Precision porcelain jacket crown technique

Dental technology DANIEL

H. GEHL

Precision

and

S. HOWARD

porcelain

jacket

PAYNE,

crown

Associate

Editors

technique

Edwin J. Riley, D.M.D.,* Ralph B. Sozio, D.&D.,** D.D.S.,*** M. Thomas Witcko, D.M.D.,**** and Alfred J. Sotera, D.M.D.***** Haward School of Dental Medicine, Boston, Mass.

Franklin

Casthely,

T

he term “porcelain jacket cro\vn” appeared in the dental literature in the earl) 1890’s. Manv dentists wrote articles and gavr clinics to introduce this new crowxl to the Iwofcssion.‘-’ Land,” HI 1903. dw.rihed the tcchniquv for porcelain jacket crolvn fabrication utilizing a platinum foil matris. The difficulty of manipulation, lack of accuracy. and varied strength experienced \\:ith this technique led other in\-estigators to attempt to eliminate the foil with various refractory die materials.“-:’ Howww. such attempts \verc unsuccessful because of unpredictability and impracticality. The technique presented herein is ;I practical. predictable, and accurate method of constructing an aluminous porcelain jackrt crown \vithout a IJatinunl matrix. TECHNIQUE ( I j Using any satisfacto? technique, obtain an inlpression of the prepared tooth ‘teeth) . and fabricate a master cast (Fig. 1 ’ 12) Trim the dies. and make an elastomeric impression$ of the prepared dies. (3 i Pour a nonc~ontaminating ceramic matrrial$ into the impression. providing thr refractor!~ die with an adequate base. Thr powder-liquid ratio emplo):rd is :< Cm. of po\\Tder to I c.c. of liquid. This ratio pro\:idcs adequate strength and optimum handling characteristics. Prcwntcd

tc, thv American

*Clinical

Fellow

Academy

in Probthetic

**Acsisrant Prosthetic.<.

Clinical

***Director.

Dental

****Clinical *****‘Clinical

Fellow in Pcriodontology. Instructor in Prosthetic

SImpregum, Lactona Corp., $Prop.

346

j.

Professor Ceramics

Premier Dental Philadelphia, Pa. Adcrcr,

Inc.,

I.ong

of Crown

and

Bridge

Prosthodontics,

Chicago,

III.

Dentistry. of

Prosthetic

Dentistry;

Director

of

Post-doctoral

Fixed

Laboratory.

Products Island

Dentihtry. Company, City,

.\.

Y.

Philadelphia,

Pa.;

.“eoPlex

rubber

base,

Volumr Number

34 3

Fig.

1. Bureau

Fig.

2. The

Porcelain

of Standards’ refractory

full-crown

crown

technique

347

die.

die is separated

Fig. 3. (A) The ceramic-metal agent is shown on the refractory

jacket

from

an elastomeric

agent is painted die after firing.

impression

on the refractory

die.

of the master

(B)

The

die.

ceramic-metal

(4) After setting for one hour, separate the die. Separation is easily accomplished by directing an air stream between the die and the impression (Fig. 2). (5) Paint a ceramic-metal agent* on the refractory die to the margin, providing a thin, uniform layer (Fig. 3, A). (6) Fire the refractory die (firing cycle: dry in front of the muffle for two minutes and then vacuum fire at 1,600°+2,0480 F.) (Fig. 3, B) . (7) If bare areas are observed, apply a second application of the ceramic-metal agent, and fire using the same firing cycle. (8) Apply aluminous porcelain core material,+ condense it, and fire it on the treated refractory die as recommended by the manufacturer (firing cycle: vacuum fire at 1,650°+2,0480 F.) . NOTE: The aluminous core material utilized should *Ceramic-metal +Vitadur-S

Genie, porcelain,

Ceramco, Unitex

Inc., Corp.,

Long Monrovia,

Island Calif.

City,

N. Y.

348

Riley

J, Prosthet. September,

et al.

Dent. 1975

.I

Fig. 4. (A) core.

First firing of aluminous

porcelain

Fig. 5. (A) The refractory die is eliminated is rc:trieved.

core. (B) Final firing of aluminous

porcelain

from the aluminous core. (B) The aluminous c:ore

fuse at a temperature several hundred degrees above the fusing temperature of the dentinal or incisal porcelains. (9) As expected, cracks are encountered in the aluminous porcelain with the first firing due to its inherent shrinkage (Fig. 4, A). The ceramic-metal agent, however, remains intact and fuses to the aluminous porcelain, preventing loss of adaptation. Fill the cracks, and fire the die as in step No. 8 (Fig. 4, B) . NOTE: Usually, only two firings are necessary. However, if cracks are not eliminated, repeat step No. 9. (10) Recover the core from the die with a blunt instrument under running water and ultrasonic cleaner. Thus, the refractory die is destroyed, leaving an alumi-

Volume

34

Number

3

Fig. 6. (A) of Standards’

Porcelain

The coping is placed die. (C) The prefired

on the stone die. (B) The crown on the sagger tray.

jacket

coping

crown

technique

is placed

349

on the Bureau

nous core lined with the ceramic-metal agent. This core can now serve as a coping (Fig. 5). (11) Return the coping to the working cast. Apply a suitable match of veneering porcelain, condense it, and fire it as recommended by the manufacturer (firing cycle: vacuum fire at 1,382O+1,724’ F.) . Coat the master cast die with a thin layer of petroleum jelly to prevent subsequent intrusion of porcelain under it during the build-up (Fig. 6). Normally, the crown can be fired on an ordinary sagger tray. However, to prevent any possible distortion on extremely thin aluminous cores, it is suggested that a second refractory die be utilized as a custom sagger tray during subsequent firings. (12) Shaping and adjusting can be performed at this time, and the restoration can be stained and glazed (Fig. 7, A) (firing cycle: two to four minutes at 1,724’ F.) .

ADVANTAGES The advantages follow: ( 1) elimination of the platinum foil matrix, fabrication, and (3) accuracy of fit (Figs. 7, B, and 8). The benefits of aluminous porcelain can now be consistently realized fitting restorations possessing predictable internal integrity.

(2) ease of with

well-

350

Riley

J. Prosthet.

et al.

September,

Fig. 7. (A) The finished crown on the Bureau of Standards’ die. (B) mar! gin al acdaptation of 5 to 20 p. (Original magnification x63.)

Fig. a. (A) Cross section of coping on master prox im al adaptation. (Original magnification with .m arginal

adaptation

of 14 p. (Original

Photomicrogl

die. (Bj Photomicrograph x63.) (C) Photomicrograph maghification x63.)

1Dent. 1975

z tph she, wing

showing occlur ;a1 and re !gion of shoulder

EtEr “3”

Porcelain

jacket

crown

technique

351

SUMMARY

A simple technique for construction of an aluminous porcelain crown has been described. An aluminous core is fabricated without platinum foil on a ceramic refractory die and, when retrieved, serves as a coping on the master cast. The technique and accuracy of fit are illustrated with the fabrication of an aluminous porcelain crown on the Bureau of Standards’ full-crown die. References 1. Capon, W. A.: Porcelain

Crown

in Front

Teeth

Without

Post,

Dent.

Cosmos

33:

268-270,

1891.

2. Downie, J. H.: Jacket Crown, 139-140. 3. 4.

Matteson, Gilbertson,

Catching’s

A. E.: Porcelain Crown, Ill. State J. C.: Clinic, Pacific Dent. Gazette

Compendium Dent. Sot. 8: 266-267,

of Practical Trans., 1900.

1895,

Dentistry,

1894, pp.

p. 183.

5. Land, C.: Porcelain Dental Arts, Dent. Cosmos 45: 615-620, 1903. 6. 7. 8. 9.

Lund, M. R., and Bonlie, D. R.: Baker Porcelain Restorations Without the Use of the Platinum Matrix, Int. Assoc. Dent. Res. 40: 94, 1962. (Abst.) Sotera, A. J.: A Study of the Dimensional Stability of a Ceramic Die Material, Master’s Thesis, Indiana University, 1968. Vickery, R. C., Badinelli, L. A., and Waltke, R. W.: The Direct Fabrication of Restorations Without Foil on a Refractory Die, J. Prosthet. Dent. 21: 227-234, 1969. Southan, D. E., and Dreyer, J.: Precise Porcelain Jacket Crowns, Aust. Dent. J. 17: 269273, 1972. HARVARD SCHOOL OF DENTAL 188 LONGWOOD AVE. BOSTON, MASS. 02115

MEDICINE