Metal-Filled Resin Composites. II. R. L. BOWEN,* H. H. CHANDLER,t H. 0. WYCKOFF, JR.,' and D. N. MISRA* American Dental Association Health Foundation Research Unit at the National Bureau of Standards, * Washington, D.C. 20234, USA, The Ohio State University College of Dentistry, t Columbus, Ohio 43210, USA, and Council on Dental Materials and Devices, American Dental Association, + Chicago, Illinois 60611, USA
Various particulate materials were combined with a BIS-GMA resin, and the resulting composites were evaluated. Thefillers prevented, altered, had no apparent
effect, or accelerated polymerization. Coupling agents also influenced polymerization. Physical properties varied widely with dafferentfillers. J Dent Res 57(2): 213-220, February 1978.
In a previous study, ' a sampling of metals, available as powders, was used as fillers for thermosetting acrylic resins. The prior treatment of the metallic (oxide) surfaces with appropriate organofunctional coupling agents significantly improved certain physical properties. Here, additional powders and coupling agents are surveyed. If good physical properties among any of these composites should be found, testing for wear resistance, and evaluation for possible use in conservative treatment of incipient lesions associated with developmental pits and fisReceived for publication February 9, 1977. Accepted for publication May 4, 1977. This investigation was supported in part by Research Grant DE-02494-06 to the American Dental Association Health Foundation from the National Institutes of HealthNational Institute of Dental Research, and is part of the dental research program conducted by the National Bureau of Standards, in cooperation with the American Dental Association Health Foundation. *Certain commercial materials are identified in this paper to specify the experimental procedure. In no instance does such identification imply recommendation or endorsement by the National Bureau of Standards or the American Dental Association Health Foundation or that the material or equipment identified is necessarily the best available for the purpose.
tLucidol 98, Pennwalt Corp., Buffalo, NY. +A-1 74, Union Carbide Corp., New York, NY.
sures in posterior teeth' would be indicated. A wear-resistant composite could fill the small cavity and be chemically united with the overlying "sealant" resin. Materials and Methods*
The principal materials used in this study are included in Tables 1 and 2. RESIN. - The monomer formulation is given in Table 1. To part of the monomer formulation was added 0.5 % N,N-dimethyl-3,5-xylidine, giving "Monomer A". To the rest was added 0.8% benzoyl peroxide,t giving "Monomer B". FILLERS. - The aluminum powder was used only in combination with the titanium oxide powder in this study. The titanium oxide pigment was used only in combination with titanium and aluminum powders (19% TiO2 with each). The potassium titanate whiskers were used only in combination with the titanium powder (5 % potassium titanate). The glass (SiO2 67, BaO 16.5, B203 10, and A1203 6.5, mole %) powder had an alkaline reaction (pH 9.3; 10 % aqueous slurry), not reported previously.3 It was washed once with distilled water, suction filtered, and dried at 115 C in a vacuum oven before it was treated with the silane coupling agent. Water-sorption characteristics4 suggest that a more thorough treatment is warranted. The glass powder was slurried in silane (3 -methacryloxypropyltrimethoxysilane +) dilued with acetone, and then tumbled and heated (100 to 130 C) with intermittent evacuation to about 200 mm Hg (26.6 kPa) for one hour. Lumps and caked ma213
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j Dent
BOWEN ET AL
214
terial were removed with a sieve (US Standard No. 20). The silane treatments of the other powders were essentially the same, except without prior aqueous washing. The mercaptan* or the NPG-GMA5-12 coupling agent was also applied in acetone and heat dried in the same manner. The powders were tested to determine if they were covered with organic coupling agent: a small pile was indented to form a slight concavity. If a drop of distilled water could stand on this for at least 5 minutes without penetrating, the powder was described as "hydrophobic." If water penetrated the powder immediately, it was "hydrophilic. " Intermediate qualities could be observed with some powders, in which instances the water would penetrate slowly; powder particles would spread over the surface of the water drop; or, when the drop was picked up after 5 minutes with a *Mercaptate Q-42 Ester, Carlisle Chemical Works, Inc., Reading, Oh.
Res
February
1978
small ball of cotton, a layer of wetted powder would stick to the surface of the water drop. SPECIMEN PREPARATION. - Each was formulated from two pastes, unless otherwise noted. Each paste contained one of the fillers listed in Table 2 and either monomer "A" or "B". The resulting "paste A" and "paste B" each had the same fillermonomer ratio (Table 2), and were as thick as possible within the limits of workability. Abbreviations (Table 2) were assigned to each formulation according to the type of filler and its surface treatment. Except for zinc specimens, the procedure consisted of mixing equal amounts of each paste for 30 seconds, loading the mold by 2.5 minutes, placement of the filled mold in a 37 C, 100% relative humidity oven by 5 minutes, removal of the specimen from the mold at 20 minutes, and storage in distilled water at 37 + 1 C for 28 + 1 days. Zinc-containing specimens for strength analysis were made from the initial pastes by mixing for one minute rather than 30
TABLE 1 POWDERS AND MONOMER FORMULATION Powder
Aluminum Barium aluminoborosilicate glass* Iron
Niobium Potassium titanate (Fibex®' TTD)
Silver-tin-copper-zinc (lathe-cut dental alloy)
Nominal Purity
99.9% Colorless 99.9 + % 99.9 ±+
Highly-refined single crystals ADA Cert. grade
Tin
99.999%
Titanium Titanium (ic) oxide Zinc
99 % reagent
Ingredient
BIS-GMA (Stypol 46-4013) Triethyleneglycol dimethacrylate Butylated hydroxytoluene (BHT)
99.2%
Source
Ventron Corp.
Corning Glass Works Ventron Corp.
Gallard-Schlesinger Chem. Mfg. Corp. E I duPont de Nemours and Co. (Pooled samples from various sources) Ventron Corp. Ventron Corp. Fisher Sci. Co. Fisher Sci. Co.
Weight %
69.9 29.9 0.2
Freeman Chem. Co.
Borden, Inc. Eastman Chem. Prod., Inc.
*"Corning 7724 glass."
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Vol. 5 7 No. 2
METAL-FILLED RESIN COMPOSITES
215
TABLE 2 FILLERS, SURFACE TREATMENTS OF FILLERS, FILLER-MONOMER RATIOS, AND ABBREVIATIONS
Surface Treatment
Fillers
Surface Condition*
Aluminum 81% plus titanium oxide 19% Glass Iron Iron Iron
Silane, 0.54%
Iron
Silane, 0.28%
Niobium
None (control)
Niobium Dental alloy Dental alloy Dental alloy
Silane, 0.13 % None (control) NPG-GMA, 0.11% Silane, 0.11 %
Tin
None (control) NPG-GMA, 0.15%
FillerMonomer Ratio
Abbreviation for Resulting Composite
4.6
Al + TiO2-S
3.5 5.0
5.0
Glass-S Fe-C Fe-M Fe-N
5.0
Fe-S
8.1
Nb-C
8.1 5.4 5.4 5.4
Nb-S Ag-Sn-C Ag-Sn-N Ag-Sn-S
6.9 6.9 6.9 3.5 3.4
Sn-C Sn-N Sn-S Ti + KTi-S
Silane, 0.15% Silane, 0.40% Silane, 0.59%
Nearly hydrophobic Hydrophobic Hydrophilic Not hydrophobic Completely hydrophobic Completely hydrophobic Nearly hydrophobic Hydrophobic Hydrophilic Hydrophobic Somewhat hydrophobic Hydrophilic Hydrophobic Hydrophobic Hydrophobic Hydrophobic
Silane, 0.43%
Hydrophobic
5.4
Ti+TiO2-S
Zinc Zinc
None (control) Mercaptan, 0.23% NPG-GMA, 0.21%
Zinc
Silane, 0.23%
Hydrophilic Hydrophobic Hydrophobic Hydrophobic
8.2 8.2 8.2 8.2
Zn-C Zn-M Zn-N Zn-S
Tin Tin
Titanium Titanium 95% plus potassium titanate 5 % Titanium 81 % plus titanium oxide 19% Zinc
Silane, 0.50% None (control) Mercaptan, 0.28% NPG-GMA, 0.28%
t
Ti-S
*Operational definitions given in the text.
tNot determined.
seconds and Zn-C and Zn-S were placed in the mold by 3.5 minutes. Those for measuring sorption were made either as described above or by mixing fresh pastes "A" and "B" for 15 seconds and placing in the mold by 30 seconds. MEASUREMENT PROCEDURES.
-
The
hardening times were determined by a method reported previously, 13at 7 to 9 days after the pastes were initially prepared, and again at 22 to 23 days. Water sorption tests were conducted and are reported in a separate publication.4 Strength values were determined using methods reported previously' except that the mold size for centrifugal tensile specimenswas2mm x 2mm x 29.6mm.
Class II restorations were placed in extracted teeth using materials AlTiO2-S, Glass-S, Nb-S, Sn-S, Ti-S, TiKTi-S, and TiTiO2-S. The teeth were kept in water, and clinical conditions were simulated as closely as possible. A conventional dental amalgam restoration was placed for comparison. Immediately after placement, the composite restorations were coated with a silicate lubricant and stored at 37 C. After 20 minutes they were finished using round burs and white finishing stones on the occlusal, and successively finer disks (ending with fine cuttlefish) on the proximal. The amalgam restoration was finished after 24 hours. All surfaces were then finished with wet pumice on a rubber prophylaxis cup
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BOWEN ET AL
216
j Dent
and finally with tin oxide and alcohol (95% ethanol) on a soft bristle brush. The restored teeth were radiographed to observe their relative X-ray opacity. In addition, the restorations were visually observed periodically for the quality of surface and marginal integrity. Upon completion of the above tests, "24hour" (27 + 5 hours), strength specimens were made with several of the apparently stronger composite formulations (Al + TiO2-S, Glass-S, Ti-S, and Ti+TiO2-S). The preparation of these specimens utilized a three-component system composed of the metallic powder and each of the two liquids "A" and "B" in quantities that would be immediately utilized in specimen preparation. The three-part system was mixed for 1.25 minutes and loaded into the mold or molds by 3 minutes. Al + TiO2-SII specimens were prepared having a lower filler to monomer ratio of 4.06. Results
Sn-N paste B, and Zn-N pastes A and B
Res
February
had polymerized before any specimens were made. Sn-N paste B and Ti + TiO2-S paste B hardened in the jars at 12 to 24 hours and 43 days, respectively. In the Zn series, all pastes except Zn-M paste B had become thicker (very "dry", but could be stirred) by 3 to 4 hours. In spite of the thickening, the pastes were still used to check hardening time and prepare fourweek strength analysis specimens, except for the Zn-N pastes which had hardened to such an extent that test specimens could not be made. The mixes containing iron or silver-tincopper-zinc (dental amalgam alloy) either did not harden or the hardening time was so extended that it was not possible to make specimens. The hardening times (Table 3) allow for only tentative qualitative comparisons since no more than two measurements were made on a material and these were not at the same time nor all made by the same investigator. The tensile strength of the polymer
TABLE 3 HARDENING TIME Hardening Times* Linear Rotational Material
Al + TiO2-S Glass-S
(min.)
(min.)
C GQ C> Lo GQ C> C>
000
e C
V
0. ._
(0
0
o
o
(^ .0 000
00
000
0 00
0
0 CZ -
n0 0E 0 tN
_
_
CZ
-o
z4
_
Various particulate materials were combined with a BIS-GMA resin, and the resulting composites were evaluated. Thefillers prevented, altered, had no apparent
effect, or accelerated polymerization. Coupling agents also influenced polymerization. Physical properties varied widely with dafferentfillers. J Dent Res 57(2): 213-220, February 1978.
In a previous study, ' a sampling of metals, available as powders, was used as fillers for thermosetting acrylic resins. The prior treatment of the metallic (oxide) surfaces with appropriate organofunctional coupling agents significantly improved certain physical properties. Here, additional powders and coupling agents are surveyed. If good physical properties among any of these composites should be found, testing for wear resistance, and evaluation for possible use in conservative treatment of incipient lesions associated with developmental pits and fisReceived for publication February 9, 1977. Accepted for publication May 4, 1977. This investigation was supported in part by Research Grant DE-02494-06 to the American Dental Association Health Foundation from the National Institutes of HealthNational Institute of Dental Research, and is part of the dental research program conducted by the National Bureau of Standards, in cooperation with the American Dental Association Health Foundation. *Certain commercial materials are identified in this paper to specify the experimental procedure. In no instance does such identification imply recommendation or endorsement by the National Bureau of Standards or the American Dental Association Health Foundation or that the material or equipment identified is necessarily the best available for the purpose.
tLucidol 98, Pennwalt Corp., Buffalo, NY. +A-1 74, Union Carbide Corp., New York, NY.
sures in posterior teeth' would be indicated. A wear-resistant composite could fill the small cavity and be chemically united with the overlying "sealant" resin. Materials and Methods*
The principal materials used in this study are included in Tables 1 and 2. RESIN. - The monomer formulation is given in Table 1. To part of the monomer formulation was added 0.5 % N,N-dimethyl-3,5-xylidine, giving "Monomer A". To the rest was added 0.8% benzoyl peroxide,t giving "Monomer B". FILLERS. - The aluminum powder was used only in combination with the titanium oxide powder in this study. The titanium oxide pigment was used only in combination with titanium and aluminum powders (19% TiO2 with each). The potassium titanate whiskers were used only in combination with the titanium powder (5 % potassium titanate). The glass (SiO2 67, BaO 16.5, B203 10, and A1203 6.5, mole %) powder had an alkaline reaction (pH 9.3; 10 % aqueous slurry), not reported previously.3 It was washed once with distilled water, suction filtered, and dried at 115 C in a vacuum oven before it was treated with the silane coupling agent. Water-sorption characteristics4 suggest that a more thorough treatment is warranted. The glass powder was slurried in silane (3 -methacryloxypropyltrimethoxysilane +) dilued with acetone, and then tumbled and heated (100 to 130 C) with intermittent evacuation to about 200 mm Hg (26.6 kPa) for one hour. Lumps and caked ma213
Downloaded from jdr.sagepub.com at UCSF LIBRARY & CKM on April 18, 2015 For personal use only. No other uses without permission.
j Dent
BOWEN ET AL
214
terial were removed with a sieve (US Standard No. 20). The silane treatments of the other powders were essentially the same, except without prior aqueous washing. The mercaptan* or the NPG-GMA5-12 coupling agent was also applied in acetone and heat dried in the same manner. The powders were tested to determine if they were covered with organic coupling agent: a small pile was indented to form a slight concavity. If a drop of distilled water could stand on this for at least 5 minutes without penetrating, the powder was described as "hydrophobic." If water penetrated the powder immediately, it was "hydrophilic. " Intermediate qualities could be observed with some powders, in which instances the water would penetrate slowly; powder particles would spread over the surface of the water drop; or, when the drop was picked up after 5 minutes with a *Mercaptate Q-42 Ester, Carlisle Chemical Works, Inc., Reading, Oh.
Res
February
1978
small ball of cotton, a layer of wetted powder would stick to the surface of the water drop. SPECIMEN PREPARATION. - Each was formulated from two pastes, unless otherwise noted. Each paste contained one of the fillers listed in Table 2 and either monomer "A" or "B". The resulting "paste A" and "paste B" each had the same fillermonomer ratio (Table 2), and were as thick as possible within the limits of workability. Abbreviations (Table 2) were assigned to each formulation according to the type of filler and its surface treatment. Except for zinc specimens, the procedure consisted of mixing equal amounts of each paste for 30 seconds, loading the mold by 2.5 minutes, placement of the filled mold in a 37 C, 100% relative humidity oven by 5 minutes, removal of the specimen from the mold at 20 minutes, and storage in distilled water at 37 + 1 C for 28 + 1 days. Zinc-containing specimens for strength analysis were made from the initial pastes by mixing for one minute rather than 30
TABLE 1 POWDERS AND MONOMER FORMULATION Powder
Aluminum Barium aluminoborosilicate glass* Iron
Niobium Potassium titanate (Fibex®' TTD)
Silver-tin-copper-zinc (lathe-cut dental alloy)
Nominal Purity
99.9% Colorless 99.9 + % 99.9 ±+
Highly-refined single crystals ADA Cert. grade
Tin
99.999%
Titanium Titanium (ic) oxide Zinc
99 % reagent
Ingredient
BIS-GMA (Stypol 46-4013) Triethyleneglycol dimethacrylate Butylated hydroxytoluene (BHT)
99.2%
Source
Ventron Corp.
Corning Glass Works Ventron Corp.
Gallard-Schlesinger Chem. Mfg. Corp. E I duPont de Nemours and Co. (Pooled samples from various sources) Ventron Corp. Ventron Corp. Fisher Sci. Co. Fisher Sci. Co.
Weight %
69.9 29.9 0.2
Freeman Chem. Co.
Borden, Inc. Eastman Chem. Prod., Inc.
*"Corning 7724 glass."
Downloaded from jdr.sagepub.com at UCSF LIBRARY & CKM on April 18, 2015 For personal use only. No other uses without permission.
Vol. 5 7 No. 2
METAL-FILLED RESIN COMPOSITES
215
TABLE 2 FILLERS, SURFACE TREATMENTS OF FILLERS, FILLER-MONOMER RATIOS, AND ABBREVIATIONS
Surface Treatment
Fillers
Surface Condition*
Aluminum 81% plus titanium oxide 19% Glass Iron Iron Iron
Silane, 0.54%
Iron
Silane, 0.28%
Niobium
None (control)
Niobium Dental alloy Dental alloy Dental alloy
Silane, 0.13 % None (control) NPG-GMA, 0.11% Silane, 0.11 %
Tin
None (control) NPG-GMA, 0.15%
FillerMonomer Ratio
Abbreviation for Resulting Composite
4.6
Al + TiO2-S
3.5 5.0
5.0
Glass-S Fe-C Fe-M Fe-N
5.0
Fe-S
8.1
Nb-C
8.1 5.4 5.4 5.4
Nb-S Ag-Sn-C Ag-Sn-N Ag-Sn-S
6.9 6.9 6.9 3.5 3.4
Sn-C Sn-N Sn-S Ti + KTi-S
Silane, 0.15% Silane, 0.40% Silane, 0.59%
Nearly hydrophobic Hydrophobic Hydrophilic Not hydrophobic Completely hydrophobic Completely hydrophobic Nearly hydrophobic Hydrophobic Hydrophilic Hydrophobic Somewhat hydrophobic Hydrophilic Hydrophobic Hydrophobic Hydrophobic Hydrophobic
Silane, 0.43%
Hydrophobic
5.4
Ti+TiO2-S
Zinc Zinc
None (control) Mercaptan, 0.23% NPG-GMA, 0.21%
Zinc
Silane, 0.23%
Hydrophilic Hydrophobic Hydrophobic Hydrophobic
8.2 8.2 8.2 8.2
Zn-C Zn-M Zn-N Zn-S
Tin Tin
Titanium Titanium 95% plus potassium titanate 5 % Titanium 81 % plus titanium oxide 19% Zinc
Silane, 0.50% None (control) Mercaptan, 0.28% NPG-GMA, 0.28%
t
Ti-S
*Operational definitions given in the text.
tNot determined.
seconds and Zn-C and Zn-S were placed in the mold by 3.5 minutes. Those for measuring sorption were made either as described above or by mixing fresh pastes "A" and "B" for 15 seconds and placing in the mold by 30 seconds. MEASUREMENT PROCEDURES.
-
The
hardening times were determined by a method reported previously, 13at 7 to 9 days after the pastes were initially prepared, and again at 22 to 23 days. Water sorption tests were conducted and are reported in a separate publication.4 Strength values were determined using methods reported previously' except that the mold size for centrifugal tensile specimenswas2mm x 2mm x 29.6mm.
Class II restorations were placed in extracted teeth using materials AlTiO2-S, Glass-S, Nb-S, Sn-S, Ti-S, TiKTi-S, and TiTiO2-S. The teeth were kept in water, and clinical conditions were simulated as closely as possible. A conventional dental amalgam restoration was placed for comparison. Immediately after placement, the composite restorations were coated with a silicate lubricant and stored at 37 C. After 20 minutes they were finished using round burs and white finishing stones on the occlusal, and successively finer disks (ending with fine cuttlefish) on the proximal. The amalgam restoration was finished after 24 hours. All surfaces were then finished with wet pumice on a rubber prophylaxis cup
Downloaded from jdr.sagepub.com at UCSF LIBRARY & CKM on April 18, 2015 For personal use only. No other uses without permission.
BOWEN ET AL
216
j Dent
and finally with tin oxide and alcohol (95% ethanol) on a soft bristle brush. The restored teeth were radiographed to observe their relative X-ray opacity. In addition, the restorations were visually observed periodically for the quality of surface and marginal integrity. Upon completion of the above tests, "24hour" (27 + 5 hours), strength specimens were made with several of the apparently stronger composite formulations (Al + TiO2-S, Glass-S, Ti-S, and Ti+TiO2-S). The preparation of these specimens utilized a three-component system composed of the metallic powder and each of the two liquids "A" and "B" in quantities that would be immediately utilized in specimen preparation. The three-part system was mixed for 1.25 minutes and loaded into the mold or molds by 3 minutes. Al + TiO2-SII specimens were prepared having a lower filler to monomer ratio of 4.06. Results
Sn-N paste B, and Zn-N pastes A and B
Res
February
had polymerized before any specimens were made. Sn-N paste B and Ti + TiO2-S paste B hardened in the jars at 12 to 24 hours and 43 days, respectively. In the Zn series, all pastes except Zn-M paste B had become thicker (very "dry", but could be stirred) by 3 to 4 hours. In spite of the thickening, the pastes were still used to check hardening time and prepare fourweek strength analysis specimens, except for the Zn-N pastes which had hardened to such an extent that test specimens could not be made. The mixes containing iron or silver-tincopper-zinc (dental amalgam alloy) either did not harden or the hardening time was so extended that it was not possible to make specimens. The hardening times (Table 3) allow for only tentative qualitative comparisons since no more than two measurements were made on a material and these were not at the same time nor all made by the same investigator. The tensile strength of the polymer
TABLE 3 HARDENING TIME Hardening Times* Linear Rotational Material
Al + TiO2-S Glass-S
(min.)
(min.)
C GQ C> Lo GQ C> C>
000
e C
V
0. ._
(0
0
o
o
(^ .0 000
00
000
0 00
0
0 CZ -
n0 0E 0 tN
_
_
CZ
-o
z4
_
