EC Dental Science

Background: Overpreparation at root apex to avoid debris accumulation may cause excessive dentinal removal compromising root strength making it prone to fracture. Most commonly used size of files is 30 and 35, taper is 4% and 6%. However, their effect on root strength is unsettled. The present study aims to assess effect of these file size and taper on fracture resistance of endodontically treated tooth.

Methodology: Forty extracted mandibular premolars having single root were selected. Teeth were decoronated and standardized to have root length of 12 mm. They were divided into two groups: Group I were instrumented with edge endo file system while group II with Hyflex controlled memory (CM) file system. They were subdivided into subgroup A (30/4%), B (35/4%), C (30/6%) and D (35/6%) containing five samples each. Prepared roots were embedded in acrylic resin till cementoenamel junction. Universal testing machine was used to test fracture resistance. Statistical analysis was done using one-way ANOVA and Post-hoc tukey.

Result: Teeth instrumented with Hyflex CM file system having 4% taper and 30 apical preparation size showed better fracture resistance than 6% and size 35, difference was non-significant.

Conclusion: NiTi files having smaller apical size and less taper shows increased fracture resistance.

 Keywords Apical Diameter; File Taper; Fracture Resistance; Hyflex Controlled Memory (CM) File System; Edge Endo File System

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