Associate Professor, University of Pennsylvania School of Dental Medicine, Department of Preventive and Restorative Sciences, Philadelphia, Pa.
Predoctoral student, University of Pennsylvania School of Dental Medicine, Department of Preventive and Restorative Sciences, Philadelphia, Pa.
J Prosthet Dent. 2018 Jun;119(6):987-993. doi: 10.1016/j.prosdent.2017.08.007. Epub 2017 Oct 14.
A recommended minimum thickness for monolithic zirconia restorations has not been reported. Assessing a proper thickness that has the necessary load-bearing capacity but also conserves dental hard tissues is essential.
The purpose of this in vitro study was to evaluate the effect of thickness and surface modifications on monolithic zirconia after simulated masticatory stresses.
Monolithic zirconia disks (10 mm in diameter) were fabricated with 1.3 mm and 0.8 mm thicknesses. For each thickness, 21 disks were fabricated. The specimens of each group were further divided into 3 subgroups (n=7) according to the surface treatments applied: untreated (control), airborne-particle abrasion with 50-μm AlO particles at a pressure of 400 kPa at 10 mm, and grinding with a diamond rotary instrument followed by polishing. The biaxial flexure strength was determined by using a piston-on-3-balls technique in a universal testing machine. Flexural loading was applied with a 1.4-mm diameter steel cylinder, centered on the disk, at a crosshead speed of 0.5 mm/min until fracture occurred. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed. The data were statistically analyzed with 2-way ANOVA, Tamhane T2, 1-way ANOVA, and Student t tests (α=.05).
The 1.3-mm specimens had significantly higher flexural strength than the 0.8-mm specimens (P<.05). Airborne-particle abrasion significantly increased the flexural strength (P<.05). Grinding and polishing did not affect the flexural strength of the specimens (P>.05).
The mean flexural strength of 0.8-mm and 1.3-mm thick monolithic zirconia was greater than reported masticatory forces. Airborne-particle abrasion increased the flexural strength of monolithic zirconia. Grinding did not affect flexural strength if subsequently polished.
尚未报道单片氧化锆修复体的建议最小厚度。评估具有必要承载能力但又能保护牙体硬组织的适当厚度至关重要。
本体外研究的目的是评估厚度和表面改性对模拟咀嚼应力后单片氧化锆的影响。
用 1.3 毫米和 0.8 毫米的厚度制作单片氧化锆圆盘（直径 10 毫米）。对于每种厚度，制作 21 个圆盘。根据应用的表面处理，将每组的试件进一步分为 3 个亚组（n=7）：未处理（对照）、在 400 kPa 压力下用 50-μm AlO 颗粒进行的空气颗粒喷砂处理、以及用金刚石旋转仪器研磨后抛光。通过在万能试验机上使用活塞-3 球技术确定双轴弯曲强度。弯曲载荷通过位于圆盘中心的 1.4 毫米直径钢柱施加，以 0.5 毫米/分钟的十字头速度施加，直到发生断裂。进行 X 射线衍射（XRD）和扫描电子显微镜（SEM）分析。使用 2 路方差分析、Tamhane T2、1 路方差分析和学生 t 检验（α=.05）对数据进行统计分析。
1.3 毫米的试件的弯曲强度明显高于 0.8 毫米的试件（P<.05）。空气颗粒喷砂显著提高了弯曲强度（P<.05）。研磨和抛光对试件的弯曲强度没有影响（P>.05）。
0.8 毫米和 1.3 毫米厚的单片氧化锆的平均弯曲强度大于报道的咀嚼力。空气颗粒喷砂提高了单片氧化锆的弯曲强度。如果随后进行抛光，研磨不会影响弯曲强度。
