title: Finite element stress analysis of diastema closure with ceramic laminate veneers.
abstract: OBJECTIVE
  The purpose of this study was to use finite element stress analysis to examine the relative importance of variables such as porcelain laminate veneer (PLV) extensions, loading angle, and loading level for the case of feldspathic ceramic veneering of teeth to manage diastema.
  
  
  METHODS
  A 3D maxillary central incisor including its internal anatomy and morphology was constructed with ANSYS software for different extensions of PLV. Internal boundaries defining the dentinoenamel junction, the pulp-dentinal junction, the interface between the enamel-luting cement, and the porcelain-luting cement were well defined. The von Mises stresses distribution and stress intensity were analyzed on the free extension of PLV for varying extensions, various angulations (0 degrees , 30 degrees , and 60 degrees ) on the incisal edge, and for different loading levels (50, 150, and 250 N).
  
  
  RESULTS
  The numerical values of stress were recorded. A significant difference in stress was observed. Increased stresses occurred with increased extensions, angulations, and loading levels. At 0 degrees angulation, compressive stresses were visualized in finite element analysis for various magnitudes of force. Higher stress values of 182 MPa and 211 MPa were obtained for the 2.5-mm extension in the mesial surface and in both proximal surfaces for 0 degrees angulation at 250 N magnitude of force. The stress occurring at 30 degrees and 60 degrees angulations was the combination of compressive and tensile stress. Higher values of 261 MPa and 232 MPa were observed when forces were applied on the mesial extension of the PLV and on both the proximal surfaces for 2.5 mm at 30 degrees , 250 N magnitude of force. A maximum stress value of 507 MPa was observed when PLV were increased in mesial width by 2.5 mm for 60 degrees angulation at 250 N magnitude of force.
  
  
  CONCLUSIONS
  The extensions of PLV in diastema closure have more of an esthetic than functional consideration, but critical factors such as angulations and the loading level acting on the free extension of PLV are important.
authors.affiliation: Reader, Department of Prosthodontics, SRM Dental College, Chennai, India. drgopichander@gmail.com
authors.forename: N Gopi
authors.initials: NG
authors.lastname: Chander
authors.forename: T V
authors.initials: TV
authors.lastname: Padmanabhan
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D003198:Computer Simulation; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods; D003799:Dental Stress Analysis / Q000379:methods*; D003801:Dental Veneers; D003970:Diastema / Q000628:therapy*; D020342:Finite Element Analysis; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology; D008437:Maxilla; D017680:Potassium Compounds / Q000737:chemistry; D013314:Stress, Mechanical; D016474:Weight-Bearing
chemical_list: D000538:Aluminum Silicates; D017680:Potassium Compounds; D003776:Dental Porcelain; C016447:feldspar