Department of Prosthodontics, University, Freiburg, Germany.
Dent Mater. 2013 Mar;29(3):307-16. doi: 10.1016/j.dental.2012.11.012. Epub 2012 Dec 8.
To evaluate the effect of framework design modification and veneering techniques in fatigue reliability and failure modes of veneered Yttria-Stabilized Tetragonal Zirconia Polycrystals (Y-TZP) crowns.
A CAD-based mandibular molar crown preparation served as a master die. Y-TZP crown cores (VITA-In-Ceram-YZ, Vita-Zahnfabrik, Bad Säckingen, Germany) in conventional (0.5mm uniform thickness) or anatomically designed fashion (cusp support) were porcelain veneered with either hand-layer (VM9) or pressed (PM9) techniques. Crowns (n=84) were cemented on 30 days aged dentin-like composite dies with resin cement. Crowns were subjected to single load to fracture (n=3 each group) and mouth-motion step-stress fatigue (n=18) by sliding a WC indenter (r=3.18 mm) 0.7 mm buccally on the inner incline surface of the mesio-lingual cusp. Stress-level curves (use level probability lognormal) and reliability (with 2-sided 90% confidence bounds, CB) for completion of a mission of 50.000 cycles at 200 N load were calculated. Fractographic analyses were performed under light-polarized and scanning electron microscopes.
Higher reliability for hand-layer veneered conventional core (0.99, CB 0.98-1) was found compared to its counterpart press-veneered (0.50 CB 0.33-65). Framework design modification significantly increased reliability for both veneering techniques (PM9 [0.98 CB 0.87-0.99], VM9 [1.00 CB 0.99-1]) and resulted in reduced veneer porcelain fracture sizes. Main fracture mode observed was veneer porcelain chipping, regardless of framework design and veneering technique.
Hand-layer porcelain veneered on conventional core designs presented higher reliability than press-veneered with similar core designs. Anatomic core design modification significantly increased the reliability and resulted in reduced chip size of either veneering techniques.
评估框架设计修改和贴面技术对贴面氧化钇稳定四方氧化锆多晶（Y-TZP）牙冠的疲劳可靠性和失效模式的影响。
以基于 CAD 的下颌磨牙冠预备作为主模具。采用传统（0.5mm 均匀厚度）或解剖设计（尖支持）的 Y-TZP 冠核（VITA-In-Ceram-YZ，Vita-Zahnfabrik，Bad Säckingen，德国），分别采用手工层（VM9）或压制（PM9）技术进行瓷贴面。将牙冠（n=84）用树脂水门汀粘接到 30 天龄的类似牙本质复合模具上。通过在近中-舌侧尖的内倾斜表面上用 WC 压头（r=3.18mm）向颊侧滑动 0.7mm，对牙冠进行单次断裂（每组 n=3）和口腔运动阶跃应力疲劳（n=18）试验。计算完成 50000 次循环任务的概率对数正态分布的应力水平曲线（使用水平概率对数正态分布）和可靠性（双侧 90%置信区间，CB），在 200N 负载下。在光偏振和扫描电子显微镜下进行断口分析。
与相应的压制贴面相比，手工层贴面的传统核（0.99，CB 0.98-1）具有更高的可靠性。框架设计修改显著提高了两种贴面技术的可靠性（PM9[0.98 CB 0.87-0.99]，VM9[1.00 CB 0.99-1]），并减小了贴面瓷的断裂尺寸。观察到的主要断裂模式是贴面瓷崩裂，无论框架设计和贴面技术如何。
与具有相似核设计的压制贴面相比，手工层贴面的传统核设计具有更高的可靠性。解剖核设计修改显著提高了可靠性，并减小了两种贴面技术的崩裂尺寸。
