Influence of apical taper on the quality of thermoplasticized root fillings assessed by micro-computed tomography

The objective of this study is to study the influence of final canal taper on the sealing ability of Real Seal 1 by using micro-computed tomography (micro-CT). Fifty-four single-rooted teeth were instrumented to apical size of 40 taper 4, 6, and 8. The teeth were divided into three groups. All teeth were filled with Real Seal 1 (RS1; SybronEndo, Orange, CA, USA). Roots were then scanned with mico-CT, and volume measurements of voids in the apical third and in sections at 1, 3, and 5 mm from the apex were calculated in the obturated roots using specialized CT software. Measurements were analyzed statistically by using ANOVA followed by Bonferroni multiple comparison correction. Data analysis showed that 0.08% and 0.06% apical tapered RS1 obturations provided better results than 0.04% tapered samples. The present study showed that none of the root canals filled teeth were gap free. Mean percentages of voids were significantly higher with Real Seal 1 taper 0.04% (P = 0.05).There was no significant difference with 0.06 and 0.08 final taper. For Real Seal 1 technique 0.06 and 0.08 tapered preparations seem to be more optimal. At 1 mm, final taper 0.08 showed less voids and gaps than the two other final tapers. In our daily practice, enlarging the apical third (last 3 mm) of root canals to an 8% taper is necessary to achieve a better sealing ability and thus long-term success for our root canal obturations.