Stress analysis of two methods of ceramic inlay preparation by finite element.
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Date
2014-05
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Abstract
Objective: Ceramic inlays are bonded to tooth structure with resin cements. During the resin
cement setting, shrinkage stress develops at the interfaces. During tooth preparation, the undercut
areas formed due to the different patterns of caries progression can either be blocked out before
taking impression with suitable cement such as glass ionomer cement, or before making the
final restoration in the laboratory. Then, the relieved space will be filled with luting cement in
clinic. The aim of this study was to compare these two methods of undercut filling in term of
stress distribution in the ceramic inlay.
Materials and Methods: An axisymmetric finite element analysis was performed to study the
stress distribution during inlay cementing. The solid model was generated from a longitudinal
section of maxillary premolar in which a class I cavity with 60 degree undercut at the preparation
wall and 20 degree divergence of the vertical walls was prepared. A thermal model was used to
simulate the polymerization shrinkage of the resin cement. Finite element analysis was carried
out in ANSYS environment.
Results: Filling the undercut by glass ionomer cement decreased the stress concentration at the
ceramic/cement interface. The dominant normal stress at the tooth cement interface in absence
of glass ionomer cement was tensile with maximum of 30 Mpa. Using glass ionomer, cement
developed stresses with different compressive and tensile signs. With increasing the thickness
of resin cement (100 μm, 150 μm, 200 μm), the stress increased.
Conclusion: Cements with minimum shrinkage and as thin layer as possible should be used.
Filling the undercut with glass ionomer cement decreases the stress. Other experimental and
clinical studies must follow this research.
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Keywords
Ceramic inlay, finite element, polymerization shrinkage, resin cement
Citation
Pishevar Leila, Ghavam Maryam, Pishevar Ahmadreza. Stress analysis of two methods of ceramic inlay preparation by finite element. Indian Journal of Dental Research. 2014 May-Jun; 25(3): 364-369.