Centric relation definition: a historical and contemporary prosthodontic perspective.

Centric relation (CR) is a core topic of dentistry in general and prosthodontics in particular. The term CR has become thoroughly confusing because of many conflicting definitions. Unfortunately definition of CR changed repeatedly over past ten decades. All the existing definitions in the dental literature, for the past 81 years, are segregated into definitions from 1929 to 1970, 1970-1980, and 1980-2010 and are critically analyzed. Both PubMed (key words: centric relation/centric jaw relation) and hand searches were employed, from citation in other publications, to identify relevant articles in English language peer reviewed PubMed journals from 1956 to 2010; although the review is from 1929. Numerous definitions for CR have been given, however, no consensus exists and the definition given by a current glossary of prosthodontic terms is confusing. It relates CR to many clinically invisible parts and cannot guide a dental surgeon to record the CR following its description. The purpose of this article is not only to review all the definitions critically but to propose a self explanatory definition to minimize the confusion in the minds of dental practitioners and students for better understanding of the concept of CR. Centric relation is clinically significant since it is the only clinically repeatable jaw relation and the logical position to fabricate prosthesis.