Associate Professor, Laboratory of Multimaterials and Interfaces, UMR CNRS 5615, Lyon 1 University; Faculty of Odontology, Department of Restorative Dentistry, Lyon Civil Hospices, Lyon, France.
Associate Professor, Laboratory of Multimaterials and Interfaces, UMR CNRS 5615, Lyon 1 University; Faculty of Odontology, Department of Prosthodontics, Lyon Civil Hospices, Lyon, France.
J Prosthet Dent. 2018 Mar;119(3):384-389. doi: 10.1016/j.prosdent.2017.03.001. Epub 2017 May 26.
Recent polymer-based computer-assisted design and computer-assisted manufacturing (CAD-CAM) materials have been commercialized for inlay restorations, a polymer-infiltrated ceramic-network (PICN) and composite resin nanoceramics. Little independent evidence regarding their mechanical properties exists. Internal adaptation is an important factor for the clinical success and longevity of a restoration, and data concerning this parameter for inlays made with these blocks are scarce.
The purpose of this in vitro study was to evaluate and compare the mechanical properties (flexural strength, flexural modulus, Vickers hardness, fracture toughness) and the internal adaptation of these recent polymer-based blocks with a lithium disilicate glass-ceramic block.
The materials tested in this study were a PICN material (Vita Enamic), 2 composite resin nanoceramics (Lava Ultimate; 3M ESPE and Cerasmart; GCDental Products), and a lithium disilicate glass-ceramic (IPS e.max CAD). Mechanical properties were evaluated according to ISO norm DIS 6872:2013. Bar-shaped specimens (18×3×3 mm) were prepared and submitted to a 3-point bend test using a universal testing machine at a cross-head speed of 0.5 mm/min. In addition, identical cavities were prepared in 60 human mandibular extracted molars (n=15) and optically scanned to receive mesioocclusodistal inlays milled with the 4 materials tested in a CEREC Inlab milling machine. The replica technique and a stereomicroscope (×20) were used to measure the internal fit of the inlays at 9 preselected locations. All data were statistically analyzed using 1-way ANOVA and the post hoc Tukey multiple comparison or Games-Howell test (α=.05).
The mean flexural strength of the tested blocks ranged from 148.7 ±9.5 MPa (Vita Enamic) to 216.5 ±28.3 MPa (Cerasmart). The mean flexural modulus ranged from 23.3 ±6.4 GPa (Vita Enamic) to 52.8 ±10.5 GPa (IPS e.max CAD). The mean Vickers hardness ranged from 0.66 ±0.02 GPa (Cerasmart) to 5.98 ±0.69 GPa (IPS e.max CAD). The mean fracture toughness ranged from 1.2 ±0.17 MPa.m (Cerasmart) to 1.8 ±0.29 MPa.m (IPS e.max CAD). The values for internal discrepancy ranged from 119 ±55 μm to 234 ±51 μm. The mean internal discrepancy was significantly higher for Lava Ultimate (P<.05) than IPS e.max CAD and Cerasmart but not for Vita Enamic. The factor ''material'' was statistically significant in relation to the mechanical properties evaluated in this study (P<.05). The Pearson correlation was negative between the flexural strength results and the internal discrepancy of the materials tested (R=0.941; P<.05).
The mechanical properties of the CAD-CAM block materials tested were within the acceptable range for fabrication of single restorations according to the ISO standard for ceramics (ISO 6872:2008). IPS e.max CAD and Cerasmart were observed to have superior flexural strength and better internal fit.
最近商业化的聚合物基计算机辅助设计和计算机辅助制造（CAD-CAM）材料用于嵌体修复，包括聚合物渗透陶瓷网络（PICN）和复合树脂纳米陶瓷。关于这些材料的机械性能的独立证据很少。内部适应性是修复体临床成功和长期使用的一个重要因素，而关于这些块制成的嵌体的参数数据却很少。
本体外研究的目的是评估和比较这些最近的聚合物基块的机械性能（弯曲强度、弯曲模量、维氏硬度、断裂韧性）和内部适应性，以及一种锂硅玻璃陶瓷块。
本研究测试的材料为 PICN 材料（Vita Enamic）、2 种复合树脂纳米陶瓷（Lava Ultimate；3M ESPE 和 Cerasmart；GCDental Products）和一种锂硅玻璃陶瓷（IPS e.max CAD）。根据 ISO 标准 DIS 6872:2013 评估机械性能。制备条状试件（18×3×3mm），并在万能试验机上以 0.5mm/min 的十字头速度进行三点弯曲试验。此外，在 60 个人下颌磨牙（n=15）上制备相同的腔体，并使用 CEREC Inlab 铣床对 4 种测试材料进行铣削，以获得近中-远中嵌体。使用复制技术和立体显微镜（×20）在 9 个预选位置测量嵌体的内部拟合度。使用单向方差分析和事后 Tukey 多重比较或 Games-Howell 检验（α=.05）对所有数据进行统计分析。
测试块的平均弯曲强度范围为 148.7±9.5MPa（Vita Enamic）至 216.5±28.3MPa（Cerasmart）。平均弯曲模量范围为 23.3±6.4GPa（Vita Enamic）至 52.8±10.5GPa（IPS e.max CAD）。平均维氏硬度范围为 0.66±0.02GPa（Cerasmart）至 5.98±0.69GPa（IPS e.max CAD）。平均断裂韧性范围为 1.2±0.17MPa·m（Cerasmart）至 1.8±0.29MPa·m（IPS e.max CAD）。内部差异值范围为 119±55μm 至 234±51μm。Lava Ultimate 的平均内部差异显著高于 IPS e.max CAD 和 Cerasmart（P<.05），但与 Vita Enamic 相比则无差异。“材料”因素在与本研究评估的机械性能有关方面具有统计学意义（P<.05）。弯曲强度结果与材料的内部差异呈负相关（R=0.941；P<.05）。
根据陶瓷 ISO 标准（ISO 6872:2008），测试的 CAD-CAM 块材料的机械性能在用于制作单修复体的可接受范围内。IPS e.max CAD 和 Cerasmart 表现出较高的弯曲强度和更好的内部拟合度。
