Leung S F, Gulabivala K
Department of Conservative Dentistry, Institute of Dental Surgery, London, UK.
Int Endod J. 1994 Jan;27(1):39-44. doi: 10.1111/j.1365-2591.1994.tb00227.x.
The effect of temperature of plasticization on the sealing ability of Thermafil obturators was evaluated. Forty-eight canals in roots of extracted human mandibular molar teeth were divided into four groups of 12. The root canals had curvatures of less than 25 degrees, as determined using the Schneider technique. Four canals were used as positive and negative controls. All canals were prepared using a step-back technique to size 30 at the working length. Roth's sealer was used in all canals. In one group the Thermafil obturators were thermoplasticized in an open flame, as recommended by the manufacturer. In the remaining three groups the obturators were thermoplasticized by immersion in water-baths maintained at constant temperatures of 60, 75 and 90 degrees C respectively. After immersion in Indian ink, the teeth were cleared and the depth of penetration of dye through the apical foramen was measured. In all specimens there was extrusion of sealer and sometimes gutta-percha beyond the apical stop. Sometimes, there was leakage up to the apical stop but not beyond. In view of this the measurements were divided into leakage from the apical foramen to the apical stop and from the apical stop coronally. It was found that in the zone between the apical foramen and the apical stop the Thermafil obturators plasticized at 60 degrees C produced a significantly better seal than those obturators plasticized in an open flame (P < 0.05). In the zone coronal to the apical stop there were no significant differences in leakage between the groups.
评估了塑化温度对Thermafil充填器封闭能力的影响。将48颗拔除的人类下颌磨牙牙根中的根管分为四组，每组12个。使用施奈德技术确定根管弯曲度小于25度。4个根管用作阳性和阴性对照。所有根管均采用逐步后退技术预备至工作长度时的30号。所有根管均使用Roth封闭剂。一组中，按照制造商的建议，将Thermafil充填器在明火中进行热塑化。在其余三组中，分别将充填器浸入保持在60、75和90摄氏度恒定温度的水浴中进行热塑化。将牙齿浸入印度墨水中后，进行清理并测量染料通过根尖孔的渗透深度。在所有标本中，均有封闭剂挤出，有时牙胶超出根尖止点。有时，存在渗漏至根尖止点但未超出的情况。鉴于此，测量分为从根尖孔到根尖止点以及从根尖止点向冠方的渗漏。结果发现，在根尖孔与根尖止点之间的区域，60摄氏度热塑化的Thermafil充填器产生的封闭效果明显优于在明火中热塑化的充填器（P<0.05）。在根尖止点冠方的区域，各组之间的渗漏无显著差异。
