Date of Award

Spring 2015

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Dentistry

First Advisor

Stover, Sheila E.

Second Advisor

Hashimoto, Lance K.

Third Advisor

Berzins, David

Abstract

Introduction: Nickel-titanium (NiTi) files, introduced over 2 decades ago, have the unique property of superelasticity, are more resistant to fracture and are more flexible than stainless steel files. Recent developments in NiTi include M wire and Controlled/Thermal Memory Technology resulting in files with claimed superior properties to conventional NiTi files. Manufacturers recommend sterilization of files prior to usage. These files may be subjected to further autoclaving if reused. The purpose of this study was to test the effect of multiple cycles of autoclaving on the flexibility of four brands of NiTi files and to evaluate differences between brands. Materials and Methods: HyFlex CM (Coltene Whaldent), Vortex, Profile and Vortex Blue (Dentsply Tulsa Dental Specialties) files of size 35 with 0.04 taper were selected for this study. All files were subjected to 0, 1, 3 and 5 cycles of autoclaving and their flexibility was assessed with cantilever bending at 37oC (n=20/brand/cycles). Non-autoclaved files were used as controls. Two-way ANOVA and Post Hoc Tukey's test were used to assess the differences in flexibility. Results: Autoclaving had no significant (p>0.05) effect on the flexibility within a given file brand but there were significant (p<0.05) differences in flexibility among the brands with the general ranking- HyFlex CM > Profile > Vortex > Vortex Blue. Conclusion: Autoclaving had no effect on the mechanical properties of these NiTi rotary files.

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