Zandparsa Roya, Albosefi Abdalah
Department of Prosthodontics and Operative Dentistry, Prosthodontics Division and Advanced Education in Esthetic Dentistry, Tufts University School of Dental Medicine, Boston, MA.
J Prosthodont. 2016 Feb;25(2):151-5. doi: 10.1111/jopr.12292. Epub 2015 Apr 9.
The purpose of part II of this in vitro study was to compare the fracture load of two-piece zirconia custom abutments with different thicknesses and angulations.
Forty zirconia custom abutments were divided into four groups as follows: group A1: 0.7 mm thickness and 0° angulations; group A2: 0.7 mm thickness and 15° angulations; group B1: 1 mm thickness and 0° angulations; group B2: 1 mm thickness and 15° angulations. As in part I, in all groups, implant replicas were mounted in self-cure acrylic jigs to support the abutments. The zirconia custom abutments were engaged in the implant replicas using a manual torque wrench. All jigs were secured and mounted in a metallic vice and subjected to shear stress till failure using a universal testing machine with a 0.5 mm/min crosshead speed with the force transferred to the lingual surface of the zirconia custom abutments 2 mm below the incisal edge. The test specimens used in this study did not include a crown. The universal testing machine was controlled via a computer software system, which also completed the stress-strain diagram and recorded the breaking fracture load. The fracture loads were recorded for comparison among the groups and subjected to statistical analysis (two-way ANOVA and Kolmogorov-Smirnov).
The mean fracture load of zirconia custom abutments across the groups (A1 to B2) ranged from 432 ± 97 N to 746 ± 275 N. The angulated zirconia custom abutment exhibited the highest fracture load, which was statistically significant (p = 0.045). The thickness of the zirconia custom abutment also had a positive influence on the strength of the specimens (p = 0.005).
In this study, the 15° angulated zirconia custom abutments showed the highest fracture load of those investigated. The 1 mm thick zirconia custom abutments also exhibited significantly higher fracture load compared to 0.7 mm abutments.
The results of this in vitro study will help dental practitioners with their decision-making process in selecting the type of custom abutment to be used clinically.
本体外研究第二部分的目的是比较不同厚度和角度的两件式氧化锆定制基台的断裂载荷。
40个氧化锆定制基台分为四组如下：A1组：厚度0.7mm，角度0°；A2组：厚度0.7mm，角度15°；B1组：厚度1mm，角度0°；B2组：厚度1mm，角度15°。与第一部分一样，在所有组中，将种植体复制体安装在自凝丙烯酸夹具中以支撑基台。使用手动扭矩扳手将氧化锆定制基台与种植体复制体连接。所有夹具均固定并安装在金属虎钳中，并使用万能试验机施加剪切应力直至破坏，十字头速度为0.5mm/min，力传递至氧化锆定制基台切缘下方2mm处的舌侧表面。本研究中使用的测试样本不包括牙冠。万能试验机通过计算机软件系统控制，该系统还完成应力-应变图并记录断裂载荷。记录断裂载荷以进行组间比较并进行统计分析（双向方差分析和柯尔莫哥洛夫-斯米尔诺夫检验）。
各组（A1至B2）氧化锆定制基台的平均断裂载荷范围为432±97N至746±275N。有角度的氧化锆定制基台表现出最高的断裂载荷，具有统计学意义（p = 0.045）。氧化锆定制基台的厚度对样本强度也有积极影响（p = 0.005）。
在本研究中，15°有角度的氧化锆定制基台在所研究的基台中显示出最高的断裂载荷。与0.7mm厚的基台相比，1mm厚的氧化锆定制基台也表现出明显更高的断裂载荷。
本体外研究的结果将有助于牙科医生在临床选择使用的定制基台类型时进行决策。
