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Bond strength of cements to crown bases
Bond strength of cements to crown bases Kai Chiu Chan, D.D.S., M.S.,* Parvin Azarbal, D.D.S., Paul E. Kerber, M. A., Ph.D. *** ‘The University
M.S.,**
and
of Iowa, College of Dentistry, Iowa City, Iowa
1 eeth with weakened cusps and endodontically treated teeth require coronal protection. Complete and partial veneer crowns are often the therapy of choice for such teeth. The preparations require solid foundations and may be made of cast gold, amalgam, or composite resin. Retention of a crown depends upon the preparation and accuracy of the casting. However, the bond strength of the luting agent to dentin, to the base material, and to the restoration also contributes retentive strength to the cemented restorations. The bond strength of different cements to dentin and cast gold has been reported.‘. .’ However, the bond strength of cements to composite resin and amalgam has not been thoroughly investigated. The purpose of this study was to compare the bond strength of three types of cement to cast gold, composite resin, and amalgam.
MATERIALS
AND METHODS
Fifty-four cylinder-shaped samples of base materials with a diameter of approximately 4.7 mm and a height of approximately 4.5 mm were prepared. There were 18 each of type II cast gold alloy,? composite resin,$ and amalgam.4 A ring was attached to each sample for the tensile test (Fig. 1). The surfaces to be cemented were lightly polished with fine grid sandpaper. The samples were then brushed under running water and air dried. Zinc phosphate,11 polycarboxylate,Jl and modified zinc This study was suported by U. S. Public Health Service Grant No. 5-Sol-RR5313-16. *Professor, Operative Dentistry. **Assistant Professor, University of Tehran, School of Dentistry, Tehran, Iran. ***Assistant Professor, Preventive and Community Dentistry. ?Modulay, J. F. Jelenko and Co., New Rochelle, NY. SAdaptic, Johnson and Johnson, East Windsor, NJ. §Dispersalloy, Johnson and Johnson, East Windsor, NJ. IIFleck’s Extraordinary, Mizzy, Inc., Clifton Forge, VA. 13M Co., St. Paul, MN.
0022-3913/81/090,297
+ 03800.30.‘00
1981 The C. V. Mosby Co.
Fig. 1. Diagram of the experimental tensile test.
THE JOURNAL
OF PROSTHETIC
assembly used for
DENTISTRY
297
CHAN, AZARBAL, AND KERBER
Table I. Analysis
Amalgam Adaptic Gold Means of materials
of variance
for retentive
strength
M
P
Z
Means of cement
4.26* 2.19t 2.62 1.07 3.01 1.20 3.30 1.67
6.54 2.60 1.12 0.46 1.44 0.74 3.03 2.96
3.35 0.84 2.77 0.91 0.70 0.35 2.27 1.36
4.72 ii.38 2.17 1.12 1.71 1.27 2.87 1.36
restorative
*Mean. TStandard deviation. Legend: In Tables I to III, M = modified ZOE, P = polycarboxylate, _ f i f statistic, and p = probability of f.
materials
with cements df 2
15.27
4.13
Material
2
141.28
38.22
DO01
Cement X material
4
73.62
9.96
.cilOl
72
133.07
Error
Table IV. Analysis amalgam
ss
2 15.03 Cement 32.64 24 Error DMR (N = 9 in each cell) (P = 2.62)b (M = 2.77)
f
P
10.24
DO06
(Z = 1.12)'
.02
Z = zinc phosphate, df = degrees of freedom, SS = sum of squares,
Multiple
df
1
Cement
Table II. Analysis
of variance and Duncan Range (DMR) test for Adaptic
f
ss
df
of variance
and DMR
ss
f
V
5.94
DOS
Cement 2 48.79 Error 24 98.52 DMR (N = 9 in each cell) (P = 6.54) (M = 4.26)b
for
(Z = 3.35)'
Means of a and b do not differ. Means of c do differ from a and b.
Means of a do differ from b and c, Means of b and c do not differ.
Table III. Analysis
rial was retained on the new surface. The were again brushed under running water dried. The samples were then cemented with cement so that each material was tested three cements.
df
of variance
and DMR
for gold
ss
f
P
17.76
.COOl
Cement 2 25.08 Error 29 16.94 DMR Gold (N = 9 in each cell) (M = 3.02)” (P = 1.44)b
(Z = 0.70)'
Means of a do differ from b and e. Means of b and e do not differ.
oxide-eugenol* cement were used according to manufacturers’ instructions to cement the samples in the following order: (1) zinc phosphate cement with cast gold, (2) polycarboxylate cement with composite resin, and (3) modified zinc oxide-eugenol cement with amalgam. The cementing pressure was approximately 1 kg. The cements were allowed to set for 24 hours at 3’7” C in 100% humidity. The tensile strength test was performed on an Instron Universal test machinet with a crosshead speed of 0.05 cm/min. After the test, the cement was carefully removed and the surfaces were again slightly polished with fine grid sandpaper to ensure that no foreign mate*Fynal, L. D. Caulk Co., Milford, tInstron Corp., Canton, MA.
298
DE.
samples and air another with the
RESULTS The first analysis of variance indicated that both the cement and the material were involved in the strength of the bond. Therefore, a separate analysis was done for each material (Table I). However, the amalgam provided significantly greater bond strength than the composite resin or cast gold. When Adaptic composite resin was used, the modified zinc oxide-eugenol and polycarboxylate cements did not differ in their retentive strengths, which were greater than the bond strength of zinc phosphate cement (Table II). With gold, the modified zinc oxide-eugenol cement was stronger than both the polycarboxylate and zinc phosphate cements, which did not differ in retentive strength (Table III). With amalgam, polycarboxylate cement had significantly more retention than either the modified zinc oxide-eugenol or zinc phosphate cements, which did not differ in retentive strength (Table IV). SEPTEMBER 1981
VOLUME 46
NUMBER 3
BOND STRENGTH
DISCUSSION Cast gold, composite resin, and amalgam are often used for crown bases. Theoretically, cementing crowns to base materials with different types of cements could produce different retentive strengths. The bond strength of different types of cements to cast gold restorations has been studied’ and may relate to the film thickness. Fusayama and Iwamoto” reported that the shear resistance of cement increased when film thickness was reduced. In this study, the cast gold, composite resin, and amalgam samples were cemented to cylinders of the same material. With such an assembly, mechanical failure of the bond would occur only between the cement and material. Therefore, a true thin film cementation, similar to a clinical situation, was achieved. Cast gold, composite resin, and amalgam each have advantages and disadvantages as base materials. While cast gold bases require careful impressions, waxing, investing, and casting procedures, they provide strong and stable foundations for the crowns. Composite resin bases are easy to construct; because composite resin polymerizes in 10 to 15 minutes, preparations may be completed in the same appointment. Amalgam bases are also easy to construct. Although the preparation cannot be completed in the same appointment, amalgam bases are less costly and require less time than gold bases. Amalgam bases experience little dimensional change and have high compressive strength. Amalgam also provides
IHE JOURNAL
OF PROSTHETIC
DENTISTRY
more bond strength to cements than composite resin and cast gold (Table I). When all points are considered, it is the authors’ opinion that amalgam should be the material of choice for crown bases.
CONCLUSIONS Amalgam crown bases provided more bond strength to cements than composite resin and cast gold. Modified zinc oxide-eugenol and polycarboxylate cements served better with composite resin bases. Modified zinc oxide-eugenol cement bonded to cast gold better than polycarboxylate and zinc phosphate cements. Polycarboxylate cement bonded to amalgam better than modified zinc oxide-eugenol and zinc phosphate cements. Amalgam was the material of choice for a crown base. REFERENCES Ady, A. B., and Fairhurst, C. W.: Bond strength of two types of cement to gold casting alloy. J PROSTHET DENT 29:217, 1967. Oldham, D. F., Swartz, M. L., and Phillips, R. W.: Retentive properties of dental cements. J PROSTHETDENT 14:760, 1964. Fusayama, T., and Iwamoto, T.: Optimum cement film thickness for maximum shear resistance between teeth and restoration. Tokyo Med Dent Univ Bull R:147, 1961. Reprint requeststo: DR. IcAl CHIU CHAN UNIVERSITY OF IOWA COLLEGE OF DENTISTRY IOWA
CITY.
IA 52242
299
M.S.,**
and
of Iowa, College of Dentistry, Iowa City, Iowa
1 eeth with weakened cusps and endodontically treated teeth require coronal protection. Complete and partial veneer crowns are often the therapy of choice for such teeth. The preparations require solid foundations and may be made of cast gold, amalgam, or composite resin. Retention of a crown depends upon the preparation and accuracy of the casting. However, the bond strength of the luting agent to dentin, to the base material, and to the restoration also contributes retentive strength to the cemented restorations. The bond strength of different cements to dentin and cast gold has been reported.‘. .’ However, the bond strength of cements to composite resin and amalgam has not been thoroughly investigated. The purpose of this study was to compare the bond strength of three types of cement to cast gold, composite resin, and amalgam.
MATERIALS
AND METHODS
Fifty-four cylinder-shaped samples of base materials with a diameter of approximately 4.7 mm and a height of approximately 4.5 mm were prepared. There were 18 each of type II cast gold alloy,? composite resin,$ and amalgam.4 A ring was attached to each sample for the tensile test (Fig. 1). The surfaces to be cemented were lightly polished with fine grid sandpaper. The samples were then brushed under running water and air dried. Zinc phosphate,11 polycarboxylate,Jl and modified zinc This study was suported by U. S. Public Health Service Grant No. 5-Sol-RR5313-16. *Professor, Operative Dentistry. **Assistant Professor, University of Tehran, School of Dentistry, Tehran, Iran. ***Assistant Professor, Preventive and Community Dentistry. ?Modulay, J. F. Jelenko and Co., New Rochelle, NY. SAdaptic, Johnson and Johnson, East Windsor, NJ. §Dispersalloy, Johnson and Johnson, East Windsor, NJ. IIFleck’s Extraordinary, Mizzy, Inc., Clifton Forge, VA. 13M Co., St. Paul, MN.
0022-3913/81/090,297
+ 03800.30.‘00
1981 The C. V. Mosby Co.
Fig. 1. Diagram of the experimental tensile test.
THE JOURNAL
OF PROSTHETIC
assembly used for
DENTISTRY
297
CHAN, AZARBAL, AND KERBER
Table I. Analysis
Amalgam Adaptic Gold Means of materials
of variance
for retentive
strength
M
P
Z
Means of cement
4.26* 2.19t 2.62 1.07 3.01 1.20 3.30 1.67
6.54 2.60 1.12 0.46 1.44 0.74 3.03 2.96
3.35 0.84 2.77 0.91 0.70 0.35 2.27 1.36
4.72 ii.38 2.17 1.12 1.71 1.27 2.87 1.36
restorative
*Mean. TStandard deviation. Legend: In Tables I to III, M = modified ZOE, P = polycarboxylate, _ f i f statistic, and p = probability of f.
materials
with cements df 2
15.27
4.13
Material
2
141.28
38.22
DO01
Cement X material
4
73.62
9.96
.cilOl
72
133.07
Error
Table IV. Analysis amalgam
ss
2 15.03 Cement 32.64 24 Error DMR (N = 9 in each cell) (P = 2.62)b (M = 2.77)
f
P
10.24
DO06
(Z = 1.12)'
.02
Z = zinc phosphate, df = degrees of freedom, SS = sum of squares,
Multiple
df
1
Cement
Table II. Analysis
of variance and Duncan Range (DMR) test for Adaptic
f
ss
df
of variance
and DMR
ss
f
V
5.94
DOS
Cement 2 48.79 Error 24 98.52 DMR (N = 9 in each cell) (P = 6.54) (M = 4.26)b
for
(Z = 3.35)'
Means of a and b do not differ. Means of c do differ from a and b.
Means of a do differ from b and c, Means of b and c do not differ.
Table III. Analysis
rial was retained on the new surface. The were again brushed under running water dried. The samples were then cemented with cement so that each material was tested three cements.
df
of variance
and DMR
for gold
ss
f
P
17.76
.COOl
Cement 2 25.08 Error 29 16.94 DMR Gold (N = 9 in each cell) (M = 3.02)” (P = 1.44)b
(Z = 0.70)'
Means of a do differ from b and e. Means of b and e do not differ.
oxide-eugenol* cement were used according to manufacturers’ instructions to cement the samples in the following order: (1) zinc phosphate cement with cast gold, (2) polycarboxylate cement with composite resin, and (3) modified zinc oxide-eugenol cement with amalgam. The cementing pressure was approximately 1 kg. The cements were allowed to set for 24 hours at 3’7” C in 100% humidity. The tensile strength test was performed on an Instron Universal test machinet with a crosshead speed of 0.05 cm/min. After the test, the cement was carefully removed and the surfaces were again slightly polished with fine grid sandpaper to ensure that no foreign mate*Fynal, L. D. Caulk Co., Milford, tInstron Corp., Canton, MA.
298
DE.
samples and air another with the
RESULTS The first analysis of variance indicated that both the cement and the material were involved in the strength of the bond. Therefore, a separate analysis was done for each material (Table I). However, the amalgam provided significantly greater bond strength than the composite resin or cast gold. When Adaptic composite resin was used, the modified zinc oxide-eugenol and polycarboxylate cements did not differ in their retentive strengths, which were greater than the bond strength of zinc phosphate cement (Table II). With gold, the modified zinc oxide-eugenol cement was stronger than both the polycarboxylate and zinc phosphate cements, which did not differ in retentive strength (Table III). With amalgam, polycarboxylate cement had significantly more retention than either the modified zinc oxide-eugenol or zinc phosphate cements, which did not differ in retentive strength (Table IV). SEPTEMBER 1981
VOLUME 46
NUMBER 3
BOND STRENGTH
DISCUSSION Cast gold, composite resin, and amalgam are often used for crown bases. Theoretically, cementing crowns to base materials with different types of cements could produce different retentive strengths. The bond strength of different types of cements to cast gold restorations has been studied’ and may relate to the film thickness. Fusayama and Iwamoto” reported that the shear resistance of cement increased when film thickness was reduced. In this study, the cast gold, composite resin, and amalgam samples were cemented to cylinders of the same material. With such an assembly, mechanical failure of the bond would occur only between the cement and material. Therefore, a true thin film cementation, similar to a clinical situation, was achieved. Cast gold, composite resin, and amalgam each have advantages and disadvantages as base materials. While cast gold bases require careful impressions, waxing, investing, and casting procedures, they provide strong and stable foundations for the crowns. Composite resin bases are easy to construct; because composite resin polymerizes in 10 to 15 minutes, preparations may be completed in the same appointment. Amalgam bases are also easy to construct. Although the preparation cannot be completed in the same appointment, amalgam bases are less costly and require less time than gold bases. Amalgam bases experience little dimensional change and have high compressive strength. Amalgam also provides
IHE JOURNAL
OF PROSTHETIC
DENTISTRY
more bond strength to cements than composite resin and cast gold (Table I). When all points are considered, it is the authors’ opinion that amalgam should be the material of choice for crown bases.
CONCLUSIONS Amalgam crown bases provided more bond strength to cements than composite resin and cast gold. Modified zinc oxide-eugenol and polycarboxylate cements served better with composite resin bases. Modified zinc oxide-eugenol cement bonded to cast gold better than polycarboxylate and zinc phosphate cements. Polycarboxylate cement bonded to amalgam better than modified zinc oxide-eugenol and zinc phosphate cements. Amalgam was the material of choice for a crown base. REFERENCES Ady, A. B., and Fairhurst, C. W.: Bond strength of two types of cement to gold casting alloy. J PROSTHET DENT 29:217, 1967. Oldham, D. F., Swartz, M. L., and Phillips, R. W.: Retentive properties of dental cements. J PROSTHETDENT 14:760, 1964. Fusayama, T., and Iwamoto, T.: Optimum cement film thickness for maximum shear resistance between teeth and restoration. Tokyo Med Dent Univ Bull R:147, 1961. Reprint requeststo: DR. IcAl CHIU CHAN UNIVERSITY OF IOWA COLLEGE OF DENTISTRY IOWA
CITY.
IA 52242
299