Influence of taper and immobilization point on the flexibility of RaCe nickel-titanium rotary instruments

Thaís Boechat e Silva, Hélio Pereira Lopes, Mônica Aparecida Schultz Neves, Victor Talarico Leal Vieira

Objective: This study compared the flexibility of RaCe nickel-titanium rotary instruments with different tapers at different diameters of the shaft (D3 and D6). Materials and Methods: Thirty RaCe files (FKG, La Chauxde Fonds, Switzerland) size #40 with tapers 0.02, 0.04 and 0.06 mm/mm, and length of 25 mm were divided in three groups of ten instruments each, according to their tapers. In the cantilever bending test (45 degrees), two tests with loads applied at D3 and D6 were performed for each group. Results: Comparison of the loads applied at D3 and D6 of RaCe files with different tapers showed significantly different maximum load values to bend the files: D3 < D6, with flexibility at D3 greater than at D6. Comparison of the loads applied at D3 in the three groups revealed significant differences between the groups (p<0.0001), while the Student-Newman-Keuls (SNK) test showed differences in flexibility between the three groups: .06 < .04 <.02 tapers. The same result was observed for the loads applied at D6. Conclusions: The flexibility of the file increases with the reduction of the taper (p <0.05), and decreases the larger the diameter of the helical shaft (p<0.05).

Keywords: Nickel-titanium rotary instruments. Flexibility. Taper. RaCe rotary files.

How to cite: Boechat e Silva T, Lopes HP, Neves MAS, Vieira VTL. Influence of taper and immobilization point on the flexibility of RaCe nickel-titanium rotary instruments. Dental Press Endod. 2018 Jan-Apr;8(1):23-8. DOI: https://doi.org/10.14436/2358-2545.8.1.023-028.oar

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