The effect of different irrigation protocols on elastic modulus of dentine and biomechanics of single‑rooted premolar tooth: A nano‑iIndentation and finite element analysis study
Aim: This study evaluated the effect of different irrigation protocols on elastic modulus and biomechanics of single‑rooted premolar tooth using with nano‑indentation and finite element analysis (FEA).
Materials and Methods: Root canals of single‑rooted human teeth were prepared, divided into eight groups, and irrigated with (1) 2.5% NaOCl + 17% EDTA; (2) 2.5% NaOCl + 17% EDTA + 2.5% NaOCl; (3) 2.5% NaOCl + SmearClear; (4) 2.5% NaOCl + 2% chlorhexidine; (5) 1.3% NaOCl + MTAD; (6) 5.25% NaOCl; (7) 17% EDTA; and (8) saline. The roots were vertically sectioned, and elastic modulus of the root dentine was measured using nano‑indenter device at coronal, middle, and apical third. Data were recorded as megapascal and statistically analyzed (one‑way analysis of variance, Tukey tests). Three‑dimensional FEA model of a premolar tooth was created, and the inner root dentine was modified to simulate the effect of irrigation protocols on root dentine. The elastic properties of inner root dentine layer in the FEA models were modified for each group according to the data obtained with nano‑indentation. A 300‑N load was applied at the buccal cusp and central fossa of the models with a 45° angle. The stresses were calculated using von Mises stress criteria.
Results: All irrigation protocols affected the elastic modulus of root dentine. Groups 2 and 3 showed similar elastic modulus values (P > 0.05), whereas the lowest values were obtained in group 7 (P < 0.05). No statistically significant differences were found between groups 4, 5, and 8 (P > 0.05).
Conclusion: Despite the effect of different clinically used irrigation protocols on elastic modulus of the inner dentine, this does not affect the biomechanics of the roots.
Keywords: Dentine, elastic modulus, finite element analysis, irrigants, nano‑indentation