J Korean Acad Conserv Dent.  2006 Jan;31(1):30-35. 10.5395/JKACD.2006.31.1.030.

Change of working length in curved canals by various instrumentation techniques

• Jo JI
• Jin MU
• Kim YK
• Kim SK

• KMID: 2175780
• DOI: http://doi.org/10.5395/JKACD.2006.31.1.030

Abstract

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.

Keyword

Working length; Curved canal; Hand instrumentation; Rotary instrumentation; ProFile; Canal curvature

MeSH Terms

Dental Instruments
Hand
Humans
Molar
Stainless Steel
Tooth Apex
Stainless Steel

Figure

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  Figure 1 Occlusal cusp and root apex were flattened to obtain an accurate measurement of working length.

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  Figure 2 Change of working length by instrumentation (mean ± SD). *Statistically significant (p < 0.05).

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  Figure 3 Change of canal curvature by instrumentation (mean ± SD). *Statistically significant (p < 0.05).

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