Dent Mater 8:238-240, July, 1992
The influence of surface conditions and silane agents on the bond of resin to dental porcelain T. Hayakawa 1, K. Horie ~, M. Aida 2, H. Kanaya 2, T. Kobayashi 2, Y. Murata 2 Department of Dental Materials, ~Departmentof Crown and Bridge Prosthodontics, Nihon University School of Dentistry, Matsudo, Japan
Abstract. The influence of porcelain surface condition and the application of silane agents on the adhesion between resin and dental porcelain were investigated. The experimental variables included three porcelain surface preparations, as polished, etched with phosphoric acid, or etched with hydrofluoric acid and three kinds of commercially available silane coupling agents. The shear bond strength between the light-cured composite and the dental porcelain was measured after one-day immersion in 37°C water. Samples without the silane agent application were also tested as controls. Without the silane agent, hydrofluoric acid-etched specimens had a higher bond strength than polished or phosphoric acidetched specimens. The combination of hydrofluoric acid-etching and an application of Cosmotech Porcelain Primer increased the bond strengths more than that of phosphoric acid-etching. With the application of Laminabond Porcelain Primer or Optec Silane Coupling Agent, high bond strengths were obtained regardless of the porcelain surface condition. Therefore, it seems the chemical reactions between the porcelain surface and silane agents were responsible for the high shear bond strengths, INTRODUCTION In this study, the influence of the porcelain surface condition and the application of silane agents on the adhesion between resin and dental porcelain were investigated. The adhesion of resin to dental porcelain was developed by etching the porcelain surface with hydrofluoric acid (Horn, 1983;Calamia, 1983)andusingsilanecouplingagents(Calamia and Simonsen, 1984). It is well known that the combination of hydrofluoric acid etching and the application of silane coupling agent is an effective method for improving the adhesion of resin (Stangel et al., 1987; Sheth et al., 1988; Aida et al., 1990). As alternatives to hydrofluoric acid, acidulated phosphate fluoride (Lacy et al., 1988) or phosphoric acid (Newburg and Pameijer, 1987;Okamotoetal., 1989;Matsumuraetal., 1989) were investigated. There are few reports about the combination of porcelain surface conditions and silane agent application on the adhesion of resin to dental porcelain. Thus this study was designed to evaluate commercially available silane agents applied to the three kinds of porcelain surfaces and compare the bond strengths between the composite and dental porcelain,
MATERIALSAND METHODS The materials used in this study are shown in the Table. Porcelaindiscs(10mmdiameterx2mm)werefabricatedfrom 238 Hayakawa et aL/Bond of resin to dental porcelain
TABLE: MATERIALSUSEDIN THISSTUDY Material Name porcelain LaminaPorcelainMasking DentinPorcelain(LMA3) silane agent CosmotechPorcelainPrimer LaminabondPorcelainPrimer OptecSilaneCouplingAgent composite LaminabondCompositePaste Universal
Manufacturer Shofu Inc.,Kyoto,Japan GC Co.,Tokyo,Japan Shofu Inc., Jeneric-PentronInc., Wallingford, CT, USA Shofu Inc.
masking dentin porcelain in a porce]ain furnace (Jelenko, Mode] HT, Jelenko Co. Armonk, NY, USA) and were embedded with chemical-cured acrylic resin (GC Unifast, GC Co.). The porcelain surfaces were treated using one of three procedures: 1) polished with #1000 SiC paper, 2) etched with phosphoric acid gel (etchinggel, Shofu Inc.) for 60 s after #1000 polishing, or 3) etched with hydrofluoricacid gel (GC hydrofluoric acid gel, GC Co.) for 60 s after #1000 polishing. Then, silane agents were applied on the porcelain surface for 30 s, which was dried with compressed air for 10 s. A silicone ring (3.2 mm diameter x 2 mm) was placed on the treated surface on the porcelain disc. The ring was filled with the light-cured composite without any unfilled bonding agent and was exposed to a photo-curing apparatus (Daylight lamp II, Shofu Inc.) for 90 s. Control specimens of the porcelain surface conditions were prepared without the silane coupling agent. After curing the resin, the silicone ring was removed. The specimens were immersed in 37°C water for one day. The shear bond strengths were then measured with a universal testingmachine (TOM 10000X, Shinkoh Co., Tokyo, Japan) at a cross head speed of 2.0 mm/min. The measurement of shear bond strengths was carried out according to the Noguchi's Method (Noguchi et al., 1985). The data were tested for significant differences by an analysis of variance, and by Scheff~'s test for a multiple comparison among the means (p=0.05). After being polished and etched with phosphoric acid or with hydrofluoric acid, each porcelain surface was observed using a scanning electron microscope (S-550, Hitachi Co., Tokyo, Japan). RESULTS Fig. I shows the shear bond strengths between the porcelain and the light-cured composite cemented using the various
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Cosmotech Laminabond OptecSilane Primer Porcelain Primer Coupling Agent BIl:phosphorica c i d
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Fig. 1. Shear bond strengths between composite and porcelain. Horizontal lines indicate no statistical difference among the porcelain surface conditions when the same sUane coupling agent was applied,
Fig. 3. Scanning electron micrograph of porcelain surface polished with #1000SiC paperand etched with phosphoric acid gel.
Fig. 2. Scanning electron micrograph of porcelain surface polished with #1000SiC paper,
Fig. 4. Scanning electron micrograph of porcelain surface polished with #1000SiC paper and etched with hydrofluoric acid gel.
procedures. Of the specimens prepared without silane coupling agents, those specimens etched with hydrofluoric acid produced the highest shear bond strength. The type of bond failure in the polished and the phosphoric acid-etched group was an adhesive failure at the interface between the porcelain and the composite; bond failure in the hydrofluoric acidetched group was amixture ofporcelain-resin adhesive failure and porcelain fracture, When the Cosmotech Porcelain Primer was used, specimens etched with hydrofluoric acid produced the highest shear bond strength. There were significant differences in the shear bond strengths between the specimens receiving the hydrofluoric acid etching and the other surface treatments. With three types of porcelain surface conditions, the type of bond failure was a mixture of porcelain-resin adhesive failure and porcelain fracture; however, the amount of porcelain fracture increased in the hydrofluoric acid-etched group,
The porcelain surface treatment had no influence on the bond strengths ofcomposite to porcelain when the Laminabond Porcelain Primer and Optec Silane Coupling Agent were used. The type of bond failure was mainly porcelain fracture. Figs. 2-4 are scanning electron micrographs ofthe porcelain surfaces. The polished specimen showed a flat surface with grooves from polishing (Fig. 2). The effect of phosphoric acid etching was weak, and the surface looked almost the same as the polished surface (Fig. 3). Hydrofluoric acid etching created the greatest roughness on the porcelain surface (Fig.4), as was previously reported (Aida et al., 1990). DISCUSSION Hydrofluoric acid-etching may have resulted in greater roughing of the porcelain surface, which is an important factor as reported by Stangel et al. (1987). However, this treatment provided greater mechanical interlocking of the composite to
Dental Materials~July 1992 239
the porcelain than the phosphoric acid-etching treatment when the Cosmotech Porcelain Primer was used. Although the detailed components of silane agents are unknown, LaminabondPorcelainPrimerorOptecSilaneCouplingAgent were thought to be in an activated state to react with OH groups on the porcelain surface, but Cosmotech Porcelain Primer was not. Cosmotech Porcelain Primer improved only the wettability of the composite to the porcelain, while the Laminabond Porcelain Primer or Optec Silane CouplingAgent reacted with OH groups on the porcelain surface, forming siloxane bonds. For Laminabond Porcelain Primer or Optec Silane Coupling Agent, the main contributor to the measured bond strengths was not the mechanical interlocking of the composite but the formation of siloxane bonds. In summary, hydrofluoric acid-etching is not needed to obtain strong adhesion between the composite and the porcelain if silane agents, which react with OH groups on the porcelain surface, are used. ReceivedMay 16, 1991/AcceptedDecember 17, 1991 Addresscorrespondence and reprint requests to: Wohru Hayakawa Departmentof Dental Materials NihonUniversity SchoolofDentistryat Matsudo 2-870-1 Sakaecho Nishi, Matsudo
Chiba 271,Japan
REFERENCES Aida M, Kanaya H, Murata Y, Hayakawa T, Horie K (1990). The evaluation of commercially available silane coupling
240 Hayakawaet aL/Bondof resin to dentalporcelain
agents for porcelain adhesion. Nihon Univ J Oral Sci 16:454-460. Calamia JR (1983). Etched porcelain facial veneers: A new treatment modality based on scientific and clinical evidence. NYJDent 53:255-259. CalamiaJR, SimonsenRJ(1984). Effect ofcoupling agents on bond strength of etched porcelain. J Dent Res 63:179, Abstr. No. 79. Horn HR (1983). Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am 27:671-684. Lacy AM, Laliz J, Watanabe LG, Dellinges M (1988). Effect of porcelain surface treatment on the bond to composite. J Prosthet Dent 60:288-291. Matsumura H, Kawahara M, Tanaka T, Atsuta M (1989). A new porcelain repair system with a silane coupler, ferric chloride, and adhesive opaque resin. J Dent Res 68:813818. Newburg R, Pameijer CH (1987). Composite resins bonded to porcelain silane solution. J A m DentAssoc 96:288-291. Noguchi H, Nakamura K, Ozonoe Y, Etchu Y (1985). On adhesive and mechanical properties of dental cements thermal influence. Jpn J Dent Mater 4:543-550. Okamoto A, Kobayashi Y, Nakai T, Nonomura I, Fukushima M, Iwaku M (1989). The study ofsilane coupling agent for repairing fractured porcelain. Jpn J Conserv Dent 32:978985.
Sheth J, Jensen M, Tolliver D (1988). Effect of surface treatment on etched porcelain bond strength to enamel. Dent Mater 4:327-337. Stangel I, Nathanson D, Hsu CS (1987). Shear strength ofthe composite bond to etched porcelain. J Dent Res 66:14601465.
The influence of surface conditions and silane agents on the bond of resin to dental porcelain T. Hayakawa 1, K. Horie ~, M. Aida 2, H. Kanaya 2, T. Kobayashi 2, Y. Murata 2 Department of Dental Materials, ~Departmentof Crown and Bridge Prosthodontics, Nihon University School of Dentistry, Matsudo, Japan
Abstract. The influence of porcelain surface condition and the application of silane agents on the adhesion between resin and dental porcelain were investigated. The experimental variables included three porcelain surface preparations, as polished, etched with phosphoric acid, or etched with hydrofluoric acid and three kinds of commercially available silane coupling agents. The shear bond strength between the light-cured composite and the dental porcelain was measured after one-day immersion in 37°C water. Samples without the silane agent application were also tested as controls. Without the silane agent, hydrofluoric acid-etched specimens had a higher bond strength than polished or phosphoric acidetched specimens. The combination of hydrofluoric acid-etching and an application of Cosmotech Porcelain Primer increased the bond strengths more than that of phosphoric acid-etching. With the application of Laminabond Porcelain Primer or Optec Silane Coupling Agent, high bond strengths were obtained regardless of the porcelain surface condition. Therefore, it seems the chemical reactions between the porcelain surface and silane agents were responsible for the high shear bond strengths, INTRODUCTION In this study, the influence of the porcelain surface condition and the application of silane agents on the adhesion between resin and dental porcelain were investigated. The adhesion of resin to dental porcelain was developed by etching the porcelain surface with hydrofluoric acid (Horn, 1983;Calamia, 1983)andusingsilanecouplingagents(Calamia and Simonsen, 1984). It is well known that the combination of hydrofluoric acid etching and the application of silane coupling agent is an effective method for improving the adhesion of resin (Stangel et al., 1987; Sheth et al., 1988; Aida et al., 1990). As alternatives to hydrofluoric acid, acidulated phosphate fluoride (Lacy et al., 1988) or phosphoric acid (Newburg and Pameijer, 1987;Okamotoetal., 1989;Matsumuraetal., 1989) were investigated. There are few reports about the combination of porcelain surface conditions and silane agent application on the adhesion of resin to dental porcelain. Thus this study was designed to evaluate commercially available silane agents applied to the three kinds of porcelain surfaces and compare the bond strengths between the composite and dental porcelain,
MATERIALSAND METHODS The materials used in this study are shown in the Table. Porcelaindiscs(10mmdiameterx2mm)werefabricatedfrom 238 Hayakawa et aL/Bond of resin to dental porcelain
TABLE: MATERIALSUSEDIN THISSTUDY Material Name porcelain LaminaPorcelainMasking DentinPorcelain(LMA3) silane agent CosmotechPorcelainPrimer LaminabondPorcelainPrimer OptecSilaneCouplingAgent composite LaminabondCompositePaste Universal
Manufacturer Shofu Inc.,Kyoto,Japan GC Co.,Tokyo,Japan Shofu Inc., Jeneric-PentronInc., Wallingford, CT, USA Shofu Inc.
masking dentin porcelain in a porce]ain furnace (Jelenko, Mode] HT, Jelenko Co. Armonk, NY, USA) and were embedded with chemical-cured acrylic resin (GC Unifast, GC Co.). The porcelain surfaces were treated using one of three procedures: 1) polished with #1000 SiC paper, 2) etched with phosphoric acid gel (etchinggel, Shofu Inc.) for 60 s after #1000 polishing, or 3) etched with hydrofluoricacid gel (GC hydrofluoric acid gel, GC Co.) for 60 s after #1000 polishing. Then, silane agents were applied on the porcelain surface for 30 s, which was dried with compressed air for 10 s. A silicone ring (3.2 mm diameter x 2 mm) was placed on the treated surface on the porcelain disc. The ring was filled with the light-cured composite without any unfilled bonding agent and was exposed to a photo-curing apparatus (Daylight lamp II, Shofu Inc.) for 90 s. Control specimens of the porcelain surface conditions were prepared without the silane coupling agent. After curing the resin, the silicone ring was removed. The specimens were immersed in 37°C water for one day. The shear bond strengths were then measured with a universal testingmachine (TOM 10000X, Shinkoh Co., Tokyo, Japan) at a cross head speed of 2.0 mm/min. The measurement of shear bond strengths was carried out according to the Noguchi's Method (Noguchi et al., 1985). The data were tested for significant differences by an analysis of variance, and by Scheff~'s test for a multiple comparison among the means (p=0.05). After being polished and etched with phosphoric acid or with hydrofluoric acid, each porcelain surface was observed using a scanning electron microscope (S-550, Hitachi Co., Tokyo, Japan). RESULTS Fig. I shows the shear bond strengths between the porcelain and the light-cured composite cemented using the various
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Control [ ] :polished
Cosmotech Laminabond OptecSilane Primer Porcelain Primer Coupling Agent BIl:phosphorica c i d
JL~0 ~
[T]'l:hydrofluoricacid
Fig. 1. Shear bond strengths between composite and porcelain. Horizontal lines indicate no statistical difference among the porcelain surface conditions when the same sUane coupling agent was applied,
Fig. 3. Scanning electron micrograph of porcelain surface polished with #1000SiC paperand etched with phosphoric acid gel.
Fig. 2. Scanning electron micrograph of porcelain surface polished with #1000SiC paper,
Fig. 4. Scanning electron micrograph of porcelain surface polished with #1000SiC paper and etched with hydrofluoric acid gel.
procedures. Of the specimens prepared without silane coupling agents, those specimens etched with hydrofluoric acid produced the highest shear bond strength. The type of bond failure in the polished and the phosphoric acid-etched group was an adhesive failure at the interface between the porcelain and the composite; bond failure in the hydrofluoric acidetched group was amixture ofporcelain-resin adhesive failure and porcelain fracture, When the Cosmotech Porcelain Primer was used, specimens etched with hydrofluoric acid produced the highest shear bond strength. There were significant differences in the shear bond strengths between the specimens receiving the hydrofluoric acid etching and the other surface treatments. With three types of porcelain surface conditions, the type of bond failure was a mixture of porcelain-resin adhesive failure and porcelain fracture; however, the amount of porcelain fracture increased in the hydrofluoric acid-etched group,
The porcelain surface treatment had no influence on the bond strengths ofcomposite to porcelain when the Laminabond Porcelain Primer and Optec Silane Coupling Agent were used. The type of bond failure was mainly porcelain fracture. Figs. 2-4 are scanning electron micrographs ofthe porcelain surfaces. The polished specimen showed a flat surface with grooves from polishing (Fig. 2). The effect of phosphoric acid etching was weak, and the surface looked almost the same as the polished surface (Fig. 3). Hydrofluoric acid etching created the greatest roughness on the porcelain surface (Fig.4), as was previously reported (Aida et al., 1990). DISCUSSION Hydrofluoric acid-etching may have resulted in greater roughing of the porcelain surface, which is an important factor as reported by Stangel et al. (1987). However, this treatment provided greater mechanical interlocking of the composite to
Dental Materials~July 1992 239
the porcelain than the phosphoric acid-etching treatment when the Cosmotech Porcelain Primer was used. Although the detailed components of silane agents are unknown, LaminabondPorcelainPrimerorOptecSilaneCouplingAgent were thought to be in an activated state to react with OH groups on the porcelain surface, but Cosmotech Porcelain Primer was not. Cosmotech Porcelain Primer improved only the wettability of the composite to the porcelain, while the Laminabond Porcelain Primer or Optec Silane CouplingAgent reacted with OH groups on the porcelain surface, forming siloxane bonds. For Laminabond Porcelain Primer or Optec Silane Coupling Agent, the main contributor to the measured bond strengths was not the mechanical interlocking of the composite but the formation of siloxane bonds. In summary, hydrofluoric acid-etching is not needed to obtain strong adhesion between the composite and the porcelain if silane agents, which react with OH groups on the porcelain surface, are used. ReceivedMay 16, 1991/AcceptedDecember 17, 1991 Addresscorrespondence and reprint requests to: Wohru Hayakawa Departmentof Dental Materials NihonUniversity SchoolofDentistryat Matsudo 2-870-1 Sakaecho Nishi, Matsudo
Chiba 271,Japan
REFERENCES Aida M, Kanaya H, Murata Y, Hayakawa T, Horie K (1990). The evaluation of commercially available silane coupling
240 Hayakawaet aL/Bondof resin to dentalporcelain
agents for porcelain adhesion. Nihon Univ J Oral Sci 16:454-460. Calamia JR (1983). Etched porcelain facial veneers: A new treatment modality based on scientific and clinical evidence. NYJDent 53:255-259. CalamiaJR, SimonsenRJ(1984). Effect ofcoupling agents on bond strength of etched porcelain. J Dent Res 63:179, Abstr. No. 79. Horn HR (1983). Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am 27:671-684. Lacy AM, Laliz J, Watanabe LG, Dellinges M (1988). Effect of porcelain surface treatment on the bond to composite. J Prosthet Dent 60:288-291. Matsumura H, Kawahara M, Tanaka T, Atsuta M (1989). A new porcelain repair system with a silane coupler, ferric chloride, and adhesive opaque resin. J Dent Res 68:813818. Newburg R, Pameijer CH (1987). Composite resins bonded to porcelain silane solution. J A m DentAssoc 96:288-291. Noguchi H, Nakamura K, Ozonoe Y, Etchu Y (1985). On adhesive and mechanical properties of dental cements thermal influence. Jpn J Dent Mater 4:543-550. Okamoto A, Kobayashi Y, Nakai T, Nonomura I, Fukushima M, Iwaku M (1989). The study ofsilane coupling agent for repairing fractured porcelain. Jpn J Conserv Dent 32:978985.
Sheth J, Jensen M, Tolliver D (1988). Effect of surface treatment on etched porcelain bond strength to enamel. Dent Mater 4:327-337. Stangel I, Nathanson D, Hsu CS (1987). Shear strength ofthe composite bond to etched porcelain. J Dent Res 66:14601465.
