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Tensile bond strength of a composite resin cement for bonded
prosthesis to various dental alloys
Jos4 Henrique Rubo, DDS, a and Luiz Fernando Pegoraro, DDS b
Dental Sch0o] of Bauru, University of S~0 Paul0, S~0 Paule, Brazil
The development of composite resin cements that chemically bond to dental alloys has
improved the construction of resin-bonded prostheses. Composite resins can be
selected for various situations, but specific clinical situations may require different
alloys. This study evaluated the ability of a composite resin cement to bond to various
dental alloys of different compositions. Ten pairs of disks for each alloy (two NiCr, two
NiCrBe, one CuAI, one gold type IV, and one gold for metal ceramic) were bonded to a
composite resin cement after air abrasion was performed with aluminum oxide. The
disks were then rinsed in tap water and were ultrasonically cleaned in distilled water
for 2 minutes. The tensile tests exhibited greater values for alloys ultrasonically
cleaned, and the best results were recorded by NiCr and NiCrBe alloys. (J PROSTHET
DENT 1995;74:230-4.)
The development of composite resins that chemi-
cally bond to enamel and air-abraded base metal alloys has
improved the construction of adhesive fLxed partial den-
tures. Techniques such as electrolytic etch and silicoating,
despite their good bond strength, require expensive labo-
ratory equipment. Errors in the estimation of surface area
of the retainer for electrolytic etching may cause great
variations in bond strength. A simpler and more reliable
technique must be used. 1' 2 Certain metal structures do not
require mechanical retention to bond to the luting agents.
Researchers have conducted studies that have demon-
strated that some composite resins designated for this
purpose, especially Panavia-Ex cement (Kuraray Co., To-
kyo, Japan), have recorded greater bond strengths than
have other systems. 3, 4
This study evaluated the possible use of Panavia-Ex ce-
ment with various dental alloys of different compositions
and also verified the influence of ultrasonic cleaning of the
metal before it was bonded to the composite resin cement.
MATERIAL AND METHODS
Ten pairs of disks of each alloy listed in Table I were
formed from wax patterns made in a matrix. The resulting
disks were 2 mm thick and had two diameters: 10 and 12
mm. A standardized loop was cast to the disks for attach-
ment to a testing machine.
After casting was done, the disks were cleaned and
ground with 600-grit sandpaper to have two parallel flat
aAssistant Professor, Department of l~'osthodontics.
bAssociate Professor, Department of Prosthodontics.
Copyright 9 1995 by The Editorial Council of THE JOURNAL OF
PROSTHETIC DENTISTRY.
0022-3913/95/$3.00 + 0. 10/1/63725
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Fig. 1. Metallic cylinder.
230 THE JOLrRNAL OF PROSTHETIC DENTISTRY VOLUME 74 NUMBER 3
RUBO
AND PEGORARO THE JOURNAL OF PROSTHETIC DENTISTRY
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Fig. 2. A, Metallic cylinder. B, Duralay acrylic resin. C, Adhesive tape. D, Disk. E, static
load.
Table
I. Alloys used in this study
Product name Type
Manufacturer
Durabond MS NiCr
Unibond NiCr
Biobond II NiCrBe
Co Span VS NiCrBe
Duracast MS CuA1
Wilkinson AuAgCu
Degudent U AuPdPt
Dental Gaucho Marquart e Cia. Ltda., Brazil
Unitek Co., Monrovia, Calif.
Dentsply Int. Inc., York, Pa.
Ceramometal Ltda., Porto Alegre, Brazil
Dental Gaucho Marquart e Cia. Ltda., Brazil
Coimpa Ltda., Brazil
Coimpa Ltda., Brazil
surfaces and were then subjected to four thermal cycles to
simulate a porcelain firing surface:
A metallic cylinder was used to align two disks during
cementation. This cylinder had a central slit and two con-
centric bases with two different diameters: the base was
10 • 3 mm, and the superior surface was 12 • 1 mm (Fig.
1).
The two metal disks were fixed surface-to-surface to
standardize space for the luting agent with 60 ~m thick
adhesive tape (Scotch double-face adhesive tape, 3M Co.,
St. Paul, Minn.). These disks were retained inside the cyl-
inder. Acrylic resin (Durallay-Relliance Dental Mfg. Co.,
Worth, Ill.) was added on the external surface of the disk
with the smaller diameter, whereas the larger disk was
sustained in position by the superior shoulder in the cyl-
inder. Acrylic resin was also added between the larger disk
and head of a static load to ensure complete contact on both
sides of the disk. After the acrylic resin was cured, the tape
was removed, and space for the luting agent was stan-
dardized (Fig. 2).
Before cementation, the surfaces were treated by two
methods: for group A the surfaces were air-abraded with
aluminum oxide and were cleaned in tap water, and for
group B the surfaces were air-abraded with aluminum ox-
ide and were ultrasonically cleaned for 2 minutes in
distilled water.
The dental adhesive Panavia-Ex cement was mixed ac-
cording to the manufacturer's instructions. It was applied
to internal surfaces of two disks that were returned to the
cylinder and was maintained under a static load of 5 kg for
SEPTEMBER 1995 231
THE JOURNAL OF PROSTHETIC DENTISTRY RUBO AND PEGORARO
9O
Tensile 80
Bond
Strength 70
(kgffcm 2)
60
50
40
30
20
10
0 Durabond Co Span VS Unibond Biobond II Wilkinson Duracast Degudent
Alloys
l
Group A
I I Group B
Fig. 3. Mean values of tensile bond strength between Panavia-Ex cement and alloys
tested.
Table
II. Means (in kg/cm 2) and standard deviations of
bond strength of samples cemented with Panavia-Ex
cement
Alloy Group Mean SD
Durabond A 78,30 4,58
B 81,09 7,09
Unibond A 77,56 7,99
B 79,55 8,89
Biobond II A 67,86 4,05
B 69,21 3,45
Co Span Vs A 78,23 7,04
B 83,38 12,19
Duracast A 55,38 3,57
B 63,10 5,09
Wilkinson A 54,92 5,60
B 56,26 6,76
Degudent U A 29,40 2,78
B 53,37 3,84
Group A, cleaned in tap water; group B, ult~'asonic cleaning.
N = 10 for each sample.
Table
III. Two-way analysis of variance
Sum of Mean
Source dr* squares square F
Alloys 6 27517,1 4586,18 110,768t
Treatments 1 1598,06 1598,06 38,5975t
Interaction 6 1979,56 329,927 7,96862t
Error 126 5216,81 41,4033
Total 139 36311,5
*f (6;126) = 2,1; f (1;126) = 3,84; f (6;126) = 2,1.
tSignificant.
6 minutes. After the excess was removed, margins were
covered with a gel (Oxyguard, Kuraray Co., Tokyo, Japan),
because this material does not cure in the presence of ox-
ygen. The disks were stored in water at 37 ~ C for 24 hours,
and the tensile tests were recorded in a universal testing
machine (Dinamometros Kratos Ltd., S~o Paulo, Brazil) at
a crosshead speed of 0.5 mm/minute.
RESULTS
AND DISCUSSION
Table II lists the means and standard deviations of
samples luted with Panavia-Ex cement. The data from
Table II were computed by a two-way analysis of variance
(ANOVA) to verify the differences among alloys and
surface treatments. The analysis presented in Table III
identified significant differences among alloys (p < 0.01),
treatments (p < 0.01), and interactions between groups
(p < 0.01). The multiple comparisons with the Tukey test
revealed significant differences among alloys within the
two groups (p < 0.05) (Tables IV through VI).
The analyses disclosed that specimens of NiCr and
NiCrBe alloys were superior to the other metals despite the
surface treatment and that these results were in agree-
ment with those of former investigations (Fig. 3). 2-5 Among
the NiCr and NiCrBe alloys, Biobond II recorded the low-
est bond strengths and was statistically significant com-
pared with Durabond and Co Span V S alloys.
CuA1 alloys had less bonding strengths than NiCr and
NiCrBe alloys, but they were similar to AuAgCu alloys and
were far superior to AuPdPt alloys. Statistical differences
were evident among these alloys. The CuA1 alloy was in-
troduced in this study to see whether it could be used as a
retainer of adhesive fixed partial dentures because of its
cost-effectiveness and popularity. The success of this pros-
thesis depends not only on the bond strength of enamel/
232 VOLUME 74 NUMBER 3
RUBO AND PEGORARO THE JOURNAL OF PROSTHETIC DENTISTRY
Table
IV, Differences between mean tensile bond strength for specimens cleaned in tap water (Tukey test)
Durabond Unibond Biobond II Co Span VS Duracast Wilkinson
Durabond
Unibond 0.73
Biobond II 10.43" 9.69
CO Span VS 0.06 0.67 10.36"
Duracast 22.72* 21.28" 12.28" 22.65*
Wilkinson 23.37* 22.64* 12.29" 23.31" 0.65
Degudent U 48.49* 48.15" 38.46* 48.82* 26.17" 25.51"
*Significant (critical value = 9.84).
Table
V. Differences between mean tensile bond strength for specimens ultrasonically cleaned (Tukey test)
Durabond Unibond Biobond II Co Span V8 Duracast Wilkinson
Durabond
Unibond 1.53
Biobond II 11.87" 10.33"
CO Span VS 5.29 6.83 17.16"
Duracast 17.98" 16.45" 6.11 23.28*
Wilkinson 24.83* 23.29* 12.95" 30.12" 6.84
Degudent U 27.72* 26.18" 15.84" 33.01" 9.73 2.89
*Significant (critical value = 9,84).
Table
VI. Differences between mean tensile bond strength for specimens under different cleansing methods (Tukey test)
Group B
Co Span Degudent
Group A Durabond Unibond Biobond II VS Duracast Wilkinson U
Durabond 2.79 1.25 9.08 8.08 15.19" 22.03* 24.93*
Unibond 3.52 1.99 8.34 8.82 14.45" 21.30" 24.19"
Biobond II 13.22" 11.68" 1.35 18.51" 4.76 11.60" 14.49"
CoSpan VS 2.85 1.31 9.01 8.14 15.13" 21.97" 24.86*
Duracast 25.70* 24.17" 13.83" 31.00" 7.72 0.87 2.01
Wilkinson 26.16" 25.30* 1&29 31.45" 8.17 1.33 1.55
Degudent U 51.58" 50.14" 39.81" 56.97* 33.69* 26.85* 23.96*
Group A, cleaned in tap water; group B, ultrasonic cleaning.
*Significant (critical value = 9.84).
resin/metal but also on the indications for placement of
resin-bonded prostheses, precise abutment design, and
suitable occlusal relationships. If these requirements are
met, CuA] alloys can be used as retainers for resin-bonded
prostheses.
Bonding between Panavia-Ex composite resin cement
and metal is possible because of a covalent link between
the phosphate monomer and metallic ions on the oxide
layer of the metal surface. Consequently, differences in
bond strength verified among alloys must be related to a
greater or lesser attraction of the monomer to the compo-
nents of alloys. 6 Studies conducted by Omura et al. 7 and
Wada 8 illustrated that the phosphate monomer of Pana-
via-Ex composite resin cement had a greater attraction to
basic metals, which was also confirmed in this research
with NiCr and NiCrBe alloys.
The bonding strengths of AuPdPt alloys were far inferior
to those of the other alloys, but two factors must be consid-
ered: the low amount of basic metal in the composition of
the AuPdPt alloys and an inadequate surface treatment
before bonding. The latter factor was critical, because
when the surface was cleaned in ultrasonic bath the results
almost doubled. Ultrasonic cleaning in distilled water con-
siderably enhanced the bond strength of AuPdPt/Pana-
via-Ex composite resin cement and did not interfere with
other alloys. This finding rejected the hypothesis that ul-
trasonic cleaning eliminated debris not removed by sand-
blasting of the metal. Although this procedure improved
SEPTEMBER 1995 233
THE JOURNAL OF PROSTHETIC DENTISTRY RUBO AND PEGORARO
the bond strength, the best surface treatment for AuPdPt
alloys is still tin electroplating, s, 9
CLINICAL IMPLICATIONS
The values recorded in this study supported the prom-
ising clinical results with Panavia-Ex cement and NiCr
and NiCrBe alloys. This composite resin cement can also
be used for dowel and crown cementation, and new
perspectives are being entertained for the use of this
cement with other alloys. However, the appropriate sur-
face treatment for each alloy should be the subject of ad-
ditional research.
CONCLUSIONS
1. Durabond recorded the greatest adhesion for the
metal samples that were air-abraded with aluminum ox-
ide and cleansed in tap water. Durabond was followed by
Co Span VS, Unibond, Biobond II, Duracast, Wilkinson,
and Degudent U for bonding strength.
2. The best bond strengths ofmetal specimens subjected
to air abrasion and ultrasonic cleaning were those of Co
Span VS, Durabond, Unibond, Biobond II, Duracast,
Wilkinson, and Degudent U, respectively.
3. Metal samples treated with ultrasonic cleaning ex-
hibited greater values, particularly with Degudent U alloy,
which recorded a statistically significant difference from
the other specimens.
We thank Dr. Gerald Barrack, Clinical Professor, Department
of Prosthodontics and Occlusion, New York University, College of
Dentistry, for his help and encouragement.
REFERENCES
1. Re GJ, Kaiser DA, Malone WF,
Garcia-Godoy
F. Shear bond strengths
and scanning electron microscope evaluation of three different reten-
tive methods for resin-bonded retainers. J PROSTh~T DENT 1988;59:568-
73.
2. Hill GL, Zidan 0, Gomez Marin O. Bond strengths of etched base met-
als: effects of errors in surface area estimation. J PROSTHET DENT
1986;56:41-5.
3. Harley KE, lbbetson RJ. The adhesive strengths of three resin cements
used with berillium-free nickel-chrome alloy [Abstract]. J Dent Res
1987;66:835.
4. Pegoraro LF, Barrack G. A comparison of bond strengths of adhesive
cast-restorations using different designs, bonding agents and luting
resins. J PROSTHET DENT 1987;57:133-8.
5. Barrack G. Etched cast restorations. A five-year review. NY St Dent J
1985;51:220-2.
6. Watanabe F, Powers JM, Lorey RE. In vitro bonding of prosthodontic
adhesives to dental alloys. J Dent Res 1988;67:479-83.
7. Omura I, Yamaguchi J, ttarada I, Wada T. Adhesive and mechanical
ProPerties of a new dental adhesive [Abstract]. J Dent Res 1984;63:233.
8. Wada T. International symposium on adhesive prosthodontics.
Nijmegen: Eurosound Drukkerij, 1986:9-19.
9. Gates WD, Diaz Arnold AM, Aquilino SA, Ryther JS. Comparison of the
adhesive strength of a BIS-GMA cement to tin-plated and non tin-
plated alloys. J PROSTHET DENT 1993;69:12-6.
Reprint requests to:
DR. Jo~ H. RUBO
AL. OCTAVIO P. BRISOLA, 9-75
CEP: 17043-101 BAtmu
S{o PA~LO
BP~Z~L
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