Clinical evaluation of four amalgam alloys: A five-year report

MORRIS

Henderson, Ph.D., VA Hospital, Hines, Ill., Associate Professor, Department of Pharmacology, Stritch School of Medicine, Loyola University, Maywood, Ill., and Assistant Adjunct Professor, Schooi of Public Health, University of Illinois, Chicago; Stanford Hamburger, D.D.S., M.P.H., Department of Health & Human Services, Food and Drug Administration, Rockville, Md.; Edith Morrison, Ph.D., National Institute of Dental Research, Bethesda, Md.; Roland Mais, VA Hospital, Hines, Ill.; Sheldon Winkler, D.D.S., Temple University School of Dentistry, Philadelphia, Pa. Coauthors: Alan Cantor, Ph.D.; Thomas Stein, D.M.D.; Jeffrey Jacobson, D.D.S.; James Pikulski, D.D.S.; Frank Lauciello, D.D.S.; John Mozrall, D.D.S.; Roger Cwynar, D.M.D.; Stephen Schlimmer,

Clinical evaluation five-year report

ET AL

D.D.S.; Richard Navarro, D.D.S., M.S.; Gregory Movsesian, D.D.S.; Lloyd Lariscy, D.D.S.; Peter Yaman, D.D.S., M.S. Executive Committee: Harold F. Morris, D.D.S., M.S., Chairman; Alan Cantor, Ph.D.; Dennis Weir, D.D.S., M.A.; David Irvin, D.D.S.; Warren Stoffer, D.M.D.; Kamal Asgar, Ph.D.; Raul Caffesse, D.D.S., M.S.; Alan Helisek; Robert Lorey, D.D.S., M.S. (ad hoc); Gerald Charbeneau, D.D.S., M.S. (ad hoc). Operations Committee: Gunnar Ryge, D.D.S., MS., Chairman; Marjorie Swartz, B.S., M.S.; Bart Hsi, Ph.D.; John Costley, D.D.S., M.S. Statistical Support Center: William G. Henderson, Ph.D.; Alan Cantor, Ph.D.; Roland Mais; Barbara Christine; Anne Horney; Jean Rowe.

of four amalgam alloys: A

Romain Doglia,* Pascal Herr,* Jacques Holz,** and Louis J. Baume*** University of Geneva, Faculty of Medicine, School of Dentistry, Geneva, Switzerland

T

lhe clinical performance of amalgam alloys of a high copper content has been subjected to much study.‘,2 These evaluations were based on the qualification of the restorations according to standard characteristics of anatomic form, tarnish, and marginal adaptation3 and were carried out either by visual examination in situ by the use of Ryge’s criteria,3-5 serial macrophotographs,‘! 6-‘3or both methods.2”4’ ” In addition to serial macrophotographs, Doglia et al.” assessed marginal adaptation micrometrically by measurement of the enamel-filling interface on serial microphotographs of replicas for the clinical qualification of four amalgam alloys after 1 year. The purpose of our present investigation was to evaluate the clinical performance of three high-copper amalgam alloys and one conventional amalgam alloy after 5 years in the mouth according to standardized methods previously described by Doglia et al.

*Lecturer, Operative Dentistry. **Professor of Operative Dentistry and Chairman, Department of Preventive and Therapeutic Dentistry. ***Honorary Professorof Preventive and Operative Dentistry.

MATERIAL

AND METHODS

The sample consisted of 110 posterior teeth that required class II restorations in 29 maxillary and mandibular quadrants of 13 patients who had satisfactory oral hygiene habits and balanced occlusion. Four amalgam alloys were used: one conventional alloy (Premix, Cendres et Metaux, Bienne, Switzerland) and three high-copper alloys (Dispersalloy, Johnson & Johnson, East Windsor, N. J.; Sybraloy, Kerr/Sybron, Romulus, Mich., and Tytin, S.S. White, Philadelphia, Pa.). According to the classification of Jorgensen,” Dispersalloy is a non-y, blended alloy and Sybraloy and Tytin are non-y, spherical alloys. The cavities in each quadrant were restored with one of the alloy forms. However, to compare the performance of the alloys under identical conditions, 11 patients had at least two alloys chosen at random placed in two quadrants and two patients had four alloys placed in four quadrants. Cavity preparation. Each cavity was prepared according to conventional biomechanical and prophylactic principles under rubber dam protection. For the finishing of the cavity border, a fine-grain stone was used at the occlusal edge and a chisel was used at the gingival margin. A matrix was stabilized with wedges inserted OCTOBER

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Fig. 1. Quantitative assessment of filling-enamel interface. A, Macrophotograph made in situ. (Original magnification x2.) B, Diagrammatic replica of restoration on its holder. C, Microphotograph of replica. (Original magnification x20.) D-F, Microphotographs (area shown in C) of replica made after placement, after 2 years, and after 3 years. (Original magnification X100.) Crevice width is measured at 10 spots (arrows) in isthmus area near proximal ridge. e = Enamel; am - amalgam restoration.

into the interdental spaces. The amalgam alloys were mixed in the amalgamator according to the manufacturer’s instructions. Condensing was done by hand and also with a mechanical condenser upon the last superficial layer of alloy. Each restoration was burnished, shaped with a carver and an explorer, and adjusted to proper occlusion. After 48 hours each filhng was polished with a fine-grain stone, polishing disks (E. C. Moore Co., Dearborn, Mich.), “brownie and greenie” rubber points THE JOURNAL

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and cups (Shofu, Menlo Park, Calif.), and brushes filled with a mix of zinc oxide and alcohol. Periods of examination. The restorations were examined immediately upon polishing, then 6 months and 1, 2, 3, and 5 years later. During the control period of 2 to 5 years, seven restorations were replaced because of fractures or deteriorated quality. One patient who had seven fillings did not come for the recall examinations. The sample of 5 years was therefore reduced to 12 407

DOGLIA

Table I. Distribution

of the restorations

evaluated

according

ET AL

to the form of alloy

No. of restorations Not evaluated Evaluated after polishing

Amalgam alloys

Replacement

2 Yr

Premix

27 26 28 110

Dispersalloy Sybraloy Tytin Total

1 1 3

3 Yr 5 Yr 5 yr 5 Yr

29

Premix

Dispersalloy

Sybraloy

Tytin

Anatomic form

Marginal integrity

Tarnish

2 3 5 2 3 5 2 3 5 2 3 5

++ ++ +++ + + ++ + + + + + +

++ ++ +++ + ++ ++ f + + + + +

+ + + + + + ++ ++ ++ + + +

damaged; ++ = moderately

damaged;

patients and 96 restorations, with 24 restorations of each alloy. Methods of evaluation. Each filling was examined by explorer and photographed in color with macrophotographic equipment previously described.16Serial macrophotographs at progressively longer postoperative periods were made at the same magnification (~2) (Fig. 1, A) and with a similar centering. According to the three characteristics of the restoration described by Ryge and Snyder3-anatomic form (proximal contacts and occlusal wear), marginal integrity (break of the restoration at the filling-enamel interface), and surface condition (tarnish)-each restoration was qualified either as unaltered, slightly damaged, moderately damaged, or severely damaged. For additional qualification of the restorations, serial replicas of the fillings were prepared according to the technique of SognnaeP (Fig. 1, B) and photographed under a scanning electron microscope (Autoscan, Etec Corp., Hayward, Calif.) at magnification x20 408

24 24 24 96

2 2 3 7

Table III. Microphotographic qualifications of the four amalgam alloys in terms of marginal integrity (crevice and microfractures) and surface condition (roughness)

Period of evaluation (yr)

- = Unaltered; + = slightly +++ = severely damaged.

24

5 1 0 1 7

Table II. Macrophotographic qualifications of the four amalgam alloys in terms of anatomic form (occlusal wear), marginal integrity (crevice), and tarnish Amalgam alloys

Evaluated after 5 yr

One patient missing

because of fracture

Amalgam alloys Premix

Dispersalloy

Sybraloy

Tytin

Period of evaluation (yr)

Marginal integrity

Surface condition

2 3 5 2 3 5 2 3 5 2 3 5

++ ++ ii+ + ii ++ + + + + + +

-I++ +++ + + + + + + + + +

- = Unaltered; + = slightly +++ = severely damaged.

damaged; ++ = moderately

damaged;

(Fig. 1, C’). On these serial microphotographs the fillings were qualified either as unaltered, slightly damaged, moderately damaged, or severely damaged with respect to the marginal integrity (loss of integrity and fracture) and to the surface condition (roughness). In addition, a spot of the filling-enamel interface with an obvious landmark in the isthmus area near the proximal ridge was photographed at magnification xl00 (Fig. 1, D, E, and F). The width of the crevice between cavity wall and filling margin was micrometrically assessedon these microphotographs at 10 spots spaced in equal intervals. The mean width of the crevice was calculated for each microphotograph and for the entire group of microphotographs corresponding to each amalgam alloy upon finishing and 2, 3, and 5 years thereafter. A one-way anylysis of variance and a Student-NewmanKeuls multiple comparison test were used at the 0.01 level of significance to indicate any significant difference in crevice width between the four amalgam alloy forms. OCTOBER

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Fig. 2. Macrophotographs of restorations made of conventional alloy Premix immediately after polishing; (A) and 2 years (B), 3 years (C), and 5 years (D) thereafter. (Original magnification ~2.) Restorations show increasing surface of occlusal wear (arrows) from 2 to 5 years. On the molar, restoration had to be replaced after 3 years because of fracture and adjacent premolar had to be reshaped. Margin of restorations was slightly damaged after 2 years, moderately damaged after 3 years, and for both premolars margin was severely deteriorated after 5 years.

RESULTS The data concerning the clinical performance of the four amalgam alloys after polishing and 2,3, and 5 years thereafter are presented with respect to (1) the replaceTHE JOURNAL

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Fig. 3. Macroph.otographs of restorations made of high-copper alloy Dispersalloy immediately after polishing (A) and 2 years (B), 3 years (C), and 5 years (D) thereafter. (Original magnification x2.) Occlusal wear of restorations was located on distal ridge and on lingua1 pit of second premolar (~T~OZUS!.Margin of restorations was slightly damaged after 1 and 3 vears, and it was slightly to moderately damaged a&r 5 years. merit of seven restorations, (2) the macrophotographic qualification of the fillings, (3) the microphotographic qualification of I:he replicas, and (4) thP quantitative assessment of the filling-enamel interface. The distribution of the replaced restorations by the type of alloy is shown in Table I. Five of seven fractured restorations occurred after use of thr c.onv~~ntional alloy 409

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ET AL

Fig. 4. Macrophotographs of restorations of spherical high-copper alloy Sybraloy immediately after polishing (A) and 2 years (B), 3 years (C), and 5 years (D) thereafter. (Original magnification X2.) In B, C, and D there is little occlusal wear on proximal ridges (arrows). Margin of restorations was slightly damaged after 3 and 5 years.

Fig. 5. Macrophotographs of restorations of spherical high-copper alloy Tytin immediately after polishing (A) and 2 years (B), 3 years (C), and 5 years (D) thereafter. (Original magnification x2.) In B, C, and D there is little occlusal wear on distal ridge of second premolar (ardamaged after rows). Margin of restorations was slightly 3 and 5 years.

Premix. Among these seven restorations, one (Tytin) had recurrent decay, two (Premix) had deteriorated margins qualified as not acceptable,3 and three (Premix) and one (Dispersalloy) were fractured in the bulk of the filling.

The macrophotographic qualifications of the four alloys in terms of anatomic form, marginal integrity, and surface condition are represented in Table II and Figs. 2 to 5. With regard to the anatomic form evaluated after 2

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Fig. 6. MI rcrophotographs of replicas of resi lrati Ion made b of P remix immediately after polishing (A an A2 years (B), 3 years (C), and 5 years (D) the eafi ter. X100.) Filling-enamel ir :erf
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Fig. 7. M icrophotographs of replicas of rcrstora tion after polis thing (A) made of II)ispersalloy immediately and 2 yea r’s (B), 3 years (C), and 5 years (D) tl herea fter. x100.) Marginal micrc tfract ures (Original magnification of restorat ion increased width of crevice betwe hen calvity wall and filling margin during period of e\ raluai Son. e = Enamc ~1;am = amalgam restoration 411

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Fig. 8. Microphotographs of replicas of ret jtoration made oIf Sybraloy immediately after polishing ( A) and 2 years tIB), 3 years (C), and 5 years (D) th ereafter. (Origin la1 magnification x100.) Crevice betwee n cavity and w,all and filling and margin increased slightly during period of evaluation. e = Enamel; am = 2amalgam restoral tion. 412

ET AL

Fig. 9. Microphotographs of replicas of rest oration made of Tytin immediately after polishing (A) and 2 years (B), 3 years (C), and 5 years (D) the] reafter. (Original magnification X100.) Filling-enamel ini which was almost imperceptible after pol ishing, increased slightly during period of assessment. e = Enamel; am = amalgam restoration. OCTOBER

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ASSESSMENT

q

after

polishing

[J

after

2 years

after

3 years

after

5 years

•g

PREMIX

DISPERSALLOY

SYBRALOY

TYTtN

Fig. 10. Mean width and standard deviation of the filling-enamel interface related to the four amalgam alloys assessed immediately after polishing and 2, 3, and 5 years thereafter.

and 3 years, there were few form variations at the occlusal face of the restorations made of high-copper alloys (Dispersalloy, Sybraloy, and Tytin) (Figs. 3 to 5, B and C). On the other hand, more marked variations in occlusal form of the fillings made of Premix are seen (Fig. 2, B and C), especially at the proximal ridges where wide facets of wear appear. After 5 years, fillings made of Sybraloy and Tytin showed a lasting anatomic form except for small facets of wear at the proximal ridges (Fig. 4, D, and Fig. 5, D), whereas restorations made of Dispersalloy had more marked occlusal wear (Fig. 3, 0). As to the restorations made of Premix, their occlusal wear worsened so much after 5 years (Fig. 2,O) that the filling of the molar shown in Fig. 2, D had to be replaced after 3 years and the filling of the adjacent premolar had to be reshaped. With respect to marginal integrity, the macrophotographs made after 2 years revealed slight damage of the high-copper restorations with Dispersalloy (Fig. 3, B), Sybraloy (Fig. 4, B), and Tytin (Fig. 5, B), whereas the margin of the restorations made of Premix was moderately damaged. After 3 and 5 years the restorations made of spherical alloys (Sybraloy and Tytin) showed lasting marginal adaptation (Fig. 4, C and D, Fig. 5, C and D),

were severely damaged and showed small fractures at their margin (Fig. 2, C and 0). Surface tarnish (visual dullness on macrophotographs) was qualified as slight on the Premix, Dispersalloy, and Tytin alloys and moderate on t,he restorations made of Sybraloy during the 5-year period. The microphotographic qualifications of the four alloys in terms of surface condition and marginal integrity are represented in Table III and Figs. 6 to 9. The surface condition of the four alloys (roughness on microphotographs) was slightly more rugged after 2 years than after polishing (Figs. 6 to 9, A and B). After 3 and 5 years the restorations made of high-copper alloys were still slightly rugged, whereas fillings made of Premix became markedly rugged with scores.

the restorations made of Dispersalloy were moderately damaged (Fig. 3, C and D), and those made of Premix

interface by alloy for each period of evaluation in Figs. 6 to 10. The significant differences

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With regard to marginal

integrity,

the spherical alloys

Sybraloy and Tytin remained slightly damaged during the 5 years of evaluation (Figs. 8 and 9). During that time the restorations made of Dispersailoy were moderately damaged at the margin (Fig. 7), and those made of Premix showed deterioration of the margin qualified as moderate after 2 years and severe from 3 to 5 years (Fig. 6). The quantitative assessment of the filling-enamel is shown in mean 413

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ET AL

Table IV. Significant (+) and insignificant (-) differences in mean width of the enamel-filling interface calculated at the 0.01 level of significance between the four amalgam alloys by the period of evaluation Period of evaluation After

polishing

After 2, 3, or 5 yr

Alloys Dispersalloy Sybraloy Tytin Dispersalloy Sybraloy Tytin

width of filling-enamel interface between the four amalgam alloys are summarized in Table IV for each period of assessment. After polishing, the mean width of the filling-enamel interface was about 6 pm for Premix and Dispersalloy and about 4 pm for Tytin. Sybraloy had the lowest mean width (3.4 pm), which differed significantly from the mean width of Premix and Dispersalloy. After 2 years the spherical alloys Sybraloy and Tytin had a filling-enamel interface about 30 pm wide, whereas the crevice of Dispersalloy was twice as large (65 pm). After 2 years, Premix had a crevice width of 93 Frn, which was already three times larger than for Sybraloy and Tytin. This ratio between the mean widths remained the same after 3 and 5 years. After 3 years the mean width of the crevice was slightly increased for the four alloys. After 5 years the width of the crevice was about 45 pm for both spherical alloys and 85 Mm for Dispersalloy, whereas the crevice of Premix stretched up to 147 brn, with an increased ratio of deterioration compared with the three high-copper alloys. Fig. 10 indicates that the sharpest marginal deterioration of all restorations occurs before 2 years. Table IV indicates that during the period from 2 to 5 years after the operation, there were significant differences in mean crevice width between Premix and the three high-copper alloys; between Dispersalloy and Premix as well as both spherical alloys; and between the spherical alloys and the two other alloys. In contrast, there were no significant differences in mean crevice width between Sybraloy and Tytin. DISCUSSION The clinical performance of the three tested types of high-copper alloys confirms the connection with their physical properties as stated by several authors.17,19-21 Concerning the replaced restorations, the inclusive percentage of failure (about 7%) is similar to the figure 10% mentioned by Letzel and Vrijhoef” and by Hamilton et a1.5,who also evaluated conventional alloys and high-copper alloys after 5 years. In the present study, a greater risk of failure for conventional alloy than 414

Premix

Dispersalloy

+ -

+ -

+ + +

+ +

Sybraloy

for high-copper alloys is noted. Moreover, the pronounced occlusal wear of Premix compared with the non-y, alloys is very likely related to the lower strength of the conventional alloy, which is consistent with several reports.4l “3 I9 The differences in marginal integrity of the four alloys are in accord with the hypothesis of correlation between creep and risk of marginal fractures,4, “1 ‘9x2obecause the tested spherical alloys have the lowest creep.‘~“~2’ Although this correlation was debated,22our present data indicate that both spherical alloys had better marginal integrity than the Dispersalloy, contrary to the data reported by several authors.‘, ‘. ‘O The marginal adaptation is also related to corrosion,‘” and there is a marked surface roughness of the conventional alloy Premix that is most likely a result of corrosion. In contrast to this microphotographic finding, Sybraloy was the dullest alloy on macrophotographs in situ. This visual dullness may be related to the high percentage of copper (29%) compared with Dispersalloy (12%) and Tytin (13%). Apart from the physical properties of the alloys, other variables could have an effect on the clinical performance of the restorations: cavity width, tooth position,‘, time under rubber dam providing isolation from wetness, and patient’s occlusion. It was noted that the spherical alloys needed more careful carving because they were more plastic and had a shorter setting time than the other alloys. As to the methods of evaluation, the macrophotographic method had some disadvantages such as difficulty in assessing marginal adaptation during the first 2 years after the operation and in assessing the tarnish of the restorations. As to microphotography, some replicas of the fillings were slightly waved, making critical evaluation of the surface condition on microphotographs difficult. The micrometric assessment of the fillingenamel interface could have been completed along the whole length of the margin. However, the isthmus seemed to be representative of the entire margin because it was submitted to high mechanical stress. Despite these disadvantages, both macrophotographic and microphotographic methods permitted comparison and accurate OCTOBER

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qualification of the clinical performance of the restorations over a period of 5 years.

SUMMARY AND CONCLUSIONS In this study 96 teeth of 12 patients were restored with either the conventional alloy Premix, the blended non-y, amalgam Dispersalloy, or one of the spherical alloys Sybraloy and Tytin. To ascertain an objective comparison of the clinical performance of these alloys, two different alloys were used in each of at least two dental arch quadrants in the same patient and consequently were placed in the same oral environment. Clinical performance of the restorations was evaluated by macrophotography and scanning electron microphotography of replicas made after placement and 2, 3, and 5 years thereafter. Standard criteria were used for the evaluation of anatomic form, surface condition, and marginal adaptation of the fillings. In addition, the filling-enamel interface was assessedfrom the microphotographs. The three high-copper alloys performed better clinically than the conventional alloy, and the spherical alloys had the best qualifications. In addition to visual examination and photographic evaluation of restorations, the micrometric assessment of replica photographs from the scanning electron microscope may render clinical trials of amalgam alloys measurable and less subjective. REFERENCES 1.

Osborne JW, Leinfelder KF, Gale EN, Sluder TB: Two independent evaluations of ten amalgam alloys. J PROSTHET DENT 43:622.

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Rydinge E, Goldberg J, Sanchez L, Lambert K, Munster E: CZlinical evaluation of high copper amalgam restorations. J Oral Rehabii 83465, 1981. 3. Rygr G, Snyder M: Evaluation the clinical quality of restorations. J Am Dent Assoc 87:369, 1973. 4. Herr P. Ciucchi B, Holz J, Baume LJ: Les traitements dentaires conswwteur~ --aspect clinique de I’&olution odonto-technique concernant Its amalgamcs et les composites (Revue de la littiraturr 1975-1078). Rev mens suisse Odontostomatol 88:1001, 197x. 5 liamilton ~JC:;Moffa JP, Ellison JA, Jenkins WA: Marginal fracture no1 a predictor of longevity for two dental amalgam alloys: A trn year study. J PROSTHET DENT 50~200, 1983. 6. Oshorne JW. Gale EN, Chew CL, Rhodes BF, Phillips RW: (Ilnical performance and physical properties of twelve amalgam ,~llnvs. .J Drni Rer 57:983, 1978. 2.

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Osborne JW, Gale EN: Failure at thr rn.wgm of amalgams as alfected by cavity width, tooth position >nti alloy selection. J Dent Res 60:681, 1981. 8. Leinfelder KF, Strickland WD, Sockwrll <:L. Eames WB: Two year clinical evaluation of high copper t’onrwt amalgams. ,J Dent Res 58(spwial issue A):l99, 1979 (Abstr No. 415). 9. Mahler DEL, Marantz RL: The eff’ecr of time on the marginal fracture hehaviour of amalgam. ~JOral Rrlrabil 6:39?, 1979. 10. Mahler DB, Marantz RL. Engle JH: :I pwdwtive model for the clinical marginal fracture of amalgam. J Dwt Res 59:14%0, 1980. 11. Let& H, Vrijhoef MMA: I,ong term perlr~rmancc of amalgam restorations J Dent Res 60(Spe&l iwic i! (130, 1981 (l\bstr No. 1282). 01 polishing on the 12. Letzrl H, Vrijhoef MMA: The inllwncr marginal integrity of amalgam rr.storatio~~~. 1 Oral Rchahil 11:89.

1984.

13. Letzel H, Vrijhoef MMA: Long term mfirxncrs on marginal fracture of amalgam restorations. J Oral R&ahil Il:9i, 1984. 14. Osborne JW, Phillips RW, (Gale EN, Bnwn PP. Three-yea1 clinical comparison of three amalgam alloy tx pcs emphasizing an nppraisal of the evaluation methods used. 1 .‘\m I)enr Assot~ 93:784, 1976. IS. Mahler DB, Engle JH: Prediction (11 ttw clinical marginal fracture of amalgam J Dent Res 63(Sp0 ial ,ww A):260. 1984 (i\hstr No. 801). 16. Doglia R, Htsrr P, Holz J, Baume LJ (:ot:tri,lc du comportement clinique de 4 amalgames j l’aidc dr m&hodes macrophotographique et Inicrophotographiquc normalist% Rev mrns suisye Odontostomatol 91:329. 1981. 17. Jorgensen KI): Recent developments in allnw for dental amalgams: their properties and proper uw. Jr,) I)rnt J 26:369, 1976. 18. Sognnaes RF: Micro-replication for warming elwtron microscopy applied to problems of art, technology ,tnd i( iencc. j J)cwt Reh 51:8O, 1972 (Ahstr No. 128). 19. Eames WB, MacNamara JF: Eight high-copper amalgam alloys and six conventional alloys compared. Oper I)enr 1:‘)s. 1976. 20 Reishick MH: Second generation dispersant-r!pe amalgam. Oral Health 67:l. 1977. en microscopir 21 Stoian M. Ml,yer JM: Etude ultrawwcturs!c ~lectronique i balayage de 15 alliagcs pour amalgames. Rev Mens Suisse Odontostomatol 90:733, 1980. 22 (iale EN, Osborne JW. Clinical pet formawe of amalqam as predicted hy physical property tests. J Dcnr krs 59:61 1080. Hqmrll req”“‘/\ 11’: DR. J.~CQUES HOLZ

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