Buckling resistance of pathfinding nickel-titanium rotary instruments in narrow root canal: an in vitro study

Introduction: Exploration is an important step of root canal preparation, because it allows the clinician to negotiate the canal to its terminus and determine its complexity. Different instruments have been developed specifically for this purpose. This study compared the buckling resistance of hand stainless steel and pathfinding nickel-titanium rotary instruments in artificial canals with different depths. Materials and methods: A total of 30 PathFile, ScoutRace and C-Pilot instruments were evaluated. The buckling resistance was tested using acrylic resin blocks with a flat surface or with 3 mm and 6 mm deep artificial canals. The load required to generate a lateral displacement of 1 mm was recorded. Data were statistically analysed using one-way analysis of variance (ANOVA) and Student-Newman-Keuls test for multiple comparisons at a significance level of P 0.05. Results: On the flat surface, C-Pilot showed the greatest buckling resistance. In 3 mm deep canals, PathFile showed resistance similar to that of C-Pilot files on the flat surface. In 6 mm deep canals, both nickel-titanium instruments showed greater buckling resistance than C-Pilot on the flat surface (P 0.001). Conclusions: The buckling resistance of nickel-titanium pathfinding instruments increases with the depth of the canal. Keywords: buckling resistance, endodontic instruments, endodontic treatment, glide path, narrow root canal