混合，經冷凝蒸餾反應十小時製得。反應後使用迴旋濃縮機進行濃縮，再依序以傅里葉轉換紅外光譜儀（fourier transform infrared spectroscopy, HORIBA）及凝膠滲透層析儀（gel permeation chromatography, Jasco）分析反應產物之官能基轉換率與分子量分布，以確認聚合反應是否成功。接著，將三環癸烷二甲醇二丙烯酸酯（Tricyclodecanedimethanol diacrylate, TCDDMDA）以重量比1:9混合。再加入光引發劑2,4,6-三甲基苯甲酰二苯基氧化膦（2,4, 6-trimethy lbenzoy ldipheny phosphine oxide, TPO），依照莫爾比1:0.01進行混合，作為後續3D列印義齒基底材料研究之核心配方。 以兩種市售3D列印義齒基底樹脂，NextDent Denture 3D+, 3D Systems (以下簡稱Control N) 和 Detax Freeprint denture resin, Detax GmbH & Co. (以下簡稱Control D) 作為對照組。依據ISO 20795-1:2013 Denture base polymers-type IV materials之規定製備試片並進行各項材料測試。獲得各組數據資料並代入各自的公式進行計算，後續以軟體SAS version 9.4 , SAS Institute Inc. 進行Oneway ANOVA以及Pair t test之統計分析。 實驗結果： 彎曲強度方面，乾燥時Control D表現最佳，顯著高於其他兩種材料。短期內Control N強度略為上升，而TIH4變化不明顯，Control D則開始下降。中期期間，TIH4與Control D彎曲強度快速下降，後續變化趨緩；Control D則在12週後才顯著下降。至長期，Control N呈現顯著上升，而TIH4與Control D趨於穩定。彈性模數方面，乾燥時Control N剛性最高，顯著高於其他材料。短期內TIH4彈性模數顯著上升，中期變化趨於穩定，而Control N與Control D則呈波動趨勢。最大應力強度因子方面，初期Control N明顯偏低，短期內Control D為最高。至12週時，TIH4與Control D皆高於Control N，唯於24週時三者間差異消失。總斷裂功方面，初期以TIH4最高，短期內則以Control D為最低。中期Control D下降最明顯，長期則以Control N持續上升最具韌性。最後，TIH4吸水率最低且變化穩定，與市售材料Control N、Control D有顯著差異，TIH4具較佳長期吸水穩定性。且僅TIH4溶出率符合ISO20795-1:2013標準，其數值顯著低於Control N與Control D。 結論： 本研究評估之新型列印義齒基底材料（TIH4）與兩款市售樹脂（Control N、Control D）在不同泡水時間下之機械與物理性質。結果顯示，雖三者於部分時間點機械性質無顯著差異，TIH4在中長期泡水後具較佳的彎曲強度、彈性模數穩定性與抗裂性。且其最大應力強度因子全程符合ISO20795-1:2013標準，相較之下，Control N與Control D在部分時間點低於標準。於吸水與溶出表現方面，TIH4吸水率最低且溶出率唯一全程符合ISO20795-1:2013規範。整體而言，TIH4表現出良好的耐水性、結構穩定性，具發展為臨床義齒基底材料之潛力。

Objective: Denture base materials must possess adequate mechanical strength and wear resistance to withstand occlusal forces and ensure long-term stability during use. However, the oral environment—characterized by prolonged exposure to saliva, temperature fluctuations, and mechanical stress—can lead to material deformation or fracture. With the advancement of digital dentistry, 3D printing has emerged as a promising method for denture fabrication, offering advantages such as high production efficiency and better material utilization. Nevertheless, 3D-printed denture base resins are still prone to fracture during clinical use, indicating insufficient long-term durability. To address this issue, this study developed a novel hyperbranched polyurethane acrylate (HBPUA)-based hybrid resin. Through in vitro experiments, its mechanical properties under prolonged humid conditions were evaluated and compared with those of two commercially available 3D-printed denture base resins. Material and methods A novel hyperbranched polyurethane acrylate (HBPUA) resin, designated as TIH4, was synthesized from trimethylolpropane, isophorone diisocyanate, and 2-hydroxyethyl acrylate through a 10-hour condensation distillation process. The resulting mixture was concentrated and analyzed using FTIR and GPC to confirm its chemical properties. Tricyclodecanedimethanol diacrylate and a photoinitiator (TPO) were then added to formulate the hybrid resin, named TC10. Two commercial 3D printing denture base resins, NextDent Denture 3D+ and Detax Freeprint® Denture, were used as controls. Specimens were designed per ISO 20795-1:2013 using Meshmixer, printed via a Phrozen Sonic 4K printer, cleaned with Form Wash, and post-cured with Form Cure. Mechanical properties including flexural strength, elastic modulus, Kmax, and total fracture work were tested at five time points up to 24 weeks. Water sorption and solubility were assessed separately at four intervals. All samples (n=15/group) were immersed in 37°C water, and statistical analyses were conducted based on the calculated data to evaluate long-term performance. Results This study evaluated the long-term mechanical behavior of three 3D-printed denture base resins—TIH4, Control N, and Control D—after water immersion. Initially, Control D exhibited the highest flexural strength, while TIH4 and Control N were comparable. Over time, Control D declined, Control N increased significantly by week 24, and TIH4 plateaued. Elastic modulus results showed that Control N had the highest initial stiffness, TIH4 increased then stabilized, and Control D remained relatively constant; by week 24, no significant group differences were found. For maximal stress intensity factor, Control N started lowest, while Control D peaked early but declined most sharply. TIH4 and Control D initially surpassed Control N, but differences leveled out by week 24. Total fracture work revealed TIH4 had the highest initial toughness, Control D degraded mid-term, and Control N showed the greatest improvement over time. In water resistance, TIH4 showed the lowest and most stable sorption and was the only material meeting ISO solubility standards throughout, indicating superior chemical durability. Overall, TIH4 demonstrated good water resistance and toughness, though its flexural strength declined over time. Conclusions This study evaluated the long-term mechanical and physical properties of a novel HBPUA-based 3D-printed denture base material (TIH4) and compared it with two commercial resins (Control N and Control D). While mechanical differences were not always statistically significant, TIH4 exhibited superior mid- to long-term stability in flexural strength, modulus, and crack resistance. Its Kmax remained compliant with ISO 20795-1:2013 throughout, whereas Control N and Control D occasionally fell below the standard. In terms of water behavior, TIH4 had the lowest water sorption and was the only material to meet solubility requirements throughout the study. Overall, TIH4 demonstrated promising water resistance and structural stability, highlighting its potential as a clinically viable denture base material. However, further evaluation is needed to fully confirm its clinical applicability.