Saw L H, Messer H H
School of Dental Science, University of Melbourne, Parkville, Australia.
J Endod. 1995 Jun;21(6):314-20. doi: 10.1016/S0099-2399(06)81008-3.
The influence of different obturation techniques (lateral condensation, Obtura, and Thermafil) on root strains was assessed in 27 upper central incisors using strain gauges mounted on the coronal and apical one-thirds of the root surface. The vertical load applied with each obturation technique was also measured. Comparison of the strains was conducted with two-way analysis of covariance (with condensation load as covariate). The technique of obturation significantly influenced the root strains, with the Obtura generating the highest strains. The Thermafil group showed significantly less strain than the Obtura or lateral condensation groups. Thermal expansion of dentin was an unexpected finding. A large proportion of strain in the Obtura and Thermafil groups was found to be thermal strain. The mean load required to cause vertical root fracture was five to six times higher than the load used in obturation.
采用安装在牙根表面冠方和根尖三分之一处的应变片，评估了27颗上颌中切牙中不同充填技术（侧向加压充填、Obtura热塑牙胶注射充填和Thermafil热塑牙胶尖充填）对牙根应变的影响。同时还测量了每种充填技术施加的垂直载荷。采用协方差双向分析（以充填压力作为协变量）对各应变进行比较。充填技术对牙根应变有显著影响，Obtura热塑牙胶注射充填产生的应变最高。Thermafil热塑牙胶尖充填组的应变明显低于Obtura热塑牙胶注射充填组或侧向加压充填组。牙本质的热膨胀是一个意外发现。发现Obtura热塑牙胶注射充填组和Thermafil热塑牙胶尖充填组中很大一部分应变是热应变。导致牙根垂直骨折所需的平均载荷比充填时使用的载荷高五到六倍。
