Ayad M F, Rosenstiel S F, Woelfel J B
Section of Restorative Dentistry, Prosthodontics, and Endodontics, University of Tanta College of Dentistry, Egypt.
Int J Prosthodont. 1998 Mar-Apr;11(2):177-82.
The object of this study was to evaluate retention of complete cast crowns cemented with different luting cements and to determine whether recemented castings are as retentive as when initially placed.
Thirty standardized Rexillium III complete crowns were made on extracted human molar teeth prepared with a modified milling machine using conventional laboratory techniques. The crowns were randomly assigned into three groups according to the luting cement used: zinc phosphate (Fleck's, Mizzy), adhesive resin (Panavia-EX, J. Morita), and glassionomer (Ketac-Cem, Aplicap, ESPE-Premier Sales). Retention was evaluated by measuring the tensile force required to dislodge the crowns from tooth preparations with an Instron testing machine after thermocycling (1,500 cycles between 5 degrees C and 55 degrees C with 1-minute dwell times). Subsequently, the tooth preparations were scraped clean and polished with flour of pumice (prophylaxis paste), and the fitting surfaces of the artificial crowns were ultrasonically cleaned and air abraded using 50-micron aluminum oxide powder prior to recementation. Results were subjected to two-way analysis of variance and Tukey's Studentized Range test.
The analysis showed the highest mean retention for cast crowns cemented with Panavia-EX cement (314 N), but the difference was not statistically significantly different from crowns cemented with glass-ionomer cement (307 N). However, crowns cemented with zinc phosphate cement (233 N) had significantly lower values (P < 0.05). Restorations recemented with zinc phosphate had significantly lower retention (190 N) than their initial cementation (P < 0.05).
Panavia-EX and glass-ionomer cements yielded the highest initial and recementation retentive strength, with values almost 32% higher than those obtained with zinc phosphate cement during the initial cementation and 59% higher than zinc phosphate for recementation. Zinc phosphate cement exhibited significantly lower retention for the initial and second trial of cementation.
本研究的目的是评估用不同粘结水门汀粘结的全冠铸件的固位情况，并确定重新粘结的铸件是否与初次就位时具有相同的固位力。
使用传统实验室技术，在经改良的铣床制备的离体人磨牙上制作30个标准化的Rexillium III全冠。根据所使用的粘结水门汀，将全冠随机分为三组：磷酸锌水门汀（Fleck's、Mizzy）、粘结性树脂水门汀（Panavia-EX、日本森田公司）和玻璃离子水门汀（Ketac-Cem、Aplicap、ESPE-Premier销售公司）。在热循环（5℃至55℃之间循环1500次，每次停留1分钟）后，使用Instron试验机测量将全冠从牙体预备上脱位所需的拉力，以此评估固位力。随后，刮净牙体预备并使用浮石粉（预防性糊剂）进行抛光，在重新粘结之前，对人造全冠的贴合面进行超声清洁并用50微米的氧化铝粉末进行空气喷砂处理。对结果进行双向方差分析和Tukey's Studentized Range检验。
分析显示，用Panavia-EX水门汀粘结的全冠铸件平均固位力最高（314 N），但与用玻璃离子水门汀粘结的全冠（平均固位力307 N）相比，差异无统计学意义。然而，用磷酸锌水门汀粘结的全冠（233 N）的数值明显较低（P < 0.05）。用磷酸锌水门汀重新粘结的修复体的固位力（190 N）明显低于初次粘结时（P < 0.05）。
Panavia-EX和玻璃离子水门汀产生了最高的初次粘结和重新粘结固位强度，其数值比初次粘结时用磷酸锌水门汀获得的数值高近32%，比重新粘结时用磷酸锌水门汀获得的数值高59%。磷酸锌水门汀在初次粘结和再次粘结试验中的固位力明显较低。
