Beattie Sean, Taskonak Burak, Jones James, Chin Judith, Sanders Brian, Tomlin Angela, Weddell James
J Can Dent Assoc. 2011;77:b90.
Demand is increasing for esthetic restorations in pediatric dentistry. When full coverage is indicated, one option is to use esthetic stainless steel crowns (SSCs). However, this type of crown is prone to fracture. The purpose of this study was to evaluate the fracture resistance of 3 types of esthetic SSCs.
Esthetic SSCs for first primary mandibular molars were cemented to idealized epoxy dies with glass ionomer cement. The die-crown units were fractured on a universal testing machine. The force was delivered by a stainless steel ball fixture, set in a uniaxial lever to replicate a cusp contact, with a crosshead speed of 1 mm/min. The differences among the 3 types of crown, in terms of force required to fracture, were compared statistically by 1-way analysis of variance. Pairwise comparisons were performed with Fisher's protected least significant difference test, at an overall significance level of 5%.
The force required to fracture, expressed as average ± standard error, did not differ significantly among the 3 brands of esthetic SSCs: 1730 N ± 50 N, 1826 N ± 62 N and 1671 N ± 68 N, respectively (p = 0.19), well below the maximum bite force of pediatric patients determined in a previous study.
Esthetic SSCs should be able to resist occlusal forces over short clinical periods. However, long-term occlusal loading and fatigue failures should be taken into account when evaluating the success of this type of crown.
儿童牙科中对美学修复体的需求日益增加。当需要全冠修复时，一种选择是使用美学不锈钢冠（SSC）。然而，这种类型的冠容易折断。本研究的目的是评估3种美学SSC的抗折性。
将用于下颌第一乳磨牙的美学SSC用玻璃离子水门汀粘固到理想化的环氧树脂代型上。将代型 - 冠单元在万能试验机上折断。力通过不锈钢球夹具施加，该夹具设置在单轴杠杆上以模拟尖牙接触，横梁速度为1 mm/min。通过单因素方差分析对3种类型的冠在折断所需力方面的差异进行统计学比较。采用Fisher保护最小显著差异检验进行两两比较，总体显著性水平为5%。
3个品牌的美学SSC折断所需力，以平均值±标准误表示，分别为1730 N±50 N、1826 N±62 N和1671 N±68 N，差异无统计学意义（p = 0.19），远低于先前研究中确定的儿科患者的最大咬合力。
美学SSC在较短临床时间内应能够抵抗咬合力。然而，在评估此类冠的成功时，应考虑长期咬合负荷和疲劳失效。
