Construction of cast-gold crowns and fixed partial dentures by use of gold bands

CONSTRUCTION OF CAST-GOLD CROWNS DENTURES BY USE OF GOLD BANDS SAMUEL

LAVINE,

Allentown,

AND FIXED

PARTIAL

D.D.S.

Pa,

FOR MAKING single or multiple veneer and gold crowns in situations where copper tube impressions are difficult to make will be described. The procedure eliminates the use of tube impressions, dies, transfer copings, and casts for occlusal registrations. This method is of great value in making a crown directly in the mouth under a clasp of a removable partial denture. The technique is shorter than gold plating copper bands for temporary fixed partial dentures, crowns, and splints. The results are more esthetic than gold-plated copper bands, for as the gold plating wears off, the copper bands become dark.

A

TECHNIQUE

PREPARATION

OF THE

TOOTH

AND

THE

GOLD

BAND*

Prepare the tooth with a bevel shoulder slightly under the gingivae (Fig. 1). Select a gold band that fits the preparation snugly (Fig. 2). Contour the band and burnish the margins under the gingivae. Cut the band so it extends occlusally to a height of 2 mm. from the gingivae. Remove the band and serrate the incisal or occlusal margin. Lubricate the preparation with petroleum jelly and remove the excess lubricant with a cotton roll. Replace, readapt, and burnish the band on the preparation (Fig. 3). Paint self-curing acrylic resin+ between the band and the tooth and allow the resin to harden (Fig. 4). Make bite-wing roentgenograms to check the gingival fit. TECHNIQUE

UTILIZING

AN

ELASTIC

IMPRESSION

MATERIAL

Make an irreversible hydrocolloid or rubber-base impression of the involved side of the dental arch before preparing the tooth (Fig. 5). Store the impression in a humidor. Secure the band on the prepared tooth with self-curing acrylic resin painted on with the brush technique. Fill the impression of the involved tooth in the irreversible hydrocolloid or rubber-base impression with acrylic resin, and seat the entire impression over the tooth and the previously adapted serrated band. *Zephyr gold band, 36 gauge, 3/16 inch wide; sizes according Hartford, Conn. tFast-setting temporary acrylic resin, shade 21, Acrylite Co., shade 66, Lang Dental Mfg. Co., Chicago, Ill.

to copper

band

sizes.

Ney

Gold

Co.,

959

New

York,

N. Y., or

Jet

Acrylic,

960

J. Pros. Den. Sept..Oct., 1960

LAVINE

Fig.

1.-A

Fig.

bevel

shoulder

is placed

slightly

under

the gingivae.

2.

Fig.

3.

Fig. 2.-A 36 gauge, 3/16 inch wide gold band is fitted to the preparation. Fig. 3.-The band is recontoured and burnished. Enough of the serrations gingivae to engage the cold-curing acrylic resin.

Fig.

4.-Cold-curing

acrylic

resin

is painted

between harden.

the

band

and

the

tooth

are

and

above

the

allowed

to

A splint can be made by filling the entire impression with acrylic resin. The bands are secured on the correspondingly prepared teeth as described. When the acrylic resin cures, remove the crown from the tooth. Add acrylic resin where it is deficient, finish, and polish the crown (Fig. 6). If it is to be used for casting, remove any remaining impression material. If a sand blaster is available,

Volume Number

10 5

CONSTRUCTION

OF

CROWNS

AND

DENTURES

BY

GOLD

961

BANDS

sand blast the crown thoroughly. Polish the crown with stones, sandpaper disks, and pumice. If the crown is to be used as a temporary restoration, polish it with whiting. If the gold crown is to be a cast veneer crown (Fig. 7), cut a space in it for the veneer. GOLD

BAND

TECHNIQUE

WlTHOUT

A

PREVIOUS

IMPRESSION

Make a mix of fast-curing acrylic resin and adapt it over the tooth with the band previously secured to the tooth by “painted-on” acrylic resin. Mold the resin with the fingers. If it is to be used for a splint, cover the part to be splinted with acrylic resin.

Fig.

5.-A

rubber-base

or

irreversible

hydrocolloid prepared.

impression

is

made

before

the

tooth

is

Have the patient close the teeth into the soft acrylic resin, and remove the resin after it cures. Finish the crown or splint, and polish as described previously. PREPARATION

FOR

A

FULL

VENEER

CROWN

Cut the desired space for the veneer in the acrylic resin crown. Form an undercut edge around the veneer with a No. 14 wheel bur. Flow a thin film of wax over the face of the veneer and add bonding material* according to the manufac turer’s instructions (Fig. 7). ’ It is advantageous to make a double check on the casting procedure. An alginate or rubber-base impression is made with the acrylic resin crown or splint in place. The cast is then poured in the following manner. Block out any undercuts within the crowns with modeling clay. Push the crowns into a mound of impression plaster so that the plaster forms a matrix for the root of the die. When the plaster has set, pour low-fusing die metal into the crowns imbedded in the plaster matrix. Break the plaster matrix and remove the crown and die. Trim the die root. *Tentaform,

Philadelphia

Dental

Co.,

Philadelphia,

Pa.

962

J. Pros. Den. Sept.-Oct., 1960

LAVINE

Place the crown with the die back into the impression which was kept in a humidor. Secure the die to the impression tray with paper clips and sticky wax, and pour a stone cast. The master cast enables the dentist or laboratory technician to carve the veneer accurately and to check the next procedure, waxing the facing for the cast veneer crown.

Fig. 6.

Fig.

Fig. B.-The gold band is covered with acrylic resin. Fig. 7.-Space for the veneer is cut in the acrylic resin, to the resin.

CASTING

and

7.

the bonding

material

is added

PROCEDURES

The casting procedure differs slightly from the technique for wax patterns because of the physical properties of the acrylic resin after investing and during the burnout. The physical properties of acrylic resin that affect the casting are: (1) acrylic resin does not become as fluid as wax prior to its ignition and volatilization, (2) because of its density up to the point of ignition, the resin does not penetrate the investment as fluid wax does, (3) unless the acrylic resin is allowed to volatilize freely, internal pressure and turbulence are set up within the mold, and (4) hygroscopic expansion cannot be obtained because of the hardness of the acrylic resin.

Fig. Fig. S.-The pattern. Fig. 9.-The

completed acrylic

Fig.

8. casting

resin

facing

shows

the

nobs

is heat cured

of gold

formed

on the crown.

9.

by the bonding

material

in

the

EkIzE:”

CONSTRUCTION

OF

CROWNS

AND

DENTURES

BY

GOLD

BANDS

963

The investment and burnout technique is completed as follows. Line the casting rings with one layer of asbestos. Invest the pattern in a threeto-one mix of a nonoxidizing inlay investment.* Allow the investment to set for 30 minutes and place the casting ring, with the sprue hole up, in a cold furnace. The sprue must be up to relieve internal pressure and turbulence and allow free volatilization of the resin. Heat the furnace to 1,250” F. and maintain this temperature for 10 minutes. Cast the restoration using any desired casting technique (Figs. 8 and 9). SUhfMARY

A procedure is described which permits the appearance, fit, occlusion, and proximal contacts of crowns to be checked accurately prior to casting. This technique eliminates the complicated systems of recording jaw relationships and using copper-tube impressions and transfer copings. This method enables the dentist to carry out his own laboratory procedures satisfactorily. 244

NORTH AI.LENTOWN,

SIXTH PA.

ST.

*Whip-Mix

Beauty

Cast,

Whip-Mix

Corp.,

Louisville,

Ky.