Ramazani Nahid, Ranjbar Mina
Assistant Professor, Children and Adolescent Health Research Center, Department of Pediatric Dentistry, Faculty of Dentistry, Zahedan University of Medical Sciences, Zahedan, Iran.
Dentist, Zahedan University of Medical Sciences, Zahedan, Iran.
J Dent (Tehran). 2015 Jan;12(1):18-24.
Incomplete adaptation of stainless steel crown margins leads to microleakage. The aim of this study was to evaluate the effect of tooth preparation on microleakage of stainless steel crowns (SSCs) placed on mesiodistally reduced primary mandibular first molars.
In this In vitro study, 60 primary mandibular first molars with reduced mesiodistal dimension were selected. Pulp cavities were filled with amalgam and occlusal surfaces were reduced. The samples were randomly divided into two groups (groups P and BLP). Standard preparation was done in group P with only proximal reduction. In group BLP, after reducing the proximal undercuts, buccal and lingual surfaces were slightly reduced. Occlusal one-third of the buccal surfaces was beveled in both groups. Then, the SSCs of the primary maxillary and mandibular first molars were fitted and cemented in P and BLP groups, respectively. After immersing the samples into deionized water, thermo-cycling, and immersion in 2% basic fuchsin, the samples were sectioned buccolingually. The mesial halves were evaluated microscopically for microleakage in both buccal and lingual margins. Data were analyzed using Mann-Whitney U test in SPSS 19 at the significant level of 0.05.
There was a significant difference in microleakage of the buccal margin (P=0.003); whereas, the difference observed in the lingual margin was not significant (P=0.54).
We suggest reduction of buccal and lingual surfaces of mesiodistally reduced primary mandibular first molars and placing lower (mandibular) crowns.
不锈钢全冠边缘适应性欠佳会导致微渗漏。本研究旨在评估牙体预备对置于近远中径减小的下颌第一乳磨牙上的不锈钢全冠(SSC)微渗漏的影响。
在本体外研究中,选取60颗近远中径减小的下颌第一乳磨牙。髓腔用汞合金充填,咬合面降低。样本随机分为两组(P组和BLP组)。P组仅进行邻面预备,采用标准预备方法。在BLP组中,在消除邻面倒凹后,颊舌面稍作降低。两组颊面的咬合三分之一均进行了斜面预备。然后,分别在P组和BLP组中试戴并粘结上颌和下颌第一乳磨牙的SSC。将样本浸入去离子水中,进行热循环,再浸入2%碱性品红中后,沿颊舌方向切片。在显微镜下评估近中半片在颊舌边缘的微渗漏情况。使用SPSS 19中的Mann-Whitney U检验在显著性水平为0.05时对数据进行分析。
颊边缘的微渗漏存在显著差异(P = 0.003);而舌边缘观察到的差异不显著(P = 0.54)。
我们建议对近远中径减小的下颌第一乳磨牙的颊舌面进行降低,并放置下颌全冠。