title: Influence of remaining tooth structure and restorative material type on stress distribution in endodontically treated maxillary premolars: A finite element analysis.
abstract: BACKGROUND
  How tooth preparation and material type affect the stress distribution of endodontically treated teeth restored with endocrowns remains unclear.
  
  
  OBJECTIVE
  The purpose of this finite element (FE) study was to determine the influence of the quantity of remaining dental tissues and material type on stress distribution in endodontically treated maxillary premolars using 3-dimensional FE analysis.
  
  
  METHODS
  Five 3-dimensional FE models were constructed on the basis of the restorative methods used and the quantity of preserved tooth tissues: a sound maxillary premolar, an endodontically treated maxillary premolar restored with composite resin, and endodontically treated maxillary premolars restored with endocrowns with thicknesses of 1.0 mm, 2.0 mm, and 3.0 mm. The following endocrown materials were used: Paradigm MZ100, IPS Empress, IPS e.max CAD, and In-Ceram Zirconia. Stress distributions were analyzed under vertical and oblique loads.
  
  
  RESULTS
  As the quantity of preserved dental tissues increased, the von Mises stress in dentin decreased, and the peak von Mises strain value of the cement layer increased. When the elastic modulus of the endocrown material increased, the von Mises stress in endocrown and dentin increased, and the peak von Mises strain value of the cement layer decreased.
  
  
  CONCLUSIONS
  Although the conservative preparation of teeth for endocrowns is likely to protect the residual tooth structure, it may cause future cohesive bonding failure. An increase in the elastic modulus of the material may benefit the durability of bonding between the endocrown and the abutment tooth; however, it may cause fracture of the residual tooth structure.
authors.affiliation: Graduate student, Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Junxin
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Associate Professor, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China.
authors.forename: Qiguo
authors.initials: Q
authors.lastname: Rong
authors.affiliation: Professor, Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing, China. Electronic address: wangxiaoyan@pkuss.bjmu.edu.cn.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Professor, Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Gao
mesh_terms: D000538:Aluminum Silicates; D001641:Bicuspid; D003188:Composite Resins / Q000737:chemistry*; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D019553:Tooth, Nonvital / Q000628:therapy*; D015040:Zirconium
chemical_list: D000538:Aluminum Silicates; D003188:Composite Resins; D003764:Dental Materials; C520133:IPS e.max CAD LT; C075815:IPS-Empress ceramic; C485633:In-Ceram Zirconia; C452079:paradigm MZ100; D003776:Dental Porcelain; D015040:Zirconium