Abstract
BackgroundMicro-CT (μCT) studies that combine simulated canals with meglucamine diatrizoate to evaluate the shaping ability of nickel-titanium (NiTi) rotary instruments are lacking in the literature. The purpose of this study was to evaluate the shaping ability of three new different nickel-titanium rotary instruments in simulated root canals using μCT.MethodsThirty simulated root canals with a curvature of 60° were randomly allocated into the following 3 groups (n = 10): Group 1, ProTaper Universal (PTU) rotary system; Group 2, Reciproc single-file system; and Group 3, K3XF rotary system. Pre- and post-instrumented images of simulated canals were scanned with μCT via a radiopaque contrast technique to build a 3-dimensional (3D) model. Canal transportation, volumetric change and centring ability were evaluated in each group. Instrument failure and preparation time were also recorded. The Kruskal-Wallis test was used for statistical analysis and the significance level was set at p = 0.05.ResultsReciproc produced greater volume change in the apical part of the canals compared with PTU and K3XF (p < 0.05). K3XF exhibited less transportation and better centring ability at the 2- and 3-mm levels from the apical foramen compared with PTU and Reciproc (p < 0.05). There were no significant differences in the centring ratio and transportation between PTU and Reciproc. Preparation time was significantly shorter in the Reciproc group (p < 0.05).ConclusionsUnder the conditions of our study, all of the canals were 3D reconstructed successfully via the radiopaque contrast technique. Reciproc showed enhanced apical volume changes and K3XF exhibited better centring ability when compared with other groups.
Highlights
Micro-CT studies that combine simulated canals with meglucamine diatrizoate to evaluate the shaping ability of nickel-titanium (NiTi) rotary instruments are lacking in the literature
The K3XF rotary system (SybronEndo, Orange, CA) has been available with an updated alloy design compared with the K3 system
Significantly less transportation was noted in the K3XF group
Summary
Micro-CT (μCT) studies that combine simulated canals with meglucamine diatrizoate to evaluate the shaping ability of nickel-titanium (NiTi) rotary instruments are lacking in the literature. Wei et al BMC Oral Health (2017) 17:39 improve the mechanical properties of NiTi instruments, including the use of R-phase or M-wire alloys and modifications in the design of the cross-section, reciprocating or rotary working motion. The mechanical properties are modified by the special heat treatment (R-phase technology) on the alloy during the manufacturing process. This system was reported to have a higher fracture resistance than traditional NiTi rotary files [6]. The differences in the metallurgy and design of these modified NiTi instruments may produce different shaping abilities, and clinicians are often confused about which is better for an individual case to produce more centred preparations and minimize apical root canal transportation
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