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Surface mercury content and roughness after delayed burnishing of amalgam
Sztrface mercwy content and rou delayed bwnishing of amalgam
after
A. N. Barb-, D.D.S., M.S.D.,* J. Galan, Jr., D.D.S., Ph.D.,** and A. Ishikiriama, D.D.S., Ph.D.**
E. S. Lopes, D.D.S., Ph.D.,***
University of S% Paulo, Dental School, Bauru, Brazil
TT
until recently, many investigators took exception to burnishing amalgam restorations. Their publications suggested that the procedure would produce a mercury-rich surface and thereby increase oxidation and corrosion.‘-5 Increased technical and scientific developments generated more precise methods, which provided definitive evaluations of the effects of burnishing. Recent publications reported that burnishing amalgam restorations reduced surface roughness.6-‘2 Similarly, another group of investigators found that burnishing decreased the concentration of mercury at the surface of amalgam restorations.‘3-‘5 The possibility that there is a propitious time after trituration to attain the best result of burnishing prompted this study. The results were evaluated on surface finish and superficial mercury content.
MATERIAL
AND
METHODS
A high-copper dispersion alloy (Dispersalloy, Johnson & Johnson Dental Products Co., East Windsor, N.J.) was chosen for the test. The alloy-to-mercury ratio and trituration conformed to the manufacturer’s instructions. The alloy and mercury mix was mechanically triturated (Torit, The Torit Co., St. Paul, Minn.) for 18 seconds, followed by 2 seconds without a pestle. Cavities 4 mm in diameter and 2.5 mm deep were prepared in circular blocks of acrylic resin. The amalgam was manually condensed with a Ward-type condenser (Duflex, Brazil) 3 mm in diameter. Excess amalgam was removed and the restorations carved to a flat surface with a No. 10 Bard-Parker scalpel blade (Beckton-Dickinson, Mexico). The specimens were divided into three groups. Group A was completed as carved and not burnished. Group B was carved after condensation and burnished 15 minutes after tritura-
*Assistant Professor, Department of Dental Materials. **Assistant Professor, Department of Operative Dentistry. ***.4ssistant Professor, Department of Preventive Dentistry.
214
Fig. 1. Amalgam magnification X800.)
surface,
carved
only.
(Original
Table I. Surface mercury content determined by microprobe analysis (in percent weight) Group Soecimen
A
B
c
1
60.79 63.60 66.66 62.35 65.14 62.67 63.54
70.34 69.18 68.78 69.13 69.39 68.73 69.26
53.08 53.24 51.68 52.25 42.69 44.51 49.58
15 minutes;
and C = bur-
2 3 Mean
A = Carved only; B = burnished nished after 24 hours.
after
tion. Group C was carved after condensation and burnished 24 hours after trituration. Each group consisted of three specimens. Groups B and C were burnished with a No. 2 gold foil burnisher (American Dental Mfg. Co., Missoula, Mont.) moving toward the margins. Group C specimens were stored in FE’BRUARY
1984
VOLUME
51
NUMBER
2
Fig. 2. Amalgam surface, carved after insertion and burnished 15 minutes after trituration. (Original magnification X800.)
E = Enamel; A = amalgam. (Original
Fig. 3. Amalgam surface, carved after insertion and burnished 24 hours after trituration. (Original magnification x800.)
Fig. 5. Margin of restoration after carving and burnishing 15 minutes after trituration. E = En;amel; A = amalgam. (Original magnification x800.)
sodium sulfite (1%) solution at 37” C for 24 hours before burnishing. This procedure was done to accelerate corrosion product formation. The acrylic resin blockswere sectionedto remove the amalgam specimens,which were affixed to aluminum plates for scanning electron microscopy and microprobe analysis (Camebax, Cameca, France). Two
areason the surface of each specimenwere rand.omly selected for microprobe analysis. Roughnessev,aluations were made from electron micrographs at se,veral areascloseto the margins. The data for mercury content were subjects :d to analysis of variance. Individual comparisons made according to Tukey’s method.16
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 4. Margin
of
restoration
after car ving. magnificmation
x800.)
215
BA RBOSA
ET AL
24 hours after trituration was a smoothersurface with only minute cavities (Fig. 3). The scratchesprobably resulted from the burnishing. Figs. 4 to 6 illustrate the amalgam margins for the three groupsof specimens.Burnishing 15 minutes after trituration tendsto move someamalgamover the cavity margins. This observation had been previously reported by Sweeney.” The results obtained by burnishing 24 hours after trituration suggest that the final poiishing may be reducedand the thermogenesiscausedby rotary instrumentsthus lessened.Excessiveheat impairs the clinical performance of amalgam.
CONCLUSIONS
Margin of restoration after carving and burnishing 24 hours after trituration. E = Enamel; A = amalgam. (Original magnification x800.) Fig. 6.
RESULTS
AND
DISCUSSION
Table I presents the microprobe analyses for the mercury content at the surfaceof the specimens.There was no significant difference in the surface mercury content between the specimensin group A (carved only) and group B (carved after condensation and burnished 15 minutes after trituration). This finding disagreedwith previous reports on the surface mercury content,i-‘. 13-15 There was a statistical difference between the surface mercury content of specimensburnished 24 hours after trituration and thosenot burnished, or burnished 15 minutes after trituration. The lower mercury content of specimensin group C (burnished 24 hours after trituration) may be explained by the lack of mercury oxide products. This hypothesisis basedon the findings of Neto,17 who observed that mercury oxide was a major corrosion product. Mercury oxide is found mainly on the silver-copper eutectic spheres,which are less visible in specimensburnished 24 hours after trituration. Figs. 1 to 3 illustrate the surfacesof the three groups of specimens.Comparison of Figs. 1 and 2 illustrates the more regular and smoothersurface of the burnished amalgam. Apparently the edgesof exposed amalgam particles were reimpressedinto the massof amalgamin Fig. 2. In addition, the small cavities caused by disturbance of the alloy particles during carving were eliminated by burnishing.6-‘2The effect of burnishing
216
The surface mercury of amalgam restorations is not significantly altered if burnished 15 minutes after trituration. If burnished 24 hours after trituration, the mercury content at the surface of amalgam is significantly reduced. Burnishing 15 minutes after trituration reducesthe surface roughnessof amalgam. Burnishing 24 hours after trituration producesan even smoother surface. REFERENCES 1.
2. 3. 4. 5.
6. 7.
8. 9.
10.
11.
12.
Blackwell, R. E.: Amalgam fillings, with some suggestions as to their practical use. J Am Dent Assoc l&l 179, 1931. McGehee, W. I-I. 0.: A Textbook of Operative Dentistry, cd 4. New York, 1956, McGraw-Hill, Inc., p 352. Markley. M. R.: Restorations of silver amalgam. ,J Am Dent Assoc 43:133, 1951. Nadal, R.: Amalgam restorations: Cavity preparation, condensing and finishing. J Am Dent Assoc 65:66, 1962. Strickland, W. D.: Amalgam restorations for Class I cavity preparations. In Studevant, C. M., editor: The Art and Science of Operative Dentistry. New York, 1968, M&raw-Hill. Inc.. p 225. Charbeneau, G. T.: A suggested technic for polishing amalgam restorations, J Mich Dent Assoc 42320. 1965 Fusayama, T., Hosoda, H., Hayashi, K., Okuda, R., and Matono, R.: Surface roughness of amalgam ftllings made by various technics. J Dent Res &1019, 1967. Fusayama, T., and Hayashi, K.: Microstructure of amalgam surfaces. J Dent Res 49:733, 1970. Tidmarsh, B. G.. and Gavin, J. B.: Finishing amalgam restorations. A scanning electron microscope suldy. NZ Dent J 69:175. 1973. Lisboa, 0.: Rugosidade do amalgama em funcitr da escultura e da brunidura e da sua adapta+o is paredrr laterais e do assoalho de uma cavidade. Florianopolis. 1974, Tese-Cniversidade Federal de Santa Catarina. Dahi-Afshar, I’.: Comparison of burnished and unburmshed amalgam before and after polishing. J Dent Kes 57 (Special issue A):82, 1978 (Abstr No. 29). Katora. hl. E., Moore, P. ,I., and Juhach. ‘I‘. S: Surface morphology of burnished versus nonburnished amalv:~n restorations. Quinttssence Int 10~9.3. 1979
FEBRUARY
1984
VOLUME
5’1
NUMBER
2
DELAYED
13.
14.
15.
16.
BURNISHING
Kanai, S.: Structure ing on the margins
OF AMALGAM
studies of amalgam. of occlusal amalgam
17.
II. Effect of burnishfdlings. Acta Odontol
Stand 24~47, 1966. Boyer, D. B., Edie, J. W., and Chan, K. C.: Effect of clinical finishing procedures on amalgam microstructure. J Dent Res 59~129, 1980. Teixeira, L. C., Kammermeyer, K., and Johnson, W.: Printing of mercury distribution on the surface of dental amalgam. J Am Dent Assoc 81:1159, 1970. Scheffe, H.: The Analysis of Variance. New York, 1959, John Wiley & Sons, Inc., pp 73-75.
ARTICLES
18.
Garone Netto, N.: Contribuiqgo para o estudo de corrosgo de superficies de amalgama. Sb Paulo, 1976, Tese-Faculdade de Odontologia da Universidade de SBo Paul”. Sweeney, J. T.: Manipulation of amalgam to prevent excessive distortion and corrosion. J Am Dent Assoc 31:375, 1944.
Krprinl
requests
tot
DR.JoAo GALAN,JR. BMJRU DENTAL SCHOOL CAIXA POSTAL 73 17.100 BAURU, S.P., BRASIL
TO APPEAR IN FUTURE ISSUES
Comparison of Bennett shift measured at the hinge axis and an arbitrary hinge axis position T. F. Lundeen, M.S., D.M.D.,
Plaque accumulation
and F. Mendoza,
M.A., D.D.S.
on Teflon-coated
metal
Teruo Maetani, D.D.S., Ph.D., Ryoichi Miyoshi, D.D.S., Yukinori Nahara, D.D.S., Yasuyuki Kawazoe, D.D.S., Ph.D., and Taizo Hamada, D.D.S., Ph.D.
Effect of concentrations
of phosphoric
acid on enamel dissolution
B. M&on-Rahemtulla, D.D.S., D. H. Retief, M.Sc., B.D.S., Ph.D.(Dent.), H. $2. Jamison, D.D.S., Dr.P.H.
Fabrication dentures
and
of full coverage restorations for existing removable
D. Ray McArthur,
partial
D.D.S., M.S.
Overdentures
for the irradiated
I. G. McDermott,
D.D.S., and S. W. Rosenberg, D.M.D.
patient
The biologic response to the single-crystal sapphire endosteal dental implant: Scanning electron microscopic observations Ralph V. McKinney, Jr., D.D.S., Ph.D., David E. Steflik, B.A., MS., David L. Koth, D.D.S., M.S.
Contoured
and
mylar matrices
Jerry W. Medlock,
D.D.S., and Gerald J. Re, D.M.D.
Using irreversible hydrocolloid to evaluate preparations temporary immediate provisional restorations Marc Eli Moskowitz,
Microleakage
JOURNAL
OF PROSTHETIC
Reynolds, D.D.S.
of a copal resin cavity varnish
Sheldon M. Newman,
THE
D.D.S., Gerald H. Loft, D.D.S., and J. Marvin
and fabricate
D.D.S., M.S.
DENTISTRY
217
after
A. N. Barb-, D.D.S., M.S.D.,* J. Galan, Jr., D.D.S., Ph.D.,** and A. Ishikiriama, D.D.S., Ph.D.**
E. S. Lopes, D.D.S., Ph.D.,***
University of S% Paulo, Dental School, Bauru, Brazil
TT
until recently, many investigators took exception to burnishing amalgam restorations. Their publications suggested that the procedure would produce a mercury-rich surface and thereby increase oxidation and corrosion.‘-5 Increased technical and scientific developments generated more precise methods, which provided definitive evaluations of the effects of burnishing. Recent publications reported that burnishing amalgam restorations reduced surface roughness.6-‘2 Similarly, another group of investigators found that burnishing decreased the concentration of mercury at the surface of amalgam restorations.‘3-‘5 The possibility that there is a propitious time after trituration to attain the best result of burnishing prompted this study. The results were evaluated on surface finish and superficial mercury content.
MATERIAL
AND
METHODS
A high-copper dispersion alloy (Dispersalloy, Johnson & Johnson Dental Products Co., East Windsor, N.J.) was chosen for the test. The alloy-to-mercury ratio and trituration conformed to the manufacturer’s instructions. The alloy and mercury mix was mechanically triturated (Torit, The Torit Co., St. Paul, Minn.) for 18 seconds, followed by 2 seconds without a pestle. Cavities 4 mm in diameter and 2.5 mm deep were prepared in circular blocks of acrylic resin. The amalgam was manually condensed with a Ward-type condenser (Duflex, Brazil) 3 mm in diameter. Excess amalgam was removed and the restorations carved to a flat surface with a No. 10 Bard-Parker scalpel blade (Beckton-Dickinson, Mexico). The specimens were divided into three groups. Group A was completed as carved and not burnished. Group B was carved after condensation and burnished 15 minutes after tritura-
*Assistant Professor, Department of Dental Materials. **Assistant Professor, Department of Operative Dentistry. ***.4ssistant Professor, Department of Preventive Dentistry.
214
Fig. 1. Amalgam magnification X800.)
surface,
carved
only.
(Original
Table I. Surface mercury content determined by microprobe analysis (in percent weight) Group Soecimen
A
B
c
1
60.79 63.60 66.66 62.35 65.14 62.67 63.54
70.34 69.18 68.78 69.13 69.39 68.73 69.26
53.08 53.24 51.68 52.25 42.69 44.51 49.58
15 minutes;
and C = bur-
2 3 Mean
A = Carved only; B = burnished nished after 24 hours.
after
tion. Group C was carved after condensation and burnished 24 hours after trituration. Each group consisted of three specimens. Groups B and C were burnished with a No. 2 gold foil burnisher (American Dental Mfg. Co., Missoula, Mont.) moving toward the margins. Group C specimens were stored in FE’BRUARY
1984
VOLUME
51
NUMBER
2
Fig. 2. Amalgam surface, carved after insertion and burnished 15 minutes after trituration. (Original magnification X800.)
E = Enamel; A = amalgam. (Original
Fig. 3. Amalgam surface, carved after insertion and burnished 24 hours after trituration. (Original magnification x800.)
Fig. 5. Margin of restoration after carving and burnishing 15 minutes after trituration. E = En;amel; A = amalgam. (Original magnification x800.)
sodium sulfite (1%) solution at 37” C for 24 hours before burnishing. This procedure was done to accelerate corrosion product formation. The acrylic resin blockswere sectionedto remove the amalgam specimens,which were affixed to aluminum plates for scanning electron microscopy and microprobe analysis (Camebax, Cameca, France). Two
areason the surface of each specimenwere rand.omly selected for microprobe analysis. Roughnessev,aluations were made from electron micrographs at se,veral areascloseto the margins. The data for mercury content were subjects :d to analysis of variance. Individual comparisons made according to Tukey’s method.16
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 4. Margin
of
restoration
after car ving. magnificmation
x800.)
215
BA RBOSA
ET AL
24 hours after trituration was a smoothersurface with only minute cavities (Fig. 3). The scratchesprobably resulted from the burnishing. Figs. 4 to 6 illustrate the amalgam margins for the three groupsof specimens.Burnishing 15 minutes after trituration tendsto move someamalgamover the cavity margins. This observation had been previously reported by Sweeney.” The results obtained by burnishing 24 hours after trituration suggest that the final poiishing may be reducedand the thermogenesiscausedby rotary instrumentsthus lessened.Excessiveheat impairs the clinical performance of amalgam.
CONCLUSIONS
Margin of restoration after carving and burnishing 24 hours after trituration. E = Enamel; A = amalgam. (Original magnification x800.) Fig. 6.
RESULTS
AND
DISCUSSION
Table I presents the microprobe analyses for the mercury content at the surfaceof the specimens.There was no significant difference in the surface mercury content between the specimensin group A (carved only) and group B (carved after condensation and burnished 15 minutes after trituration). This finding disagreedwith previous reports on the surface mercury content,i-‘. 13-15 There was a statistical difference between the surface mercury content of specimensburnished 24 hours after trituration and thosenot burnished, or burnished 15 minutes after trituration. The lower mercury content of specimensin group C (burnished 24 hours after trituration) may be explained by the lack of mercury oxide products. This hypothesisis basedon the findings of Neto,17 who observed that mercury oxide was a major corrosion product. Mercury oxide is found mainly on the silver-copper eutectic spheres,which are less visible in specimensburnished 24 hours after trituration. Figs. 1 to 3 illustrate the surfacesof the three groups of specimens.Comparison of Figs. 1 and 2 illustrates the more regular and smoothersurface of the burnished amalgam. Apparently the edgesof exposed amalgam particles were reimpressedinto the massof amalgamin Fig. 2. In addition, the small cavities caused by disturbance of the alloy particles during carving were eliminated by burnishing.6-‘2The effect of burnishing
216
The surface mercury of amalgam restorations is not significantly altered if burnished 15 minutes after trituration. If burnished 24 hours after trituration, the mercury content at the surface of amalgam is significantly reduced. Burnishing 15 minutes after trituration reducesthe surface roughnessof amalgam. Burnishing 24 hours after trituration producesan even smoother surface. REFERENCES 1.
2. 3. 4. 5.
6. 7.
8. 9.
10.
11.
12.
Blackwell, R. E.: Amalgam fillings, with some suggestions as to their practical use. J Am Dent Assoc l&l 179, 1931. McGehee, W. I-I. 0.: A Textbook of Operative Dentistry, cd 4. New York, 1956, McGraw-Hill, Inc., p 352. Markley. M. R.: Restorations of silver amalgam. ,J Am Dent Assoc 43:133, 1951. Nadal, R.: Amalgam restorations: Cavity preparation, condensing and finishing. J Am Dent Assoc 65:66, 1962. Strickland, W. D.: Amalgam restorations for Class I cavity preparations. In Studevant, C. M., editor: The Art and Science of Operative Dentistry. New York, 1968, M&raw-Hill. Inc.. p 225. Charbeneau, G. T.: A suggested technic for polishing amalgam restorations, J Mich Dent Assoc 42320. 1965 Fusayama, T., Hosoda, H., Hayashi, K., Okuda, R., and Matono, R.: Surface roughness of amalgam ftllings made by various technics. J Dent Res &1019, 1967. Fusayama, T., and Hayashi, K.: Microstructure of amalgam surfaces. J Dent Res 49:733, 1970. Tidmarsh, B. G.. and Gavin, J. B.: Finishing amalgam restorations. A scanning electron microscope suldy. NZ Dent J 69:175. 1973. Lisboa, 0.: Rugosidade do amalgama em funcitr da escultura e da brunidura e da sua adapta+o is paredrr laterais e do assoalho de uma cavidade. Florianopolis. 1974, Tese-Cniversidade Federal de Santa Catarina. Dahi-Afshar, I’.: Comparison of burnished and unburmshed amalgam before and after polishing. J Dent Kes 57 (Special issue A):82, 1978 (Abstr No. 29). Katora. hl. E., Moore, P. ,I., and Juhach. ‘I‘. S: Surface morphology of burnished versus nonburnished amalv:~n restorations. Quinttssence Int 10~9.3. 1979
FEBRUARY
1984
VOLUME
5’1
NUMBER
2
DELAYED
13.
14.
15.
16.
BURNISHING
Kanai, S.: Structure ing on the margins
OF AMALGAM
studies of amalgam. of occlusal amalgam
17.
II. Effect of burnishfdlings. Acta Odontol
Stand 24~47, 1966. Boyer, D. B., Edie, J. W., and Chan, K. C.: Effect of clinical finishing procedures on amalgam microstructure. J Dent Res 59~129, 1980. Teixeira, L. C., Kammermeyer, K., and Johnson, W.: Printing of mercury distribution on the surface of dental amalgam. J Am Dent Assoc 81:1159, 1970. Scheffe, H.: The Analysis of Variance. New York, 1959, John Wiley & Sons, Inc., pp 73-75.
ARTICLES
18.
Garone Netto, N.: Contribuiqgo para o estudo de corrosgo de superficies de amalgama. Sb Paulo, 1976, Tese-Faculdade de Odontologia da Universidade de SBo Paul”. Sweeney, J. T.: Manipulation of amalgam to prevent excessive distortion and corrosion. J Am Dent Assoc 31:375, 1944.
Krprinl
requests
tot
DR.JoAo GALAN,JR. BMJRU DENTAL SCHOOL CAIXA POSTAL 73 17.100 BAURU, S.P., BRASIL
TO APPEAR IN FUTURE ISSUES
Comparison of Bennett shift measured at the hinge axis and an arbitrary hinge axis position T. F. Lundeen, M.S., D.M.D.,
Plaque accumulation
and F. Mendoza,
M.A., D.D.S.
on Teflon-coated
metal
Teruo Maetani, D.D.S., Ph.D., Ryoichi Miyoshi, D.D.S., Yukinori Nahara, D.D.S., Yasuyuki Kawazoe, D.D.S., Ph.D., and Taizo Hamada, D.D.S., Ph.D.
Effect of concentrations
of phosphoric
acid on enamel dissolution
B. M&on-Rahemtulla, D.D.S., D. H. Retief, M.Sc., B.D.S., Ph.D.(Dent.), H. $2. Jamison, D.D.S., Dr.P.H.
Fabrication dentures
and
of full coverage restorations for existing removable
D. Ray McArthur,
partial
D.D.S., M.S.
Overdentures
for the irradiated
I. G. McDermott,
D.D.S., and S. W. Rosenberg, D.M.D.
patient
The biologic response to the single-crystal sapphire endosteal dental implant: Scanning electron microscopic observations Ralph V. McKinney, Jr., D.D.S., Ph.D., David E. Steflik, B.A., MS., David L. Koth, D.D.S., M.S.
Contoured
and
mylar matrices
Jerry W. Medlock,
D.D.S., and Gerald J. Re, D.M.D.
Using irreversible hydrocolloid to evaluate preparations temporary immediate provisional restorations Marc Eli Moskowitz,
Microleakage
JOURNAL
OF PROSTHETIC
Reynolds, D.D.S.
of a copal resin cavity varnish
Sheldon M. Newman,
THE
D.D.S., Gerald H. Loft, D.D.S., and J. Marvin
and fabricate
D.D.S., M.S.
DENTISTRY
217