Endodontology (Jan 2019)
In vitro comparison of the force required to fracture roots vertically following the use of two instrument retrieval systems
Abstract
Objective: The objective of this study was to compare the force required to fracture the roots in a vertical direction following the use of two instrument retrieval systems. Introduction: A vertical root fracture is a longitudinal fracture of the root, extending throughout the dentin from the root canal to the periodontium. The fracture strength of teeth after the application of two systems used for instrument retrieval, i.e. ultrasonic (P5 Booster Company Irrisafe, Satelec ACTEON, North America) and instrument removal system (iRS Switzerland) was compared. Materials and Methods: Freshly extracted 60 maxillary central incisor teeth with straight roots and single canal were collected. The anatomical crowns of all the teeth were sectioned. The samples were cleaned and shaped with the crown down technique using Pro-Taper (DENTSPLY, Maillefer, USA) rotary instruments up to a size F2. The fracture of rotary file was deliberately induced by the pressure that was applied during rotary motion of F3 file. The samples were then randomly divided into three groups each having 20 teeth, i.e., Groups A, B, and C. Retrieval of separated file was performed in Groups B and C by means of Ultrasonic and Instrument retrieval system, respectively, while no retrieval of separated file was done in Group A. Each sample was then subjected to load by Instron testing machine until the sample got fractured. That load at the time of fracture of each sample was recorded. The data collected from all the samples were then subjected to statistical analysis using ANOVA and Tukey's HSD. Results: The results showed statistically significant difference among all the groups. The group in which no retrieval system was employed showed the best fracture resistance. The group in which ultrasonic removal system was used showed better fracture resistance as compared to the group in which iRS was used. The fracture resistance of Group A, Group B, and Group C ranged from 265.23–289.66, 114.67–135.66, and 70.56–97.56, respectively, with mean (± standard error) 277.60 ± 1.94, 124.65 ± 1.53, and 84.98 ± 1.76, respectively, and median 276.54, 123.95, and 85.78, respectively. Conclusion: According to the results of the present study, the difference between the force required to fracture roots vertically after removal of a fracture instrument with the ultrasonic and instrument removal system was statistically significant.
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