Biomechanical performance of chitosan-nanoparticle-modified bulk-fill and conventional resin composites: a combined finite element and in-vitro study.

Authors

Hitesh Chohan, Mohammed Sayed, Harisha Dewan, Taif Nasser Alrajhi, Amwaj Yahya Alamer, Ruaa Mohammed Akoor, Thilla Sekar Vinothkumar, Hemant Ramesh Chourasia, Apathsakayan Renugalakshmi

Published in

BMC oral health. Volume 26. Issue 1. Oct 28, 2026. Epub Oct 28, 2026.

Abstract

This study aimed to evaluate and compare the stress distribution of chitosan-modified and unmodified Bulk-fill and conventional composite resins using finite element analysis (FEA) and in-vitro fracture resistance testing.
A three-dimensional (3D) FEA model of a maxillary premolar (34,253 nodes; 17,851 tetrahedral elements) with a Class II mesio-occluso-distal (MOD) cavity was subjected to 900 N vertical occlusal loading to record von Mises stress, total deformation, and XY-plane shear stress. The groups analyzed were: Sound Tooth Control; Unmodified/Plain Conventional: Tetric N-Ceram 2 composite; Chitosan-Modified Conventional: Tetric N-Ceram 2 composite; Unmodified/Plain Bulk-Fill: Tetric PowerFill composite; and Chitosan-Modified Bulk-Fill: Tetric PowerFill composite. In parallel, fifty extracted premolars (restored according to the same grouping) underwent in-vitro fracture resistance testing after thermocycling (5-55 °C, 10,000 cycles). Data was analyzed using Two-Way Analysis of Variance (ANOVA) test and Bonferroni Post hoc analysis. A 95% confidence range was used to determine statistical significance for p ≤ 0.05.
Intact enamel produced von Mises stress of 66.69 MPa with minimal deformation (0.0039 mm). Intact dentin showed comparable stress (66.89 MPa) but 4.4-fold higher deformation (0.0175 mm). Among restorative groups, modified Bulk-fill demonstrated lowest deformation (0.0069 mm), highest calculated shear stress (32.4 MPa), and highest fracture resistance (107.55 MPa). The maximum von Mises stresses were 78.26 MPa for Bulk-fill, 104.6 MPa for Tetric N-Ceram 2 (highest), 101.3 MPa for modified Bulk-fill, and 75.4 MPa for modified Tetric N-Ceram 2, indicating material-dependent stress distributions following chitosan modification.
Chitosan modification altered the modeled biomechanical response and was associated with favorable numerical trends, particularly in Bulk-fill, but a significant independent chitosan effect on fracture resistance was not demonstrated.
Not applicable.

PMID:
42958543
Bibliographic data and abstract were imported from PubMed on 30 Oct 2026.

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