Determining the accuracy of articulator interchangeability and hinge axis reproducibility.
BACKGROUND
It has been reported that articulators are interchangeable, which means that a clinician should be able to use one articulator and send casts to a dental laboratory with the assurance that the casts will be remounted with positional accuracy on a similar articulator.


OBJECTIVE
The purpose of the study was to determine whether mounted casts could be transferred from 1 articulator to another with positional accuracy and whether the hinge axis was reproducible in each of the articulators tested.


METHODS
This study compared left and right second premolars and first molar occlusal contact areas with respective contact areas of like-mounted casts. Five calibrated Whip Mix 3040, 5 calibrated Girrbach Artex AL, and 5 calibrated KaVo Protar articulators were tested. Impact-resistant resin casts mounted in occlusion on 1 articulator were transferred to 4 like articulators. Each of the 5 articulators of each brand was opened and closed 10 times. Ten vinyl polysiloxane right and left posterior interocclusal records of the occluded casts were made for each articulator. The use of a computerized image analysis program provided quantitative measurements of light transmitted through the occlusal records. A Kruskal-Wallis test was used for each of the 4 independent variables of the study (molar differences, premolar differences, left differences, right differences). By using a calibrated grid, a numerical assessment of positional changes was made in millimeters.


RESULTS
None of the articulator systems was found to be exact, and no single articulator was an exact duplicate of another (P<.01). The Whip Mix articulator showed greater deviation both in hinge axis repeatability and in articulator interchangeability than the KaVo. The Artex articulator provided the most consistent hinge axis repeatability and interchangeability of the 3 brands of articulators.


CONCLUSIONS
The Artex brand reproduced dental cast positions more consistently than the other articulators tested.
School of Dental Medicine, Tufts University, Boston, Mass, USA.
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Hatzi
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Millstein
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Maya
D000180:Acrylic Resins; D000704:Analysis of Variance; D001641:Bicuspid / Q000033:anatomy & histology; D002138:Calibration; D003725:Dental Articulators; D003768:Dental Occlusion, Centric; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007574:Jaw Relation Record / Q000295:instrumentation* / Q000379:methods; D003765:Models, Dental; D008963:Molar / Q000033:anatomy & histology; D011145:Polyvinyls; D012833:Siloxanes; D018709:Statistics, Nonparametric
D000180:Acrylic Resins; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane