title: Difference in vacuum-formed mouthguard thickness according to timing of vacuum application.
abstract: OBJECTIVE
  The purpose of this study was to examine the differences of the vacuum-formed mouthguard thickness by the timing of vacuum application.
  
  
  METHODS
  The material used in this study was a mouthguard sheet of 3.8-mm ethylene vinyl acetate. Three conditions of the timing of vacuum application were examined: the vacuum was applied immediately, 5 s after, and 10 s after the sheet holder was lowered over the vacuum-forming stand. We measured mouthguard thickness at the labial surface of the central incisor, buccal surface of the first molar, and occlusal surface of the first molar. Differences in thickness in different regions of mouthguards formed under different timing of vacuum application were analyzed by two-way analysis of variance and Bonferroni method.
  
  
  RESULTS
  We found that mouthguard thickness differed in different regions of the central incisors and the first molars (P < 0.01). The mouthguard thickness at the labial surface of the central incisor and buccal surface of the first molar became thinner when the vacuum was applied immediately after the sheet holder was lowered over the forming stand. The thickness at the occlusal surface of the first molar did not vary with the timing of vacuum application.
  
  
  CONCLUSIONS
  Our results suggest that the thicknesses of the labial surface of the central incisor and buccal surface of the first molar became larger when the vacuum was applied several seconds after the sheet holder was lowered over the forming stand. This finding is necessary knowledge when forming a mouthguard sheet.
authors.affiliation: Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
authors.forename: Fumi
authors.initials: F
authors.lastname: Mizuhashi
authors.affiliation: Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Koide
authors.affiliation: Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D004867:Equipment Design; D006801:Humans; D008963:Molar; D009064:Mouth Protectors; D014618:Vacuum
keywords: mouthguard; thickness; vacuum forming