title: Strengthening of a model composite restoration using shape optimization: a numerical and experimental study.
abstract: OBJECTIVE
  This study aims to validate a cavity shape optimization approach for improving the debonding resistance of dental restorations by carrying out fracture tests on restored model teeth with standard and optimized cavity designs.
  
  
  METHODS
  The bio-mimetic stress-induced material transformation (SMT) optimization method was incorporated into the finite element (FE) program ABAQUS as a user material (UMAT) subroutine. The method uses stress minimization to optimize the cavity shape of a MOD restoration in an artificial premolar with special reference to the tooth-restoration interface under occlusal loads. The mechanical performance of the optimized design was first verified through FE analysis and then compared with that of the conventional design using fracture tests on model teeth.
  
  
  RESULTS
  The SMT optimization process indicated a T-shape cavity as a more favorable design for the MOD restoration in the artificial premolar. Compared with the conventional parallel wall, or undercut design, the T-shape cavity was shown numerically to reduce the interfacial stresses by up to 69%, and experimentally to increase the mean debonding resistance of the model teeth by 23% (p<0.05).
  
  
  CONCLUSIONS
  Cavity shape optimization can help increase the debonding resistance of restored teeth by reducing the interfacial stresses between tooth and restoration under occlusal loads.
authors.affiliation: Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, 16-212 Moos Tower, 515 Delaware Street SE, Minneapolis, MN 55455, USA. lihaiyan2002@hotmail.com
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: X
authors.initials: X
authors.lastname: Yun
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: L
authors.initials: L
authors.lastname: Shi
authors.forename: A S
authors.initials: AS
authors.lastname: Fok
authors.forename: M J
authors.initials: MJ
authors.lastname: Madden
authors.forename: J F
authors.initials: JF
authors.lastname: Labuz
mesh_terms: D001732:Bite Force; D003188:Composite Resins; D019245:Compressive Strength; D003198:Computer Simulation; D003487:Cyanoacrylates; D003737:Dental Cavity Preparation / Q000379:methods*; D017005:Dental Debonding; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis / Q000379:methods; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D019279:Resin Cements; D033081:Shear Strength; D012822:Silicon Dioxide; D013314:Stress, Mechanical; D014093:Tooth, Artificial; D015040:Zirconium
chemical_list: D003188:Composite Resins; D003487:Cyanoacrylates; D019279:Resin Cements; C083568:Z100 composite resin; C029054:ethyl 2-cyanoacrylate; D012822:Silicon Dioxide; D015040:Zirconium