- Email: [email protected]
Polishing dental amalgam restorations
Polishing
dental amalgam restorations
J. de Vries, B.Ch.D., M.Dent.,
F. A. de Wet, B.Ch.D., M.Dent.,
and J. D. Eick, Ph.D.***
Medical University of Southern Africa, Faculty of Dentistry, Medunsa, South Africa, and University of Missouri-Kansas City, School of Dentistry, Kansas City, MO
TT unpolished amalgam restorations are rough and therefore conducive to plaque accumulation.‘~2 Finishing and polishing of amalgam restorations is an important component in the ultimate clinical success of restorations.3,4Unfortunately, many dentists neglect this important step.4-7 Amalgam restorations may not be polished because an additional visit is required, certain polishing techniques may generate heat which might damage the pulp,” or dentists may not know a method for finishing and polishing. Several polishing techniques have been reported in the literature.‘, ‘15,9,lo In this study we evaluated the surface produced by different polishing techniques on three dental amalgam alloys. MATERIAL
AND METHODS
Premeasured capsules of an admixed nongamma 2 amalgam (Dispersalloy, Johnson and Johnson, East Windsor, N. J.), a platinum modified spherical amalgam (Lojic, Southern Dental Industries, Melbourne, Australia), and a spherical amalgam (Unison, Johnson and Johnson) were triturated according to manufacturer’s instructions and hand condensed into class I cavities in extracted human molar teeth previously stored in 10% formalin solution. To minimize experimental errors, preparation and restoration were performed by a single investigator. To aid in measurement, tooth surfaces to be studied were flattened with an Isomet (Buehler Ltd., Lake Bluff, Ill.) low-speed mechanical saw. Test cavities were prepared (2 mm deep, 5 mm wide, and 9 mm long) with a dome-shaped diamond fissure bur (IS0 044). The cavities were overfilled and excess amalgam was Sponsored in part by a research grant from A. D. Laboratories, Johannesburg, South Africa. Presented at the International Association for Dental Research (South African Division), Pretoria, South Africa. *Professor and Chairman, Department of Operative Dentistry, Medical University of Southern Africa, Faculty of Dentistry. **Professor and Chairman, Department of Stomatological Studies, Medical University of Southern Africa, Faculty of Dentistry. ***Professor, Department of Oral Biology, University of MissouriKansas City, School of Dentistry.
148
removed with a sharp stainless steel carver. All restorations were burnished with a smooth-face burnisher by using 24 strokes in only one direction. Forty-five specimens were prepared for each of the three amalgams. The samples were divided into nine groups of five and subjected to nine different polishing regimens. After dry storage for 24 hours, baseline surface roughness was determined for the first eight groups (120 samples). They were then subjected to eight different polishing regimens. The remaining group of five samples (group 9) was polished immediately (15 minutes after placement) with prophylaxis paste and rubber cup. Light pressure and a speed of 2500 rpm were used for finishing. Twenty-four polishing strokes (in only one direction) were used with each polishing agent. A new (unused) polishing device was used for each specimen. The nine finishing and polishing techniques studied were: Group 1. Samples only carved and burnished Group 2. Carved, burnished, and wiped with a wet cotton pellet Group 3. Polished with pumice in a soft rubber cup Group 4. Polished with green stone, amalgam finishing bur, pumice, and zinc oxide in sequence in rubber cups Group 5. Polished with Brownie cup and Brownie mini point (Shofu, Kyoto, Japan) Group 6. Polished with Brownie mini point, Greenie mini point (Shofu), and Super Greenie mini point (Shofu) Group 7. Polished with amalgam finishing burs, Brownie mini points, Greenie mini points, and Super Greenie mini points Group 8. Treated with Prophy-Jet polishing agent (Dentsply, York, Pa.) Group 9. Immediate polishing by using a rubber cup with Nupro (Johnson and Johnson) prophylaxis and polishing paste. Samples in groups 3 through 9 were subjected to additional polishing (perpendicular in direction to the first) after analysis of the first polish with a profilometer.
AUGUST
1987
VOLUME
58
NUMBER
2
POLISHING
I3EN TAL PLM ALGAM
RESTORATIONS
Fig. 1. Carved and burnished.
Fig. 2. Carved, burnished
MEASURING
OF SURFACE
with cotton pellet.
ROUGHNESS
A Bendix (Bendix, Dayton, Ohio) surface profile roughness testing machine was used for measuring the surface roughness of the samples. The baseline data (before any polishing), first polish, and the second polish were evaluated. A stylus with a radius of 0.0025 and pressure of 100 milligrams was used to obtain data. The results were expressed in micrometers. The stylus traversed the surface of each sample to determine the surface roughness. One investigator measured five different surfaces of each sample, and the average surface roughness for each sample was determined. Random samples of representative specimens were subjected to evaluation with a JEOL (JEOL, Tokyo, Japan) scanning electron microscope (SEM). Samples were coated with gold/palladium, and micrographs made at Xl00 and ~400 magnification, operative at 6 kV.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
(Magnification
x400.)
(Magnification
x400.)
The data were analyzed by analysis of variance (ANOVA) and Scheffes rank test (p < .Ol). The different techniques (the amalgams, first, and second polishing procedures) were statistically compared and analyzed. RESULTS The surface of a well-condensed amalgam, carved and burnished, lacked smoothness (Fig. 1). The surface was craterous in appearance with many irregularities. SEM micrographs showed that the surface of freshly placed amalgam that had been scrubbed with a firm moistened cotton pledget was damaged by the procedure (Fig. 2). All so-treated amalgams became significantly rougher (p < .Ol) than untouched, unpolished amalgam surfaces. The surface roughnesses of the three different amalgam alloys at baseline (A) and after being subjected to
149
DE
Table I. Surface roughness
(pm) of three amalgams after treatment Polishing technique No.
Preparation (A) Basic data
(B) First polish
(C) Second polish (perpendicular)
VRIES,
with various polishing
Dispersalloy
DE WET, AND
EICK
techniques
Unison
Lojic
x
SD
R
SD
52
SD
1 2 3 4 5 6 7 a 3 4 5 6 7 8 9
3.51 6.10 2.95 3.39 3.82 2.78 3.10 3.00 2.50 1.81 2.44 2.52 1.70 3.06 6.03
0.66 1.48 0.89 1.39 0.96 0.30 0.43 0.61 0.82 0.35 0.36 0.39 0.10 0.33 1.91
3.30 2.98 3.20 2.05 2.58 3.32 2.98 2.86 2.71 1.26 1.55 2.10 1.79 2.89 3.64
0.47 1.75 0.72 0.62 0.75 0.59 1.19 1.75 0.89 0.22 0.53 0.24 0.59 1.80 0.40
3.21 5.57 3.11 3.13 2.77 2.15 1.85 2.16 1.90 2.29 1.79 1.32 1.12 1.88 4.82
0.60 0.61 1.84 0.67 1.11 0.52 0.44 0.73 0.54 0.55 0.65 0.46 0.43 0.58 1.46
3 4 5 6 7 8 9
2.40 1.03 1.88 1.60 1.04 2.81 5.59
1.05 0.07 0.35 0.34 0.26 0.51 1.04
2.40 0.87 1.34 1.40 1.04 2.95 3.78
0.63 0.22 0.49 0.31 0.38 1.79 0.60
2.29 1.08 1.33 1.16 0.80 2.08 3.33
1.32 0.34 0.43 0.32 0.20 0.54 1.10
Number of samples = 5.
Table II. Amalgam roughness ranked in
Table III. Difference
decreasing
produced
Amalgam
order (p < .Ol) Number
Mean
Dispersalloy
90
2.44
Unison
90
2.19
Lojic
90
1.90
Scheffe grouping
B B B
A A A
the first (B) and second series (C) of the polishing techniques are seen in Table I. Significant differences (p < .Ol) were evident when techniques 3 through 8, the alloys, at baseline, first polish, and perpendicular polish were compared by three-way ANOVA. The Scheffes test revealed the following: Dispersalloy and Unison amalgams were statistically the same, and Unison and Lojic amalgams were also statistically the same. Lojic amalgam, however, was significantly smoother than the Dispersalloy amalgam (Table II). In evaluating the differences between the polishing techniques, the Scheffes test showed groups 3,5, and 8 to be roughest, without statistical difference (Table III). Groups 4, 6, and 7 were smoothest, without statistically significant difference. 150
Technique
in surface roughness by techniques 3 to 8 Number
Scheff e grouping
Mean
8
45
2.64
3
45
2.61
5
45
2.17
6
45
2.04
4
45
1.88
7
45
1.72
B B B B B B B
A A A A A
C C C C C C C
Group 8, on which the Prophy-Jet polishing agent was used was roughest (Fig. 3), and group 7 (finishing burs and special abrasive points used) was smoothest (Fig. 4). The difference between baseline (A), first polish (B), and perpendicular polish (C) were found to be statistically significant (p < .Ol) where A was the roughest, B more smooth, and C the smoothest (Table IV). Baseline data of carved and burnished surfaces (A) with the immediately polished surfaces (first, B, and second, C, polish), with a two-way ANOVA showed AUGUST
1987
VOLUME
58
NUMBER
2
POLISHING
DENTAL
AMALGAM
RESTORATIONS
Fig. 3. Polished with Trophy-Jet polishing agent. (Magnification
Fig. 4. Polished with finishing points. (Magnification x400.)
burs and Brownie, Greenie, Super Greenie, and mini
statistically significant differences. The Dispersalloy amalgam was significantly more rough than the Unison and Lojic amalgams (Table V). A statistically significant difference was also found between the baseline data (A) (smoother) and the first (B) and second (C) polishes on the amalgams that were immediately polished. B and C (immediate polishing data) proved to be rougher than baseline A, with B (first polish) statistically more rough than A (unpolished surface) (Table VI).
DISCUSSION Although burnishing is beneficial to the surfaces of some modern amalgams,” reportedly improving the THE JOURNAL
OF PROSTHETIC
DENTISTRY
x400.)
surface smoothness and reducing the amount of mercury, the SEM study showed that this surface was far from optimum. Lojic amalgam was found to be statistically smoother than Dispersalloy amalgam. The technique that provided the smoothest surface was No. 7 whereby the amalgams were treated with amalgam finishing bum, Brownie mini points, and two grades of Greenie mini points. This technique produced smoother surfaces than No. 4 (pumice and zinc oxide). However, rubber points may generate more heat than other systems. Technique 8 (Prophy-Jet polishing) caused the roughest surfaces. The study showed that both the first polish (B) and 151
DE VRIES,
Table IV. Differences
Number 90 90 90
A B C
Mean
Scheff e grouping
2.85 2.04 1.64
second (C) polishing when the amalgam samples were finished immediately
A B
C
Table V. Differences
in surface roughness of amalgams for techniques 1 and 9 Amalgam Dispenalloy Lojic Unison
Number
Mean
Scheff e grouping
15
5.05 3.79 3.58
A B B
15
15
There is a significant difference between the alloys (p < 0.01); D is roughest, significantly more rough than U and L.
the perpendicular second polish (C) improved the surface smoothness for all samples tested. Dentists should use a polishing method whereby the direction of the polishing strokes is perpendicuiar as finer polishing agents are used. Surface roughness will be decreased significantly. Similar techniques are used routinely to prepare highly polished metallurgic specimens for photomicroscopy. All amalgams undergo setting, hardening, and dimensional changes for at least 24 hours after placement. Amalgams should only be polished after 24 hours or longer. This supf~~rts work of other researchers who showed that immediate polishing is unacceptable.2~9~‘o Studies’osl2 indicated that some high-copper alloys can be polished from 15 to 30 minutes after condensation, but conventional alloys exhibit rough surfaces when polished so soon. These studies used only SEM observations. It is possible that a surface roughness detector (such as Talysurf or Bendix) might reveal all of the early polished surfaces to be inferior to 24-hour specimens. Another study demonstrated that even after a short period of in vivo evaluation, there were almost no differences between the surface of an immediately polished amalgam and one left unpolished.13
CONCLUSIONS 1. This study showed that the smoothest surface on the occlusal surfaces of amalgam is obtained by using the Brownie, Greenie, and Super Greenie polishing system. This rating was closely followed by that for polishing with pumice and zinc oxide (or white rouge). 2. Immediate polishing of the three amalgams tested produced rougher surfaces than unpolished surfaces. 152
EICK
Table VI. Difference in surface roughness between baseline data (A) and first (B) and
in surface roughness between baseline data (A), first polish (B), and second polish (C) Preparation
DE WET, AND
Preparation
Number
Mean
B
15
4.83
C
15
4.24
A
15
3.34
Scheffe grousina
B B B
A A A
3. The direction of polish should be varied. 4. Of the three products evaluated, Lojic amalgam alloy was found to be smoothest after polishing with various polishing techniques. 5. Freshly placed amalgam should not be smoothed (burnished) with a moist cotton pellet because this produces rougher surfaces. We thank Mr. H. J. Els and Ms. Elsabe Malan of the SEM unit at Medunsa for assistance with the SEM work and photography.
REFERENCES 1. Chan KC, Edie JW, Boyer DG. Microstructure of amalgam surfaces. J PROSTHET DENT 1976;36:644-8. 2. Goldfogel MH, Smith GE, Bomberg TJ. Amalgam polishing. Oper Dent 1976;1:146-50. 3. Charbeneau GT. A suggested technique for polishing amalgam restorations. J Mich State Dent Assoc 1965;47:135-8. 4. Heath JR, Wilson HJ. Surface roughness of restorations. Br Dent J 1976;140:131-7. 5. De Maar FER. Historically, when and by whom was silver amalgam introduced? Int COB Dent Sci Educ Bull 1972;5:236. 6. O’Brien WJ, Johnston WM, Heinkel DE. Surface properties of dental amalgam: Roughness produced by setting reaction. J Am Dent Assoc 1977;94:891-4. 7. Mosteller JH. Factors influencing finish of dental amalgam. J Ky Dent Assoc 1957;9:5-12. 8. Grajower R, Kaufman E, Rajstein J. Temperature in the pulp chamber during polishing of amalgam restorations. J Dent Res 1974;53:1189-95. 9. Creaven PJ, Dennisson JB, Charbeneau GT. Surface roughness of two dental amalgams after various polishing techniques. J PRO~THET DENT 1980;43:289-97.
10.
Nitkin DA, Goldberg AJ. Placing and polishing amalgam in one visit. Quintessence Int 1979;6:23-31. 11. De Wet FA. Bruinering van amalgam-Ja of Nee? (Burnishing of amalgams-yes or no?). J Dent Assoc of SA 1977;32:151-2. 12. Nuckles DB, Miller RA, Olson JC. Early and delayed finishing of amalgam with different polishing procedures. J PROSTHET DENT 1982;47:612-5.
13. Fenton RA, Samples RJ. Immediate-polished
and as carved Tytin restorations after 12 months. J Dent 1984;12:165-74.
Reprint requests to: DR. J. D. EICK UNWERSITV OF MISSOURI-KANSAS SCHOLL OF DENTISTRY KANSAS Cm, MO 64108 AUGUST
CITY
1987
VOLUME
58
NUMBER
2
dental amalgam restorations
J. de Vries, B.Ch.D., M.Dent.,
F. A. de Wet, B.Ch.D., M.Dent.,
and J. D. Eick, Ph.D.***
Medical University of Southern Africa, Faculty of Dentistry, Medunsa, South Africa, and University of Missouri-Kansas City, School of Dentistry, Kansas City, MO
TT unpolished amalgam restorations are rough and therefore conducive to plaque accumulation.‘~2 Finishing and polishing of amalgam restorations is an important component in the ultimate clinical success of restorations.3,4Unfortunately, many dentists neglect this important step.4-7 Amalgam restorations may not be polished because an additional visit is required, certain polishing techniques may generate heat which might damage the pulp,” or dentists may not know a method for finishing and polishing. Several polishing techniques have been reported in the literature.‘, ‘15,9,lo In this study we evaluated the surface produced by different polishing techniques on three dental amalgam alloys. MATERIAL
AND METHODS
Premeasured capsules of an admixed nongamma 2 amalgam (Dispersalloy, Johnson and Johnson, East Windsor, N. J.), a platinum modified spherical amalgam (Lojic, Southern Dental Industries, Melbourne, Australia), and a spherical amalgam (Unison, Johnson and Johnson) were triturated according to manufacturer’s instructions and hand condensed into class I cavities in extracted human molar teeth previously stored in 10% formalin solution. To minimize experimental errors, preparation and restoration were performed by a single investigator. To aid in measurement, tooth surfaces to be studied were flattened with an Isomet (Buehler Ltd., Lake Bluff, Ill.) low-speed mechanical saw. Test cavities were prepared (2 mm deep, 5 mm wide, and 9 mm long) with a dome-shaped diamond fissure bur (IS0 044). The cavities were overfilled and excess amalgam was Sponsored in part by a research grant from A. D. Laboratories, Johannesburg, South Africa. Presented at the International Association for Dental Research (South African Division), Pretoria, South Africa. *Professor and Chairman, Department of Operative Dentistry, Medical University of Southern Africa, Faculty of Dentistry. **Professor and Chairman, Department of Stomatological Studies, Medical University of Southern Africa, Faculty of Dentistry. ***Professor, Department of Oral Biology, University of MissouriKansas City, School of Dentistry.
148
removed with a sharp stainless steel carver. All restorations were burnished with a smooth-face burnisher by using 24 strokes in only one direction. Forty-five specimens were prepared for each of the three amalgams. The samples were divided into nine groups of five and subjected to nine different polishing regimens. After dry storage for 24 hours, baseline surface roughness was determined for the first eight groups (120 samples). They were then subjected to eight different polishing regimens. The remaining group of five samples (group 9) was polished immediately (15 minutes after placement) with prophylaxis paste and rubber cup. Light pressure and a speed of 2500 rpm were used for finishing. Twenty-four polishing strokes (in only one direction) were used with each polishing agent. A new (unused) polishing device was used for each specimen. The nine finishing and polishing techniques studied were: Group 1. Samples only carved and burnished Group 2. Carved, burnished, and wiped with a wet cotton pellet Group 3. Polished with pumice in a soft rubber cup Group 4. Polished with green stone, amalgam finishing bur, pumice, and zinc oxide in sequence in rubber cups Group 5. Polished with Brownie cup and Brownie mini point (Shofu, Kyoto, Japan) Group 6. Polished with Brownie mini point, Greenie mini point (Shofu), and Super Greenie mini point (Shofu) Group 7. Polished with amalgam finishing burs, Brownie mini points, Greenie mini points, and Super Greenie mini points Group 8. Treated with Prophy-Jet polishing agent (Dentsply, York, Pa.) Group 9. Immediate polishing by using a rubber cup with Nupro (Johnson and Johnson) prophylaxis and polishing paste. Samples in groups 3 through 9 were subjected to additional polishing (perpendicular in direction to the first) after analysis of the first polish with a profilometer.
AUGUST
1987
VOLUME
58
NUMBER
2
POLISHING
I3EN TAL PLM ALGAM
RESTORATIONS
Fig. 1. Carved and burnished.
Fig. 2. Carved, burnished
MEASURING
OF SURFACE
with cotton pellet.
ROUGHNESS
A Bendix (Bendix, Dayton, Ohio) surface profile roughness testing machine was used for measuring the surface roughness of the samples. The baseline data (before any polishing), first polish, and the second polish were evaluated. A stylus with a radius of 0.0025 and pressure of 100 milligrams was used to obtain data. The results were expressed in micrometers. The stylus traversed the surface of each sample to determine the surface roughness. One investigator measured five different surfaces of each sample, and the average surface roughness for each sample was determined. Random samples of representative specimens were subjected to evaluation with a JEOL (JEOL, Tokyo, Japan) scanning electron microscope (SEM). Samples were coated with gold/palladium, and micrographs made at Xl00 and ~400 magnification, operative at 6 kV.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
(Magnification
x400.)
(Magnification
x400.)
The data were analyzed by analysis of variance (ANOVA) and Scheffes rank test (p < .Ol). The different techniques (the amalgams, first, and second polishing procedures) were statistically compared and analyzed. RESULTS The surface of a well-condensed amalgam, carved and burnished, lacked smoothness (Fig. 1). The surface was craterous in appearance with many irregularities. SEM micrographs showed that the surface of freshly placed amalgam that had been scrubbed with a firm moistened cotton pledget was damaged by the procedure (Fig. 2). All so-treated amalgams became significantly rougher (p < .Ol) than untouched, unpolished amalgam surfaces. The surface roughnesses of the three different amalgam alloys at baseline (A) and after being subjected to
149
DE
Table I. Surface roughness
(pm) of three amalgams after treatment Polishing technique No.
Preparation (A) Basic data
(B) First polish
(C) Second polish (perpendicular)
VRIES,
with various polishing
Dispersalloy
DE WET, AND
EICK
techniques
Unison
Lojic
x
SD
R
SD
52
SD
1 2 3 4 5 6 7 a 3 4 5 6 7 8 9
3.51 6.10 2.95 3.39 3.82 2.78 3.10 3.00 2.50 1.81 2.44 2.52 1.70 3.06 6.03
0.66 1.48 0.89 1.39 0.96 0.30 0.43 0.61 0.82 0.35 0.36 0.39 0.10 0.33 1.91
3.30 2.98 3.20 2.05 2.58 3.32 2.98 2.86 2.71 1.26 1.55 2.10 1.79 2.89 3.64
0.47 1.75 0.72 0.62 0.75 0.59 1.19 1.75 0.89 0.22 0.53 0.24 0.59 1.80 0.40
3.21 5.57 3.11 3.13 2.77 2.15 1.85 2.16 1.90 2.29 1.79 1.32 1.12 1.88 4.82
0.60 0.61 1.84 0.67 1.11 0.52 0.44 0.73 0.54 0.55 0.65 0.46 0.43 0.58 1.46
3 4 5 6 7 8 9
2.40 1.03 1.88 1.60 1.04 2.81 5.59
1.05 0.07 0.35 0.34 0.26 0.51 1.04
2.40 0.87 1.34 1.40 1.04 2.95 3.78
0.63 0.22 0.49 0.31 0.38 1.79 0.60
2.29 1.08 1.33 1.16 0.80 2.08 3.33
1.32 0.34 0.43 0.32 0.20 0.54 1.10
Number of samples = 5.
Table II. Amalgam roughness ranked in
Table III. Difference
decreasing
produced
Amalgam
order (p < .Ol) Number
Mean
Dispersalloy
90
2.44
Unison
90
2.19
Lojic
90
1.90
Scheffe grouping
B B B
A A A
the first (B) and second series (C) of the polishing techniques are seen in Table I. Significant differences (p < .Ol) were evident when techniques 3 through 8, the alloys, at baseline, first polish, and perpendicular polish were compared by three-way ANOVA. The Scheffes test revealed the following: Dispersalloy and Unison amalgams were statistically the same, and Unison and Lojic amalgams were also statistically the same. Lojic amalgam, however, was significantly smoother than the Dispersalloy amalgam (Table II). In evaluating the differences between the polishing techniques, the Scheffes test showed groups 3,5, and 8 to be roughest, without statistical difference (Table III). Groups 4, 6, and 7 were smoothest, without statistically significant difference. 150
Technique
in surface roughness by techniques 3 to 8 Number
Scheff e grouping
Mean
8
45
2.64
3
45
2.61
5
45
2.17
6
45
2.04
4
45
1.88
7
45
1.72
B B B B B B B
A A A A A
C C C C C C C
Group 8, on which the Prophy-Jet polishing agent was used was roughest (Fig. 3), and group 7 (finishing burs and special abrasive points used) was smoothest (Fig. 4). The difference between baseline (A), first polish (B), and perpendicular polish (C) were found to be statistically significant (p < .Ol) where A was the roughest, B more smooth, and C the smoothest (Table IV). Baseline data of carved and burnished surfaces (A) with the immediately polished surfaces (first, B, and second, C, polish), with a two-way ANOVA showed AUGUST
1987
VOLUME
58
NUMBER
2
POLISHING
DENTAL
AMALGAM
RESTORATIONS
Fig. 3. Polished with Trophy-Jet polishing agent. (Magnification
Fig. 4. Polished with finishing points. (Magnification x400.)
burs and Brownie, Greenie, Super Greenie, and mini
statistically significant differences. The Dispersalloy amalgam was significantly more rough than the Unison and Lojic amalgams (Table V). A statistically significant difference was also found between the baseline data (A) (smoother) and the first (B) and second (C) polishes on the amalgams that were immediately polished. B and C (immediate polishing data) proved to be rougher than baseline A, with B (first polish) statistically more rough than A (unpolished surface) (Table VI).
DISCUSSION Although burnishing is beneficial to the surfaces of some modern amalgams,” reportedly improving the THE JOURNAL
OF PROSTHETIC
DENTISTRY
x400.)
surface smoothness and reducing the amount of mercury, the SEM study showed that this surface was far from optimum. Lojic amalgam was found to be statistically smoother than Dispersalloy amalgam. The technique that provided the smoothest surface was No. 7 whereby the amalgams were treated with amalgam finishing bum, Brownie mini points, and two grades of Greenie mini points. This technique produced smoother surfaces than No. 4 (pumice and zinc oxide). However, rubber points may generate more heat than other systems. Technique 8 (Prophy-Jet polishing) caused the roughest surfaces. The study showed that both the first polish (B) and 151
DE VRIES,
Table IV. Differences
Number 90 90 90
A B C
Mean
Scheff e grouping
2.85 2.04 1.64
second (C) polishing when the amalgam samples were finished immediately
A B
C
Table V. Differences
in surface roughness of amalgams for techniques 1 and 9 Amalgam Dispenalloy Lojic Unison
Number
Mean
Scheff e grouping
15
5.05 3.79 3.58
A B B
15
15
There is a significant difference between the alloys (p < 0.01); D is roughest, significantly more rough than U and L.
the perpendicular second polish (C) improved the surface smoothness for all samples tested. Dentists should use a polishing method whereby the direction of the polishing strokes is perpendicuiar as finer polishing agents are used. Surface roughness will be decreased significantly. Similar techniques are used routinely to prepare highly polished metallurgic specimens for photomicroscopy. All amalgams undergo setting, hardening, and dimensional changes for at least 24 hours after placement. Amalgams should only be polished after 24 hours or longer. This supf~~rts work of other researchers who showed that immediate polishing is unacceptable.2~9~‘o Studies’osl2 indicated that some high-copper alloys can be polished from 15 to 30 minutes after condensation, but conventional alloys exhibit rough surfaces when polished so soon. These studies used only SEM observations. It is possible that a surface roughness detector (such as Talysurf or Bendix) might reveal all of the early polished surfaces to be inferior to 24-hour specimens. Another study demonstrated that even after a short period of in vivo evaluation, there were almost no differences between the surface of an immediately polished amalgam and one left unpolished.13
CONCLUSIONS 1. This study showed that the smoothest surface on the occlusal surfaces of amalgam is obtained by using the Brownie, Greenie, and Super Greenie polishing system. This rating was closely followed by that for polishing with pumice and zinc oxide (or white rouge). 2. Immediate polishing of the three amalgams tested produced rougher surfaces than unpolished surfaces. 152
EICK
Table VI. Difference in surface roughness between baseline data (A) and first (B) and
in surface roughness between baseline data (A), first polish (B), and second polish (C) Preparation
DE WET, AND
Preparation
Number
Mean
B
15
4.83
C
15
4.24
A
15
3.34
Scheffe grousina
B B B
A A A
3. The direction of polish should be varied. 4. Of the three products evaluated, Lojic amalgam alloy was found to be smoothest after polishing with various polishing techniques. 5. Freshly placed amalgam should not be smoothed (burnished) with a moist cotton pellet because this produces rougher surfaces. We thank Mr. H. J. Els and Ms. Elsabe Malan of the SEM unit at Medunsa for assistance with the SEM work and photography.
REFERENCES 1. Chan KC, Edie JW, Boyer DG. Microstructure of amalgam surfaces. J PROSTHET DENT 1976;36:644-8. 2. Goldfogel MH, Smith GE, Bomberg TJ. Amalgam polishing. Oper Dent 1976;1:146-50. 3. Charbeneau GT. A suggested technique for polishing amalgam restorations. J Mich State Dent Assoc 1965;47:135-8. 4. Heath JR, Wilson HJ. Surface roughness of restorations. Br Dent J 1976;140:131-7. 5. De Maar FER. Historically, when and by whom was silver amalgam introduced? Int COB Dent Sci Educ Bull 1972;5:236. 6. O’Brien WJ, Johnston WM, Heinkel DE. Surface properties of dental amalgam: Roughness produced by setting reaction. J Am Dent Assoc 1977;94:891-4. 7. Mosteller JH. Factors influencing finish of dental amalgam. J Ky Dent Assoc 1957;9:5-12. 8. Grajower R, Kaufman E, Rajstein J. Temperature in the pulp chamber during polishing of amalgam restorations. J Dent Res 1974;53:1189-95. 9. Creaven PJ, Dennisson JB, Charbeneau GT. Surface roughness of two dental amalgams after various polishing techniques. J PRO~THET DENT 1980;43:289-97.
10.
Nitkin DA, Goldberg AJ. Placing and polishing amalgam in one visit. Quintessence Int 1979;6:23-31. 11. De Wet FA. Bruinering van amalgam-Ja of Nee? (Burnishing of amalgams-yes or no?). J Dent Assoc of SA 1977;32:151-2. 12. Nuckles DB, Miller RA, Olson JC. Early and delayed finishing of amalgam with different polishing procedures. J PROSTHET DENT 1982;47:612-5.
13. Fenton RA, Samples RJ. Immediate-polished
and as carved Tytin restorations after 12 months. J Dent 1984;12:165-74.
Reprint requests to: DR. J. D. EICK UNWERSITV OF MISSOURI-KANSAS SCHOLL OF DENTISTRY KANSAS Cm, MO 64108 AUGUST
CITY
1987
VOLUME
58
NUMBER
2