Relationship between sandblasting and composite resin alloy bond strength by a silica coating
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Relationship between sandblasting and composite resin-alloy bond strength by a silica coating Masami Mukai, DDS, PhD, a Hisao Fukui, DDS, PhD, b and Jiro Hasegawa, DDS, PhD c Aichi-Gakuin University, School of Dentistry, Nagoya, Japan Modification of alloys for resin-bonded fixed partial dentures has been suspect since the introduction of the conservative procedure. This study investigated the effect of sandblasting on composite resin-alloy bond strengths with the Silicoating technique. Ag-Pd and Ni-Cr alloys were prepared for casting. The specimens then were sand- blasted with 37 pm or 250 pm A1203 particles under the following conditions: 3 kg/cm 2 for 30 seconds; 5 kg/cm 2 for 10 seconds, 30 seconds, and 45 seconds; and 7 kg/cm 2 for 30 seconds. After each sandblasting treatment, the surfaces of the alloys were examined with the scanning electron microscope and the wettability of the alloy surfaces was measured. After sandblasting, the alloy surface was silica-coated, and light-cured composite resin then was bonded to the alloy. Specimens were divided, stored in dry air for I week, and thermocycled from 4 ~ to 60 ~ C for 104 cycles. Bond strength was measured by applying compressive shear stress. It was found that sandblasting made the alloy-water contact angle smaller and wettability greater. The adhesive strength of composite resins with alloys was influenced by sandblasting. (J PROSTHET DENT 1995;74:151-5.) Composite resin-veneered artificial crowns and resin-bonded metal restorations have generated interest as an alternative to a porcelain-fused-to-metal restora- tions. Composite resin-metal bonding systems have been developed to enhance the bonding capacity of composite resin veneers to metal surfaces.I, 2 One problem with com- posite resin-metal restorations is the relatively low bond strength between metal and composite resin cements. Surface treatment of the metal by sandblasting with A12O 3 particles (37-250 pm) has improved the effectiveness of the surface area of the metal and increased the compos- ite resin-metal bond strengths. 3 Electrolytic etching of base metal, Ag-Pd, and other types of alloy has improved mechanical bonding of composite resin-metal retainers. Concern has been expressed regarding the long-term effectiveness of resin-bonded restorations, however, be- cause of interfacial separation. Chemical bonding is more desirable than mechanical bonding when the former is available. Silane bonding agents have been used success- fully to chemically bond ceramic glass filler particles to the resinous matrix of traditional composite resin materials. Silane bonding agents are ineffective in bonding compos- ite resin to metal, however, because of the lack of suitable bonding sites on the metal, such as Si-OH or A1-OH groups. 4 aAssociate Professor, Department of Operative Dentistry. bAssociate Professor, Department of Dental Materials. cProfessor and Chairman, Department of Dental Materials. Copyright 1995 by The Editorial Council of THE JOURNAL OF PROSTHETIC DENTISTRY. 0022-3913/95/$3.00 +0. 101116412~ An approach that involves chemical bonding between composite resin and alloy has been presented. In this method, after the alloy substrate is sandblasted, a bond layer, proported as SiOx-C, is flame-sprayed on the sub- strata. The next step is silanization of the surface to cre- ate a bond between the alloy substrata and a layer of a light-curing dimethacrylate-based composite resin veneer. The complete process is frequently called the Silicoating system (Kulzer and Co. GmbH, Friedrichsdorf, Germany). A special technique is used to apply the SiOx-C:layer, in which Si-organic molecules are decomposed in the oxidiz- ing part of a propane-air flame to create a thin intermedi- ate bonding layer. This study investigated the relationship between sand- blasting conditions and the composite resin-alloy bond strengths with Silicoating. MATERIAL AND METHODS Alloy specimen preparation Two alloys were selected for this investigation. The first alloy was an Ag-Pd alloy (Pd 25 wt%, Ag 55 wt%, Cu 18 wt%, and other 2 wt%) (MIROCAST MC, G-C Co., Tokyo, Japan) and the second a Ni-Cr alloy (Ni 71 wt%, Cr 19 wt%, and Cu 5 wt%) (AD-CAST II, Nihon Shiken Co., Tokyo, Japan). The alloys were cast with a centrifugal casting machine in 20 x 10 x 1.5 mm plates with gypsum-bonded and phosphate-bonded investment for Ag-Pd and Ni-Cr alloy, respectively. The alloy specimen was made by grinding the alloy surface with #400 grit sandpaper to cre- ate a flat, even surface. Specimens were then sandblasted; their conditions are listed in Table I. AUGUST 1995 THE JOURNAL OF PROSTHETIC DENTISTRY 151
Transcript
Relationship between sandblasting and composite resin-alloy bond strength by a silica coating
M a s a m i M u k a i , D D S , P h D , a H i s a o F u k u i , D D S , P h D , b a n d J i r o H a s e g a w a , D D S , P h D c
Aichi-Gakuin University, School of Dentistry, Nagoya, Japan
Modification of alloys for resin-bonded fixed partial dentures has been suspect s ince the introduction of the conservative procedure. This study invest igated the effect of sandblast ing on composite resin-alloy bond strengths with the Si l icoating technique. Ag-Pd and Ni-Cr alloys were prepared for casting. The specimens then were sand- blasted wi th 37 p m or 250 p m A1203 particles under the fo l lowing conditions: 3 kg/cm 2 for 30 seconds; 5 kg/cm 2 for 10 seconds, 30 seconds, and 45 seconds; and 7 kg/cm 2 for 30 seconds. After each sandblast ing treatment, the surfaces of the alloys were examined wi th the scanning electron microscope and the wettabi l i ty of the alloy surfaces was measured. After sandblasting, the alloy surface was silica-coated, and light-cured composite resin then was bonded to the alloy. Specimens were divided, stored in dry air for I week, and thermocycled from 4 ~ to 60 ~ C for 104 cycles. Bond strength was measured by applying compress ive shear stress. It was found that sandblast ing made the al loy-water contact angle smaller and wettabi l i ty greater. The adhesive strength of composi te resins wi th alloys was inf luenced by sandblasting. (J PROSTHET DENT 1995;74:151-5.)
Composi te resin-veneered artificial crowns and resin-bonded metal restorations have generated interest as an alternative to a porcelain-fused-to-metal restora- tions. Composite resin-metal bonding systems have been developed to enhance the bonding capacity of composite resin veneers to metal surfaces.I, 2 One problem with com- posite resin-metal restorations is the relatively low bond strength between metal and composite resin cements.
Surface treatment of the metal by sandblasting with A 1 2 O 3 particles (37-250 pm) has improved the effectiveness of the surface area of the metal and increased the compos- ite resin-metal bond strengths. 3 Electrolytic etching of base metal, Ag-Pd, and other types of alloy has improved mechanical bonding of composite resin-metal retainers. Concern has been expressed regarding the long-term effectiveness of resin-bonded restorations, however, be- cause of interfacial separation. Chemical bonding is more desirable than mechanical bonding when the former is available. Silane bonding agents have been used success- fully to chemically bond ceramic glass filler particles to the resinous matrix of traditional composite resin materials. Silane bonding agents are ineffective in bonding compos- ite resin to metal, however, because of the lack of suitable bonding sites on the metal, such as Si-OH or A1-OH groups. 4
aAssociate Professor, Department of Operative Dentistry. bAssociate Professor, Department of Dental Materials. cProfessor and Chairman, Department of Dental Materials. Copyright �9 1995 by The Editorial Council of THE JOURNAL OF
An approach that involves chemical bonding between composite resin and alloy has been presented. In this method, after the alloy substrate is sandblasted, a bond layer, proported as SiOx-C, is flame-sprayed on the sub- strata. The next step is silanization of the surface to cre- ate a bond between the alloy substrata and a layer of a light-curing dimethacrylate-based composite resin veneer. The complete process is frequently called the Silicoating system (Kulzer and Co. GmbH, Friedrichsdorf, Germany). A special technique is used to apply the SiOx-C:layer, in which Si-organic molecules are decomposed in the oxidiz- ing part of a propane-air flame to create a thin intermedi- ate bonding layer.
This study investigated the relationship between sand- blasting conditions and the composite resin-alloy bond strengths with Silicoating.
M A T E R I A L A N D M E T H O D S
A l l o y s p e c i m e n p r e p a r a t i o n
Two alloys were selected for this investigation. The first alloy was an Ag-Pd alloy (Pd 25 wt%, Ag 55 wt%, Cu 18 wt%, and other 2 wt%) (MIROCAST MC, G-C Co., Tokyo, Japan) and the second a Ni-Cr alloy (Ni 71 wt%, Cr 19 wt%, and Cu 5 wt%) (AD-CAST II, Nihon Shiken Co., Tokyo, Japan). The alloys were cast with a centrifugal casting machine in 20 x 10 x 1.5 mm plates with gypsum-bonded and phosphate-bonded investment for Ag-Pd and Ni-Cr alloy, respectively. The alloy specimen was made by grinding the alloy surface with #400 grit sandpaper to cre- ate a flat, even surface. Specimens were then sandblasted; their conditions are listed in Table I.
AUGUST 1995 THE JOURNAL OF PROSTHETIC DENTISTRY 1 5 1
THE JOURNAL OF PROSTHETIC DENTISTRY MUKAI, FUKUI, AND HASEGAWA
Shearing load
Metal
Light-cured opaque resin
Light-cured composite resin
Fig. 1. Schematic illustration of shear compressive ap- paratus for measurement of bond strength.
The sandblasted alloy surfaces were observed using scanning electron microscopy (JCMA model 733, JEOL).
Measurement of contact angle (wettability)
The wettability of the surface of the alloy after sand- blasting was determined by the following: 4 pl of water from a micro-pipette was positioned on the alloy surface in the thermostatic chamber, and a photograph was made at the moment of contact. The contact angle was measured from the shape of the drop of water in this photograph. The contact angle was determined from five measurements of each condition and the data were analyzed using a three- factor analysis of variance (ANOVA). 5
Shear bond strength testing
After the sandblasted alloy specimens were cleaned with Siliclean (ethyl acetate, Kulzer and Co.), theywere mounted in the Silicoating apparatus (Silicoater, Kulzer and Co.), and coated with specimens sustained in the oxidizing re- gion of a propane-tetraethoxysilane-oxygen flame accord- ing to the manufacturer. After being cooled, the surface was painted with Silicoup adhesion primer solution (Kulz- er and Co.). The silane coupling agent of Silicoup is 3-methacryloxypropyl-trimethoxy-silane. A piece of tape with a circular hole 6 mm in diameter was secured to the
sandblasted alloy surface to indicate the bond site. There- after, a thin layer of the methylmethacrylate-containing composite resin, Dentacolor opaquer (Kulzer and Co.) was applied to the sandblasted alloy surface to a thickness of approximately 200 ~m and cured with a photo-curing ap- paratus (Dentacolar XS, Kulzer and Co.) for 90 seconds. A plastic ring 2 mm thick with a circular hole 6 mm in diam- eter was positioned over the tape. The ring was filled with a light-cured veneering resin (Dentacolar D-120, Kulzer and Co.), which then was cured for 90 seconds. Ten alloy specimens were used for each sandblasted condition for a total of 200 specimens. Ten specimens from each treatment were divided into two groups of five pieces and were sub- jected to the following: (1) dry storage for 7 days, and (2) 10,000 thermal cycles between 4 ~ and 60 ~ C. The alloy- composite resin bond strength then was measured by shear stress (Fig. 1) mounted on an Instron testing machine (Model 1125, Instron Co., Canton, Mass.) at the crosshead speed of 1 mm/min and recorded. The means of each sandblasted group were analyzed by ANOVA.
R E S U L T S
Observation of alloy surfaces Scanning electron microscopy was used to compare the
surface of Ag-Pd and Ni-Cr alloys after sandblasting with 37 pm A1203 (#400) particles, but revealed no significant differences. When 250 pm A1203 (#60) particles were selected as the sandblasting medium, however, the scale of surface deformation was different on the surface of Ag-Pd alloy (Fig. 2).
Wettability of alloy surface a f t e r sandblasting
The contact angle of water to a polished surface was 58.5 ~ and 50.5 ~ for Ag-Pd and Ni-Cr alloys, respectively, but this angle decreased for both alloys after sandblasting (Fig. 3). ANOVA demonstrated statistically significant differences between particle size (p < 0.001, contribution rate 32.8%), alloys (p < 0.001, contribution rate 19.7%), and pressure and time (p < 0.001, contribution rate 13.7%) (Table II).
Resin-alloy bond strengths
The resin-alloy bond strengths improved remarkably after sandblasting regardless of whether the specimens were stored dry or thermocycled. After 1 week of dry stor- age after sandblasting with 37 l~m A1203 (#400) particles, the maximal bond strength improved from 9.8 (polished surface) to 19.5 MPa and 9.9 (polished surface) to 19.5 MPa for Ag-Pd alloy and Ni-Cr alloy, respectively. Conversely,
when 250 > ~na h l 2 0 3 (#60) particles were used, the max- imal bond strength reached 20.9 (Ag-Pd alloy) and 19.5 MPa (Ni-Cr alloy). When using 37 ~m A1203 (#400) parti- cles followed by thermocycling, the bond strengths in- creased from 3.9 (polished surface) to 12.7 MPa for Ag-Pd alloy and 4.4 (polished surface) to 15.7 MPa for Ni-Cr al- loy, respectively. By using 250 ~m A1203 (#60) particles to sandblast, the bond strengths reached a maximal of 7.9
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and 12.7 MPa for Ag-Pd and Ni-Cr, respectively (Fig. 4). Tables I I I and IV show ANOVA da ta from the Ag-Pd and Ni-Cr alloys. The contr ibut ion coefficient of s torage after sandblas t ing was the grea tes t percentage for both alloys.
DISCUSSION Various adhesive bonding methods have been used in
labora tory procedures. 4, 6-13 Ishi j ima et al. 9 repor ted tha t adhesive s t rengths of composite resins and alloys wi th Sil- icoating was superior to t ha t of other adhesive methods. Using this technique, the surface t r ea tmen t of sandblas t - ing t ha t was performed as p re t r ea tmen t for the Sil icoating process exerted an inordinate influence. Sandblas t ing in- creased surface a rea of the alloy surfaces, expanded the energy of alloy surfaces, and also heightened act ivi ty of the surfaces.
The wet tabi l i ty of sandblas ted metall ic surfaces was confirmed by measur ing the contact angle by use of a liq- uid drop method. I t was discovered tha t the type of alloy and size of the part icle used for sandblas t ing influenced wettabi l i ty . I t was hypothesized tha t the act ivated alloy surfaces and s t rengthened coating of the SiOx-C layer, and by bet ter ing wet t ing with adhesives, chemical adhesion between composite resins and meta ls was improved.
A subs tan t ia l difference was clearly observed for the ad- hesive s t rength of composite resins with alloys between the group preserved in a tmosphere for 1 week and the ther- mocycled group for both Ag-Pd and Ni-Cr alloys. For all conditions of sandblast ing, measured values were less in the thermocycled group. The decrease for Ag-Pd alloy was approximate ly 45% in the thermocycled group compared with the group preserved in a tmosphere for 1 week, and approximate ly 67% for Ni-Cr alloy. Peutzfeldt and Asmus- sen, 2 Tiller et al., 14 Jakobe and Marx, 15 Re et al., 16 and Hill
et a l ) 7 repor ted tha t the adhesive s t rengths of composite resins wi th alloys by Sil icoating despite h igher humid i ty were not reduced, but in this research, the adhesive s t rengths were lowered.
The adhesive s t rength in the Ag-Pd alloy was sharply reduced. The reduction was a t t r ibu ted to grea ter shear ing s t resses at the interface of Ag-Pd alloys and composite resins t han those found in Ni-Cr alloys. The differences in propert ies of the alloys, such as thermal coefficient of ex- pansion, hardness , roughness, and surface propert ies were responsible for this result . The effect of t empera tu re change and wa te r absorpt ion of composite resins were also responsible for this result . Moreover, because the Ag-Pd alloy is soft compared with the Ni-Cr alloy (Fig. 2 ), the surfaces of Ag-Pd alloy samples t rea ted by sandblas ing were abraded and rounded. This indicated tha t reductions in surface areas and rounding of the edges were also con- s idered to be causes of d iminished adhesive strength.
The adhesive s t rength of composite resins wi th alloys was signif icantly improved by sandblast ing.
C L I N I C A L I M P L I C A T I O N
The adhesive s t rength between composite resins and alloys were clearly improved by sandblast ing. Sandblas t -
F ig . 2. Scanning electron micrographs of Ag-Pd alloy and Ni-Cr alloy surface sandblas ted (7 kg/cm 2 30 sec). A, Ag-Pd alloy surface sandblas ted with 37 p m A1203 particles; B, Ag-Pd alloy surface sandblas ted with 250 ]am A1203 part i - cles; C, Ni-Cr alloy surface sandblas ted with 37 ]am A1203
particles; D, Ni-Cr alloy surface sandblas ted with 250 tim A120 3 particles.
ing increased surface a rea and improved alloy sur- faces.
CONCLUSION
1. Sta t i s t ica l ly significant differences were observed for adhesive s t rengths of composite res ins with alloys between the group preserved in a tmosphere for 1 week and the group thermocycled for both Ag-Pd and Ni-Cr alloys. Ad- hesive s t rengths were less in the thermocycled group for both alloys.
2. A significant difference was observed for the Ag-Pd alloy in par t ic le size, t ime, and pressure dur ing sandblast- ing t rea tment , but the contribution ra te was 2.8 and 0.9%. A significant difference in t ime and pressure was observed for the Ni-Cr alloy dur ing sandblas t ing t rea tment , but the contribution ra te was 1.4%.
REFERENCES
1. Greene LL, Greene NA. Technic for repair of acrylic resin veneers and incisal fractures. Dent Survey 1973;49:50-3.
2. Peutzlfeldt A, Asmussen E. Silicoating evaluation of a new method of bonding composite resin to metal. Scand J Dent Res 1988;96:171-6.
3. Fuang SM. In vivo and in vitro evaluation of gold and palladium alloys for etched metal resin bonded retainer [Masters Thesis]. Birmingham, Alabama: University of Alabama at Birmingham, 1985.
4. Musil R, Tiller DH. Molecular coupling ofresin veneers to alloy surfaces (Die molekulare Kopplung der Kunststof- Verblendung an die Legierungsoberfltiche). Dent Labor 1984;32:1156-61.
A, Alloy; B, particle size; C, sandblasting pressure and time. *Five specimens were used for each sandblast treatment.
7. Barzilay I, Myers ML, Cooper LB, Graser GN. Mechanical and chem- ical retention of laboratory cured composite to metal surfaces. J PRos- WHET DENT 1988;59:131-7.
8. Naegeli DG, Duke DE, Schwartz R, Norling BK. Adhesive bonding of composites to a casting alloy. J PROSTHET DENT 1988;60:279-83.
9. Ishijima T, Caputo AA, Mito R. Adhesion of resin to casting alloys. J PROSTHET D~NT 1992;67:445-9.
10. Guggenberger R. Rocatec system: adhesion by tribochemical coating. (Das Rocatec-System - HafLung durch tribochemische Beschichtung). Dtsch Zahnfirztl Z 1989;44:874-6.
11. Pr6bster L, Kourtis S. Surface morphology of alloys treated with the Rocatec system (Zur Oberflfichennmorphotogie von mit dem Rocatec- System behemdelten Legierungen). Dtsch Zahn~rztl Z 1991;46:135-9.
12. Hansson O, Moberg L-E. Evaluation of three silicoating methods for resin-bonded prostheses. Scand J Dent Res 1993;101:243-51.
13. Chang JC, Powers JM, Hart D. Bond strength of composite to alloy treated with bonding systems. Int J Prosthdont 1993;2:110-4.
14. Tiller HJ, Musi] R, Magnus B, Garschke A, GSble R, Lockowandt P. Sand blasting procedures and its effect on the surface properties of dental alloys: II (Der SmldstrahlprozeB und seine Ein Wirkung aufden
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*Five specimens were used for each sandblast treatment. Key as in Table III.
Oberfl~ichenzustand von Dentallegierungen: II). Die Quintessenz 1985; 11:2151-8.
15. Jakobe E, Marx R. Silicoater method for bonded bridgework (Silicoat- erverfahren fiir die K]ebebrticke). Dtsch Zahnarztl Z 1988;43:461-4.
16. Re GJ' Kaiser DA' Mal~ WF' Garcia'G~176 F" Sheer b~ strengths and scanning electron microscope evaluation of three different retentive methods for resin-bonded retainers. J PROSTHET DENT 1988;59:568-73.
17. 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.
Reprint requests to." DR. MASAMI MUKAI
AUGUST 1995
DEPARTMENT OF OPERATIVE DENTISTRY SCHOOL OF DENTISTRY AICHI-GAKUIN UNIVERSITY 2-11 SUEMORI-DoRI CHIKUSA-KU NAGOYA 464 JAPAN
CONTRIBUTING AUTHOR
I{aruo Nakagaki, DDS, PhD, Profes so r a n d C h a i r m a n ,
D e p a r t m e n t of P r e v e n t i v e D e n t i s t r y a n d D e n t a l Pub l i c
H e a l t h , School of D e n t i s t r y , A i c h i - G a k u i n U n i v e r s i t y ,
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