title: Early resin luting material damage around a circular fiber post in a root canal treated premolar by using micro-computerized tomographic and finite element sub-modeling analyses.
abstract: This study utilizes micro-computerized tomographic (micro-CT) and finite element (FE) sub-modeling analyses to investigate the micro-mechanical behavior associated with voids/bubbles stress behavior at the luting material layer to understand the early damage in a root canal treated premolar. 3-dimensional finite element (FE) models of a macro-root canal treated premolar and two sub-models at the luting material layer to provide the void/bubble distribution and dimensions were constructed from micro-CT images and simulated to receive axial and lateral forces. The boundary conditions for the sub-models were determined from the macro-premolar model results and applied in sub-modeling analysis. The first principal stresses for the dentin, luting material layer and post in macro-premolar model and for luting material void/bubble in sub-models were recorded. The simulated results revealed that the macro-premolar model dramatically underestimated the luting material stress because the voids/bubbles at the adhesive layer cannot be captured due to coarse mesh and high stress gradient and the variations between sub- and macro-models ranging from 2.65 to 4.5 folds under lateral load at the mapping location. Stress concentrations were found at the edge of the voids/bubbles and values over 20 MPa in sub-modeling analysis immediately caused the luting material failure/micro-crack. This study establishes that micro-CT and FE sub-modeling techniques can be used to simulate the stress pattern at the micro-scale luting material layer in a root canal treated premolar, suggesting that attention must be paid to resin luting material initial failure/debonding when large voids/bubbles are generated during luting procedures.
authors.affiliation: Department of General Dentistry, Chang Gung Memorial Hospital, 123, Ding-Hu Road, Kuei-Shan, Tao-yuan 333, Taiwan. Electronic address: cgucaeb@yahoo.com.tw.
authors.forename: Yen-Hsiang
authors.initials: YH
authors.lastname: Chang
authors.affiliation: Department of Biomedical Engineering, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 112, Taiwan. Electronic address: mike771129.me96@g2.nctu.edu.tw.
authors.forename: Hao
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Biomedical Engineering, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 112, Taiwan. Electronic address: cllin2@ym.edu.tw.
authors.forename: Chun-Li
authors.initials: CL
authors.lastname: Lin
mesh_terms: D001641:Bicuspid / Q000000981:diagnostic imaging* / Q000601:surgery*; D020342:Finite Element Analysis; D055595:Mechanical Phenomena; D019279:Resin Cements / Q000737:chemistry*; D012390:Root Canal Therapy; D013314:Stress, Mechanical; D055114:X-Ray Microtomography
chemical_list: D019279:Resin Cements
keywords: Finite element analysis; Luting material; Micro-CT; Sub-modeling; Void/bubble