Quality of Root Canal Fillings in Curved Canals Prepared with ProTaper : Comparison of Various Obturation Techniques

Abstract

Pro Taper nickel-titanium rotary instruments may cause outer canal widening when used to prepare curved canals, which might affect the quality of root canal fillings. The purpose of this study was to compare the apical density of four obturation techniques when used in ProTaper-prepared simulated curved canals. Forty simulated canals with a 30-degree curvature in clear resin blocks were divided into 2 groups (n=20, each) and were prepared with the ProTaper system to a size #25/.08 taper (F2) or #30/.09 taper (F3). The canals in both groups were further divided into four groups (n=5, each) and filled using one of the four different gutta-percha root filling techniques: Thermafil (TF), single-cone obturation with a ProTaper point (PT) or a .06 taper point (06), and lateral condensation (LC) using a .02 taper master point. The blocks were sectioned horizontally at 0-, 1-, 2-, 3- and 5-mm levels from the working length, and the percentage of gutta-percha-filled area was measured in each cross-section with image analysis software. Data were analyzed statistically using analysis of variance and the Bonferroni Dunn test. Results demonstrated that: (1) TF showed a significantly higher percentage compared with all other techniques at the 5-mm level in both groups and 1- to 3-mm levels in the F3 group (p<0.05); (2) values for LC were significantly lower than those for PT and 06 at the majority of the levels in the canal (p<0.05); and (3) PT showed significantly higher values than 06 only at the 0-mm level in the F2 group (p<0.05). It was concluded that, under the conditions of the study, TF produced the largest percentage of gutta-percha-filled area followed by PT and 06, and LC yielded the smallest percentage.