title: Pressure generated on a simulated oral analog by impression materials in custom trays of different designs.
abstract: OBJECTIVE
  To measure the pressure exerted by maxillary edentulous impressions composed of 3 commonly used impression materials using four different impression tray configurations.
  
  
  METHODS
  The study was performed using an oral analog that simulated an edentulous maxillary arch. Three pressure transducers were imbedded in the oral analog, 1 in the mid-palate area and the other 2 in the right and left ridge (maxillary first premolar areas). Custom trays of 4 different configurations were fabricated. The 3 impression materials tested were irreversible hydrocolloid, light-body and medium-body vinyl polysiloxane, and polysulfide. A total of 128 impressions were made. The custom tray and the oral analog were mounted using a reline jig. A Satec universal testing machine was used to apply a constant pressure of 2 kg/cm(2) over a period of 5 minutes on the loaded custom tray. The pressure was recorded every 10 seconds. Factorial analysis of variance and Tukey's multiple comparison test were used to analyze the results.
  
  
  RESULTS
  A significant difference in the pressure produced using different impression materials was found (p < or =0.001). Irreversible hydrocolloid and medium-body vinyl polysiloxane produced a significantly higher pressure than light-body vinyl polysiloxane and polysulfide impression materials. The presence of holes and/or relief did not significantly alter the magnitude of pressure.
  
  
  CONCLUSIONS
  All impression materials produced pressure during maxillary edentulous impression making. Tray modification was not important in changing the amount of pressure produced. The impression materials used had more effect on the pressure produced during impression making on the simulated oral analog.
authors.affiliation: Department of Restorative Dentistry, University of Maryland, Baltimore 21201, USA. rmm002@dental.umaryland.edu
authors.forename: Radi
authors.initials: R
authors.lastname: Masri
authors.forename: Carl F
authors.initials: CF
authors.lastname: Driscoll
authors.forename: John
authors.initials: J
authors.lastname: Burkhardt
authors.forename: Anthony
authors.initials: A
authors.lastname: Von Fraunhofer
authors.forename: Elaine
authors.initials: E
authors.lastname: Romberg
mesh_terms: D000464:Alginates / Q000737:chemistry; D000704:Analysis of Variance; D003724:Dental Arch; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique / Q000295:instrumentation*; D004867:Equipment Design; D005163:Factor Analysis, Statistical; D006801:Humans; D007575:Jaw, Edentulous; D008437:Maxilla; D008953:Models, Anatomic; D010159:Palate; D011145:Polyvinyls / Q000737:chemistry; D011312:Pressure; D012833:Siloxanes / Q000737:chemistry; D013223:Statistics as Topic; D013440:Sulfides / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D014160:Transducers, Pressure; D016474:Weight-Bearing
chemical_list: D000464:Alginates; D003760:Dental Impression Materials; D011145:Polyvinyls; D012833:Siloxanes; D013440:Sulfides; C034183:vinyl polysiloxane; C032915:polysulfide