Comparison of the effect of fixed and variable taper on the quality of obturation

Abstract

Purpose It has long been accepted that the quality of obturation is determined by the final shape of the root canal. This study uses μCT to examine the effect of two canal preparation geometries, fixed and variable taper, on the quality of obturation. The study also compares the effect of shape geometry on the volume of extruded GP. Methodology Sixty-four extracted teeth were randomly divided into two groups and prepared using two different file systems: Wave One Gold and One Shape files. The obturation was standardized for both groups using GuttaCore obturator and then each tooth was scanned with μCT. The following parameters were measured: POV, 3-D difference, 2-D area of voids (at 2, 6 and 9mm) and volume of extrusion (E). Results The WO group had a significantly higher POV (P = 0.045) and a lower D% (p = 0.0034) than the OS group but the correlation between canal taper and quality of obturation was small (r=0.38). The 2-D analysis showed no significant differences between the OS and WO group. The OS group had a significantly (P = 0.0013) greater value of extruded GP than the WO group but the correlation was low (r=042). Conclusion Within the limitation of this study, this study shows that when the apical taper is large enough, 6 - 8%, the geometrical shapes of fixed and variable tapers have a small impact on the quality of the obturation. The variable tapered preparation had a slightly less GP extrusion than the fixed tapered preparation.