Silvio Lottanti1, Tobias T Tauböck1, Matthias Zehnder2. 1. Department of Preventive Dentistry, Periodontology and Cariology, University of Zurich, Center of Dental Medicine, Zurich, Switzerland. 2. Department of Preventive Dentistry, Periodontology and Cariology, University of Zurich, Center of Dental Medicine, Zurich, Switzerland. Electronic address: matthias.zehnder@zzm.uzh.ch.
Abstract
INTRODUCTION: The temperature and related shrinking kinetics of gutta-percha injected from heat guns are not known; therefore, we investigated them in this study. METHODS: 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). RESULTS: 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. CONCLUSIONS: Gutta-percha designed for thermoplastic application shrinks quickly and extensively upon cooling.
INTRODUCTION: The temperature and related shrinking kinetics of gutta-percha injected from heat guns are not known; therefore, we investigated them in this study. METHODS: 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). RESULTS: 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. CONCLUSIONS: Gutta-percha designed for thermoplastic application shrinks quickly and extensively upon cooling.
Authors: Islam Ali Abdel Raheem; Amro Abdul Razek; Abeer Abdelaziz Elgendy; Doaa Ahmed Labah; Noha Mohamed Saleh Journal: Int J Nanomedicine Date: 2020-07-27