Oclusion

CLINICAL RESEARCH

Comparison of the Replicability of Routinely Used Centric Relation Registration Techniques
Alireza Keshvad, DDS, PhD,1 and Raymond B. Winstanley, BDS, MDS2
Purpose: This study was conducted to determine statistically the most repeatable mandibular position of 3 centric relation methods. Materials and Methods: Three centric relation recording methods commonly reported in theliterature were selected: bimanual mandibular manipulation with a jig, chin point guidance with a jig, and Gothic arch tracing. Fourteen healthy adult volunteers (7 males and 7 females), with an average age of 26.61 4.20 years and no history of extractions, temporomandibular joint dysfunction, or orthodontic treatment, were selected for the study. Accurate casts were mounted on an articulator(Denar D4A) by means of a facebow and maximum intercuspation silicone registration record. A mechanical 3-dimensional mandibular position indicator was constructed and mounted on the articulator enabling the operator to analyze the mandibular positions in 3 spatial axes (x, anteroposterior; y, superoinferior; z, mediolateral shift). Each centric relation method was recorded four times on each subject(at baseline, 1 hour, 1 day, and 1 week at approximately the same time of day). Records were transferred to the articulator, and data were extracted using a stereomicroscope modified to accept the mandibular position indicator. Results: Variability within subjects ranged from 0.03 mm (left-side z axis for the bimanual method) to 1.6 mm (left-side y axis for the Gothic arch method). To indicate theleast variable (most repeatable) method a comparison was made using the F test. The bimanual method was the most consistent, showing between 10.11 (p 1) and 0.438 (p 0.005) times less variation than the Gothic arch method (the least consistent). The repeatability of the chin point guidance method was somewhere between the other 2 methods. Conclusions: The results of this study showed that of the3 centric relation methods evaluated, the bimanual manipulation method positioned the condyles in the temporomandibular joint with a more consistent repeatability than the other 2 methods, whereas the Gothic arch was the least consistent method. J Prosthodont 2003;12:90-101. Copyright © 2003 by The American College of Prosthodontists. INDEX WORDS: jaw relation, maxillomandibular relations,articulator, Gothic arch tracing, bimanual mandibular manipulation, chin point guidance, anterior jig, clinical research, human subject, occlusion, repeatability

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ARIOUS METHODS for assessing the validity of centric relation records have been suggested. Repeatability still remains 1 of the most

From the Department of Adult Dental Care, School of Clinical Dentistry, University of Sheffield,Sheffield, U.K. 1 Visiting Lecturer 2 Reader in Restorative Dentistry Accepted February 13, 2003 Presented as a poster at the American Association for Dental Research annual meeting, Minneapolis, MN, March 1998 Correspondence to Raymond B. Winstanley, Department of Adult Dental Care, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, S10 2TA, Sheffield, U.K. E-mail:r.winstanley@sheffield.ac.uk Copyright © 2003 by The American College of Prosthodontists 1059-941X/03/1202-0001$30.00/0 doi: 10.1016/S1059-941X(03)00036-6

suitable methods for evaluating a mandibular record to be used for articulator cast mounting, denture construction, and occlusal equilibration. If a mandibular record is physiological and provides comfort for the patient but is not reproducible, then the dentistcannot evaluate treatment outcomes. Repeatability is 1 of the criteria for accepting a centric relation record, and many investigators have used this method as a review of the literature demonstrates.

Review of the Literature
The literature on centric relation is vast, and the definition and methods of attaining centric relation

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Journal of Prosthodontics, Vol 12, No 2 ( June),...