Lottanti Silvio, Tauböck Tobias T, Zehnder Matthias
Department of Preventive Dentistry, Periodontology and Cariology, University of Zurich, Center of Dental Medicine, Zurich, Switzerland.
Department of Preventive Dentistry, Periodontology and Cariology, University of Zurich, Center of Dental Medicine, Zurich, Switzerland.
J Endod. 2014 May;40(5):721-4. doi: 10.1016/j.joen.2013.09.043. Epub 2013 Nov 7.
The temperature and related shrinking kinetics of gutta-percha injected from heat guns are not known; therefore, we investigated them in this study.
The temperatures of 3 different backfill gutta-percha brands extruded from 3 commercially available heat guns set to 200°C were studied. To validate the results, temperature development of 1 gutta-percha brand injected from a heat gun during a simulated backfilling procedure was assessed in single-rooted human teeth containing thermocouples in a water bath of 37°C. These values were compared with the counterparts obtained in a tabletop testing device for shrinkage at an ambient temperature of 37°C. Using this device, linear shrinkage upon cooling was assessed for all 3 gutta-percha brands under investigation. Results were compared by parametric statistics (alpha = .05).
The temperatures of extruded gutta-percha differed significantly (P < .05) between heat guns and gutta-percha brands. Mean temperatures ranging between 57.6° ± 4.5°C and 103.9° ± 7.8°C could be observed with different combinations. The temperature of extruded gutta-percha in tabletop experiments equaled that observed in the root canals. However, the cooling of gutta-percha was (P < .05) faster in the tabletop measuring device compared with the root canal environment. Within the controlled temperature drop from 75°C to 37°C, the total shrinkage differed significantly (P < .05) between the 3 gutta-percha brands under investigation and ranged between 0.96% ± 0.20% and 2.31% ± 0.26% after 10 minutes (P < .05). Shrinking kinetics showed different patterns between the gutta-percha brands.
Gutta-percha designed for thermoplastic application shrinks quickly and extensively upon cooling.
通过热喷枪注入的牙胶的温度及相关收缩动力学尚不明确；因此，我们在本研究中对其进行了调查。
研究了从3种市售热喷枪在200°C下挤出的3种不同的牙胶回填品牌的温度。为验证结果，在37°C水浴中，对含热电偶的单根人牙在模拟回填过程中通过热喷枪注入的1种牙胶品牌的温度变化进行了评估。将这些值与在37°C环境温度下用于收缩率测试的台式测试装置中获得的对应值进行比较。使用该装置，对所有3种被研究的牙胶品牌冷却时的线性收缩率进行了评估。结果通过参数统计进行比较（α = 0.05）。
热喷枪和牙胶品牌之间挤出牙胶的温度存在显著差异（P < 0.05）。不同组合下可观察到平均温度在57.6°±4.5°C至103.9°±7.8°C之间。台式实验中挤出牙胶的温度与根管内观察到的温度相等。然而，与根管环境相比，牙胶在台式测量装置中的冷却速度更快（P < 0.05）。在从75°C到37°C的可控温度下降范围内，被研究的3种牙胶品牌之间的总收缩率存在显著差异（P < 0.05），10分钟后收缩率在0.96%±0.20%至2.31%±0.26%之间（P < 0.05）。不同牙胶品牌的收缩动力学呈现出不同模式。
设计用于热塑性应用的牙胶在冷却时会迅速且大量收缩。
