Direct bonding to porcelain: vitro study Bahram Ghassemi-Tary, Tehran,
An in
D.M.D., M.Sc.D.*
lran
A
dult orthodontics and its relationship to other fields of dentistry, especially periodontics and prosthetics, is receiving much attention in today’s literature and courses. Considering this fact, a situation might arise in which the orthodontist could be confronted with the necessity of placing an attachment on a porcelain crown or a porcelain bridge. The purpose of this article is to evaluate material which is useful in bonding directly to porcelain. Since the introduction of adhesive systems’ and their usefulness in orthodontics, clinical use and laboratory experiments have provided a variety of products and systems. Different bonding systems have been produced and investigated by many researchers and clinicians.2p6 Improvement of directly bonded brackets has aided in the success of the bonding systems.7’ ’ Researchers and clinicians have started to bring new ideas to help improve the bonding systems. Indirect bonding is one of the recent techniques to save chair time and accuracy of positioning brackets.g, lo Material and method Thirty unglazed bisque baked porcelain Ceramco metal surfaces (J. F. Jelenco & Co., Inc., New Rochelle, New York) were prepared for this research. The metal base was made in a cylindrical shape so as to be adjustable in the grips of an Instron (Instron Corporation, Canton, Massachusetts 0202 1) Model 1125 testing machine. Each sample was cleaned with absolute alcohol and air dried. A coating of Fusion (George Taub Products, Jersey City, New Jersey) was applied by brush according to the manufacturer’s recommendations. After application of Fusion, an 0.002 by 0.028 inch edgewise bracket (T. P. Laboratories, La Porte, Indiana) with a solid steel mesh pad backing was bonded to the labial surface of the porcelain teeth by an acrylic filling material, Sevritron (Amalgamated Dental Trade Distributors, Ltd., London, England). The acrylic material was applied to the mesh pad of the brackets, and they were pressed against the porcelain teeth with cotton pliers at a moderate pressure until the acrylic material was polymerized (about 5 minutes). Then all specimens were transferred for shear, tensile, and rotation tests. The Instron testing machine mode was set at a crosshead speed of 2 mm. per minute. Samples were divided into three groups of ten. Four of the samples were discarded from the study because of lack of full contact of brackets to the porcelain teeth. The first group consisted of nine samples used for the shear strength test. The second *At present Pedodontist, Research Fellow, and Graduate Boston University Goldman School of Graduate Dentistry,
80
Student in Department Boston, Mass.
0002~9416/79/070080+04$00.40/0
0
of Orthodontics,
1979 The C. V. Mosby
Co.
Volume 76 Number I
Direct bonding to porcelain
Fig.
1. lnstron
Model
1125
testing
81
machine.
group consisted of eight samples used for the tensile test, and the last group, consisting of nine samples, was used for the rotation test. The test was done as follows: The cylindrical part of the porcelain teeth was adjusted in grips of the testing machine (Fig. 1) and it was connected to the load cells by ligature wire, as shown in Fig. 2. In the shear strength test, the pull of the Instron machine was parallel to the porcelain base, and the bulk of the hardness pressure was against the lateral surface of the bracket. In the tensile strength test, the pull of the Instron machine was perpenticular to the porcelain base, with the hardness around and through the bracket slot. In the rotation test, an 0.021 by 0.025 inch wire was ligated in the slot of the bracket, and the pull of the Instron machine was parallel to the lateral side of the bracket and perpendicular to 0.021 by 0.025 inch wire. The direction of the pull was also parallel to the porcelain tooth. Each sample was then tested by applying force from 0 to 20,000 pounds, and each test was completed when the force was able to break the bond of the bracket. Results and discussion The raw shear, tensile, and coupled strength values of all samples are presented in Table I.
Am. J. Orthod. Julv 1979
Fig. 2.
Schematic
direction
of the applied
forces.
A, Rotation.
6, Tensile.
C, Shear.
A statistical summary of these data, including the mean, standard deviation, and range of all the different groups, is shown in Table II. It is clear from the analysis of the two tables that the mean shear strength is greater than the other values, as the resistance of the bracket to the pulling effect and the mean for the coupled force are within the lowest range. There was a direct relationship between fitness of bracket to porcelain and breaking point. The values which are found in all the groups are sufficient for resistance to orthodontic forces (torquing forces were not tested). The result of bonding strength for Fusion” seems acceptable, as it lies in the range of forces commonly used in orthodontics. The manufacturers of Fusion claim that this product is a bonding material to be used with gold and porcelain, and they also state that this material contains commonly used bonding chemicals and other proprietary agents. The manufacturers also claim that Fusion creates a chemical bond of acrylic or composite resins to porcelain. Surface roughness of porcelain is considered to be an important factor affecting the adhesion. The roughness can be achieved on porcelain by removing the glaze with a sandpaper disk. Of course, after completion of the orthodontic treatment and removal of brackets, porcelain can be polished with porcelain-polishing kits available on the market. Summary and conclusion Three different force strengths were tested to investigate the effect of Fusion in direct bonding of brackets to porcelain. The resistance values of shear, tensile, and rotation strength forces are acceptable in the range of forces commonly used in orthodontics. The mean shear strength had greater resistance values to breaking than two other groups. The roughness of glazed porcelain and the fit of brackets to contoured porcelain teeth seems to be of great importance in the bonding effects. The role of Fusion in direct bonding is comparable to that of other sealants which are commonly being used in direct-bonding systems. It is claimed that Fusion creates a chemical bond with acrylic or composite resins to porcelain. The technique could be summarized as follows: (l)Glaze is removed in the area which
Volume 16 Number 1
Direct
Table I. Raw, shear, tensile and coupled strength of twenty-eight
bonding
to porcelain
83
samples
(expressed in pounds) Samples
I
2
3
4
5
6
7
8
9
Group I Group II Group III
9.633 7.105 2.795
5.260 2.669 2.137
8.233 2.172 2.889
4.763 3.751 2.270
4.167 7.325 2.074
7.811 4.611 3.415
7.747 4.335 5.405
9.951 5.763 3.120
9.049 2.302
Table II. A statistical summary of shear tensile and coupled strength of twenty-eight samples
(expressed
in pounds) Mean
Group I Group II Group III
7.398 4.640 3.045
Standard
deviation 2.161 1.919 1.101
Range 4.167 2.172 2.137
- 9.951 - 7.325 - 5.405
is supposed to be bonded directly. (2) Fusion is applied over the roughened surface. (3) Acrylic or composite resin is mixed and applied on the mesh part of brackets. (4) The bracket is pressed against the porcelain teeth by moderate pressure until final polymerization. The author is indebted to the following persons: Dr. Kenneth B. Drizen, Associate Professor, Department of Orthodontics, Boston University Henry Goldman School of Graduate Dentistry, for his guidance, interest, and encouragement during the research; Dr. Fereidoon Daftary, Assistant Professor, Department of Prosthetics, New York University, New York, for his gracious assistance in preparing the porcelain samples; and Mr. David L. Whitney, Manager, Application Laboratory, Instron Corporation, Boston, Massachusetts. REFERENCES
1. Buonocore, M. G.: Principles of adhesive retention and adhesive restorative materials, J. Dent. Res 67: 382-391, 1963. 2. Gorelick, L.: Bonding metal brackets with a self-polymerizing sealant-composite: A 12-month assessment, AM. J. ORTHOD.71: 542-553, 1977. 3. Hocevar, R. A.: Direct bonding metal brackets with Concise-enamel bond system, J. Clin. Orthol. 11: 473-482, 4.
5. 6. 7. 8. 9. 10. 11.
1977.
Moser, J. B., Dowling, D. B., Greener, E. H., and Marshall, G. W.: Adhesion of orthodontic cements to human enamel, J. Dent. Res. 55: 411-418, 1976. Reynolds, R. R., and Fraunhofer, J. A.: Direct bonding of orthodontic brackets-A comparative study of adhesives, Br. J. Orthod. 3: 143-146, 1976. Mitchem, J. C., and Turner, L. R.: The retentive strengths of acid-etched retained resins, J. Am. Dent. Assoc. 89: 1107- 1110, 1974. Miura, F.: Direct bonding of plastic brackets, J. Clin. Orthod. 6: 446454, 1972. Silverman, E., Cohen, M., Gianelly, A. A., and Dietz, V. S.: A universal direct bonding system for both metal and plastic brackets, AM. J. ORTHOD.62: 236244, 1972. Silverman, E., and Cohen, M.: Current adhesives for indirect bracket bonding, AM. J. ORTHOD.65: 76-84, 1974. Moin, K., and Dogon, I. L.: Indirect bonding of orthodontic attachments, AM. J. ORTHOD.72: 261-275, 1977. Eames, W. B., Rogers, L. B., Feller, P. R., and Price, W. R.: Bonding agents for repairing porcelain and gold, J. Operative Dent. 2: 118- 124, 1977.
An in
D.M.D., M.Sc.D.*
lran
A
dult orthodontics and its relationship to other fields of dentistry, especially periodontics and prosthetics, is receiving much attention in today’s literature and courses. Considering this fact, a situation might arise in which the orthodontist could be confronted with the necessity of placing an attachment on a porcelain crown or a porcelain bridge. The purpose of this article is to evaluate material which is useful in bonding directly to porcelain. Since the introduction of adhesive systems’ and their usefulness in orthodontics, clinical use and laboratory experiments have provided a variety of products and systems. Different bonding systems have been produced and investigated by many researchers and clinicians.2p6 Improvement of directly bonded brackets has aided in the success of the bonding systems.7’ ’ Researchers and clinicians have started to bring new ideas to help improve the bonding systems. Indirect bonding is one of the recent techniques to save chair time and accuracy of positioning brackets.g, lo Material and method Thirty unglazed bisque baked porcelain Ceramco metal surfaces (J. F. Jelenco & Co., Inc., New Rochelle, New York) were prepared for this research. The metal base was made in a cylindrical shape so as to be adjustable in the grips of an Instron (Instron Corporation, Canton, Massachusetts 0202 1) Model 1125 testing machine. Each sample was cleaned with absolute alcohol and air dried. A coating of Fusion (George Taub Products, Jersey City, New Jersey) was applied by brush according to the manufacturer’s recommendations. After application of Fusion, an 0.002 by 0.028 inch edgewise bracket (T. P. Laboratories, La Porte, Indiana) with a solid steel mesh pad backing was bonded to the labial surface of the porcelain teeth by an acrylic filling material, Sevritron (Amalgamated Dental Trade Distributors, Ltd., London, England). The acrylic material was applied to the mesh pad of the brackets, and they were pressed against the porcelain teeth with cotton pliers at a moderate pressure until the acrylic material was polymerized (about 5 minutes). Then all specimens were transferred for shear, tensile, and rotation tests. The Instron testing machine mode was set at a crosshead speed of 2 mm. per minute. Samples were divided into three groups of ten. Four of the samples were discarded from the study because of lack of full contact of brackets to the porcelain teeth. The first group consisted of nine samples used for the shear strength test. The second *At present Pedodontist, Research Fellow, and Graduate Boston University Goldman School of Graduate Dentistry,
80
Student in Department Boston, Mass.
0002~9416/79/070080+04$00.40/0
0
of Orthodontics,
1979 The C. V. Mosby
Co.
Volume 76 Number I
Direct bonding to porcelain
Fig.
1. lnstron
Model
1125
testing
81
machine.
group consisted of eight samples used for the tensile test, and the last group, consisting of nine samples, was used for the rotation test. The test was done as follows: The cylindrical part of the porcelain teeth was adjusted in grips of the testing machine (Fig. 1) and it was connected to the load cells by ligature wire, as shown in Fig. 2. In the shear strength test, the pull of the Instron machine was parallel to the porcelain base, and the bulk of the hardness pressure was against the lateral surface of the bracket. In the tensile strength test, the pull of the Instron machine was perpenticular to the porcelain base, with the hardness around and through the bracket slot. In the rotation test, an 0.021 by 0.025 inch wire was ligated in the slot of the bracket, and the pull of the Instron machine was parallel to the lateral side of the bracket and perpendicular to 0.021 by 0.025 inch wire. The direction of the pull was also parallel to the porcelain tooth. Each sample was then tested by applying force from 0 to 20,000 pounds, and each test was completed when the force was able to break the bond of the bracket. Results and discussion The raw shear, tensile, and coupled strength values of all samples are presented in Table I.
Am. J. Orthod. Julv 1979
Fig. 2.
Schematic
direction
of the applied
forces.
A, Rotation.
6, Tensile.
C, Shear.
A statistical summary of these data, including the mean, standard deviation, and range of all the different groups, is shown in Table II. It is clear from the analysis of the two tables that the mean shear strength is greater than the other values, as the resistance of the bracket to the pulling effect and the mean for the coupled force are within the lowest range. There was a direct relationship between fitness of bracket to porcelain and breaking point. The values which are found in all the groups are sufficient for resistance to orthodontic forces (torquing forces were not tested). The result of bonding strength for Fusion” seems acceptable, as it lies in the range of forces commonly used in orthodontics. The manufacturers of Fusion claim that this product is a bonding material to be used with gold and porcelain, and they also state that this material contains commonly used bonding chemicals and other proprietary agents. The manufacturers also claim that Fusion creates a chemical bond of acrylic or composite resins to porcelain. Surface roughness of porcelain is considered to be an important factor affecting the adhesion. The roughness can be achieved on porcelain by removing the glaze with a sandpaper disk. Of course, after completion of the orthodontic treatment and removal of brackets, porcelain can be polished with porcelain-polishing kits available on the market. Summary and conclusion Three different force strengths were tested to investigate the effect of Fusion in direct bonding of brackets to porcelain. The resistance values of shear, tensile, and rotation strength forces are acceptable in the range of forces commonly used in orthodontics. The mean shear strength had greater resistance values to breaking than two other groups. The roughness of glazed porcelain and the fit of brackets to contoured porcelain teeth seems to be of great importance in the bonding effects. The role of Fusion in direct bonding is comparable to that of other sealants which are commonly being used in direct-bonding systems. It is claimed that Fusion creates a chemical bond with acrylic or composite resins to porcelain. The technique could be summarized as follows: (l)Glaze is removed in the area which
Volume 16 Number 1
Direct
Table I. Raw, shear, tensile and coupled strength of twenty-eight
bonding
to porcelain
83
samples
(expressed in pounds) Samples
I
2
3
4
5
6
7
8
9
Group I Group II Group III
9.633 7.105 2.795
5.260 2.669 2.137
8.233 2.172 2.889
4.763 3.751 2.270
4.167 7.325 2.074
7.811 4.611 3.415
7.747 4.335 5.405
9.951 5.763 3.120
9.049 2.302
Table II. A statistical summary of shear tensile and coupled strength of twenty-eight samples
(expressed
in pounds) Mean
Group I Group II Group III
7.398 4.640 3.045
Standard
deviation 2.161 1.919 1.101
Range 4.167 2.172 2.137
- 9.951 - 7.325 - 5.405
is supposed to be bonded directly. (2) Fusion is applied over the roughened surface. (3) Acrylic or composite resin is mixed and applied on the mesh part of brackets. (4) The bracket is pressed against the porcelain teeth by moderate pressure until final polymerization. The author is indebted to the following persons: Dr. Kenneth B. Drizen, Associate Professor, Department of Orthodontics, Boston University Henry Goldman School of Graduate Dentistry, for his guidance, interest, and encouragement during the research; Dr. Fereidoon Daftary, Assistant Professor, Department of Prosthetics, New York University, New York, for his gracious assistance in preparing the porcelain samples; and Mr. David L. Whitney, Manager, Application Laboratory, Instron Corporation, Boston, Massachusetts. REFERENCES
1. Buonocore, M. G.: Principles of adhesive retention and adhesive restorative materials, J. Dent. Res 67: 382-391, 1963. 2. Gorelick, L.: Bonding metal brackets with a self-polymerizing sealant-composite: A 12-month assessment, AM. J. ORTHOD.71: 542-553, 1977. 3. Hocevar, R. A.: Direct bonding metal brackets with Concise-enamel bond system, J. Clin. Orthol. 11: 473-482, 4.
5. 6. 7. 8. 9. 10. 11.
1977.
Moser, J. B., Dowling, D. B., Greener, E. H., and Marshall, G. W.: Adhesion of orthodontic cements to human enamel, J. Dent. Res. 55: 411-418, 1976. Reynolds, R. R., and Fraunhofer, J. A.: Direct bonding of orthodontic brackets-A comparative study of adhesives, Br. J. Orthod. 3: 143-146, 1976. Mitchem, J. C., and Turner, L. R.: The retentive strengths of acid-etched retained resins, J. Am. Dent. Assoc. 89: 1107- 1110, 1974. Miura, F.: Direct bonding of plastic brackets, J. Clin. Orthod. 6: 446454, 1972. Silverman, E., Cohen, M., Gianelly, A. A., and Dietz, V. S.: A universal direct bonding system for both metal and plastic brackets, AM. J. ORTHOD.62: 236244, 1972. Silverman, E., and Cohen, M.: Current adhesives for indirect bracket bonding, AM. J. ORTHOD.65: 76-84, 1974. Moin, K., and Dogon, I. L.: Indirect bonding of orthodontic attachments, AM. J. ORTHOD.72: 261-275, 1977. Eames, W. B., Rogers, L. B., Feller, P. R., and Price, W. R.: Bonding agents for repairing porcelain and gold, J. Operative Dent. 2: 118- 124, 1977.
