Hafezeqoran Ali, Koodaryan Roodabeh, Hemmati Yasser, Akbarzadeh Ayshin
Department of Prosthodontics, Dental faculty, Tabriz University of Medical Sciences, Tabriz, Iran.
J Dent Res Dent Clin Dent Prospects. 2020 Fall;14(4):218-222. doi: 10.34172/joddd.2020.039. Epub 2020 Nov 9.
Designing a high strength all-ceramic fixed partial denture with favorable esthetics can be challenging for clinicians; this study aimed to evaluate the effect of connector size and design on the fracture resistance of monolithic zirconia fixed dental prostheses. Two groups of twenty 3-unit monolithic zirconia (Sirona inCoris TZI, Sirona Dental Systems GmbH) bridges, extending from the mandibular first premolar to the first molar with different connector sizes (9 mm and 12 mm), were divided into two subgroups with different connector designs (round and sharp). The specimens were subjected to the three-point bending test to obtain the fracture-bearing load. The results were reported using descriptive statistics (mean ± standard deviation). Mann-Whitney U test was used to compare the fracture load in two types of designs for each connector size and two connector size types for each connector design. The significance level was considered at <0.05. The minimum failure load was related to the group with a 9-mm connector size and a sharp embrasure design (1054.4±133.89 N), and the highest mean value belonged to the group with 12-mm connector size and rounded embrasure design (1599.8±167.09 N). Mann-Whitney U test indicated a significant difference between the mean failure load of the rounded and sharp embrasure designs in the 9-mm connector size ( =0.007). However, the difference was insignificant in the 12-mm connector size ( =0.075). Sharp embrasure design is not recommended for high-stress areas with restricted occlusogingival height. A 9-mm2 connector size for 3-unit monolithic zirconia fixed dental prosthesis (FDP), which is recommended by the manufacturer, should be used more cautiously.
对于临床医生而言，设计一款兼具高强度与良好美学效果的全瓷固定局部义齿颇具挑战性；本研究旨在评估连接体尺寸和设计对整体式氧化锆固定义齿抗折性的影响。两组各20个3单位整体式氧化锆（Sirona inCoris TZI，Sirona Dental Systems GmbH）桥体，从下颌第一前磨牙延伸至第一磨牙，连接体尺寸不同（9毫米和12毫米），再分为连接体设计不同的两个亚组（圆形和尖形）。对样本进行三点弯曲试验以获取抗折载荷。结果采用描述性统计（均值±标准差）报告。使用曼-惠特尼U检验比较每种连接体尺寸的两种设计类型以及每种连接体设计的两种连接体尺寸类型的抗折载荷。显著性水平设定为<0.05。最小破坏载荷与连接体尺寸为9毫米且为尖形龈外展隙设计的组相关（1054.4±133.89牛），最高均值属于连接体尺寸为12毫米且为圆形龈外展隙设计的组（1599.8±167.09牛）。曼-惠特尼U检验表明，9毫米连接体尺寸的圆形和尖形龈外展隙设计的平均破坏载荷之间存在显著差异（=0.007）。然而，12毫米连接体尺寸时差异不显著（=0.075）。对于咬合龈高度受限的高应力区域，不建议采用尖形龈外展隙设计。制造商推荐的用于3单位整体式氧化锆固定义齿（FDP）的9平方毫米连接体尺寸应更谨慎使用。
