Procedural errors using two instrumentation techniques

Aim: The purpose of this study was to compare the arith-metic crown-down dynamic tactile (ACDT) techniquewith the single length technique (SLT) when shaping se-verely curved root canals in terms of procedural errors.Methodology: The participants were 339 dental internsover 9 months. A presentation of the describing SLT andACDT was shown to the interns. Each intern was requiredto shape 4 root canals, 2 for each technique. The root ca-nals included in the study had degrees of curvature ofmore than 30°. They were mandibular mesial canals andmaxillary buccal canals. The SLT was performed usinga 10 K file followed by sequential enlargement by sizes17/.04, 20/.04, 25/.04 and finishing with a 30/.04, each tothe full working length (WL). For ACDT, a formula wasused to calculate the maximum insertion depths of highertapered instruments to prevent over-flaring of the canaland preserve the pericervical dentine. Based upon the for-mula, the following sequence was used: the 25/.12 insertedto 10.25 mm short of the WL, 20/.06 inserted to 3.67 mmshort of the WL, or to the beginning of the curve, which-ever came first. Then, the 17/.04, 25/.04 and 30/.04 wereinserted to the full WL. The martensitic nickel-titaniumrotary files were activated upon dentinal engagement fol-lowed by 3 apical strokes. Procedural errors were recordedand statistically analysed. Post hoc pairwise comparisonswere used to compare the 2 techniques with the signifi-cance level set at p < 0.05.Results: The percentage of canals instrumented usingACDT that had errors (19.6%) was significantly lowerthan those instrumented using SLT (53.2%) (p < 0.001).SLT showed a significantly higher percentage of transpor-tation, broken and deformed instruments (p < 0.001).Conclusion: The ACDT is a safe and predictable tech-nique for severely curved canals.