A technique for verifying centric relation at the established vertical relation

A technique est&li&ed John

1. Shannon,

for verifying centric vertical relation D.D.S.,

relatim

at the

M.Sc.*

The Ohio State University, College of Dentistry, Columbus, Ohio

T

his article describesa method of verifying centric relation at an establishedvertical relation without resetting individual posterior teeth to test the position of centric relation. TECMNIQUE

1. Thirty-four short 33O porcelain posterior teeth (right and left, upper and lower) t are cast together in four separate blocks with gold. The first premolan are not used (Fig. 1). The blocks of teeth are set together in the wax in such a manner that they intercuspate well in centric occlusion. The teeth should be in very tight occlusion, especially when seenfrom the buccal aspect (Fig. 2) . 2. The try-in appointment is prepared for by setting the anterior upper and lower teeth plus the first premolars in a position indicated by esthetics, phonetics, and mechanics (Fig. 3) . 3. The four blocks of posterior teeth are set in their respective positions (Fig. 4). 4. At the try-in appointment the position of centric relation is tested first. 5. The trial denture basesare placed in the patient’s mouth, and the ball of the index finger and the ball of the thumb on the samehand are interposed between thus upper and lower posterior teeth. The patient is asked to pull his lower jaw back and closeon his back teeth until initial contact is made; then the patient is askedto clench his teeth together. If there is an error in centric relation, it will be evident as thra incline planes of the porcelain cusps slide over each other while the patient closes from the interceptive contact position to the clenching position1 (Fig. 5). 6. If there is an error in centric relation, the upper right- and left-position block teeth and the first premolars are removed from the upper trial denture base (Fig. 6). *AssistantProfessor,Division of Prosthodontics. @uppliedby DentsplyInternational, York, Pa.

586

Shannon

J. Prosthet. December,

Dent. 1972

Fig. 1. The teeth on each of the blocks are held together with metal. Fig. 2. The upper and lower blocks are held together in centric occlusion.

Fig. 3. The anterior teeth are set on trial denture bases for the try-in appointment. Fig. 4. The posterior blocks are set in centric occlusion for try-in.

7. Quick-setting impression plaster is interposed between the teeth on the lower trial denture baseand the wax surface of the upper trial denture basewhere the upper blocks of teeth had been. The interocclusal record of centric relation is made with the same hand position as described for testing the occlusion. Removal of the upper posterior teeth a.llows the centric relation record to be made at the desired vertical relation of occlusion without any cuspal interception. 8. There must be no contact between the teeth and the material of the upper trial base when this record is made. The lower cast is remounted on the articulator by meansof the plaster interocclusal record (Fig. 7). 9. After the lower cast has been remounted in the articulator, the upper right and left blocks of teeth are reattached to the upper trial denture base in centric

Fig.

Fig. 6. The making

a new

Fig. 7. The upper

one

5. The

hand

position

for

testing

the centric

blocks of upper posterior teeth have plaster interocclusal record of centric

new before

interocclusal record of centric . . rt IS reattached to the lower

Verifying

centric

occlusion

in centric

relati~ln.

from

trial

been removed relation.

relation member

holds the lower of the articulator

the

relatio9t

bases

587

before

cast in relation to the in its new position.

occlusion, with the lower teeth and coinciding with centric relation. The trial bases are once again placed in the patient’s mouth, and centric relation is tested again for accuracy. 10. The entire procedure must be repeated if an error in centric relation can still be detected. 11. After the position of centric relation has been positively identified, the posi-

588

J. Prosthet. December,

Shannon

Dent. 197’2

tions of the anterior teeth can be changed to fulfill the requirements of esthetics for the patient. 12. At the conclusion of the try-in appointment, the posterior teeth which have been selectedspecifically for the patient will be set into the desired occlusal scheme. 13. The block posterior teeth may now be sterilized in an autoclave and made ready for usefor the next patient. SUMMARY

Blocks of porcelain teeth are used for making positive identification of errors in coincidence between centric relation and centric occlusion with a minimum amount of chair-time. The large occlusal surfaces of the 33O porcelain block teeth afford a greater tactile stimulus to the dentist as the incline planes of porcelain passover each other.2 The time involved is greatly diminished, becausethe teeth are mechanically fastened together with metal so the entire block of teeth is set in a single operation. This allows sterilization without mixing up the teeth. No matter what technique or philosophy of occlusion a dentist follows for recording centric relation, he must continually strive to prove his records to be wrong as he records the centric relation. He must not simply accept what he has done. References 1. Boucher, Company, 2. Boucher, Company, THE OHIO COLLEGE

305 w.

C. p. C. p.

STATEUNIVERSITY OF DENTISTRY

12~~

COLUIUBUS,

0.: Swenson’s Complete 146. 0.: Swenson’s Complete 150.

AVE. 0111043210

Dentures, ed. 6, St. Louis, 1970, The C. V. Mosby Dentures, ed. 6, St. Louis, 1970, The C. V. Mosby