Colán Guzmán Paola, Freitas Fernando Furtado Antunes de, Ferreira Paulo Martins, Freitas César Antunes de, Reis Kátia Rodrigues
Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
J Appl Oral Sci. 2008 Mar-Apr;16(2):111-5. doi: 10.1590/s1678-77572008000200006.
In long-term oral rehabilitation treatments, resistance of provisional crowns is a very important factor, especially in cases of an extensive edentulous distal space. The aim of this laboratorial study was to evaluate an acrylic resin cantilever-type prosthesis regarding the flexural strength of its in-balance portion as a function of its extension variation and reinforcement by two types of fibers (glass and polyaramid), considering that literature is not conclusive on this subject. Each specimen was composed by 3 total crowns at its mesial portion, each one attached to an implant component (abutment), while the distal portion (cantilever) had two crowns. Each specimen was constructed by injecting acrylic resin into a two-part silicone matrix placed on a metallic base. In each specimen, the crowns were fabricated with either acrylic resin (control group) or acrylic resin reinforced by glass (Fibrante, Angelus) or polyaramide (Kevlar 49, Du Pont) fibers. Compression load was applied on the cantilever, in a point located 7, 14 or 21 mm from the distal surface of the nearest crown with abutment, to simulate different extensions. The specimen was fixed on the metallic base and the force was applied until fracture in a universal test machine. Each one of the 9 sub-groups was composed by 10 specimens. Flexural strength means (in kgf) for the distances of 7, 14 and 21 mm were, respectively, 28.07, 8.27 and 6.39 for control group, 31.89, 9.18 and 5.16 for Kevlar 49 and 30.90, 9.31 and 6.86 for Fibrante. Data analysis ANOVA showed statistically significant difference (p<0.05) only regarding cantilever extension. Tukey's test detected significantly higher flexural strength for the 7 mm-distance, followed by 14 and 21 mm. Fracture was complete only on specimens of non-reinforced groups.
在长期口腔修复治疗中，临时冠的抗力是一个非常重要的因素，尤其是在存在广泛无牙远中间隙的情况下。本实验室研究的目的是评估一种丙烯酸树脂悬臂式修复体，其失衡部分的弯曲强度作为其伸展变化和两种纤维（玻璃纤维和聚芳酰胺纤维）增强作用的函数，鉴于文献在该主题上尚无定论。每个样本在其近中部分由3个全冠组成，每个全冠连接到一个种植体部件（基台），而远中部分（悬臂）有两个冠。每个样本通过将丙烯酸树脂注入放置在金属底座上的两部分硅胶模具中制成。在每个样本中，冠由丙烯酸树脂（对照组）或由玻璃纤维（Fibrante，安杰卢斯公司）或聚芳酰胺纤维（凯夫拉49，杜邦公司）增强的丙烯酸树脂制成。压缩载荷施加在悬臂上，在距离最近带有基台的冠的远中表面7、14或21毫米处的一点上，以模拟不同的伸展情况。样本固定在金属底座上，在万能试验机上施加力直至断裂。9个亚组中的每一组由10个样本组成。对照组在7、14和21毫米距离处的弯曲强度平均值（以千克力计）分别为28.07、8.27和6.39，凯夫拉49组分别为31.89、9.18和5.16，Fibrante组分别为30.90、9.31和6.86。数据分析方差分析显示仅在悬臂伸展方面存在统计学显著差异（p<0.05）。Tukey检验检测到7毫米距离处的弯曲强度显著更高，其次是14毫米和21毫米。仅在未增强组的样本上出现完全断裂。
