title: Innovative gas injection technique for closed-hollow obturator.
abstract: OBJECTIVE
  The purpose of this study was to determine the proper prerequisite conditions for gas injection and the steps for applying gas injection for obturator fabrication.
  
  
  METHODS
  Optimal prerequisite conditions were investigated by using thermocoupling to verify exothermic changes in the resin during polymerization. Three experimental groups were designated: in the control group (C), resin was packed into the mold without argon gas injection; in the gas injection group (GI), after resin packing, gas was injected into the resin bulb in the mold; and in the plunger/gas injection group (PGI), after resin packing, the syringe plunger was drawn out before gas injection.
  
  
  RESULTS
  The 55 degrees C mold temperature and addition of 0.3% DMPT to the monomer liquid caused differences in exothermic temperature increase in various parts of the resin. Without gas injection and plunger drawing, porosity was observed in the thick bulbs of groups C and PGI. In group PGI, a balloon-like elliptic hollow was observed. Compared to group C, the weight reduction in group PGI was approximately 10%.
  
  
  CONCLUSIONS
  Proper mold temperature with secondary venting and the addition of DMPT were required before the injection of gas. The resulting prosthesis could be fabricated in one step and required no resin seal.
authors.affiliation: Department of Maxillofacial Prosthetics, Graduate School, Tokyo Medical and Dental University, Japan. iwasana@hotmail.com
authors.forename: Wasana
authors.initials: W
authors.lastname: Iramaneerat
authors.forename: Fumihisa
authors.initials: F
authors.lastname: Seki
authors.forename: Akihiko
authors.initials: A
authors.lastname: Watanabe
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mukohyama
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Kazunari
authors.initials: K
authors.lastname: Akiyoshi
authors.forename: Hisashi
authors.initials: H
authors.lastname: Taniguchi
mesh_terms: D001128:Argon; D017267:Dental Prosthesis Design; D006358:Hot Temperature; D006801:Humans; D010158:Palatal Obturators; D019904:Polymethyl Methacrylate; D014052:Toluidines
chemical_list: D014052:Toluidines; D001128:Argon; D019904:Polymethyl Methacrylate; C015835:dimethyl-4-toluidine