Abstract
To compare the shaping ability of different single-file systems in the preparation of mesial curved canals of mandibular molars using micro-CT technology. Fifteen mesial roots of mandibular molars with two independent and curved canals (n = 30) were selected, scanned at a resolution of 26.7 μm anatomically matched, and distributed into three groups (n = 10), according to the preparation system: WaveOne 25.08, Reciproc 25.08, and OneShape 25.06. A final micro-CT scanning was performed, data sets were registered with their respective counterparts, and compared regarding the three-dimensional (volume, surface area, and structure model index - SMI) and two-dimensional (perimeter, area, roundness, major and minor diameters) parameters, as well as, canal transportation, using ANOVA and post hoc Tukey tests (α = 5%). Overall, no difference was observed between groups regarding area, perimeter, volume, surface area, and canal transportation (p > 0.05). Within group, no canal transportation was significantly higherobserved in the apical third (0.10 ± 0.05 mm) compared to coronal (0.08±0.040 mm) and middle (0.07 ± 0.03 mm) thirds (p < 0.05). Structure model index (SMI) was statistically higher after preparation with OneShape instrument (0.36 ± 0.26) compared to other systems (p < 0.05). Within the parameters of this study, similar shaping ability was observed in the preparation of mesial curved root canals of mandibular molars with Reciproc, OneShape and WaveOne systems.
Highlights
Within the parameters of this study, similar shaping ability was observed in the preparation of mesial curved root canals of mandibular molars with Reciproc, OneShape and WaveOne systems
Many technical advances have been made in endodontics with the development of nickel-titanium instruments with different designs, surface treatment and movement kinematics,[3,4,5] canal preparation is still adversely influenced by the highly variable anatomy, especially in curved root canals.[5,6]
Regarding 3D parameters, the three file systems increased the surface area, volume and Structure model index (SMI) after instrumentation of root canals. 3D analyses showed no significant differences between the groups for surface area (p=0.128) and volume (p = 0.584), for the SMI statistical difference was found between Reciproc and OneShape (p < 0.05) (Table 1)
Summary
Recent studies using micro-CT technology have shown the existence of different anatomical complexities of the root canal system in different groups of teeth including isthmus, ramifications, recesses, and curvatures.[1,2] many technical advances have been made in endodontics with the development of nickel-titanium instruments with different designs, surface treatment and movement kinematics,[3,4,5] canal preparation is still adversely influenced by the highly variable anatomy, especially in curved root canals.[5,6] The different curvature angles and the radius of the root canal are important aspects to be observed, since, during the preparation of these root canals, iatrogenic such as steps, zips, perforations, and canalBraz. Single instrument systems with reciprocating kinematics appeared on the market,[8,10] made with M-wire NiTi, changing pitch, helical angle, reverse helix, and two distinct cross-sections along the length of the active portion of the instrument These characteristics result in greater flexibility, fracture, and fatigue resistance, which increases safety during preparation mainly in curved root canals.[8] Another concept in the preparation of root canals utilizing a single instrument, but with rotational kinematics, is the OneShape system (MicroMega, Besançon, France). This system is characterized by instruments with 0.06 constant taper and different models of cross section with a changing pitch length along the working part that eliminates the threading effect and binding of the instrument in continuous rotation inside the root canal.[11,12] The shaping ability and canal transportation of the single-file rotary systems has been compared with single-file reciprocating systems with encouraging results, once both techniques are able to shape curved root canals.[11,12,13,14,15,16,17,18,19]
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