- Email: [email protected]
Porcelain fused to gold inlays for restoration of incisal angles
Porcelain fused to gold inlays for restoration of incisal angles
Darwin W. Engen, DDS, Houston
In the technic described, porcelain inlay invest ment is used as a die material. The inlay, which has gold margins on the gingival, lingual, and in cisal step and a porcelain margin on the labial surface, is an excellent restoration for incisal angles.
84
There is a great need for a satisfactory, conserva tive restoration for maxillary anterior teeth with fractured or weakened incisal angles. To obtain a restoration with sufficient strength to withstand the forces of mastication and still give a satisfac tory esthetic appearance, it has been necessary to use porcelain jacket crowns or full veneer crowns. A more conservative technic, in which a gold in lay is fabricated to restore the incisal angle and porcelain is fused to the inlay to obtain the de sired esthetic result, is described in this paper. There has been little information in the litera ture regarding this type of restoration. The only information available describes a difficult technic in which a platinum foil matrix is used to bake the porcelain1 and one in which impressions of the tooth preparation and of the die with the casting in place are used .2 Silicate cements and acrylic resins have been frequently used to restore incisal angles. The use of these materials is undesirable because o f their many disadvantages. Some of them are of insuffi cient strength to withstand the forces of mastica tion, disintegration of the restoration which is caused by the silicate cements that are slightly soluble in mouth fluids, poor color stability, fre quent replacement which results in a definite loss of tooth structure, ,. tendency to stain at margins, and the great differential in the coefficient of thermal expansion between tooth structure and acrylic resins, which results in percolation of mouth fluids i nder the restoration.
Fig 1 ■ Note location o f pinholes, incisal step, and lingual box form ; lin e angles have been o u tlin e d w ith pencil.
A porcelain-fused-to-gold Class IV restoration has the following advantages: adequate strength, good adaptation to the cavity wall which keeps percolation at a minimum, insolubility in mouth fluids, excellent color stability, and minimal tooth reduction.
Technic ■ Cavity preparation: A Class IV inlay prepara tion is made by use of a pin in the incisal step and one in the gingival seat. The usual box form is prepared for the lingual margin. The preparation is illustrated in Figure 1. A 0.027-inch twist drill is used for pinholes that must be parallel and made in a direction that will “draw” with the labial wall o f the incisal step and the lingual wall of the box form. The 0.026-inch nylon bristles with heads are placed in the pinholes (Fig 2), and a sectional rubber base impression is taken. When the im pression is removed, the nylon pins are retained in the impression material (Fig 3). The shade is selected and a temporary restoration constructed. The impression is poured with porcelain inlay investment rather than with stone. A technic that will produce a removable die without the use of a brass pin should be utilized. A modified Di-lok tray* technic in which the impression is poured and the Di-lok tray filled in one operation pro duces satisfactory results. Although in most instances the porcelain inlay investment die can be successfully separated from the rubber base impression by use of a routine method, it is a good practice to remove the plastic tray first by sectioning it and then by dissecting the rubber base from the die with a scalpel. The die m aterial is thin around the pinholes, which makes
Fig 2 ■ Preparation w ith 0.026-inch nylon b ristle s placed in pinholes; heads have been placed on b ristles by use o f a hot in stru m e n t for re te n tio n in im pression.
Fig 3 ■ Im pression showing pins in place. Engen: PORCELAIN AND GOLD INCISAL RESTORATIONS ■ 85
Fig 4 ■ Die, made from porcelain inlay investm ent, has been sectioned and removed from Di-lok tray (left); wax pattern has been carved on die to show approxim ate contours and position o f labial m argin o f casting relative to labial surface o f tooth (right).
it fragile. As a result, the die is easily fractured if the pins are not removed in a path parallel to their insertion. Undue lateral stresses placed on the pins can be avoided if the impression is removed by the method described. When the die is obtained, 0.025-inch nylon bristles with heads are placed in the pinholes. The inlay is waxed up, leaving the labial margin about 1 to 1.5 mm short of the labial surface of the tooth. The pattern is waxed to a contour that will result in a 1.5-mm thickness of porcelain in all regions. There are no sharp angles on the regions to be veneered (Fig 4).
Fig5 ■ F inishe d in lay viewed from la bial surface (left); fin ish e d inlay show ing porcelain to gold m argin and approx im ate th ickn e ss of porcelain (right).
The inlay is then cast in high-fusing gold and prepared in the usual m anner for veneering with porcelain. The casting is placed on the porcelain inlay investment die and not removed again until the inlay is completed. After the metal conditioner and opaque layers have been fired, the porcelain is applied to the casting and die by means of a small sable brush. Because of the porosity of the die material, the moisture is drawn through the porcelain and ab sorbed by the die, which aids in condensation of the porcelain. The porcelain is over-contoured to allow for shrinkage and then fired. After the initial firing, the porcelain-to-die mar gin will be opened somewhat because of the shrink age of the porcelain. Additional wet porcelain is added at the margin by use of a brush and the por celain is drawn into the defect by capillary action. Excess porcelain is carefully carved from the mar gin, other desired corrections are made, and the porcelain is fired again. If the margin then appears to be adequate, a cuttlefish disk is used to remove the small amount of excess flash that unavoidably overlaps the in vestment, the dentist being careful not to disk away any of the die material. This procedure gives a good right-angle margin and reduces the chances of chipping, which is a problem when the flash is removed after separation. The contours and con tact with the adjacent tooth are checked, and the porcelain is glazed. The dentist carefully tries the inlay in the pa tient’s mouth, observing any regions o f interfer ence where the porcelain meets the tooth. If any are seen, they must be eliminated because undue pressure may cause the porcelain to fracture. If the fit is satisfactory, the inlay is cemented in place by use of zinc phosphate cement (Fig 5, 6).
Fig 6 ■ Finished inlay inserted in tooth on m odel as viewed from labial surface; note porcelain to tooth m argin; in patient, gingival seat should be below free gingival m argin as in other inlays (left). Lingual view (right). 86 ■ JADA, Vol. 77, July 1968
Table ■ Comparison o f plaster, stone, and porcelain inlay investm ent.
M aterial
Compressive strength (dry)
Plaster
3 ,4 0 0 Ib/sq in
to-gold inlay would have an equally strong bond relative to the surface region.
Setting expansion %
Summary Class 1 stone
6 ,0 0 0 -7 ,0 0 0 Ib/sq in
0.1 0 -0.13
Class II stone
10,000 Ib/sq in
0.06
Porcelain inlay investment
5,000 Ib/sq in *
0 .0 5 *
^Manufacturer's specifications.
Discussion Satisfactory dies were obtained with porcelain in lay investment, but meticulous handling of the ma terial was necessary. Unless the pins were parallel, it was easy to fracture the die in the regions of the pinholes, particularly when the rigid casting was placed on the die. As shown in the Table, porcelain inlay invest ment has a compressive strength greater than that of plaster but less than that of stone. Setting expansion of porcelain inlay invest ment is slightly greater than that of stone. The fit o f the casting appeared to be good, but this ex pansion can be compensated for in the casting pro cedure, if desired, by increasing the ratio of water to powder of the casting investment. However, this procedure is unnecessary. The porcelain-to-tooth margin obtained with this technic is adequate. The gold margins are easily burnished. The strength of the porcelain-togold bond has been demonstrated by the thousands of successful porcelain-fused-to-gold full crowns in service to be strong enough to withstand masti cation. It can be assumed that a porcelain-fused-
A technic has been proposed for the restoration of maxillary anterior teeth with fractured or weak ened incisal angles. In this technic, porcelain in lay investment rather than stone is used as a die material. The wax pattern is carved on the invest ment die. The casting is prepared for veneering and placed on the die, and the porcelain is fused to the gold with the die providing the labial mar gin. The result is an inlay that has gold margins on the gingival, lingual, and incisal step and a porcelain margin on the labial surface. As a re sult, no gold shows from the labial surface. The strength of gold and the esthetics of porcelain are combined to produce an excellent, conservative restoration for incisal angles.
Presented at th e jo in t m eeting o f th e Commissioned O ffi cers Association and th e C linical Society of th e US Public Health Service, Atlanta, May 1967. The author th a nks C. C. Swoope, DDS, fo r his assistance in th e developm ent o f th is technic, and Surgident, Ltd. fo r supplying the porcelain inlay investm ent. T his study was supported by gra n t no. KY67-17 from the Division o f D irect Health Services, Bureau o f Health Ser vices, USPHS. Doctor Engen was fo rm e rly a t th e US P ublic Health Ser vice Hospital, New Orleans. His present address is US Public Health Service O u tp atie n t C linic, 701 San Jacinto, Houston.
1. Howard, W.W. Porcelain fused to gold class IV inlays. J Prosth Dent 13:761 July-Aug 1965. 2. Baum, L.; Hayden, J., and Bonlie, D. Cast restorations w ith baked porcelain incisal edges fo r fractu re d young per m anent incisors. J Dent C hild 28:177 3rd q uart 1961. 3. Skinner, E.W., and P hillips, R.W. The science o f den ta l m aterials, ed 5. Philadelphia, W. B. Saunders Co., 1960.
Engen: PORCELAIN AND GOLD INCISAL RESTORATIONS ■ 87
Darwin W. Engen, DDS, Houston
In the technic described, porcelain inlay invest ment is used as a die material. The inlay, which has gold margins on the gingival, lingual, and in cisal step and a porcelain margin on the labial surface, is an excellent restoration for incisal angles.
84
There is a great need for a satisfactory, conserva tive restoration for maxillary anterior teeth with fractured or weakened incisal angles. To obtain a restoration with sufficient strength to withstand the forces of mastication and still give a satisfac tory esthetic appearance, it has been necessary to use porcelain jacket crowns or full veneer crowns. A more conservative technic, in which a gold in lay is fabricated to restore the incisal angle and porcelain is fused to the inlay to obtain the de sired esthetic result, is described in this paper. There has been little information in the litera ture regarding this type of restoration. The only information available describes a difficult technic in which a platinum foil matrix is used to bake the porcelain1 and one in which impressions of the tooth preparation and of the die with the casting in place are used .2 Silicate cements and acrylic resins have been frequently used to restore incisal angles. The use of these materials is undesirable because o f their many disadvantages. Some of them are of insuffi cient strength to withstand the forces of mastica tion, disintegration of the restoration which is caused by the silicate cements that are slightly soluble in mouth fluids, poor color stability, fre quent replacement which results in a definite loss of tooth structure, ,. tendency to stain at margins, and the great differential in the coefficient of thermal expansion between tooth structure and acrylic resins, which results in percolation of mouth fluids i nder the restoration.
Fig 1 ■ Note location o f pinholes, incisal step, and lingual box form ; lin e angles have been o u tlin e d w ith pencil.
A porcelain-fused-to-gold Class IV restoration has the following advantages: adequate strength, good adaptation to the cavity wall which keeps percolation at a minimum, insolubility in mouth fluids, excellent color stability, and minimal tooth reduction.
Technic ■ Cavity preparation: A Class IV inlay prepara tion is made by use of a pin in the incisal step and one in the gingival seat. The usual box form is prepared for the lingual margin. The preparation is illustrated in Figure 1. A 0.027-inch twist drill is used for pinholes that must be parallel and made in a direction that will “draw” with the labial wall o f the incisal step and the lingual wall of the box form. The 0.026-inch nylon bristles with heads are placed in the pinholes (Fig 2), and a sectional rubber base impression is taken. When the im pression is removed, the nylon pins are retained in the impression material (Fig 3). The shade is selected and a temporary restoration constructed. The impression is poured with porcelain inlay investment rather than with stone. A technic that will produce a removable die without the use of a brass pin should be utilized. A modified Di-lok tray* technic in which the impression is poured and the Di-lok tray filled in one operation pro duces satisfactory results. Although in most instances the porcelain inlay investment die can be successfully separated from the rubber base impression by use of a routine method, it is a good practice to remove the plastic tray first by sectioning it and then by dissecting the rubber base from the die with a scalpel. The die m aterial is thin around the pinholes, which makes
Fig 2 ■ Preparation w ith 0.026-inch nylon b ristle s placed in pinholes; heads have been placed on b ristles by use o f a hot in stru m e n t for re te n tio n in im pression.
Fig 3 ■ Im pression showing pins in place. Engen: PORCELAIN AND GOLD INCISAL RESTORATIONS ■ 85
Fig 4 ■ Die, made from porcelain inlay investm ent, has been sectioned and removed from Di-lok tray (left); wax pattern has been carved on die to show approxim ate contours and position o f labial m argin o f casting relative to labial surface o f tooth (right).
it fragile. As a result, the die is easily fractured if the pins are not removed in a path parallel to their insertion. Undue lateral stresses placed on the pins can be avoided if the impression is removed by the method described. When the die is obtained, 0.025-inch nylon bristles with heads are placed in the pinholes. The inlay is waxed up, leaving the labial margin about 1 to 1.5 mm short of the labial surface of the tooth. The pattern is waxed to a contour that will result in a 1.5-mm thickness of porcelain in all regions. There are no sharp angles on the regions to be veneered (Fig 4).
Fig5 ■ F inishe d in lay viewed from la bial surface (left); fin ish e d inlay show ing porcelain to gold m argin and approx im ate th ickn e ss of porcelain (right).
The inlay is then cast in high-fusing gold and prepared in the usual m anner for veneering with porcelain. The casting is placed on the porcelain inlay investment die and not removed again until the inlay is completed. After the metal conditioner and opaque layers have been fired, the porcelain is applied to the casting and die by means of a small sable brush. Because of the porosity of the die material, the moisture is drawn through the porcelain and ab sorbed by the die, which aids in condensation of the porcelain. The porcelain is over-contoured to allow for shrinkage and then fired. After the initial firing, the porcelain-to-die mar gin will be opened somewhat because of the shrink age of the porcelain. Additional wet porcelain is added at the margin by use of a brush and the por celain is drawn into the defect by capillary action. Excess porcelain is carefully carved from the mar gin, other desired corrections are made, and the porcelain is fired again. If the margin then appears to be adequate, a cuttlefish disk is used to remove the small amount of excess flash that unavoidably overlaps the in vestment, the dentist being careful not to disk away any of the die material. This procedure gives a good right-angle margin and reduces the chances of chipping, which is a problem when the flash is removed after separation. The contours and con tact with the adjacent tooth are checked, and the porcelain is glazed. The dentist carefully tries the inlay in the pa tient’s mouth, observing any regions o f interfer ence where the porcelain meets the tooth. If any are seen, they must be eliminated because undue pressure may cause the porcelain to fracture. If the fit is satisfactory, the inlay is cemented in place by use of zinc phosphate cement (Fig 5, 6).
Fig 6 ■ Finished inlay inserted in tooth on m odel as viewed from labial surface; note porcelain to tooth m argin; in patient, gingival seat should be below free gingival m argin as in other inlays (left). Lingual view (right). 86 ■ JADA, Vol. 77, July 1968
Table ■ Comparison o f plaster, stone, and porcelain inlay investm ent.
M aterial
Compressive strength (dry)
Plaster
3 ,4 0 0 Ib/sq in
to-gold inlay would have an equally strong bond relative to the surface region.
Setting expansion %
Summary Class 1 stone
6 ,0 0 0 -7 ,0 0 0 Ib/sq in
0.1 0 -0.13
Class II stone
10,000 Ib/sq in
0.06
Porcelain inlay investment
5,000 Ib/sq in *
0 .0 5 *
^Manufacturer's specifications.
Discussion Satisfactory dies were obtained with porcelain in lay investment, but meticulous handling of the ma terial was necessary. Unless the pins were parallel, it was easy to fracture the die in the regions of the pinholes, particularly when the rigid casting was placed on the die. As shown in the Table, porcelain inlay invest ment has a compressive strength greater than that of plaster but less than that of stone. Setting expansion of porcelain inlay invest ment is slightly greater than that of stone. The fit o f the casting appeared to be good, but this ex pansion can be compensated for in the casting pro cedure, if desired, by increasing the ratio of water to powder of the casting investment. However, this procedure is unnecessary. The porcelain-to-tooth margin obtained with this technic is adequate. The gold margins are easily burnished. The strength of the porcelain-togold bond has been demonstrated by the thousands of successful porcelain-fused-to-gold full crowns in service to be strong enough to withstand masti cation. It can be assumed that a porcelain-fused-
A technic has been proposed for the restoration of maxillary anterior teeth with fractured or weak ened incisal angles. In this technic, porcelain in lay investment rather than stone is used as a die material. The wax pattern is carved on the invest ment die. The casting is prepared for veneering and placed on the die, and the porcelain is fused to the gold with the die providing the labial mar gin. The result is an inlay that has gold margins on the gingival, lingual, and incisal step and a porcelain margin on the labial surface. As a re sult, no gold shows from the labial surface. The strength of gold and the esthetics of porcelain are combined to produce an excellent, conservative restoration for incisal angles.
Presented at th e jo in t m eeting o f th e Commissioned O ffi cers Association and th e C linical Society of th e US Public Health Service, Atlanta, May 1967. The author th a nks C. C. Swoope, DDS, fo r his assistance in th e developm ent o f th is technic, and Surgident, Ltd. fo r supplying the porcelain inlay investm ent. T his study was supported by gra n t no. KY67-17 from the Division o f D irect Health Services, Bureau o f Health Ser vices, USPHS. Doctor Engen was fo rm e rly a t th e US P ublic Health Ser vice Hospital, New Orleans. His present address is US Public Health Service O u tp atie n t C linic, 701 San Jacinto, Houston.
1. Howard, W.W. Porcelain fused to gold class IV inlays. J Prosth Dent 13:761 July-Aug 1965. 2. Baum, L.; Hayden, J., and Bonlie, D. Cast restorations w ith baked porcelain incisal edges fo r fractu re d young per m anent incisors. J Dent C hild 28:177 3rd q uart 1961. 3. Skinner, E.W., and P hillips, R.W. The science o f den ta l m aterials, ed 5. Philadelphia, W. B. Saunders Co., 1960.
Engen: PORCELAIN AND GOLD INCISAL RESTORATIONS ■ 87