title: Effects of aging on the dimensional stability of custom-made mouthguards.
abstract: OBJECTIVE
  The purpose of this investigation was to assess the effects of aging on the dimensional stability of vacuum-formed, pressure-formed, and pressure-laminated custom-made mouthguards.
  
  
  METHODS
  A master model representing the dental arch was fabricated in acrylic resin. Two ethylene vinyl acetate thermoplastic materials were tested: Essix (regular) and Proform (prelaminated). The model was benchmarked in five places along the curvature of the arch. The model was used to fabricate 10 specimens for each of the following groups: 1 = vacuum-formed (3-mm) Essix; 2 = vacuum-formed (4-mm) Proform; 3 = pressure-formed (3-mm) Essix; 4 = pressure-formed (4-mm) Proform; 5 = pressure-laminated (3-mm + 2-mm) Essix; 6 = pressure-laminated (3-mm + 3-mm) Essix. Die stone was poured into the newly made specimens and measured. Aging of the specimens was simulated by reproducing cleaning cycles (48 hours' soaking in water at 60 degrees F and brushing 100 times with a soft denture brush in soapy water at 140 degrees F for 20 minutes). Die stone was poured into the aged specimens and measured. Initial and postaging measurements were compared.
  
  
  RESULTS
  All specimens showed dimensional changes post-aging, mainly decreases. Pressure-laminated specimens showed the best dimensional stability.
  
  
  CONCLUSIONS
  Aging induced various dimensional changes in mouthguards, depending on the materials and processing techniques used. Most of the dimensional change for all mouthguards occurred at the central incisor region, the most important area for the protection of the anterior teeth and the premaxilla. Pressure-laminated mouthguard specimens showed the smallest range of changes at the central incisor region, suggesting potentially improved fit, comfort, and protection.
authors.affiliation: Division of Restorative Dentistry, University of California, Los Angeles, School of Dentistry, Los Angeles, California 90095, USA.
authors.forename: Emile J
authors.initials: EJ
authors.lastname: Waked
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Lee
authors.forename: Angelo A
authors.initials: AA
authors.lastname: Caputo
mesh_terms: D000704:Analysis of Variance; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D003765:Models, Dental; D009064:Mouth Protectors; D011145:Polyvinyls; D011312:Pressure; D018709:Statistics, Nonparametric; D013997:Time Factors; D014618:Vacuum
chemical_list: D011145:Polyvinyls; C016438:ethylenevinylacetate copolymer