Push-Out Bond Strength of Root Canal Sealers in Curved versus Straight Root Canals: An Invitro Research

Abstract

Background: The success of endodontic treatment depends on effective cleaning, shaping, and obturation of the root canal system. Root canal sealers contribute significantly to the sealing ability of the obturation complex. Canal curvature may influence sealer penetration, adaptation, and adhesion to root dentin.

Aim: To compare the push-out bond strength of root canal sealers in curved and straight root canals.

Materials and Methods: Forty extracted human mandibular premolars were selected and divided into two groups according to canal morphology: straight canals (n = 20) and curved canals (n = 20). All canals were prepared using rotary nickel-titanium instruments and irrigated with sodium hypochlorite and EDTA. Specimens were obturated using gutta-percha and a bioceramic sealer. After storage at 37°C and 100% humidity for 7 days, roots were sectioned into 2-mm-thick slices. Push-out bond strength was evaluated using a universal testing machine. Data were analyzed using an independent t-test with a significance level of p < 0.05.

Results: The mean push-out bond strength was significantly higher in straight canals (8.42 ± 1.31 MPa) than in curved canals (6.75 ± 1.24 MPa) (p = 0.001). The coronal third exhibited higher bond strength values than the middle and apical thirds in both groups. Mixed and adhesive failure modes were more frequent in curved canals.

Conclusion: Canal curvature negatively affects the push-out bond strength of root canal sealers. Straight canals demonstrated superior adhesion, likely due to improved instrumentation, irrigation effectiveness, and sealer penetration.