Intraoral repair of metal ceramic restorations

Intraoral Robert

repair E. Rada,

of metal

ceramic

restorations

D.D.S.*

LoyolaUniversity, Schoolof Dentistry, Maywood,Ill. The porcelain-fused-to-metal restoration is and will remain one of the most common restorations in dentistry. However, with the many variables that exist in fabrication and function of these restorations, there also is a potential for failure. This failure usually involves the porcelain portion of the restoration. A simple and predictable technique is extremely advantageous in prolonging the longevity of these restorations. A combination of metal preparation along with specific porcelain treatment. will result in such a repair. The specific porcelain treatment involves a combination of hydrofluoric acid etching and a saline bonding agent. The technique has been used for numerous repairs with excellent success. (J PROSTAET DENT 1991;66:348-50.)

we

lth the prevalent useof porcelain restorationsin dentistry, the ability to simply and predictably repair these restorationsis highly advantageous.Several older methods

*AssistantProfessor,Departmentof OperativeDentistry. 10/l/20617

Fig. Fig. Fig.

348

of salvagingtheserestorations have beendescribed.l However, these methods can often be as difficult as remaking the entire restoration and often require laboratory procedures.Although a few articles describebonding composite resin to porcelain,2-5little information specifically details this method of repair.s-8 The techniquesfor repair of fractured porcelain restora-

1. Possibleporcelain-fused-to-metal fracture. 2. Bevel placed on porcelain surface. Retentive groovesplaced in metal coping. 3. Porcelain surface being etched with hydrofluoric acid.

MARCH

1091

VOLUME66

NUMBERS

INTRAORAL

PORCELAIN

REPAIR

Fig. 4. Scanning electron microscope photograph of etch at ~160 and ~1300 magnification.

Ceramic

HO-&

0

-OH

&I

Adheslvs

HO-

H

R

PrimOr

Rosh

6 c

C-tbll W

>H

Fig.

TECHNIQUE 1. The porcelain surface adjacent to the fracture site is beveled with a coarsediamond bur. This preparation is crucial and removal of the glaze is essential(Fig. 1). 2. The metal is prepared with deep retentive groovesand undercuts to provide mechanical retention of the composite resin to the metal surface (Fig. 2). If the under-

JOURNAL

OF PROSTHETIC

DENTISTRY

IL& -Si-O-Si-O-Si-

5. Silane bonding chemistry.

tions include: (1) rebonding the fractured chip to the fixed restoration, (2) making a porcelain veneer to bond to the fractured porcelain, or (3) usinga compositeresinto restore the fractured porcelain. This last method is a simple, reliable, cost-effective, repair technique that is described in this article.

THE

‘R

Si -OH

lying tooth structure is inadvertently exposed,it is covered with calcium hydroxide or glassionomer liner. 3. The beveled porcelain surface is then etched with hydrofluoric acid (Ceram-Etch, Gresco Products, Inc., Stafford, Texas) for 5 minutes using a rubber dam (Fig. 3). The etching agent should be washedfrom the preparation using copious irrigation with high-volume suction and the area shouldbe dried. The porcelain surface will show a frosted appearancewhen etched, similar to that of etched enamel(Fig. 4). Hydrofluoric acid creates irregularities in the porcelain surface, allowing for a greater bonding surface.3 4. The surface should then be treated with a silanebonding agent (Scotchprime Ceramic Primer, 3M, St. Paul, 349

RADA

Fig. 6. Composite resin opaquer on metal coping. Fig. 7. Completed repair. Minn.). The Scotchprime bonding agent is painted on the porcelain and is allowed to dry. This coupling agent or adhesion promoter absorbs onto and alters the porcelain surface so that chemical and physical bonding are possible (Fig. 5). Unfilled resin is applied to both the metal and porcelain surface and is allowed to cure. A composite resin metal opaquer (Porcelain Repair Kit, 3M) is applied in a thin layer so that as little grey as possible can be seen from the underlying metal (Fig. 6). Appropriate shade-filled resins are then contoured to restore the missing porcelain. The occlusion is adjusted to achieve light contacts and eliminate interferences. The restoration is polished using routine methods (Fig. 7).

SUMMARY A simple method of repairing a fractured porcelainfused-to-metal restoration has been described. This technique uses both a silane bonding agent and hydrofluoric acid etching of the porcelain. Patient selection is vital to the predictability, as bonding to the adjacent porcelain surface

350

is extremely important. This technique has been used for numerous repairs with excellent success. REFERENCES 1. Finger IM. Salvaging the restoration.

Dent Clin North Am 1987;31:487-

503. 2. Eames WB,

3. 4. 5. 6.

Rogers LB, Feller PR, Price WR. Bonding agents for repairing porcelain and gold: an evaluation. Oper Dent 1977;2:118-24. Jochen DG, Caputo AA. Composite resin repair of porcelain denture teeth. J PROSTHET DENT 1977;38:673-9. Newberg R, Pameijer CH. Composite resins bonded to porcelain with silane solution. J Am Dent Assoc 1978;96:288-91. Wood DP, Jordan RE, Way DC, Galil KA. Bonding to porcelain and gold. Am J Orthod 1986;89:194-205. Barr&o MT, Bottaro BF. A practical approach to porcelain repair. J PROSTHET

DENT

1982;48:349-51.

7. Highton RM, Caputo AA, Matyas J. Effectiveness of porcelain repair systems. J PROSTHE-T DENT 1979;42:292-4. 8. Nowlin TP, Barghi N, Norling BK. Evaluation of the bonding of three porcelain repair systems. J PROSTHET DENT 1981;46:516-8.

Reprint requests to: DR. ROBERT E. RADA SCHOOL OF DENTISTRY LOYOLA UNIVERSITY 2160 SOUTH FIRST AVE. hhWOOD, IL 60153

MARCH

1901

VOLUME

66

NUMBER

3