Observations on a composite resin for Class II restorations: Two-year report

Operative dentistry

Observations restorations: Ralph Rita

W. Mehra,

Robert

J.

Department Indianapolis,

on a composite Two-year report

Phillips,

D.Sc.,*

D.D.S.,

David

M.S.D.,***

McCune,

D.D.S.,

of Dental Ind.

resin for

R. Avery, Marjorie

Class II

D.D.S.,

M.S.D.,**

1. Swartz,

M.S.,****

and

M.S.D.*****

Materials,

Indiana

University

School

of

Dentistry,

A

one-year clinical evaluation of Class II amalgam and composite tions has been rep0rted.l These restorations have now been re-examined This report deals with the results of that evaluation. METHODS

AND

resin restoraat two years.

MATERIALS

The composite resin (Adaptic) $ served as the experimental material, while amalgam (Velvalloy) $ was the control. The formula for the Adaptic was that marketed prior to June, 1971. The respective physical properties of the two materials and the data for the one-year evaluation may be found in the first pub1ication.l Likewise, the reader is referred to that paper for a description of the manipulation of the materials, the techniques employed in placing and finishing the restorations, and the criteria employed for evaluating their performance. Two dentists placed 124 pairs of Class II composite resin and amalgam restorations in the bicuspid and/or molar teeth of 73 patients. Within two months after insertion of the restorations, a baseline evaluation was conducted by two examiners from the Materials and Technology Branch of the Division of Dental Health, United States Public Health Service, in San Francisco. The restorations were then re-examined after one and two years of service. *Assistant Dean for Research and Research Professor of Dental Materials. **Assistant Professor and Chairman, Division of Undergraduate Pedodontics. ***Assistant

Professor

****Professor ****“Chief,

of Dental Biomaterials

t Johnson & Johnson, $S. S. White Dental 164

of Dental

Materials.

Materials. Program,

New Brunswick, Products, Division

National

Institute

N. J. of Pennwalt

of Dental Corp.,

Research,

Philadelphia,

Bethesda, Pa.

Md.

Volume Number

28 2

Composite

resin for Class II restorations

165

Table I. Rating of restorations -. Category Anatomic form

Restoration Restoration

Bravo

Restoration material Sufficient

Charlie Marginal adaptation

Alfa

with

existing

anatomic

form.

is discontinuous with existing anatomic is not sufficient to expose dentin or base. material lost to expose dentin or base.

form,

but

missing

Delta Hotel

Metallic

Alfa

Restoration matches the adjacent tooth structure in color and/or translucency. Mismatch in color and translucency is within the normal range of tooth color and translucency. Mismatch in color and/or translucency is outside normal range of tooth color and/or translucency.

Charlie

Bravo Charlie

Cavosurface marginal discoloration

is continuous

Restoration appears to adapt closely to tooth along periphery of restoration. Explorer does not catch when drawn across margins; if it dory catch, it will only catch in one direction. No crevice is visible. Explorer catches, and there is visible evidence of crevice into which explorer will penetrate. However, dentin or base is not visible. Explorer penetrates into crevice that is of such depth that dentin or has{. is exposed. Restoration is fractured, mobile, or missing.

Bravo

Color match

Rating

Alfa

restorations-no

Hotel

Metallic

Alfa

No discoloration anywhere on margin between restoration and structure. Discoloration has not penetrated along margin in pulpal direction. Discoloration has penetrated along margin in a pulpal direction.

Bravo Charlie

restorations-no

rating.

rating.

tooth

-

At each examination, both the amalgam and composite resin restorations were rated with respect to (1) anatomic form, (2) marginal adaptation, and (3) secondary caries. In addition, the composite resin restorations were scored for color match and marginal stain discoloration. It should be pointed out that, when one restoration of a pair was replaced, the pair was not included in future evaluations. Five pairs were dropped from the study following the one-year evaluation. However, patients who had 5 pairs of restorations and who were not available at the time of the one-year evaluation were examined at the two-year interval. They are included in these data. RESULTS For the convenience of the reader, the criteria used in evaluating the restorations are repeated in Table I.

166

Phillips

et al.

J. Prosthet. Dent. August, 1972

The baseline and two-year evaluation data are shown in Table II. In order to compare the changes which occurred during the second year, this Table also contains the one-year data. Caries was not detected in teeth restored with either material at the one or two year examination. Although the baseline examination indicated that restorations of the two materials were essentially comparable with respect to anatomic form, the data favored the amalgam at one year. At this time, all of the amalgam restorations were scored as “alfa,” while 79 per cent of the composite resins received the “alfa” rating. At the end of two years, 45 per cent of the composite resin restorations were rated as “alfa,” while 98 per cent of the amalgam restorations were still scored as “alfa.” Among the 92 pairs of restorations examined, there were 34 untied pairs in the mouths of different patients. In two of these patients, the rating favored the composite resin, but in 32 patients, it favored the amalgam. A statistical analysis of the data indicated the results to be significant at the 99 per cent level of confidence. The change in the anatomic form of the composite resin took the form of occlusal wear, although not to a degree requiring replacement. With respect to marginal adaptation, the two-year result showed an increase in the incidence of marginal discrepancies in both types of restorations as compared to the one-year result. At one year, a statistical analysis of the data on marginal breakdown indicated a significant difference in the two materials in favor of the composite resin. At two years, although the numbers still favor the composite resin, the difference is no longer highly statistically significant with respect to either the incidence or the degree of marginal breakdown. One of the amalgam restorations was replaced because of a suspected fracture. There appeared to be a hairline crack on the occlusal surface, but this was not confirmed. At the baseline examination, 83 per cent of the composite resin restorations were rated as “alfa” when evaluated for color match. At one year, 42 per cent received the “alfa” rating, and at two years, 36 per cent were scored as “alfa.” With one exception, all remaining restorations were rated as “bravo.” This rating means that the restoration is in the realm of acceptability, i.e., is still in the color and translucency range of tooth structure. In most instances, the color shift appeared to be due principally to surface stain. There was an increase in the cavosurface marginal discoloration of the resin restorations with time. At the baseline examination, 79 per cent of the resin restorations were free of marginal stain. At one year, the number was 43 per cent. At two years, the number had decreased to 27 per cent.

DISCUSSION The data obtained in this study regarding maintenance of anatomic form and marginal adaptation are in general agreement with those of an earlier study in which amalgam was compared to a different brand of composite resin.*> 3 In that investigation, the marginal adaptation of the composite resin was found to be superior to that of amalgam at one year; it was inferior at three years. In this research, the composite was superior at one year, but after two years, there was no significant difference in the two materials. In both studies, the amalgam restorations were superior in main-

Volume Number

28

Table

II

Composite

2

No. restorations examined

Category Anatomic

resin for

1

Bravo

Charlie

Delta

167

NO. restorations replaced*

form

Baseline Resin ilmalgam

109 109

108 109

1 Year Resin Amalgam

92 92

71 92

19

2 Year Resin Amalgam

92 92

41 90

49 2

Baseline Resin Amalgam

109 109

104 108

5 1

1 Year Resin Amalgam

92 92

87 80

3 9

2 Year Resin Amalgam

92 92

75 70

14 21

Baseline Resin

109

90

19

1 Year Resin

92

37

53

2 Year Resin

92

32

57

Marginal

Color

restorations

of restoration

Type Alfo

Class II

adaptation

1 1

match

C’nuosurface

marginal

discoloration

Baseline Resin

109

79

30

1 Year Resin

92

43

47

2 Year Resin

92

24

63

*The restoration

1

restoration was replaced during was unknown, and it was not

3

the interim at another facility. The included in the statistical analysis.

2 condition

of the

168

Phillips

J. Prwthet. Dent. August, 1972

et al.

tenance of anatomic form. Observation of wear on composite resins in Class II restorations has been reported by others. 4* The loss of anatomic form was confined to the occlusal portion of the restoration. Loss of proximal contour or contact was not observed. A comparison of the clinical data with that of laboratory tests indicates that, apparently, there is no specific relationship between a particular property and clinical performance. Loss of material through occlusal wear was found to be the greatest problem associated with the composite resin restorations. The laboratory test employed in this study to assess abrasion resistance consisted of mechanical tooth brushing of the specimens in a slurry of abrasive. By this test, the amalgam was markedly more susceptible to abrasion than the composite resin. However, the reverse was true when the materials were subjected to in vivo masticatory wear. It is obvious that this test did not satisfactorily predict the wear potential of the material. SUMMARY A clinical study was conducted to compare the performance of a commercial composite direct-filling resin with that of amalgam in Class II cavities. Of 124 paired restorations placed in 73 patients, 92 pairs were available at the two-year period. The restorations were subsequently evaluated at one and two years by a team of examiners from the Materials and Technology Branch of the Division of Dental Health, United States Public Health Service, San Francisco. Caries was not detected with either material during the two year period. No gross fractures occurred in the composite resin restorations. Three amalgam restorations fractured during the first year, and one amalgam restoration was replaced at the time of the second examination because of suspected, although not confirmed, fracture. At the end of two years, a number of restorations of each material exhibited some degree of marginal breakdown. Amalgam restorations had little or no change in anatomic form, while a moderate change was observed in approximately one half of the composite resin restorations. The change in anatomic form appeared to be the result of occlusal wear. Until formulations are improved in this respect, the use of composite systems in Class II restorations should probably be limited to those situations where esthetics is the major consideration and the cavity preparations are conservative. Composite restorations were also evaluated with respect to color match and cavosurface marginal discoloration. A change in color match was observed in approximately 60 per cent of the composite resin restorations with time. However, the change appeared to be due to surface stain rather than color shift of the material. Slight marginal discoloration was detected in approximately 70 per cent of the composite restorations. The authors wish to acknowledge the assistance of Richard Weaver and John Clark who made the clinical evaluations, Penelope Brown who processed the data, and Jack Cvar who *McLean, tion, 1971,

J, W.;

Personal communication,

1971; Ambrose, E. R.: Personal communica-

Volume Nnmber

analyzed Branch, Dewitt

28

2 the data. All of these individuals Division of Dental Health, United served as dental assistant.

Composite resin for Class II restorations 149 were States

members of the Materials and Technolog) Public Health Service, San Francisco. Jerrri

References 1.

Phillips, R. W., Avery, D. R., Mehra, R., Swartz, M. L., and McCune, R. J.: One-Year Observations on a Composite Resin for Class II restorations, J. PROSTHET. DENT. 26: 6R77, 1971. L’. McCune, R. J., Johnson, B. E., Cvar, J. F., and Ryge, G.: Clinical Comparison of Posterior Restorative Materials. Presented at the Annual Meeting of the International Association for Dental Research, Washington, D. C., March, 1967, Abst. No. 546. Comparison of Anterior and Posterior 3. McCune, R. J., Cvar, J. F., and Ryge, G.: Clinical Restorative Materials. Presented at the Annual Meeting of the International Association for Dental Research, Houston, March, 1969, Abst. No. 482. 4. Schroeder, A.: The New Composite Filling Materials Based on the Bowen Formula. Paper presented at F.D.I. Congress, Munich, 1971. DRS. PHILLIPS, AVERY, MEHRA, AND SWARTZ INDIANA UNIVERSITY SCHOOL OF DENTISTRY DEPARTMENT OF DENTAL MATERIALS 112 1 W. MICHIGAN ST. INDIANAPOLIS, IND. 46202 DR. MCCIJNE CHIEF BIOMATERIALS PROGRAM NIDR, EMP, NIH WESTWOOD BLDG.,ROOM522 9000ROCKVILLE PIKE BETHESDA, MD. 20014