title: Difference in pressure-formed mouthguard thickness according to heating condition.
abstract: OBJECTIVE
  The purpose of this study was to investigate the differences of pressure-formed mouthguard thickness by varying the heating conditions within the proper heating temperature.
  
  
  METHODS
  The material used in this study was a mouthguard sheet of 3.8-mm ethylene vinyl acetate. The sheets were formed by pressure forming using a vacuum-pressure former. Three heating conditions were varied as follows: the sheet was heated until the center was displaced by 10, 15, and 20 mm from baseline. We measured the 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 by measurement region of the mouthguards formed under different heating conditions were analyzed by two-way analysis of variance and Bonferroni's method.
  
  
  RESULTS
  We found that mouthguard thickness varied in different regions of the central incisors and the first molars (P < 0.01). The incisal (cusp) region was thinner than the cervical region. There were statistically significant differences among the heating conditions at the labial surface of the central incisor (P < 0.05), and the thickness became larger as the sheet was heated. Mouthguard thickness at the buccal surface and occlusal surface of the first molar did not differ among the three heating conditions.
  
  
  CONCLUSIONS
  Our results suggest that the best heating condition of the pressure-forming method was the condition that the sheet was heated until its center displaced by 20 mm. This finding is an important fact when fabricating a mouthguard.
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; D008422:Materials Testing; D009064:Mouth Protectors; D011312:Pressure; D014618:Vacuum; D014753:Vinyl Compounds
chemical_list: D014753:Vinyl Compounds; C011566:vinyl acetate
keywords: heating condition; mouthguard; pressure forming; thickness