School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Int J Oral Sci. 2013 Sep;5(3):167-71. doi: 10.1038/ijos.2013.52. Epub 2013 Aug 2.
This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading. Fifty extracted single-rooted mandibular premolars were randomized into five groups. Each group was prepared according to numbers of residual walls ranged from 0 to 4. Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts. In no-post groups, gutta percha point 2 mm below cemento-enamel junction was removed. Composite resin was adapted to the well and used to shape the core directly. Each tooth was restored with a complete metal crown. Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles. Then a quasi-statically load was applied in a universal testing machine 30° to the long axis with a crosshead speed of 1 mm⋅min(-1) until fracture. Data were analyzed with one-way analysis of variance and pairwise comparison (P<0.05). No specimens failed during dynamic loading. The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant (P<0.05). Placement of fiber posts had a significant effect when fewer than two walls remained (P<0.05), but it had no significant influence in groups with two, three or four walls (P>0.05). Fiber post did not change failure mode, and the fracture pattern was mainly favorable. More dentin walls need to be retained in clinic. When no less than two walls remained, a fiber post is not always necessary.
本研究旨在评估在动态载荷下，不同牙体缺损的根管治疗后前磨牙中石英纤维桩的放置对其抗折能力的影响。将 50 颗下颌单根前磨牙随机分为五组。每组按剩余牙壁数（0 至 4）进行预备。然后，每组再分为两组，一组用石英纤维桩修复，另一组不用。无桩组，将牙本质釉牙骨质界下 2mm 的牙胶尖去除。复合树脂适应窝洞并直接用于形成核。每颗牙均用全金属冠修复。在咀嚼模拟器中进行动态加载，名义载荷为 50N，频率为 2Hz，加载 30 万次。然后在万能试验机上以 30°的角度对长轴施加准静态载荷，十字头速度为 1mm/min，直至发生断裂。采用单因素方差分析和两两比较（P<0.05）进行数据分析。在动态加载过程中，没有试件发生失效。随着牙冠壁数量的增加，抗折能力增强，差异有统计学意义（P<0.05）。当剩余牙壁少于 2 个时，纤维桩的放置有显著影响（P<0.05），但在剩余牙壁为 2、3 或 4 个的组中无显著影响（P>0.05）。纤维桩并未改变失效模式，断裂模式主要为有利。临床上需要保留更多的牙本质壁。当剩余牙壁不少于 2 个时，不一定需要使用纤维桩。
