University of Birmingham, School of Dentistry, St Chads Queensway, Birmingham B4 6NN, UK.
J Dent. 2010 May;38(5):437-42. doi: 10.1016/j.jdent.2010.02.003. Epub 2010 Feb 25.
It is suggested that fibre-reinforced composite (FRC) posts have lower elastic moduli than metal posts and this will reduce the incidence of root fracture. However, the mechanical properties may be altered in the oral environment. The aims of this study were to determine the effect on the flexural properties of FRC and metal post materials produced by: (1) a thermocycling regime which was clinically relevant and representative of that which would occur during 1 year in the mouth and (2) storage for 1 year at body temperature.
Nine FRC and two metal post material samples were sealed in polythene sleeves and thermocycled between 10 degrees C and 50 degrees C for 10,000 cycles. Additional samples were stored dry at 37 degrees C for 1 year. The flexural strength and moduli were determined by three-point bending and compared with untreated control samples.
Thermocycling and storage at 37 degrees C for 1 year decreased the mean flexural modulus of all materials. This was statistically significant for 8 of 11 materials after thermocycling, and 4 of 11 materials after storage at 37 degrees C (p<0.05). Thermocycling and storage at 37 degrees C produced a non-significant increase in yield strength for both metal post materials. Thermocycling significantly increased the flexural strength of Postec while it decreased for the other FRC materials. Storage at 37 degrees C increased the flexural strength of three FRC materials (significantly for Postec) while it was decreased among the other materials.
Although some of the changes noticed in flexural properties were statistically significant, it is doubtful that they are of sufficient magnitude to affect clinical performance.
有研究表明，纤维增强复合材料（FRC）桩的弹性模量低于金属桩，这将降低根折的发生率。然而，其机械性能可能会在口腔环境中发生改变。本研究的目的是确定以下两种方法对 FRC 和金属桩材料的弯曲性能的影响：（1）临床相关且代表在口腔中 1 年内发生的热循环处理，（2）在体温下储存 1 年。
将 9 个 FRC 和 2 个金属桩材料样本密封在聚乙烯套管中，在 10℃至 50℃之间进行 10000 次热循环。另外的样本在 37℃下干燥储存 1 年。通过三点弯曲法测定弯曲强度和模量，并与未经处理的对照样本进行比较。
热循环和 37℃储存 1 年降低了所有材料的平均弯曲模量。经过热循环后，11 种材料中有 8 种，37℃储存 1 年后有 4 种材料的变化具有统计学意义（p<0.05）。热循环和 37℃储存对两种金属桩材料的屈服强度产生了非显著的增加。热循环显著增加了 Postec 的弯曲强度，而其他 FRC 材料的弯曲强度则降低。37℃储存增加了三种 FRC 材料的弯曲强度（对 Postec 显著），而其他材料的弯曲强度则降低。
尽管弯曲性能的一些变化具有统计学意义，但它们的幅度是否足以影响临床性能还值得怀疑。
