Purpose: This in-vitro study was to investigate the influence of heat-treated single file rotary systems (TruNatomy, Reciproc blue, and Hyflex EDM) on remaining dentin thickness in the danger zone of mandibular first molars utilizing cone beam computed tomography (CBCT).

Materials and methods: Thirty human mandibular first molars were chosen. After determining the working length and preparing the access cavity, pre-instrumentation CBCT scans were taken and recorded 4mm apical to the furcation area in the distal aspect of the mesiobuccal root canal. Instrumentation was done according to the recommended instructions of the used file. Teeth were randomly divided into three groups (n=10) based on the respective single file system, group 1: TruNatomy, group 2: Reciproc blue, and group 3: Hyflex EDM. Post-instrumentation CBCT scans were captured and recorded under the same protocol as the pre-instrumentation scans. Finally, comparisons were performed between the post and pre-instrumentation CBCT scans to calculate the remaining dentin thickness.
Data of residual dentin thickness were statistically analyzed using one-way ANOVA, followed by Tukey post hoc test at a significance level of P ≤ 0.05.
Results: TruNatomy removed the minimum amount of dentin in the danger zone of mandibular first molar while Reciproc blue removed the maximum amount, while no significant difference was recorded among groups (P ˃ 0.05).
 


Conclusions: The tested heat-treated single file system had no noticeable effect on residual dentin thickness at the danger zone of the mandibular first molar.