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A simple cathode holder for electroplating copper-band impressions
A simple cathode holder for electroplating copperband impressions Rafael Grajower, Ph.D.,* and Noah Stern, D.M.D., M.S.D.** The Hebrew University-Hadassah School of Dental Medicine, Jerusalem, Israel
The electroplating of impressions in copper bands is used to improve the abrasive resistance of the resultant die surfaces. The impressions are coated with a graphite suspension]" for electrical conductance a n d t o improve electrical contact with the copper band. Usually electrical conductance is achieved by contacting the occlusal end of the copper band to the slightly concave metal platform of the cathode using sticky wax, The uncovered portion Of the cathode platform is insulated with Supported in part from the Joint Research Fund of the Hebrew University-Hadassah School of Dental Medicine. *Head, Laboratory of Dental Materials. **Senior Lecturer in Fixed Prosthodontics, Department of Oral Rehabilitation. "~Flash metallizer, Hana u Engineering Co., Inc., Buffalo, N. Y.
wax having a lower melting point, and the sides of the band are covered with soft casting-wax sheets. Possible disadvantages of this procedure are: (1) The sticky wax m a y relax and impair the electrical contact between the copper band and the electrode platform. (2) The use of w a r m wax m a y distort the impression, (3) Connecting the copper band to the platform and cleaning the platform after use is time consuming. T h e following method of cathode attachment is suggested as a way to eliminate some of these disadvantages. CATHODE ATTACHMENT T h e bend of a large copper-plated paper clip is extended to form a loop slightly smaller than the
Fig. 1. Assembly of the cathode holder. (a) The paper clip with an extended bend. (b) The trimmed loop with copper band. (c) The application of the insulating sleeve. (d) The contact block. (e) The final assembly.
0022-3913/78/0339-0285500.20/0 9 1978 The C. V. Mosby Co
THE JOURNAL OF PROSTHETIC DENTISTRY
285
GRAJOVVER AND STERN
Fig. 2. The copper band is inserted into the loop. diameter of the copper band (Fig. 1 (a)). Any metal rod of appropriate thickness may be used as a mandrel for bending. By application of pressure to the short end of the loop it is sufficiently enlarged to allow insertion of the copper band (Fig. 2). After the pressure is released the elasticity of the p a p e r clip secures the occlusal part of the band and maintains electrical contact (Fig. 1 (b)). The ends of the loop are trimmed with a cutter and insulated with plastic sleeves (Fig. 1 (c)).* The long end of the loop is *Schuricht Bremen, West Germany.
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connected to a thick insulated wire by means of a small contact block,'~ the metal screws of which are replaced by plastic ones (Fig. I (d)). T h e entrance of the contact block and the screw-heads are insulated with silicon grease* and plugs of utility wax. The copper band and the uncovered parts of the paper clip are insulated with unheated soft casting-wax sheets (Fig. 1 (e)). The procedure m a y be completed in less than 3 minutes. The paper clip cathode holders are discarded after use. No evidence has been found of insufficient electrical contact or deformation of an impression due to the pressure on a band. T h e plastic parts of the system do not deteriorate in the copperplating solutions and may be reused. This method is not indicated for impressions made with elastomeric impression materials, since pressure on the band m a y cause deformations of these impressions. Reprmt requests to: DR. R. GRAJOWER HEBREW UN[VERSITY-HADASSAHSCHOOLOF DENTAL MEDICINE P. O. Box 1172 JERUSALEM ISRAEL *Schuricht Bremen, West Germany. tElectro-Aspaka, Tel Aviv, Israel.
MARCH 1978.
VOLUME39
NUMBER3
The electroplating of impressions in copper bands is used to improve the abrasive resistance of the resultant die surfaces. The impressions are coated with a graphite suspension]" for electrical conductance a n d t o improve electrical contact with the copper band. Usually electrical conductance is achieved by contacting the occlusal end of the copper band to the slightly concave metal platform of the cathode using sticky wax, The uncovered portion Of the cathode platform is insulated with Supported in part from the Joint Research Fund of the Hebrew University-Hadassah School of Dental Medicine. *Head, Laboratory of Dental Materials. **Senior Lecturer in Fixed Prosthodontics, Department of Oral Rehabilitation. "~Flash metallizer, Hana u Engineering Co., Inc., Buffalo, N. Y.
wax having a lower melting point, and the sides of the band are covered with soft casting-wax sheets. Possible disadvantages of this procedure are: (1) The sticky wax m a y relax and impair the electrical contact between the copper band and the electrode platform. (2) The use of w a r m wax m a y distort the impression, (3) Connecting the copper band to the platform and cleaning the platform after use is time consuming. T h e following method of cathode attachment is suggested as a way to eliminate some of these disadvantages. CATHODE ATTACHMENT T h e bend of a large copper-plated paper clip is extended to form a loop slightly smaller than the
Fig. 1. Assembly of the cathode holder. (a) The paper clip with an extended bend. (b) The trimmed loop with copper band. (c) The application of the insulating sleeve. (d) The contact block. (e) The final assembly.
0022-3913/78/0339-0285500.20/0 9 1978 The C. V. Mosby Co
THE JOURNAL OF PROSTHETIC DENTISTRY
285
GRAJOVVER AND STERN
Fig. 2. The copper band is inserted into the loop. diameter of the copper band (Fig. 1 (a)). Any metal rod of appropriate thickness may be used as a mandrel for bending. By application of pressure to the short end of the loop it is sufficiently enlarged to allow insertion of the copper band (Fig. 2). After the pressure is released the elasticity of the p a p e r clip secures the occlusal part of the band and maintains electrical contact (Fig. 1 (b)). The ends of the loop are trimmed with a cutter and insulated with plastic sleeves (Fig. 1 (c)).* The long end of the loop is *Schuricht Bremen, West Germany.
286
connected to a thick insulated wire by means of a small contact block,'~ the metal screws of which are replaced by plastic ones (Fig. I (d)). T h e entrance of the contact block and the screw-heads are insulated with silicon grease* and plugs of utility wax. The copper band and the uncovered parts of the paper clip are insulated with unheated soft casting-wax sheets (Fig. 1 (e)). The procedure m a y be completed in less than 3 minutes. The paper clip cathode holders are discarded after use. No evidence has been found of insufficient electrical contact or deformation of an impression due to the pressure on a band. T h e plastic parts of the system do not deteriorate in the copperplating solutions and may be reused. This method is not indicated for impressions made with elastomeric impression materials, since pressure on the band m a y cause deformations of these impressions. Reprmt requests to: DR. R. GRAJOWER HEBREW UN[VERSITY-HADASSAHSCHOOLOF DENTAL MEDICINE P. O. Box 1172 JERUSALEM ISRAEL *Schuricht Bremen, West Germany. tElectro-Aspaka, Tel Aviv, Israel.
MARCH 1978.
VOLUME39
NUMBER3