Editorial
Centric Relation : Didactic or Practical ?
Julian B . WOELFEL DDS , FACD , FICD Professor Emeritus College of Dentistry
The Ohio State University Columbus , USA
Is centric relation only a didactic tool for the dental student and novice dentist , and if not so , why is it such an enigma or obscure belief ? Centric relation is defined as the most posterior relationship of the mandible to the maxillae where the anatomy of healthy muscles and joints can comfortably guide the mandible into a closed position prior to any tooth contact . It is a reproducible relationship with a hinge-type of opening and closing . It is often used to mount diagnostic casts on an articulator for the purpose of discovering the location of the premature contacts which minutely deflect the jaw forward and / or laterally . Most people have premature contacts on centric relation closures without experiencing any problems . Proprioceptive nerves surrounding the roots of all natural teeth send signals to the temporomandibular joints which enable the mandible to avoid closing onto the deflective tooth contacts , thus avoiding problems which might develop from bruxing on them ( sensitivity , fremitus , TMD , facets , etc .). With the totally edentulous patient centric relation is used to help determine the desirable vertical and horizontal relationship for the complete denture maximum intercuspal position ( MIP ). Dr . Woelfel has studied , observed and used centric relation for sixty-six years and he firmly believes that no one ( dentulous or edentulous ) experiences problems when provided with centric relation occlusion ( CR = MIP ). In fact , both retention and stability usually improve with complete dentures when the two positions coincide . How to best obtain and record centric relation on dentulous patients : the mandible should first be deprogrammed or tripodized ( each temporomandibular joint plus an incisor stop or anterior guide ). With the patient ’ s head tipped backwards , explain and rehearse the entire procedure of closing the retruded jaw firmly onto a leaf gauge or sliding forward and then backward into centric relation several times on the sliding guide . Be sure that the patient maintains the final closed centric relation position on the leaf gauge or sliding guide while you prepare and make the registration . How to best record centric relation on edentulous patients : Using a large mirror , have the patient watch closely as they move their jaw forward and backward several times with your thumb gently on their chin . Tell them when their jaw is in the correct backward position . You should feel the mandible pop back into centric after the patient has protruded and then retrudes . Explain that this is the “ back ” position that you want to record . Have the patient practice opening and closing a few more times in the “ back ” position before recording it . The centric relation registration should be made with the mandible
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