Wax patterns are removed from the set impression by flexing the impression. A stone cast is obtained by use of a double-pour technique (Fig. 2). A porcelain cutback guide is made by removing selected segments of the impression. A guide for assessing incisal or occlusal cutback is obtained by cutting away the lingual half of the impression, leaving the facie-occlusal or facioincisal line angles (Fig. 3). A guide for assessing facial cutback is obtained by removing the incisal portion of the previous porcelain cutback guide (Fig. 4). REFERENCES
Fig. 4. Cutback guide replaced on working cast to assess facial porcelain cutback dimensions.
1.
An impression is made of the full-contour wax-up by use of an addition silicone putty (Reprosil, L.D. Caulk, Milford, Del.). The putty is adapted to the facial, occlusal, and lingual surfaces of the wax-up and the die bases of the working cast (Fig. 1).
Shear bond strength Jeffrey Robert
@hang, DDS,a Warren Martini, BA.C
New York University,
of a 4-META Scherer,
College of Dentistry,
1. Shillingburg HT Jr, Hobo S, Whit&t LD. Fundamentals of fixed prosthodontics. 2nd ed. Chicago: Quintessence, 1981:426. 2. Rosenstiel SF, Land MF, Fujimoto J. Contemporary fixed prosthodontics. St Louis: CV Mosby Co, 1988:300-l. 3. Lau CS, Yamada HN. Metal-ceramic crowns and fixed part&I dentures. In: Rhoads JE, Rudd KD, Morrow RM, eds. Dental laboratory procedures. vol 2. Fixed partial dentures. 2nd ed. St Louis: CV Mosby Co, 1986:270-6.
Reprint requests to: DR.PETERS.LUND S421 DENTAL SCIENCE BUILDING UNIVERSITY OF IOWA IOWA CITY, IA 52242
adhesive
DDS,b Antoinette
syste
Tauk, BA,c and
New York, N.Y.
This study evaluated the shear bond strength between amalgam and amalgam, amalgam and composite resin, and amalgam and dentin using a I-META adhesive. Eighty samples were divided into four groups of 20 and were then divided into subgroups of 10 samples for thermocycling procedures. This study indicated that amalgam bonded to amalgam with a 4-META adhesive yielded bond strengths that were weaker than the shear strength of amalgam itself Cp < 0.05), and that thermocycling appeared to significantly weaken bond values (p < 0.02). (J PROSTHET DENT 1992;67:42-5.)
ental materials containing the monomer 4-methacryloxyethyl trimellitate anhydride (4-META) were introduced nearly a decade ago in Japan. This monomer contains both hydrophilic and hydrophobic components aAssistant Professor, Department of Prosthodontics, The Dental School, University of Texas Health Science Center, Houston, Texas. bDirector, Advanced Education Program in General Dentistry, New York University, College of Dentistry. CJunior student, New York University, College of Dentistry. 10/1/28254
and appears to promote adhesion when applied to a to0th.l Investigators have also confirmed that the 4-META monomer aids in elevating bond strengths with certain metal al10ys.~-~A new 4-META derivative, Amalgambond (Parkell, Farmingdale, N.Y.) has been recently developed to bond fresh amalgam to dentin, enamel, and existing amalgam. This study: (1) evaluated the shear bond strength between amalgam and amalgam, amalgam and composite resin, and amalgam and dentin using Amalgambond material and (2) it also compared the shear bond strengths of ali the samples before and after thermocycling.
SHEAR
BOND
STRENGTH
OF J-META
ADHESIVE
am Fig.
METHODS
1. Prepared
samples.
AND MATERIAL
Eighty samples were divided into four groups of 20 and were then divided into subgroups of 10 samples each: Group I-amalgam (control) Subgroup A-not thermocycled Subgroup B-thermocycled Group II-amalgam bonded to amalgam Subgroup A-not thermocycled Subgroup B-thermocycled Group III-amalgam bonded to composite resin Subgroup A-not thermocycled Subgroup B-thermocycled Group IV-amalgam bonded to dentin Subgroup A-not thermocycled Subgroup B-thermocycled Sixty amalgam cyclinders 7 mm in diameter and 12 mm high were constructed in a specific acrylic resin jig for the samples in groups I, II, and III for this purpose. This jig was designed with a hollow cylindrical-shaped area, 7 mm in diameter and 15 mm high. After setting, the amalgam cylinders were removed and submerged in a distilled water bath at 37’ C for 24 hours before additional preparation and testing. Twenty of the amalgam cylinders were designated as group I. Group II samples were prepared by flattening and smoothing the top surfaces of 20 amalgam cylinders with a No. 57 carbide bur in a high-speed handpiece using a water coolant. The adhesive under investigation was applied to one of the prepared surfaces of each sample according to the manufacturer’s directions. Dispersalloy (Johnson and Johnson, Skillman, N.J.) amalgam was then condensed against these surfaces to a height of 3 mm using the acrylic resin jig (Figs. 1 and 2). Twenty group III samples were prepared identically to those in group II except the application of the bonding agent was followed by the polymerization of Lumifor visible-light-curing composite resin (Columbus Dental, Division of Miles, Inc., St. Louis, MO.) to a height of 3 mm using a transparent matrix. The composite resin was polymerized on two sides of the amalgamto-composite resin junction for 40 seconds, including the top surface of the composite resin. The samples in group IV were created using 20 freshly extracted, noncarious molar teeth. Occlusal preparations 7 mm wide and 3 mm deep were prepared in each tooth with a 57 carbide bur in a high-speed handpiece using a water coolant. The prepara-
THE
JOURNAL
OF PROSTHETIC
corn am
DENTISTRY
a a
am - amalgam corn - composite den- dentin Fig.
2. Diagrammatic
illustration
BeforeThermocycling fY;z
of prepared
samples.
After Thermocycling m
MeanBondStrengthKg/cm*
Am-Am Am-Corn SampleGroups Am=AmalgamCorn=CompositeDen=Dentin
Am
n
Fig. 3. Histogram of bond strengths of all groups before and after thermocycling.
tions were rinsed and air-dried. The adhesive was placed into each preparation according to the manufacturer’s directions, and Dispersalloy amalgam was then condensed into the preparation. After the amalgam set, enamel and dentin were removed with a No. 57 carbide bur in a highspeed handpiece using water coolant, exposing an amalgam cylinder (Figs. 1 and 2). The prepared samples in groups II, III, and IV were inserted in distilled water at 37’ C for 24 hours before test-
43
CBANG ET AL
Table
I. Bond strength of all samples before thermocycling Sample No. -1
2 3 4 5
Am
Am-Am
Am-Corn
Am-Den
127.24 116.64 104.86 108.39
133.13 107.21 128.42 123.71
18.26 15.32 15.32 22.97
7.07 13.55 8.25 11.78
108.39 122.53
121.35 123.71
14.73
10.60 8.25 10.02
7 8
142.56 131.96
91.90
17.67 14.14 12.96 16.49
9
143.74
110.75
13.55
124.89
116.64
17.67
123.12 13.79
115.34 13.55
16.44 2.93
6
10 Mean SD
96.61
9.43 7.07 9.43
2.63
Am, Amalgam; Cum, composite; Den, dentin.
Table
II.
Bond strength of all samples after thermocycling Sample No.
Am
117.82
Am-Am
Am-Corn
Am-Den
94.25
17.67 16.49 11.78 20.03 18.85 12.96
8.25 4.71 8.25 9.43
16.49 14.14 15.32 17.67 16.14 2.61
1 2 3 4 6
103.68 103.68 110.75 98.97
6
117.82
96.61 101.32 115.46 108.39 111.93
7 8 9 10 Mean SD
120.17 119.00 127.24 122.53 114.17 9.37
106.04 94.25 110.75 117.82 105.68 8.68
12.96 14.14 4.71 9.43 8.25 10.60 9.07 3.05
Am, Amalgam; Corn, composite; Den, dentin.
ing. All samples in the “B” subgroups were thermocycled 1000 times at 5” to 55” C, with a 30-second dwell time at each temperature. The samples were evaluated using an Instron Universal Testing machine (Instron Corporation, Canton, Mass.), with pressure exerted on the interfaces at a crosshead rate of 0.5 mm per minute, using a shear force until fracture. The data were examined by a two-way analysis of variance (ANOVA). The Scheffe contrast analysis was used to identify differences between groups at an 0.05 level of significance.
Table I lists the results of the shear bond tests. The shear strength of the amalgam yielded a mean shear bond of 123.12 kg/cm2, while amalgam bonded to amalgam with the adhesive yielded a mean shear bond of 115.34 kg/cm2. Amalgam bonded to composite resin with the adhesive yielded a mean shear bond of 16.44 kg/cm2. A mean shear bond of 10.02 kg/cm2 was produced when amalgam was
bonded to dentin with the same adhesive. The results obtained after thermocycling of the samples in the “B” subgroups are presented in Table II. The mean shear bond value of amalgam was 114.17 kg/cm2, and the mean shear
bond values of amalgam bonded to amalgam was 105.68 kg/cm2 (Fig. 3). The mean shear bond values of amalgam to composite resin and amalgam to dentin, respectively, were: 16.14 kg/cm2 and 9.07 kg/cm2 (Fig. 3). Results were subjected to a two-way analysis of variance (Table III). Significant differences were found between the groups for thermocycling versus nonthermocycling procedures (p < 0.02) and for the types of bonds evaluated (p < 0.001). These bonding conditions were subjected to the Scheffe contrast analysis (Table IV). This analysis at the p < 0.05 level revealed three subsets: amalgam, amalgam-amalgam, amalgam-composite, and amalgam-dentin.
No interaction thermocycling
effects were noted between groups and conditions.
Analysis of the shear bond values of amalgam bonded to amalgam with the 4-META bonding agent indicated
SHEAR
BOND
STRENGTH
OF I-META
ADHESIVE
Table
III.
Analysis of variance Sum of squares
DF
Mean square
Main effects
208,767.974
4
Thermo Cond 2-way interactions Therm0 Cond Explained Residual Total
468.270 208,299.704 398.410 398.410 209J66.385 5,080.157 214,246.541
1
52J91.994 468.270
739.706 6.637
69,433.235
984.063
0.012 0.000
132.803 132.803 29,880.912 70.558
1.882 1.882 423.496
0.140 0.140 0.000
Source of variation
3 3 3 7 72 79
-
F
Significance
of F
0.000
2,711.982
Thermo, Thermocycle; Cond, condition.
that the strength of the bonded samples appeared to be weaker than the strength of the original amalgam (p < 0.05).
DISCUSSION Carboxyl compounds have the ability to react with metals to form organometallic compounds. This propensity can be attributed to the formation of ionic bonds with formed metallic oxides or with the active metal components of the amalgam. However, the results of this study indicated that even though metallic bonds did form between the amalgam-amalgam group, these bonds were weaker than the amalgam material itself but were stronger than the bonds between the amalgam-composite and amalgam-dentin groups. Even though the 4-META adhesive may react with or promote adhesion to the collagen in dentin,l the bonds obtained with dentin in this study appear to be weak and not well established. One can speculate that greater shear bond values may be achieved if mechanical retention were placed in the dentin samples. Investigators have demonstrated that high bond strengths may be maintained with 4-META derivatives after subjecting samples to a substantial number of thermocycling procedures. However, the results obtained from this study indicated that subsequent thermocycling significantly weakened shear bond values using the 4-META adhesive.
Table
IV.
Scheffe contrast analysis
Subset 1
Group mean Subset 2 Group mean Subset 3 Group mean
Group 4 9.3090
Group 3 16.2875
Group 2 110.5L25 Group 1 118.6295
3. Mechanical retention may be necessary to improve the bond of amalgam to dentin with a 4-META adhesive. REFERENCES 1. Nakabayashi N, Kojima K, Masuhara E. The promotion of adhesion by the infiltration of monomers into tooth substrates. J Biomed Mater Res 1982;16:265-73. 2. Takeyama M. Adhesion between new self-curing resin and denture base alloys. J Stomatol Sot Jpn 1986;61:129-35 (In Japanese) 3. Tanaka T, Atsuta M, Nakabayasi N, Masuhara E. Surface treatment of gold alloys for adhesion. J PROSTHET DENT 1988;60:271-9. 4. Tanaka T, Hirano M, Kawahara M, Matsumura H, Atsuta M. A new ioncoating treatment of alloys for dental adhesive resins. J Dent Res 1988;67:1376-80. 5. Watanabe F, Powers JM, Lorey RE. In vitro bonding of prostbodontic adhesives to dental alloys. J Dent Res 1988;67:479-83. 6. Jacobson TE, Chang JC, Keri PP, Watanabe LG. Bond strength of 4-META acrylic resin denture base to cobalt chromium alloy. J PROSTHET DENT 1988;60:570-6.
CONCLUSIONS 1. Amalgam bonded to amalgam with a 4-META adhesive created bond strengths that were weaker than the shear strength of the amalgam. 2. Thermocycling appears to affect the shear bonds established cles.
THE
with the 4-META
JOURNAL
OF PROSTHETIC
adhesive after 1000 thermocy-
DENTISTRY
7. Mojon P, Hawbolt EB, MacEntee MI, Belser UC. Maximum bond strength of dental luting cement to amalgam alloy. J Dent Res 1989;68:1545-9. ;5eprint requests to: DR. JEFFREY C. CHANG UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER DENTAL SCHOOL DEPARTMENT OF PROSTHODONTICS HOUSTON, TX 77225
45
Fig. 4. Cutback guide replaced on working cast to assess facial porcelain cutback dimensions.
1.
An impression is made of the full-contour wax-up by use of an addition silicone putty (Reprosil, L.D. Caulk, Milford, Del.). The putty is adapted to the facial, occlusal, and lingual surfaces of the wax-up and the die bases of the working cast (Fig. 1).
Shear bond strength Jeffrey Robert
@hang, DDS,a Warren Martini, BA.C
New York University,
of a 4-META Scherer,
College of Dentistry,
1. Shillingburg HT Jr, Hobo S, Whit&t LD. Fundamentals of fixed prosthodontics. 2nd ed. Chicago: Quintessence, 1981:426. 2. Rosenstiel SF, Land MF, Fujimoto J. Contemporary fixed prosthodontics. St Louis: CV Mosby Co, 1988:300-l. 3. Lau CS, Yamada HN. Metal-ceramic crowns and fixed part&I dentures. In: Rhoads JE, Rudd KD, Morrow RM, eds. Dental laboratory procedures. vol 2. Fixed partial dentures. 2nd ed. St Louis: CV Mosby Co, 1986:270-6.
Reprint requests to: DR.PETERS.LUND S421 DENTAL SCIENCE BUILDING UNIVERSITY OF IOWA IOWA CITY, IA 52242
adhesive
DDS,b Antoinette
syste
Tauk, BA,c and
New York, N.Y.
This study evaluated the shear bond strength between amalgam and amalgam, amalgam and composite resin, and amalgam and dentin using a I-META adhesive. Eighty samples were divided into four groups of 20 and were then divided into subgroups of 10 samples for thermocycling procedures. This study indicated that amalgam bonded to amalgam with a 4-META adhesive yielded bond strengths that were weaker than the shear strength of amalgam itself Cp < 0.05), and that thermocycling appeared to significantly weaken bond values (p < 0.02). (J PROSTHET DENT 1992;67:42-5.)
ental materials containing the monomer 4-methacryloxyethyl trimellitate anhydride (4-META) were introduced nearly a decade ago in Japan. This monomer contains both hydrophilic and hydrophobic components aAssistant Professor, Department of Prosthodontics, The Dental School, University of Texas Health Science Center, Houston, Texas. bDirector, Advanced Education Program in General Dentistry, New York University, College of Dentistry. CJunior student, New York University, College of Dentistry. 10/1/28254
and appears to promote adhesion when applied to a to0th.l Investigators have also confirmed that the 4-META monomer aids in elevating bond strengths with certain metal al10ys.~-~A new 4-META derivative, Amalgambond (Parkell, Farmingdale, N.Y.) has been recently developed to bond fresh amalgam to dentin, enamel, and existing amalgam. This study: (1) evaluated the shear bond strength between amalgam and amalgam, amalgam and composite resin, and amalgam and dentin using Amalgambond material and (2) it also compared the shear bond strengths of ali the samples before and after thermocycling.
SHEAR
BOND
STRENGTH
OF J-META
ADHESIVE
am Fig.
METHODS
1. Prepared
samples.
AND MATERIAL
Eighty samples were divided into four groups of 20 and were then divided into subgroups of 10 samples each: Group I-amalgam (control) Subgroup A-not thermocycled Subgroup B-thermocycled Group II-amalgam bonded to amalgam Subgroup A-not thermocycled Subgroup B-thermocycled Group III-amalgam bonded to composite resin Subgroup A-not thermocycled Subgroup B-thermocycled Group IV-amalgam bonded to dentin Subgroup A-not thermocycled Subgroup B-thermocycled Sixty amalgam cyclinders 7 mm in diameter and 12 mm high were constructed in a specific acrylic resin jig for the samples in groups I, II, and III for this purpose. This jig was designed with a hollow cylindrical-shaped area, 7 mm in diameter and 15 mm high. After setting, the amalgam cylinders were removed and submerged in a distilled water bath at 37’ C for 24 hours before additional preparation and testing. Twenty of the amalgam cylinders were designated as group I. Group II samples were prepared by flattening and smoothing the top surfaces of 20 amalgam cylinders with a No. 57 carbide bur in a high-speed handpiece using a water coolant. The adhesive under investigation was applied to one of the prepared surfaces of each sample according to the manufacturer’s directions. Dispersalloy (Johnson and Johnson, Skillman, N.J.) amalgam was then condensed against these surfaces to a height of 3 mm using the acrylic resin jig (Figs. 1 and 2). Twenty group III samples were prepared identically to those in group II except the application of the bonding agent was followed by the polymerization of Lumifor visible-light-curing composite resin (Columbus Dental, Division of Miles, Inc., St. Louis, MO.) to a height of 3 mm using a transparent matrix. The composite resin was polymerized on two sides of the amalgamto-composite resin junction for 40 seconds, including the top surface of the composite resin. The samples in group IV were created using 20 freshly extracted, noncarious molar teeth. Occlusal preparations 7 mm wide and 3 mm deep were prepared in each tooth with a 57 carbide bur in a high-speed handpiece using a water coolant. The prepara-
THE
JOURNAL
OF PROSTHETIC
corn am
DENTISTRY
a a
am - amalgam corn - composite den- dentin Fig.
2. Diagrammatic
illustration
BeforeThermocycling fY;z
of prepared
samples.
After Thermocycling m
MeanBondStrengthKg/cm*
Am-Am Am-Corn SampleGroups Am=AmalgamCorn=CompositeDen=Dentin
Am
n
Fig. 3. Histogram of bond strengths of all groups before and after thermocycling.
tions were rinsed and air-dried. The adhesive was placed into each preparation according to the manufacturer’s directions, and Dispersalloy amalgam was then condensed into the preparation. After the amalgam set, enamel and dentin were removed with a No. 57 carbide bur in a highspeed handpiece using water coolant, exposing an amalgam cylinder (Figs. 1 and 2). The prepared samples in groups II, III, and IV were inserted in distilled water at 37’ C for 24 hours before test-
43
CBANG ET AL
Table
I. Bond strength of all samples before thermocycling Sample No. -1
2 3 4 5
Am
Am-Am
Am-Corn
Am-Den
127.24 116.64 104.86 108.39
133.13 107.21 128.42 123.71
18.26 15.32 15.32 22.97
7.07 13.55 8.25 11.78
108.39 122.53
121.35 123.71
14.73
10.60 8.25 10.02
7 8
142.56 131.96
91.90
17.67 14.14 12.96 16.49
9
143.74
110.75
13.55
124.89
116.64
17.67
123.12 13.79
115.34 13.55
16.44 2.93
6
10 Mean SD
96.61
9.43 7.07 9.43
2.63
Am, Amalgam; Cum, composite; Den, dentin.
Table
II.
Bond strength of all samples after thermocycling Sample No.
Am
117.82
Am-Am
Am-Corn
Am-Den
94.25
17.67 16.49 11.78 20.03 18.85 12.96
8.25 4.71 8.25 9.43
16.49 14.14 15.32 17.67 16.14 2.61
1 2 3 4 6
103.68 103.68 110.75 98.97
6
117.82
96.61 101.32 115.46 108.39 111.93
7 8 9 10 Mean SD
120.17 119.00 127.24 122.53 114.17 9.37
106.04 94.25 110.75 117.82 105.68 8.68
12.96 14.14 4.71 9.43 8.25 10.60 9.07 3.05
Am, Amalgam; Corn, composite; Den, dentin.
ing. All samples in the “B” subgroups were thermocycled 1000 times at 5” to 55” C, with a 30-second dwell time at each temperature. The samples were evaluated using an Instron Universal Testing machine (Instron Corporation, Canton, Mass.), with pressure exerted on the interfaces at a crosshead rate of 0.5 mm per minute, using a shear force until fracture. The data were examined by a two-way analysis of variance (ANOVA). The Scheffe contrast analysis was used to identify differences between groups at an 0.05 level of significance.
Table I lists the results of the shear bond tests. The shear strength of the amalgam yielded a mean shear bond of 123.12 kg/cm2, while amalgam bonded to amalgam with the adhesive yielded a mean shear bond of 115.34 kg/cm2. Amalgam bonded to composite resin with the adhesive yielded a mean shear bond of 16.44 kg/cm2. A mean shear bond of 10.02 kg/cm2 was produced when amalgam was
bonded to dentin with the same adhesive. The results obtained after thermocycling of the samples in the “B” subgroups are presented in Table II. The mean shear bond value of amalgam was 114.17 kg/cm2, and the mean shear
bond values of amalgam bonded to amalgam was 105.68 kg/cm2 (Fig. 3). The mean shear bond values of amalgam to composite resin and amalgam to dentin, respectively, were: 16.14 kg/cm2 and 9.07 kg/cm2 (Fig. 3). Results were subjected to a two-way analysis of variance (Table III). Significant differences were found between the groups for thermocycling versus nonthermocycling procedures (p < 0.02) and for the types of bonds evaluated (p < 0.001). These bonding conditions were subjected to the Scheffe contrast analysis (Table IV). This analysis at the p < 0.05 level revealed three subsets: amalgam, amalgam-amalgam, amalgam-composite, and amalgam-dentin.
No interaction thermocycling
effects were noted between groups and conditions.
Analysis of the shear bond values of amalgam bonded to amalgam with the 4-META bonding agent indicated
SHEAR
BOND
STRENGTH
OF I-META
ADHESIVE
Table
III.
Analysis of variance Sum of squares
DF
Mean square
Main effects
208,767.974
4
Thermo Cond 2-way interactions Therm0 Cond Explained Residual Total
468.270 208,299.704 398.410 398.410 209J66.385 5,080.157 214,246.541
1
52J91.994 468.270
739.706 6.637
69,433.235
984.063
0.012 0.000
132.803 132.803 29,880.912 70.558
1.882 1.882 423.496
0.140 0.140 0.000
Source of variation
3 3 3 7 72 79
-
F
Significance
of F
0.000
2,711.982
Thermo, Thermocycle; Cond, condition.
that the strength of the bonded samples appeared to be weaker than the strength of the original amalgam (p < 0.05).
DISCUSSION Carboxyl compounds have the ability to react with metals to form organometallic compounds. This propensity can be attributed to the formation of ionic bonds with formed metallic oxides or with the active metal components of the amalgam. However, the results of this study indicated that even though metallic bonds did form between the amalgam-amalgam group, these bonds were weaker than the amalgam material itself but were stronger than the bonds between the amalgam-composite and amalgam-dentin groups. Even though the 4-META adhesive may react with or promote adhesion to the collagen in dentin,l the bonds obtained with dentin in this study appear to be weak and not well established. One can speculate that greater shear bond values may be achieved if mechanical retention were placed in the dentin samples. Investigators have demonstrated that high bond strengths may be maintained with 4-META derivatives after subjecting samples to a substantial number of thermocycling procedures. However, the results obtained from this study indicated that subsequent thermocycling significantly weakened shear bond values using the 4-META adhesive.
Table
IV.
Scheffe contrast analysis
Subset 1
Group mean Subset 2 Group mean Subset 3 Group mean
Group 4 9.3090
Group 3 16.2875
Group 2 110.5L25 Group 1 118.6295
3. Mechanical retention may be necessary to improve the bond of amalgam to dentin with a 4-META adhesive. REFERENCES 1. Nakabayashi N, Kojima K, Masuhara E. The promotion of adhesion by the infiltration of monomers into tooth substrates. J Biomed Mater Res 1982;16:265-73. 2. Takeyama M. Adhesion between new self-curing resin and denture base alloys. J Stomatol Sot Jpn 1986;61:129-35 (In Japanese) 3. Tanaka T, Atsuta M, Nakabayasi N, Masuhara E. Surface treatment of gold alloys for adhesion. J PROSTHET DENT 1988;60:271-9. 4. Tanaka T, Hirano M, Kawahara M, Matsumura H, Atsuta M. A new ioncoating treatment of alloys for dental adhesive resins. J Dent Res 1988;67:1376-80. 5. Watanabe F, Powers JM, Lorey RE. In vitro bonding of prostbodontic adhesives to dental alloys. J Dent Res 1988;67:479-83. 6. Jacobson TE, Chang JC, Keri PP, Watanabe LG. Bond strength of 4-META acrylic resin denture base to cobalt chromium alloy. J PROSTHET DENT 1988;60:570-6.
CONCLUSIONS 1. Amalgam bonded to amalgam with a 4-META adhesive created bond strengths that were weaker than the shear strength of the amalgam. 2. Thermocycling appears to affect the shear bonds established cles.
THE
with the 4-META
JOURNAL
OF PROSTHETIC
adhesive after 1000 thermocy-
DENTISTRY
7. Mojon P, Hawbolt EB, MacEntee MI, Belser UC. Maximum bond strength of dental luting cement to amalgam alloy. J Dent Res 1989;68:1545-9. ;5eprint requests to: DR. JEFFREY C. CHANG UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER DENTAL SCHOOL DEPARTMENT OF PROSTHODONTICS HOUSTON, TX 77225
45
