title: Custom-Fitted EVA Mouthguards: what is the ideal thickness? a dynamic finite element impact study.
abstract: OBJECTIVE
  The aim of this study was to evaluate the tooth stresses and strains, shock absorption, and displacement during impact of custom-fitted mouthguards with different thicknesses.
  
  
  METHODS
  Six bar-shaped specimens of the EVA were made and subjected to tensile test for elastic modulus assessment. Two-dimensional plane-strain models of a human maxillary central incisor, periodontal ligament, bone support, soft tissue, and mouthguard (MTG) were created. The mouthguards were modeled in five different thicknesses (2, 3, 4, 5, and 6 mm). One model was created without mouthguard. A nonlinear dynamic impact analysis was performed in which a rigid object hit the model at 1 m s(-1). Strain and stress (von Mises and Critical modified von Mises) distributions were evaluated, and the displacement of the mouthguard with respect to the tooth was calculated.
  
  
  RESULTS
  The mean [SD] for the EVA elastic modulus was 18.075 [0.457] MPa. The model without mouthguard showed the highest stress values at the enamel and dentin structures in the tooth crown during the impact. For the MTG models, the location of the stress concentrations changed to the root, regardless of the MTG thickness, but maximum stresses in the enamel and dentin were lower compared with the model without MTG. Increasing the mouthguard thickness did not notably decrease the stress-strain values.
  
  
  CONCLUSIONS
  It was concluded that the use of a mouthguard promoted lower stresses and strains in teeth during an impact with a rigid object. There was no substantial difference in peak stresses and strains and in shock absorption among the different mouthguard thicknesses.
authors: Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Minas Gerais, Brazil.
authors: Crisnicaw
authors: C
authors: Verissimo
authors: Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Minas Gerais, Brazil.
authors: Paulo Victor Moura
authors: PV
authors: Costa
authors: Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Minas Gerais, Brazil.
authors: Paulo Cesar Freitas
authors: PC
authors: Santos-Filho
authors: Department of Restorative Dentistry, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN, USA.
authors: Daranee
authors: D
authors: Tantbirojn
authors: Department of Bioscience Research, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN, USA.
authors: Antheunis
authors: A
authors: Versluis
authors: Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Minas Gerais, Brazil.
authors: Carlos José
authors: CJ
authors: Soares
mesh_terms: D055119:Elastic Modulus; D004867:Equipment Design; D020342:Finite Element Analysis; D006801:Humans; D009064:Mouth Protectors; D011145:Polyvinyls; D019876:Sports Equipment; D013314:Stress, Mechanical
chemical_list: D011145:Polyvinyls; C016438:ethylenevinylacetate copolymer
keywords: biomechanics; finite element analysis; impact absorption ability; mouthguard; stress