Crown and Bridge Department, Suez Canal University, Ismailia, Egypt.
J Prosthodont. 2012 Jan;21(1):28-32. doi: 10.1111/j.1532-849X.2011.00773.x. Epub 2011 Oct 18.
The aim of this study was to determine effect of compressive cyclic loading on fatigue resistance and microleakage of monolithic CAD/CAM molar ceramic and composite crowns.
Thirty-two extracted molars were prepared to receive CEREC crowns according to manufacturer's guidelines using a special paralleling device (Parallel-A-Prep). Sixteen feldspathic ceramic crowns (VITABLOCS Mark II) (VMII) and 16 resin-composite crowns (Paradigm-MZ100 blocks) (PMZ) were milled using a CEREC-3D machine. Eight crowns of each group were cemented to their respective teeth using self-etching resin cement (Panavia-F-2.0) (PAN), and eight were cemented using self-adhesive resin cement (RelyX-Unicem-Clicker) (RXU). Following storage for 1 week in water, specimens were subjected to uniaxial compressive cyclic loading in an Instron testing machine at 12 Hz for 1,000,000 cycles. Load was applied at the central fossa, and the cycle range was 60-600 N. Specimens were then subjected to microleakage testing. Data were statistically analyzed using factorial ANOVA and Post Hoc (Tukey HSD) tests.
All composite crowns survived compressive cyclic loading without fracture, while three ceramic crowns from the subgroup cemented with RXU developed surface cracks at the center of occlusal surfaces, extending laterally. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other three subgroups (p < 0.05).
After 1,000,000 cycles of compressive cyclic loading, PMZ composite molar crowns were more fatigue-resistant than VMII ceramic crowns. Cement type had a significant effect on fatigue resistance of the ceramic crowns but not the composite ones. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other subgroups (p < 0.05).
本研究旨在确定压缩循环载荷对整体式 CAD/CAM 磨牙陶瓷和复合冠的疲劳抗力和微渗漏的影响。
将 32 颗离体磨牙按制造商的指南使用特殊的平行装置（Parallel-A-Prep）预备以接收 CEREC 冠。使用 CEREC-3D 机器分别加工 16 个长石陶瓷冠（VITABLOCS Mark II）（VMII）和 16 个树脂复合冠（Paradigm-MZ100 块）（PMZ）。每组的 8 个冠用自酸蚀树脂粘结剂（Panavia-F-2.0）（PAN）粘结到相应的牙齿上，8 个用自粘结树脂粘结剂（RelyX-Unicem-Clicker）（RXU）粘结。水储存 1 周后，在 Instron 试验机上以 12 Hz 的频率进行单轴压缩循环载荷，施加 100 万次循环。载荷施加在中央窝，循环范围为 60-600 N。然后对试件进行微渗漏测试。使用因子方差分析和事后检验（Tukey HSD）检验对数据进行统计学分析。
所有复合冠在压缩循环载荷下均未发生断裂，而 RXU 粘结的 3 个陶瓷冠在牙合面中心出现表面裂纹，向侧面扩展。用 PAN 粘结的陶瓷冠的微渗漏评分明显低于其他三个亚组（p < 0.05）。
经过 100 万次压缩循环载荷后，PMZ 复合磨牙冠比 VMII 陶瓷冠更具耐疲劳性。粘结剂类型对陶瓷冠的耐疲劳性有显著影响，但对复合冠没有影响。用 PAN 粘结的陶瓷冠的微渗漏评分明显低于其他亚组（p < 0.05）。
