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The contraindication of restoration to centric relation: Aclinical report

Howard Sutcher, DDS, MSaCollege of Dent istry, University of I l linois at Chicago, Chicago, I l l .

M any dent ists bel ieve that an occlusion estab-l ished with the condyles in the mos t retruded posit ion inthe glenoid fossa, near or accessible to centric relation(CR), is the best way to rebuild a seriously mut i latedocclusion for al l pat ients. l-4 Howe ver, there are some pa-t ients for whom access to CR unimpeded by the teeth isclearly contraindicated.

A variety of pat ients have been treated successful ly bypositioning the mandible anteriorly in occlus ion. Anteriormandibular placement has been used in the fabrication ofcomplete dentures for many pat ients who had dif f icultywearing convent ional complete dentures.5 Dentulous pa-t ients have also been treated in this manner but have notbeen reported. Nine pat ients with idiopathic or spontane-ous orofacial dyskinesia and one with a condylotomy havebeen the subjects of numerous art ic les.6-g Pat ients withtardive dyskines ia also require anterior mandibu lar posi-t ioning when the disorder is t reated dental ly.

With many of these patients repeated attemp ts to use amandibular retruded occlusion were ineffectual or unat-tainable or even exacerbated symp toms. In contrast, man-dibular protruded occlusions helped these pat ients. Thiscl inical report describes the treatment of a pat ient who wasan except ion to the use of CR as a true maxil lomandibularregistrat ion record for removable part ial dentures.CLINICAL REPORT

A 61-year-old woman had her dent it ion careful ly recon-structed with her condyle in CR by a graduate student su-pervised by the staf f of the University of I l l inois College o fDent istry. Maxil lary reconstruct ion consisted of an eight-unit anterior fixed partial denture and a posterior remo v-able partial den ture. The mandibular remova ble partialdenture replaced a nterior and posterior teeth.

The pat ient subsequent ly had unusual subject ive andobject ive complaints. The pat ient perceived a postnasaldrip and felt that she did not have enough room for hertongue to rest comfortably in her mouth. She also had dif-f iculty swallowing. The t ip of her tongue appeared to beuncontrol lably hyperact ive and would seek sharp edges onthe maxil lary removable part ial denture. The tonguebecame so re, irr itated, and abraded.

Because the pat ient was uncomfortable with her recon-struct ion, her removable prostheses were select ively

Vwsociate Professor, Department of Restorat ive Dent istry.J PROSTHET DENT 1996;75:588-90.

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ground to provide her with a long centric. Howe ver, thesymp toms did not abate, and she visited the cl inic f re-quent ly for several ye ars.Later she reported that for 3 years her preoccupat ionwith her son, who was dying of cancer, had reduced thefrequency of her complaints to her dent ists but not thepresence of her symp toms. After the death of her son, shereturned to the University of I l linois with her numerousand unusual symp toms . Ult imately, the large number ofdent ists involved in her t reatment felt that her complaintswere psychogenic, and she was referred to me.

Successful therapy began with the belief that the pa-t ient s complaints were based in real i ty.lO By use of an al-ternate approach that was successfu l in t reat ing other pa-t ients, the pat ient s mandible was repositioned into an an-terior occlusal posit ion. While she was leaning sl ight lyforward in a posture to simulate eat ing, the pat ient wasasked to approximate her jaws in a comfortable posit ionwithout retruding or protruding the mandible. This posi-t ion was recorded by placing a rol l of doughy autopolymer-iz ing acryl ic resin on the occlusal surface of the maxil laryremovable part ial denture and by having the pat ient closeinto it until her lubricated mandibu lar teeth touchedsomething hard with a feather touch. The acryl ic resinwas aI lowed to set while the pat ient s teeth were approx-imated to form an occlusal appliance that locked hermandibular teeth into posit ion. This posit ion was morethan 9 mm anterior to their placem ent when the condylewas in CR (Fig. 1). The pat ient had an orthodont ic class I Iocclusion so severe that the anterior posit ioning of themandible was accomplished without increasing the vert i-cal dimension of occlusion. The appliance was initial ly ad-justed so that there were indentat ions approximately 1mm deep into which the mandibular teeth fi t .

Within 2 weeks the pat ient no longer perceived a post-nasal drip. Her tongue rested comfortably in her mouthwithout any evidence of hyperact iv ity, and she swallowednormally.

At a later date, to test whether she would be able to moveher mandible on her own to I ind a more advantageous po-sition, the appliance wa s ground flat. All the initial signsand symp toms reappeared by the next day. When thelocking)) fea ture was reintroduce d, all her problem s againdisappeared almost immediately. The pat ient volunteeredthat, without the locking feature of the appliance, she feltthat her mandible would dri f t backward, especial ly whenshe was sleeping on her back.

The eff icacy of locking the pat ient s mandible into a po-

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Fig. 1. Solid line, Mandibular retrnded (uncomfortable)occlusion. Dotted l&e, Ivfandibular protruded tcomfo~able)occlusion.

sition substantially anterior to CR was tested further withthe patients informed consent. With a Joe Dandy disk, ajagged area was cut into the anter ior palatal edge of theexisting maxillary removable partial denture. Even theresultant metal burs remained in place.

One week later the patient reported that she perceivedthe roughened area but simply avoided touching it with hertongne, which remained unabraded. She did not considerthe jagged area to bs a problem.

When the condyles were in CR, the tongue appeared tobe too large for the patients mouth and prot~d~ betweenthe max illary and mandibular inciso rs. When the mandimble was locked into the protruded position, the tonguerested comfortably inside the patients mouth because ad-equate space was provided (Figs . 2 and 3).

After 6 months, during which the patient reported nosymptoms or company, new removable partial dentures(RPDs) were constructed with 33-degree porcelain poste-rior teeth. These dentures locked her occlusion into thepredetermined position. The rn~~b~~ condyles weremore than 9 mm anterior to CR.

The patient was recalled at 6-month intervals for 2years, and she continued to report that her mouth wascomfortable. Her symptoms of irritated tongue, postnasaldrip, and d.ifficulty in swallowing no longer existed. Heronly complaint was with the poor esthetics of the RPDsthat were fabricated for heq she was unhappy with theappearance of the ~b~t-c~o~~ clasps.

After 2 years of follow-up, the patient was returned tothe regular routine of the dental clinic. On her next6-month recal1, a new graduate student and instructor didnot give credence to the extensive notes in the chart andcorre&ed her occlusion to allow this patient to approxi-mate her teeth w&b the condyle in CR.

Fig. 2. In arbitrary retruded occlusion, tongue pressedforward fo rcefully between max illary and mandibular in-cisors.

Fig. 3. In arbitrary protruded occlusion, tongue restedcomfortably in mouth.All her original symptoms reappearedwithin days. Then

the 33- degree teeth locking her mandible more than 9 mmanterior to CR were reintroduced. Her symptoms againdisappeared almost immediately.

This report i s anecdotal, so it lacks the safeguardsagainst bias and misinterpretation inherent in the scien-tific epistemology. However, the large number of patientswho have responded positively to a mandibular anteriorocclus ion challenge the presnmption that CR is the bestregistration treatment for all patients.

This clinical report contains three cycles of s~ptom al-leviation and relapse in the same patient. In each cyc leCR-based occlusal reconstruction led to symptoms thatwere soon resolved by anterior positioning of the mandible.When the patient% RPD was originally roconstrncted withthe mandible in a retrnded position, CR, the mandibularmuse~at~ was forced posteriorly, which rodueed space

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for the tongue. The posterior part of the tongue was pressedagainst the posterior wall o f the pharynx to reduce thepharyngeal space and cause the sensation of a postnasaldrip. Pressure of the pharynx on the posterior part of thetongue could cause avoidance behavior or hyperact iv ity inthe anterior part of the tongue. Previous studies of spon-taneous orofacial dyskinesia l ink mandibular protrudedocclusion to rel ief of l ingual hyperact iv ity.

Posterior posit ioning of the mandible in occlusion hasbeen considered the best way to rebuild a severely mut i-lated occlusion or to fabricate complete dentures. CR hasbeen considered to be a posit ion of the mandibular condylesin the glenoid fossa that is inviolate, immutable, eternal,universa l, and reproducible. It has been defined differentlyat least twice, and the concept is now becoming obso-lete.lO, l1

Wha t began simply as a reference point has achieved thestatus of an ideal physiologic posit ionl , I2 I t mus t be em-phasized that the universal applicabili ty of CR has neverbeen scient i f ically proved. Constant repet ition may wellhave created a truth, but has reproducibi li ty been con-fused with val idity? Anecdotal information suggests thatmany dent ists may soon abandon CR as ineffect ive inpract ice.

The concept of CR as a universal or ideal physiologic po-sit ion is inval id. I t is more l ikely that, with the teethoccluded, no single physiologic posit ion exists for al l peo-ple.CONCLUSIONS

1. With the teeth occluded no single posit ion of thecondyles in the glenoid fossa exists that is physiologicallyacceptable for al l pat ients.

2. Centric relation is val id only as a convenience or ref-erence posit ion. For any other use it is a specious concept.

3. Free access of the mandibular condyles to CR , withthe teeth in occlusion, is unacceptable for some pat ientswho require a mandibular protruded occlusion.

4. Further research is required to determine the per-centage of the populat ion the various groups represent.

I thank members of the staff of the University of Illinois Colleg eof Dentistry for critical reviews of this manuscript; Cyril Sad-owsky, DD S, MS, for tracing the cephalometric radiographs; andJohn Everingham, PhD, and my wife, Rosalie, for invaluable ed-itorial assistance.R EF ER EN C ES

1. Stuart CE, Stalard H. Principles involved in restoring occlusion to nat-ural teeth. J PROSTH ET DENT 1960;10:304 -13.

2. Lucia VO. Modern gnathologica l concepts-updated. Chicago: Quin-tessence, 1983.

3. Mann AW, Pankey LD. Concepts of occlusion: the PM philosophy of oc-clusal rehabi l i tation. Dent Cl in North A m 1963:621-36.

4. Damo n PE. Evaluation, diagnosis and treatment of occlusal problems.2nd ed. St. Louis, CV Mosby, 1989:261-73.

5. Sutcher HD, Beatty RA , Underwood RB. Orofacial dyskinesia: effectiveprosthetic therapy. J PROSTHE T DENT 1973;30:257-8.

6. Sutcher HD, Underwood RB, Beatty RA, Sugar 0. Orofacial dyskine-six a dental dimen sion. JAMA 1971;216:14 59-63.

7. Sutcher HD, Beatty RA , Underwood RB. Orofacial dyskinesia: effectiveprosthetic therapy. J PROSTH ET DENT 1973;30:252-62 .8. Sutcher HD, Sugar 0. Etiology and dental treatment of severe invol-

untary orofacial-cervical movem ent disorders. J PROSTHE T DENT1982;48:703-7.

9. Sutcher HD, Andria L. Occlusal therapy to correct ap ertognatbia tiermandibu lar osteotomy. Gen Dent 1985;33:212-6.

10. Sutcher HD. Special problems in restorative dentistry for wind musi-cians: four cases. Compendium Cant Dent Ed 1986;7:365-8.

11. Zwemer TJ, ed. Bowh e& cl inical de ntal terminology: a glossary of ac-cepted terms in al l discipl ines of dentistry. 3rd ed. St. Louis: C V Mosby,1982.

12. Academy of Prosthodontics. Glossary of prosthodontic terms. J PROS-TEIET DENT 1994;71:41-112 .

Reprint requests to:DR. HOWARD SLWXERDEPARTME~OFRESTORATIVEDENTISTRYUNIVERSITYOFklNOISAT&ICAGO~O~S.PAULWAST.CHICAGO, IL 60612-7212Copyright 0 1996 by The Editoria l Council of THE JOURNAL OF

F~OSTHETIC DENTISTRY.0022-3913/96/$5.00 + 0. 10/l/71655

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