Int J Prosthodont. 2020 Mar/Apr;33(2):202-211. doi: 10.11607/ijp.6531.
To evaluate the amount of residual cement (ECL) around the margins of zirconia crown copings after careful luting and cleaning procedures and to investigate these factors in relation to two tested luting materials.
An experimental model of a maxillary arch was selected for this in vitro study. The maxillary first molar was prepared to receive an all-ceramic, single, full-crown restoration with a finish line located 1 mm below the artificial gingiva. After scanning of the prepared tooth, 20 paired zirconia coping-abutment assemblies were CAD/CAM fabricated. A slot in the model allowed for insertion and removal of the assemblies for each new test. Specimens were divided into two groups according to the cementation procedure: half (n = 10) were luted using a resin-modified glass-ionomer (RMGI) (Ketac-Cem Plus) (GI group), and the other half with a dual-curing self-adhesive resin agent (RelyX Unicem 2) (UN group). The substructures were loaded with cement, and a customized preseating device was adopted for preliminary reduction of excess. The zirconia copings were finally seated on their respective abutments located on the simulation model. A blinded investigator attempted to remove all excess cement with clinically available instruments. The amount of excess cement left in situ after cleaning procedures was weighed in grams. Dislodging forces of luted coping-abutment assemblies were obtained by using pull-off tests in a universal testing machine (crosshead speed of 0.5 mm/minute) after 24 hours of water storage. Means and standard deviations were calculated for ECL and for retention force values, and Mann-Whitney and ANOVA tests were carried out to detect significant differences (α = .05) among groups.
Cement remnants were found in all specimens despite the cleaning procedures, with a typical distribution in interproximal areas. Mean ECL values for the GI and UN groups were 0.0079 ± 0.0060 and 0.0107 ± 0.0081, respectively. No statistically significant differences were found between tested cements (P = .3284). Removal stress values (MPa) were significantly higher (P = .0313) for the UN group (12.4 ± 6.5) than for the GI group (6.57 ± 4.69).
Similar amounts of undetected cement remnants were discovered around the esthetic margins of zirconia crown copings regardless of cement type. The luting procedure using the self-adhesive resin cement provided significantly higher early retention values than the RMGI material.
评估经过仔细粘固和清洁程序后氧化锆冠修复体边缘周围残留的粘固剂（ECL）的量，并研究这两个测试粘固材料的相关因素。
本体外研究选择了上颌弓的实验模型。上颌第一磨牙被制备成接受全陶瓷、单冠、全冠修复，修复体的边缘线位于人造牙龈下方 1 毫米处。在预备牙体扫描后，使用 CAD/CAM 制作了 20 个配对的氧化锆冠基台组件。模型上的一个插槽允许每个新测试插入和取出组件。根据粘固程序将样本分为两组：一半（n=10）使用树脂改良型玻璃离子（RMGI）（Ketac-Cem Plus）（GI 组）粘固，另一半使用双固化自粘接树脂剂（RelyX Unicem 2）（UN 组）。将子结构用粘固剂加载，并采用定制的预压装置初步减少多余的粘固剂。最后将氧化锆冠基台组件安装在位于模拟模型上的相应基台上。由一位盲法研究者试图用临床可用的器械去除所有多余的粘固剂。经过清洁程序后，用临床可用的器械去除所有多余的粘固剂，将留在原位的多余粘固剂称重，以克为单位。将粘固的冠基台组件在经过 24 小时水储存后，使用万能试验机（十字头速度为 0.5 毫米/分钟）进行拉脱试验，以获得粘固的冠基台组件的保持力值。计算 ECL 和保留力值的平均值和标准差，并进行 Mann-Whitney 和 ANOVA 检验，以检测组间的显著差异（α=0.05）。
尽管进行了清洁程序，但所有样本中都发现了粘固剂残留物，典型的分布在邻面区域。GI 组和 UN 组的平均 ECL 值分别为 0.0079±0.0060 和 0.0107±0.0081。两种测试粘固剂之间没有统计学上的显著差异（P=0.3284）。UN 组（12.4±6.5）的去除应力值（MPa）明显高于 GI 组（6.57±4.69）（P=0.0313）。
无论粘固剂类型如何，在氧化锆冠修复体的美学边缘周围都发现了相似数量的未检测到的粘固剂残留物。使用自粘接树脂粘固剂的粘固程序提供的早期保持力值明显高于 RMGI 材料。
