title: Effect of elasticity on stress distribution in CAD/CAM dental crowns: Glass ceramic vs. polymer-matrix composite.
abstract: OBJECTIVE
  Further investigations are required to evaluate the mechanical behaviour of newly developed polymer-matrix composite (PMC) blocks for computer-aided design/computer-aided manufacturing (CAD/CAM) applications. The purpose of this study was to investigate the effect of elasticity on the stress distribution in dental crowns made of glass-ceramic and PMC materials using finite element (FE) analysis.
  
  
  METHODS
  Elastic constants of two materials were determined by ultrasonic pulse velocity using an acoustic thickness gauge. Three-dimensional solid models of a full-coverage dental crown on a first mandibular molar were generated based on X-ray micro-CT scanning images. A variety of load case-material property combinations were simulated and conducted using FE analysis. The first principal stress distribution in the crown and luting agent was plotted and analyzed.
  
  
  RESULTS
  The glass-ceramic crown had stress concentrations on the occlusal surface surrounding the area of loading and the cemented surface underneath the area of loading, while the PMC crown had only stress concentration on the occlusal surface. The PMC crown had lower maximum stress than the glass-ceramic crown in all load cases, but this difference was not substantial when the loading had a lateral component. Eccentric loading did not substantially increase the maximum stress in the prosthesis.
  
  
  CONCLUSIONS
  Both materials are resistant to fracture with physiological occlusal load. The PMC crown had lower maximum stress than the glass-ceramic crown, but the effect of a lateral loading component was more pronounced for a PMC crown than for a glass-ceramic crown.
  
  
  CONCLUSIONS
  Knowledge of the stress distribution in dental crowns with low modulus of elasticity will aid clinicians in planning treatments that include such restorations.
authors.affiliation: Department of Biomedical Materials Science, University of Mississippi Medical Center, MS, USA.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Duan
authors.affiliation: Department of Biomedical Materials Science, University of Mississippi Medical Center, MS, USA. Electronic address: Jgriggs@umc.edu.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Griggs
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns / Q000145:classification*; D003738:Dental Cements / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D004548:Elasticity; D006801:Humans; D008334:Mandible / Q000737:chemistry; D008963:Molar / Q000737:chemistry; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D003776:Dental Porcelain; C023506:Glass ceramics
keywords: CAD/CAM; Dental ceramics; Dental crowns; Finite element method