title: Difference in the thickness of mouthguards fabricated from step-type polyolefin-polystyrene copolymer sheets differently arranged v-shaped grooves.
abstract: OBJECTIVE
  The aim of this study was to evaluate the change in thickness of different types of step-type mouthguard sheets after suction molding in response to heating conditions for more effective use.
  
  
  METHODS
  Four types of mouthguard sheets (Impact Guard(®)) were compared: a step-type sheet; a step-type sheet with a v-shaped groove 30 mm from the anterior end; a step-type sheet with a v-shaped groove at the inferior margin of the step portion; and a step-type sheet with a v-shaped groove at the center of the step portion. The working model was trimmed to a height of 20-mm at the incisor and 15-mm at the first molar. The thickness of sheet was measured at points defined on the incisor and molar portion. The heating condition was defined when the sheet sagged by 15-mm below the level of the clamp. Differences in the percent change in thickness from types of sheets were analyzed using Scheffé's multiple comparison test. Additionally, the sheet type of thickness change with smallest was compared between the 15-mm and 20-mm sheet-sagging condition by paired t-test.
  
  
  RESULTS
  The sheet with a v-shaped groove at the center of the step portion showed smallest reduction in thickness. With this type of sheet, no significant difference in thickness was observed under heating conditions.
  
  
  CONCLUSIONS
  The present results demonstrate the thickness of the incisor and molar portions of a step-type mouthguard sheet can be maintained by creating a v-shaped groove at the center of the step portion, regardless of heating condition.
authors.affiliation: Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, 1-8, Hamaura-cho, Chuo-ku, Niigata 951-8580, Japan. mutsumit@ngt.ndu.ac.jp
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Takahashi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Koide
authors.forename: Fumi
authors.initials: F
authors.lastname: Mizuhashi
mesh_terms: D004867:Equipment Design; D006361:Heating; D009064:Mouth Protectors; D011090:Polyenes; D011137:Polystyrenes
chemical_list: D011090:Polyenes; D011137:Polystyrenes; C035051:PL 732