title: Interchangeability of semiadjustable articulators after 2 to 7 years of use.
abstract: OBJECTIVE
  The purpose of this study was to test the interchangeability of articulators that had been in use from 2 to 7 years and compare these results with the interchangeability of the same articulators 1 year earlier.
  
  
  METHODS
  Forty-six Whip Mix model #2240 articulators (Whip Mix Corporation, Louisville, KY) that were in clinical use from 2 to 7 years were checked for interchangeability using the Whip Mix #2245 check system. The horizontal tolerance of the check system was 94 microm. Articulators were also evaluated in the vertical dimension at 4 predetermined locations around the check system cylinders using 26-microm-thick shimstock. Vertical discrepancies between the cylinders were recorded as the thickness of 0, 1, 2, or more than 2 pieces of shimstock. Interchangeability results were compared with those determined 1 year previously using the same evaluation methods using the Exact McNemar's Test of Agreement (alpha = 0.05).
  
  
  RESULTS
  Using the Whip Mix 2245 check system, 35 (76%) articulators were interchangeable after 2 to 7 years of use. This compares to 38 (83%) that were interchangeable upon evaluation 1 year earlier. The decrease in interchangeability was not significant (p =.4531). Forty-three (94%) of the articulators had vertical discrepancies of 52 microm or less at the initial evaluation. One year later, 45 (98%) of the articulators had vertical discrepancies of 52 microm or less. After 1 year, there were significant differences in the amount of vertical space between the cylinders only at the right side (p =.014).
  
  
  CONCLUSIONS
  The Whip Mix model #2240 articulator can remain interchangeable during clinical use for 7 years, but should be routinely checked for calibration.
authors.affiliation: Department of Dental Clinical Sciences, Faculty of Dentistry, Dalhousie University, Halifax, Canada. rbprice@is.dal.ca
authors.forename: R B
authors.initials: RB
authors.lastname: Price
authors.forename: R W
authors.initials: RW
authors.lastname: Loney
authors.forename: P
authors.initials: P
authors.lastname: Andreou
mesh_terms: D002138:Calibration; D003725:Dental Articulators; D004867:Equipment Design; D006801:Humans; D007574:Jaw Relation Record / Q000295:instrumentation; D016013:Likelihood Functions; D013223:Statistics as Topic; D013499:Surface Properties; D013997:Time Factors; D014716:Vertical Dimension