Preparing the S-Shape Canal: Does Coronal Enlargement Prevent Transportation?

Turkish Endodontic Journal, vol.11, no.2, pp.164-170, 2026 (Scopus, TRDizin)

Purpose: This study evaluated the effects of coronal enlargement files with different tapers, apical di-

ameters, and heat treatments on canal transportation in standardized S-shaped simulated canals.

Methods: Sixty resin blocks with a 50° double curvature were assigned to four groups (n=15): UniGold

Sx, UniBlue Sx, N1, and Control. All canals were prepared to size 25/.04 using the K7 system. Pre- and

post-instrumentation images were superimposed in Fiji, and transportation was measured at five levels.

ANOVA and Bonferroni tests were used (α=0.05).

Results: No significant differences were observed at the apical constriction. At 2 mm, coronal enlarge-

ment groups showed transportation opposite the furcation, whereas the control group showed trans-

portation toward it (p<0.05). At 5 and 8 mm, the N1 group exhibited the least transportation (p<0.05).

UniGold Sx showed the highest transportation at 11 mm (p<0.05).

Conclusion: Minimally invasive, flexible files reduced transportation in critical areas, while all forms of

coronal preparation improved apical shaping safety.

Keywords: Canal transportation; coronal enlargement; root canal preparation; S-shaped canal.