Comparison of dentine removal using V‐taper and K‐Flexofile instruments

Abstract

Akhlaghi NM, Kahali R, Abtahi A, Tabatabaee S, Mehrvarzfar P, Parirokh M. Comparison of dentine removal using V-taper and K-Flexofile instruments.Aim To compare the dentine removal ability of VTaper and K-Flexofile instruments in mesiobuccal canals of extracted mandibular first molar teeth. Methodology Preoperative images of 40 mesiobuccal canals of mandibular first molars (with a curvature between 20°and 35°) were obtained at 2, 4.5, and 7 mm from the root apices by CT-scan and divided into two groups. Group F was prepared with K-Flexofiles and Gates Glidden drills and Group V with V-Taper Ni-Ti rotary and stainless steel hand instruments. Post-instrumentation images were then obtained and compared with the preoperative images. The ratio of dentine removal based on pre-and postoperative images was calculated, and data was analysed by anova and Tukey post hoc test. Results In group F in the coronal sections, the least ratio of the dentine removal to the initial root thickness was on the buccal aspect (15.14% ± 6.72), and the greatest ratio was found on the distolingual (29.38% ± 8.19). In group V in the coronal, the least ratio of the dentine removal to the initial root thickness was on the buccal aspect (9.81% ± 3.26); the greatest ratio was found on the distolingual surface in the coronal sections (34.38% ± 10.51). In the middle sections, the least ratio was on the buccal (10.51% ± 3.39) and the greatest on the distolingual aspects (27.46% ± 12.34) of the roots. In the apical sections, the amount of the dentine removed from the mesial and distal surfaces in group V was significantly more than group F (P < 0.01). Conclusion The distolingual aspect of the root canal is a danger zone for the mesiobuccal canal of the mesial root in mandibular molar teeth, and preparation of that area should be performed with caution. Except the apical part of the canal, no significant difference was found between the two preparation files or techniques used. Apart from the apical part of the canal, neither instrument maintained the original shape of the coronal and middle parts of the canal.

Effects of Two Nickel-Titanium Instrument Systems, Mtwo versus ProTaper Universal, on Root Canal Geometry Assessed by Micro–Computed Tomography

“…Accuracy and reproducibility of the mCT system have been verified previously, and it is accepted as an important scientific tool for the effect analysis of different shaping techniques (13,(16)(17)(18).…”

Morphometric evaluation and planning of anticurvature filing in roots of maxillary and mandibular molars

“…3 This technique has been used since the 1980s, first with hand instruments and Gates-Glidden drills and later with rotary instruments. 10,12,13,14 However, recent studies have shown that there is no reduction in the perforation risk in danger zones (furcal region) when anticurvature filing is performed, even with Nickel-Titanium (NiTi) rotary systems.…”

“…11 Conversely, overflaring of root canals should be avoided, because it promotes weakening of dental structure and can result in perforations, mainly on the furcal regions of teeth with curved root canals. 12 The risk of perforation in areas with reduced dentin volume, considered danger zones, can be reduced by directed filing to areas of higher dentin volume, or safety zones, as recommended in the anticurvature filing. 3 This technique has been used since the 1980s, first with hand instruments and Gates-Glidden drills and later with rotary instruments.…”

“…Several investigations have been carried out on the danger zones in curved canals, 11,12,17 but studies on the filing of the safety zone are still lacking.…”

Computed tomography evaluation of residual root thickness after pre-flaring using gates Glidden drills: The sequence effect

“…The relative percentage of dentin removal was calculated by dividing the amount of dentin removed to the initial root thickness multiplied by 100. [20]…”