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Effects of Na OC l, EDTA and MTAD when applied to dentine on stress distribution in post‐restored roots with flared canals
Author(s) -
Belli S.,
Eraslan O.,
Eraslan O.,
Eskitascioglu M.,
Eskitascioglu G.
Publication year - 2014
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/iej.12260
Subject(s) - von mises yield criterion , finite element method , materials science , stress (linguistics) , stress concentration , post and core , orthodontics , dentin , composite material , dentistry , structural engineering , crown (dentistry) , engineering , medicine , philosophy , linguistics
Aim To evaluate the effect of Na OC l, EDTA and MTAD on the stress distribution and levels in roots with flared canals and three different aesthetic post systems using finite element stress analysis ( FEA ). Methodology Three‐dimensional (3D) FEA models simulating a maxillary incisor with excessive structural loss and flared root canals were created. The dentine of the first models of each post group was assumed as homogenous, whereas the others were deemed as having their elastic modulus affected up to 100 μm deep as a result of irrigation protocol (5.25 Na OC l, 17% EDTA and MTAD for 2 h). A sound incisor tooth model was used as the control. Restorations were created according to the post system used (pre‐fabricated fibre post ( PFP )), polyethylene fibre (Ribbond) post and core build‐up ( RBP ), and one‐piece milled zirconia post and core ( ZP ). Ceramic crowns were added to the models. A 300‐N static load was applied at the centre of the palatal surface of the models to calculate the stress distributions. The SolidWorks/Cosmosworks structural analysis programmes were used for FEA analysis. Results were presented by considering von Mises criteria. Results The analysis of the von Mises stresses revealed that RBP created less stress in the remaining root dentine when compared to PFP and ZP . ZP maintained the stresses inside its body and reduced stress on the palatal surface of the root; however, it forwarded more stress towards the apical area. Na OC l‐, EDTA ‐ and MTAD ‐treated dentine increased the stresses within the root structure regardless of the effect of the post system used (11–15.4 MP a for PFP , 9.5–13.02 MP a for RBP and 14.2 MP a for ZP ). Amongst the irrigation solutions used, EDTA and MTAD increased the stresses more than Na OC l in all models. All the irrigation solutions showed the same stress levels and distributions in the ZP model. Conclusion Na OC l‐, EDTA ‐ and MTAD ‐ treated dentine and a rigid post with high elastic modulus may increase fracture risk in roots with flared canals by increasing the stresses within root dentine. Therefore, solutions that alter the elastic modulus of dentine less (such as Na OC l) or an individually shaped post–core system constructed with a material that has an elastic modulus close to dentine (polyethylene fibre) should be used in weak roots.