Effect of Gap Size Between the Intracanal Post and Gutta-Percha on Stress Distribution in Teeth With Post-And-Core Restorations: A Finite Element Analysis Publisher

Summary: Does the gap size in post-and-core restorations matter? Research suggests a 3-mm gap raises dentinal stress by 35-37%, increasing fracture risk. Optimal gap for fiber posts is ≤ 2 mm. #DentalResearch #Biomechanics

Niavarzi S ; Geramipanah F ; Sedighpour L ; Marvi M
Source: Journal of Research in Dental and Maxillofacial Sciences Published:2026

Abstract

Background and Aim: This study evaluated the effect of gap size between the intracanal post and gutta-percha on stress distribution in teeth with post-and-core restorations using finite element analysis (FEA). Materials and Methods: In this FEA, eight 3D models of maxillary central incisors were created: four with fiber-reinforced composite posts (FRCPs) and four with nickel-chromium metal cast posts (MCPs). Also, 0 mm (no gap), 1 mm, 2 mm, and 3 mm gaps were modeled. A 100-N oblique load (at 135 degrees relative to the longitudinal tooth axis) was applied, and the von Mises (VM), tensile, and compressive stress values were analyzed. Results: For the FRCPs, the VM stress patterns in dentin remained consistent in presence of 0-2 mm gap, but a 3-mm gap increased stress by 35%-37%. The MCP models showed similar stress distribution patterns across different gap sizes, with a peak VM stress (13.11 MPa) localized at the buccal mid-root. The FRCPs demonstrated uniform stress distribution; whereas, the MCPs exhibited higher overall stress levels by 85%-89%. Conclusion: The results indicated that a 3-mm gap significantly elevated dentinal stress, increasing the fracture risk. The FRCPs with ≤ 2 mm gap had an optimal performance; whereas, the MCPs induced higher stress levels regardless of the gap size. Failure modes differed as well, such that the FRCPs were predisposed to cervical fractures, whereas the MCPs increased the risk of apical fractures. These findings highlight the importance of management of intracanal post-gutta-percha gap as a critical parameter in post-and-core restorations to mitigate biomechanical failure. © 2026 Faculty of Dentistry, Tehran Medical Sciences, Islamic Azad University.