Hammamy Mohammed, Rojas-Rueda Silvia, Nejat Amir H, Hamdan Suleiman, Ning Haibin, Lawson Nathaniel C
Resident, Department of Clinical and Community Sciences, The University of Alabama at Birmingham School of Dentistry, Birmingham, Ala.
Associate Professor, Division of Prosthodontics, Louisiana State University School of Dentistry, New Orleans, La.
J Prosthet Dent. 2025 Aug;134(2):471.e1-471.e8. doi: 10.1016/j.prosdent.2025.04.011. Epub 2025 Apr 23.
The best method of characterizing the strength of 3-dimensionally (3D) printed occlusal devices is unknown.
The purpose of this in vitro study was to compare the flexural strength, flexural modulus, fracture toughness, and impact strength of flexible and stiff 3D printed occlusal device materials with those of milled and conventionally processed materials under wet and dry conditions.
Specimens were fabricated from flexible (KeySplint Soft, NightGuard Flex 2) and stiff (KeySplint Hard, NightGuard Firm) 3D printed resins using a Digital Light Processing (DLP) printer and milled (ProArt CAD) and heat-polymerized (Excel Formula) materials. Specimen dimensions varied based on testing: flexural strength and flexural modulus (65×10×3.3 mm), toughness (4×8×39 mm, 3-mm cut with a 100- to 400-µm notch), and impact strength (63.5×12.7×4 mm, 1.2 mm, 45-degree notch). Specimens were stored wet (37 °C, 48 h) or dry (37 °C in water and then air dried for 24 h). Flexural strength and flexural modulus and fracture toughness were tested on a universal testing machine until fracture or 15-mm deflection, while impact strength was assessed with an Izod impact machine (7.5 J, 150 degrees). Data were analyzed using 2-way ANOVA and Tukey tests (α=.05).
Milled and heat-polymerized materials demonstrated higher flexural strength and flexural modulus than stiff 3D printed materials, which outperformed flexible 3D printed materials. Fracture toughness was better in milled and heat-polymerized materials under dry conditions, but one flexible 3D printed material outperformed all others under wet conditions. Flexible 3D printed materials exhibited significantly higher impact strength under both conditions.
Flexible 3D printed occlusal device materials excel in impact strength and show variable performance in other mechanical properties depending on material type and testing conditions.
表征三维（3D）打印咬合装置强度的最佳方法尚不清楚。
本体外研究的目的是比较柔性和刚性3D打印咬合装置材料在湿态和干态条件下与铣削和传统加工材料的弯曲强度、弯曲模量、断裂韧性和冲击强度。
使用数字光处理（DLP）打印机，由柔性（KeySplint Soft、NightGuard Flex 2）和刚性（KeySplint Hard、NightGuard Firm）3D打印树脂以及铣削（ProArt CAD）和热聚合（Excel Formula）材料制作标本。标本尺寸根据测试而变化：弯曲强度和弯曲模量（65×10×3.3毫米）、韧性（4×8×39毫米，带有100至400微米切口的3毫米切口）和冲击强度（63.5×12.7×4毫米，1.2毫米，45度切口）。标本储存于湿态（37°C，48小时）或干态（在水中37°C，然后空气干燥24小时）。在万能试验机上测试弯曲强度、弯曲模量和断裂韧性，直至断裂或15毫米挠度，而冲击强度用悬臂梁式冲击试验机（7.5焦耳，150度）评估。使用双向方差分析和Tukey检验（α = 0.05）分析数据。
铣削和热聚合材料的弯曲强度和弯曲模量高于刚性3D打印材料，刚性3D打印材料优于柔性3D打印材料。在干燥条件下，铣削和热聚合材料的断裂韧性更好，但一种柔性3D打印材料在湿态条件下优于所有其他材料。柔性3D打印材料在两种条件下均表现出显著更高的冲击强度。
柔性3D打印咬合装置材料在冲击强度方面表现出色，并且根据材料类型和测试条件，在其他机械性能方面表现出不同的性能。
