Int J Comput Dent. 2024 Jun 6;27(2):161-167. doi: 10.3290/j.ijcd.b3963385.
Endodontically treated teeth are more susceptible to fractures than vital teeth because of significant coronal and radicular dentin loss during endodontic therapeutic procedures. The objective of the present in vitro study was to estimate and compare the influence of the post length and type on the fracture strength of endodontically treated maxillary central incisors.
Sixty extracted human maxillary central incisors were decoronated 2 mm above the cementoenamel junction. The teeth were selected and subjected to standard endodontic treatment, resulting in three groups with different preparation lengths: 5, 7.5, and 10 mm. Each group was randomly divided into two subgroups according to the post type: zirconia or fiber. After appropriate surface treatment, they were cemented with adhesive resin cement and restored with zirconia crowns. Thermocycling (5°C to 55°C, 60 s, 1500 cycles) was performed after cementing the zirconia crowns onto each tooth. Prepared samples were subjected to a compressive static load of 0.5 mm/min, at an angle of 130 degrees to the long axis of the roots, using a universal testing machine (Matest) at a crosshead speed of 0.5 mm/min, until fracture. The significance of the results was assessed using two-way analysis of variance (ANOVA) and the Tukey-Kramer test (α = 0.05).
The ANOVA analysis indicated significant differences (P < 0.05) between the groups. The Tukey-Kramer test revealed no significant differences among the zirconia posts with lengths of 5 mm (26.5 N ± 13.4), 7.5 mm (25.2 N ± 13.9), and 10 mm (17.1 N ± 5.2). Also, in the fiber post group, there was no significant difference when the posts with lengths of 7.5 mm (13.4 N ± 11.0) were compared with those of 5 mm (6.9 N ± 4.6) and 10 mm (31.7 N ± 13.1). The 10-mm-long post displayed superior fracture strength, and the 5-mm-long post showed significantly lower mean values (P < 0.001).
The fracture strength of zirconia posts (with lengths of 5 and 7.5 mm) was found to be significantly higher than that of fiber posts (with lengths of 5 and 7.5 mm). The 10-mm-long fiber post group demonstrated significantly higher fracture strength values, and the 5-mm-long fiber post group showed the lowest values for the force resulting in root fracture; these groups were significantly different from each other (P < 0.001). The fracture strength analysis with a universal testing machine is the only method that enables the estimation of the differences between zirconia and fiber posts with different lengths in endodontically treated teeth.
由于在根管治疗过程中会导致明显的冠根牙本质丧失，因此根管治疗后的牙齿比活髓牙更容易发生折裂。本体外研究的目的是评估和比较不同长度和类型的桩对根管治疗后的上颌中切牙的抗折强度的影响。
将 60 颗人上颌中切牙从牙颈下 2mm 处截冠。选择这些牙齿并进行标准的根管治疗，使每组的制备长度分别为 5mm、7.5mm 和 10mm，共分为 3 组。每组随机分为两组，根据桩的类型分为氧化锆或纤维：每组的桩长为 5mm、7.5mm 和 10mm。每组再根据桩的类型随机分为两组。每组的桩长为 5mm、7.5mm 和 10mm。根管治疗后，对每组牙齿的表面进行适当的处理，并用树脂粘结剂粘结，并用氧化锆冠修复。在粘结氧化锆冠后，将每个牙在 5°C 至 55°C 之间以 1500 次/循环、60s 的热循环条件下进行热循环。在万能试验机（Matest）上，以 0.5mm/min 的十字头速度对制备好的样本进行压缩静态加载，角度为根长的 130°，直到发生断裂。使用双因素方差分析（ANOVA）和 Tukey-Kramer 检验（α=0.05）评估结果的显著性。
ANOVA 分析表明组间有显著差异（P<0.05）。Tukey-Kramer 检验显示 5mm 长的氧化锆桩（26.5N±13.4）、7.5mm 长的氧化锆桩（25.2N±13.9）和 10mm 长的氧化锆桩（17.1N±5.2）之间没有显著差异。同样，纤维桩组中，7.5mm 长的纤维桩（13.4N±11.0）与 5mm 长的纤维桩（6.9N±4.6）和 10mm 长的纤维桩（31.7N±13.1）之间也没有显著差异。10mm 长的桩显示出较高的抗折强度，5mm 长的桩显示出显著较低的平均强度（P<0.001）。
发现氧化锆桩（5mm 和 7.5mm 长）的抗折强度明显高于纤维桩（5mm 和 7.5mm 长）。10mm 长的纤维桩组显示出显著较高的抗折强度值，5mm 长的纤维桩组显示出导致根折的力的最低值；这些组之间有显著差异（P<0.001）。使用万能试验机进行抗折强度分析是唯一能够评估不同长度的氧化锆和纤维桩在根管治疗后的牙齿中的差异的方法。
