Canal-centring ability of three rotary file systems in simulated curved canals: A comparative study.

Objective: To compare the canal-centring ability of M two , ProFile and RaCe rotary files, in simulated curved canals. Materials and Methods: About 30 simulated canals were prepared by M two , ProFile and RaCe rotary files. Pre and post-operative pictures were super-imposed and transportations recorded. Measurements were carried out at five different points: Canal orifice (O); half-way to the orifice in the straight section (HO); the beginning of the curve (BC); the apex of the curve (AC); the end point (EP). Intra- and inter-group comparisons were carried out by Wilcoxon`s signed ranks test and Kruskal-Wallis test respectively, using SPSS 14.0 software. Results: ProFile did not change canal centricity in any point. RaCe kept centricity at HO, BC, AC and EP. M two changed canal centricity in points BC, AC and EP. M two group kept the centricity significantly less than the other two groups at BC (P = 0.004), AC (P = 0.015) and EP (P = 0.01). There was no significant difference between these three rotary files at HO. However, the difference between RaCe, M two and ProFile was significant at O (P = 0.015). Conclusion: ProFile and RaCe rotary files remained better centred than M two rotary files.

Change of working length in curved canals by various instrumentation techniques / 대한치과보존학회지

To evaluate the change of working length with various instrumentation techniques in curved canals, working length and canal curvature were determined before and after canal instrumentation in buccal or mesial canals of extracted human molars. Stainless steel K-files (MANI(R), Matsutani Seisakusho Co. Takanezawa, Japan), nickel-titanium K-files (Naviflex NT(TM), Brassler, Savannah, USA), ProFile(R), and ProTaper(TM) (Dentsply-Maillefer, Ballaigues, Switzerland) were used to prepare the canals with crown-down technique. In two hand instrumentation groups, coronal flaring was made with Gates Glidden burs. Apical canals were instrumented until apical diameter had attained a size of 30. Positional relation between the tooth apex and the #10 K-file tip was examined by using AutoCAD 2000 (Autodesk Corp., San Rafael. CA, USA) under a stereomicroscope before and after coronal flaring, and after apical instrumentation. Degree of canal curvature was also measured with Schneider's method in radiographs. Data of working length and canal curvature changes were statistically analyzed with one-way ANOVA and Tukey's studentized range test. Working length and canal curvature were decreased significantly in each step in all instrumentation groups. Coronal flaring using Gates Glidden burs in hand instrument groups and whole canal instrumentation using stainless steel hand K-files caused significantly more working length change than in ProFile instrumentation group (p < 0.05). The result of this study demonstrates that all of the above kinds of instrumentation in curved canals cause reduction of working length and canal curvature at each instrumentation steps, and hand instrumentation causes more working length change than ProFile.

Effect of anticurvature filing method on preparation of the curved root canal using ProFile / 대한치과보존학회지

This study investigated the effect of anticurvature filing method on preparation of the curved root canal using ProFile. Thirty six resin blocks were divided equally into three groups by instrumentation motions: anticurvature filing motion, circumferential filing motion and straight up-and-down motion. Each resin block was sectioned at 8 mm level from the apex and at the greatest curvature of the canal and reassembled in metal mold by a modified Bramante technique. All groups were instrumented with the ProFile system. At each levels, image of sectioned surface were taken using CCD camera under a stereomicroscope at x40 magnification and stored. Distances of transportation at the inner and outer area of curvature and the centering ratio were determined and compared by statistical analysis, along with the assessment of the increase of root canal cross-sectional area. The results were as follows; 1. In all groups, there was no statistical difference in the mean increase of root canal cross-sectional area, the centering ratio, and the mean distances of transportation at the inner area of curvature at each level. 2. At 8 mm level from the apex, the mean distances of transportation at the outer area of curvature decreases in following order anticurvature filing motion, circumferential filing motion, straight up-and-down motion but, no significant difference at the greatest curvature of the canal among three groups. Effect of anticurvature filing motion using ProFile does not seem to be different from other instrumentation motions at the inner area of curvature in curved root canal.