title: Comparison of apical transportation in four Ni-Ti rotary instrumentation techniques.
abstract: A new radiographic technique was used to compare apical transportation in four Ni-Ti rotary instrumentation sequences. Mesiobuccal canals of 60 extracted mandibular molars were randomly divided into four groups. Groups 1 and 3 were instrumented by crown-down and groups 2 and 4 by step-back technique with 0.06 ProFiles series 29 to size 6. In groups 3 and 4 Greater Taper files were first used in a crown-down manner. The central axes of initial and final instruments were radiographically superimposed to measure loss of working length (WL) and transportation at 0, 0.5, 1, 3, and 5 mm from WL. ANOVA test showed no significant differences among groups regarding degree of transportation or loss of WL. Transportation was negatively correlated with radius of curvature at 0.5 and 5 mm from WL. The results indicate that the operational sequence of ProFiles or preinstrumentation with GT files has no effect on degree of transportation and loss of WL.
mesh_terms: D000704:Analysis of Variance; D003722:Dental Alloys; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging* / Q000473:pathology; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008963:Molar; D009532:Nickel; D019252:Radiography, Dental, Digital; D012044:Regression Analysis; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D014025:Titanium; D019227:Tooth Apex / Q000000981:diagnostic imaging / Q000473:pathology
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium