Minim P R, de Azevedo-Silva L J, Ferrairo B M, Pereira L F, Goulart C A, Monteiro-Sousa R S, Lisboa Filho P N, Fortulan C A, Salomão R, Borges A F S, Rubo J H
Department of Prosthodontics and Periodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
J Mech Behav Biomed Mater. 2023 Aug;144:105993. doi: 10.1016/j.jmbbm.2023.105993. Epub 2023 Jun 26.
Hydroxyapatite (HA) from bovine bones has been used as a biomaterial in dentistry due to its biocompatibility and bioactivity. However, dense HA bioceramics still present inadequate properties for applications that require high mechanical performance, such as infrastructure. Microstructural reinforcements and control of ceramic processing steps are methods to improve these shortcomings. The present study assessed the effects of polyvinyl butyral (PVB) addition in combination with two sintering methodologies (2-step and conventional), on the mechanical properties of polycrystalline bovine HA bioceramics. The samples were divided into four groups (with 15 samples per group): conventional sintering with binder (HBC) and without binder (HWC) and 2-step sintering with (HB2) and without binder (HW2). HA was extracted from bovine bones, turned into nanoparticles in a ball mill, and subjected to uniaxial and isostatic pressing into discs, according to ISO 6872 standards. All groups were characterized by x-ray diffractometry (XRD), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and relative density. Besides, mechanical analyses (biaxial flexural strength (BFS) and modulus of elasticity) were also performed. The characterization results demonstrated that adding agglutinants or the sintering method did not affect HA's chemical and structural characteristics. Even so, the HWC group showed the highest mechanical values for BFS and modulus of elasticity being 109.0 (98.0; 117.0) MPa and 105.17 ± 14.65 GPa, respectively. The HA ceramics submitted to conventional sintering and without the addition of binders achieved better mechanical properties than the other groups. The impacts of each variable were discussed and correlated to the final microstructures and mechanical properties.
牛骨来源的羟基磷灰石（HA）因其生物相容性和生物活性，已被用作牙科生物材料。然而，致密的HA生物陶瓷对于需要高机械性能的应用（如牙体组织）来说，其性能仍显不足。微观结构增强和陶瓷加工步骤的控制是改善这些缺点的方法。本研究评估了聚乙烯醇缩丁醛（PVB）添加物与两种烧结方法（两步烧结法和传统烧结法）相结合，对多晶牛HA生物陶瓷力学性能的影响。样品分为四组（每组15个样品）：添加粘结剂的传统烧结组（HBC）、不添加粘结剂的传统烧结组（HWC）、添加粘结剂的两步烧结组（HB2）和不添加粘结剂的两步烧结组（HW2）。HA从牛骨中提取，在球磨机中制成纳米颗粒，并根据ISO 6872标准进行单轴和等静压制成圆盘。所有组均通过X射线衍射（XRD）、差示热分析（DTA）、傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）和相对密度进行表征。此外，还进行了力学分析（双轴弯曲强度（BFS）和弹性模量）。表征结果表明，添加粘结剂或烧结方法均未影响HA的化学和结构特性。即便如此，HWC组的BFS和弹性模量的力学值最高，分别为109.0（98.0；117.0）MPa和105.17±14.65 GPa。经过传统烧结且未添加粘结剂的HA陶瓷比其他组具有更好的力学性能。讨论了每个变量的影响，并将其与最终微观结构和力学性能相关联。
