- Email: [email protected]
Clinical comparison of composite, amalgam, and silicate restorations
In a th re e -p h a s e investigation, com posite dental restoratives w e re co m p ared c lin ica lly w ith am alg am in Class I resto ratio ns a fte r fo u r years, in Class II resto ratio ns a fte r th re e years, and w ith silic ate in Class III, IV, and V an terio r restorations a fte rth re e years. C aries re cu rren ce w as not found to be a p ro blem w ith any o f th ese m aterials. C om p o sites did hot fra c tu re in any class o f cavity p rep aratio n . T h e ir m arginal ad ap tatio n w as su p erio r to th a t of a m a lg a m a fte r o n e year, b u t they tend to lose an ato m ic fo rm s o o n e r th an am alg am . Gross d eterio ra tio n w as seen w ith silicates.
Clinical comparison of composite, amalgam, and silicate restorations W ilm e r B. E a m e s , DDS Jon D. S tra in , DDS R. T e rre ll W e itm a n , DDS A lfre d K. W illia m s , DDS, M S, A tlanta
The need for a dental restorative material that is durable, easily manipulated, and esthetic is read ily apparent. Amalgam possesses the first two characteristics, yet many find its appearance ob jectionable. The physical appearance of the sili cates is acceptable, but they tend to be soluble and are prone to leakage and discoloration. In addition, the high acidic nature of the silicates makes them a threat to the dental pulp.1 Within the past ten years the scope of restor ative dentistry has been expanded by the intro duction of composite resins. The earlier acrylic resins were deficient in hardness and strength, had a high coefficient of thermal expansion, and did not adapt well to the teeth. Many of these faults have been eliminated in a composite con sisting of silane-treated filler particles bonded to gether with dimethacrylate resin formed from an epoxy intermediate.2 Laboratory studies of the new composite resins have shown that they shrink less when setting, are harder and stronger, and have a significantly lower coefficient of ther mal expansion than the earlier resins. Although accurate clinical evaluation is diffi cult in view of subjective preferences of indi vidual evaluators, well-controlled clinical stud ies are necessary to determine the practical value of new materials. Concurrent studies have been reported.3,4 The Materials and Technology Branch, Divi sion of Dental Health, US Public Health Center has selected certain criteria to facilitate the eval
uation of composite resins. These criteria, as de scribed by Ryge and co-workers,5,6 were used in this study to evaluate and to compare the clin ical performance of composite resins. Certain factors that are directly related to the viability of a composite restoration as compared with that of silicate and amalgam restorations demanded attention. These included the extent, if any, of caries recurrence, the degree of sur face deterioration, the maintenance of marginal adaptation, the frequency of fracture, and the permanence of anatomic form. A priori objec tions relating to each of these factors have, per haps, impeded the effective use of composite resins in dentistry. The determination of the val idity of these objections was the goal of this study.
Materials and methods Composite materials were compared with stan dard dental restoratives in Class I, Class II, and anterior (Class III, Class IV , and Class V) res torations. In the study of Class I restorations, the clinical performances of a quartz-filled com posite (Adaptic*), a glass-filled composite (Addent 12t), and an amalgam (New True Dentalloyt) as a control were compared. In the evalua tion of Class II restorations, the performance of Adaptic was compared with that of an amalgam JADA, Vol. 89, November 1974 ■ 1111
prepared with Velvalloy.§ The final comparison was that of Adaptic and a conventional silicate cem ent (M. Q. Silicatet) in various classes of an terior restorations. Conservative cavity preparations were made following standard operative techniques. Man ipulation and insertion of the materials were in accordance with the manufacturer’s directions, and finishing procedures were standardized for all restorations according to accepted methods.
was applied to the surface of the dentin. After preparing a pair of cavities in a given patient, the dentist used a random statistical table to deter mine which restorative would be placed in each cavity. N o attempt was made to match tooth shades in the composite restorations. The res torations were examined at the base line and at recalls after one, two, and three years following the same criteria as those used in the study of Class I restorations.
■ Study o f Class I restorations: Twenty-four patients were chosen on the basis of their having at least three similar carious lesions. Each pa tient received three restorations, one each of A daptic, Addent, and New True Dentalloy, at the same sitting. A total of 34 sets of three were placed. (Some patients received more than one set.) One patient, however, received four restor ations, two of the composite materials and an amalgam control for each. Each patient was given a prophylaxis. When practical, a rubber dam was used to isolate the treated teeth; however, if it could not be used for one of the restorations in the set, it was not used for the others. After the placement of all test and control res torations, two examiners inspected the patients to establish base-line ratings on each of the res torations for three characteristics3,4: anatomic form, marginal adaptation, and caries. Each restoration was examined with a sharp no. 17 explorer, and each characteristic was rated “ al p ha,” “ bravo,” “ charlie,” or “ delta.” Alpha indicated the characteristic was superior, bravo m eant there were clinically detectable faults that did not require the replacement of the restora tion (except in the instance of caries), and Char lie or delta indicated an unacceptable character istic requiring replacement of the restoration. If disagreements occurred on independent exam inations, a final rating was determined in consul tation. Additional examinations were done at the three- and four-year recalls.
■ Anterior restorations, classes III, IV, and V: Twenty-nine patients who had at least two cari ous lesions or defective restorations of about the same size in anterior teeth were selected by screening. In each patient, a pair of cavity prep arations of similar size with comparable reten tion and resistance form was completed. The fa cial margin was made visible in most restora tions so that they could be viewed without a mir ror. On occasion, the incisal angle was involved in the preparation. In those restorations, resist ance and retention were achieved with lingual locks or placement of threaded pins. After completion of cavity preparations, a rubber dam was used to isolate the teeth in volved, and Dycal was placed as a base. A ran dom table was used to select the material, Adap tic or M. Q. Silicate, to be used for each prep aration. Because the manufacturer of the com posite material recommended it for use in stressbearing areas, it was used in all but one restora tion in which the incisal angle was involved. Fifty-one pairs of restorations were placed in the 29 patients. (Again, some patients had more than one pair of restorations placed.) O f the 102 restorations, 86 were Class III, 10 were Class IV , and 6 were Class V. In addition to the evaluation under the same three criteria as in the previous two studies, these anterior restorations were rated for color match and cavosurface marginal discoloration. Exam inations were conducted at the base line and at recalls after one, two, and three years.
■ Study o f Class II restorations: Thirty-one patients, each having one or more pairs of Class II lesions, were selected. F or each pair of teeth restored, one was filled with Velvalloy and the other with Adaptic. Forty-eight pairs of teeth were filled in the 31 patients. (Some patients had more than one pair of teeth restored.) T he cavities were prepared conservatively with proximal retentive grooves. If a base was required, a calcium hydroxide paste (Dycal§)
■ Evaluation procedures and statistical method: Each composite restoration in all of the clinical studies was considered the test restoration and was paired in the same oral environment with a control restoration of the same or comparable class. The study of Class I restorations was, in effect, two separate comparisons with one com mon control restoration. The two composite res torations in a set were compared independently with the same amalgam restoration. Thus, each
1112 ■ JADA, Vol. 89, November 1974
T a b le 1 ■ R a tin g s * fo r C la s s I resto ra tio n s. A n a t o m ic fo r m
D
A
B
NE
0 2
0 0
35 34
0 1
0 0
0 0
2
0
0
36
0
0
0
6 8
0 1
0 0
25 24
0 2
2 1
7 6
14
14
0
0
28
0
2
6
0 0
15 14
5 6
0 1
0 0
19 18
1 3
1 0
11 11
0
13
9
0
0
21
1
3
11
0 0
0 0
31 28
4 5
36
0
0
34
17 13
8 13
0 0
19 17
25
3
0
6 3
14 18
20
2
B ase 35 35 36
35 35
B
C a rie s
C
A
A
lin e (1 0 6) A d a p tic Addent N e w T ru e D e n ta llo y T h r e e y r (79) 2 5 A d a p tic 26 A d d e n t 2 8 N e w T ru e D e n ta llo y F o u r y r (63) 20 A d a p tic 21 A d d e n t 2 2 N e w T ru e D e n ta llo y
M a r g in a l a d a p ta tio n
C
N o . r e s t o r a t io n s
B
NO
• R a t in g ke y. A n a to m ic f o r m : A , r e s t o r a t iv e m a t e r ia l is c o n t in u o u s w ith e x is t in g a n a to m ic f o r m ; B, r e s t o r a t iv e m a t e r ia l is u n d e r c o n t o u r e d ; C , t h e r e is s u f f ic ie n t r e s t o r a t iv e m a t e r ia l m is s in g s o a s t o e x p o s e d e n t in o r b a s e . M a r g in a l a d a p t a t io n : A , r e s t o r a t iv e m a t e r ia l is c o n t in u o u s w ith t h e c a v o s u r fa c e m a r g in ; B , t h e r e is v is ib le e v id e n c e o f a m a r g in a l c r e v ic e in t o w h ic h t h e e x p lo r e r w il l p e n e t r a t e ; C , th e c r e v ic e is d e e p e n o u g h t o e x p o s e d e n t in o r b a s e ; D , th e r e s t o r a t io n is m o b ile , f r a c tu r e d , o r m is s in g in p a r t o r in to t a l. C a r ie s : A , t h e r e is n o e v id e n c e o f c a r ie s c o n t ig u o u s w it h th e r e s t o r a t io n ; B , t h e r e is e v id e n c e o f c a r ie s c o n t ig u o u s w it h t h e r e s t o r a t io n . N E , n o t e v a lu a te d (a r e s t o r a t io n o f a s e t o r p a ir h a d b e e n r e p la c e d ) . N O , n o t o b s e r v e d (th e p a t ie n t w a s n o t a v a ila b le f o r r e c a ll) .
Table 2 ■ Changes in patient scores from the base line to latest recall periods favorable to specified m aterials, for Class I restorations. C h a r a c t e r is t ic s
3 rd y r r e c a ll
4 th y r r e c a ll
A d a p tic A n a t o m ic fo r m M a r g in a l a d a p ta tio n C a r ie s
2 7 0
A n a t o m ic fo r m M a r g in a l a d a p ta tio n C a r ie s
2 7 1
3 rd y r r e c a ll
4 th y r re c a ll
3 rd y r r e c a ll
No change
N e w T r u e D e n t a llo y 0 5 1
Addent
6 2 0
9* 2 1
9 8 17
8 0 2
1 2* 0 2
5 7 12 No change
N e w T ru e D e n t a llo y 0 6 1
4 th y r r e c a ll
7 10 14
3 9 12
• S ig n if ic a n t d if fe r e n c e a t 9 5 % c o n f id e n c e le v e l in fa v o r o f t h i s m a te r ia l.
set of three restorations had two test-control pairs. The other two studies were strictly pair wise matched. On every examination, the ratings for each pair were recorded and tabulated according to the characteristics evaluated. For each charac teristic, the pair was scored plus if the test ma terial received a superior rating, minus if the con trol material was superior, or zero if the ratings for both materials were the same for the partic ular set of criteria used. The effect that different oral environments might have on one pair (set) versus multiple pairs (sets) of restorations per patient was minimized in that a patient score, summarizing the pair scores for every pair in an individual mouth, was determined for each characteristic rated. A ma jority of plus pair scores for a patient yielded a plus patient score. A majority of minus pair scores yielded a minus patient score. An equal number of plus and minus pair scores gave a zero patient score.
The patient scores were tested for significant difference in their change from the base line to subsequent recall examinations either in favor of the test material or in favor o f the control ma terial. The instances in which the patient scores from the base line to the recall did not change were split equally between those favoring the test and those favoring the control. A binomial test (two-tailed) was used to determine signifi cance beyond the 95% level of confidence.
Results
■ Study o f Class I restorations: The ratings for anatomic form, marginal adaptation, and caries of evaluated restorations of each material are given in Table 1, and the changes in patient scores from the base line to the latest recall per iods are shown in Table 2. These data are from patients available at the base-line, three-, and
Eames—others: COMPOSITE, AMALGAM, SILICATE RESTORATIONS ■ 1113
T a b le 3 ■ R a tin g s * fo r C la s s II resto ra tio n s. A n a t o m ic fo r m N o . r e s t o r a t io n s B a s e lin e (8 6 ) 4 3 A d a p tic 43 V e lv a llo y O n e y r (86) 4 3 A d a p tic 4 3 V e lv a llo y T w o y r (66) 3 3 A d a p tic 3 3 V e lv a llo y T h re e y r (60) 3 0 A d a p tic 3 0 V e lv a llo y
A
B
M a r g in a l a d a p ta tio n
C
A
B
C a r ie s
C
D
A
B
NE
NO
43 43
0 0
0 0
43 42
0 1
0 0
0 0
43 43
0 0
0 0
5 5
6 35
37 8
0 0
33 26
10 17
0 0
0 0
42 43
1 0
0 0
5 5
4 29
29 3
0 1
30 25
3 7
0 0
0 1
33 33
0 0
0 0
15 15
2 26
28 3
0 1
26 12
4 17
0 0
0 1
30 30
0 0
1 1
18 18
'R a t in g k e y , s a m e a s f o r T a b le 1.
Table 4 ■ Changes in patient scores from the base line to latest recall periods favorable to specified materials, for Class It restorations. C h a r a c t e r is t ic s
2nd y r r e c a ll
3 rd y r r e c a ll
2nd y r r e c a ll
1 11* 0
1 7* 1 0
A d a p tic A n a to m ic fo rm M a r g in a l a d a p ta tio n C a rie s
1 5 0
3 rd y r r e c a ll
2nd y r r e c a ll
V e lv a llo y
3 rd y r r e c a ll N o change
14* 0 0
3 15 21
4 8 19
• S ig n if ic a n t d if fe r e n c e a t 9 5 % c o n f id e n c e le v e l in f a v o r o f t h i s m a te r ia l.
four-year examinations. The number of restora tions evaluated at any recall period was depen dent on the number of patients available for re call and also on the number of test-control pairs within sets in those available patients. Restora tions in those patients not available for recall were included in the table as “ not observed.” Restorations that had been replaced between re call examinations were included as “ not eval uated.” I f the amalgam control restoration had been replaced, two pairs (the set) were lost from the study. Replacement of either composite restora tion caused the loss of only one test-control pair from the number evaluated. The remaining composite-amalgam pair of the set was included in the clinical comparison. As a general rule, if a clinical failure, denoted by an unacceptable rat ing on any criterion, had caused the replacement of any restoration, that rating was continued over to subsequent examinations and compared with the current rating of the remaining member of the pair. Table 1 shows a definite tendency for the amal gam to retain better anatomic form than either composite material. Also, an analysis of the change in patient scores from the base line to the fourth year, as seen in Table 2, reveals signifi cant differences beyond the 95% level of confi dence between the composites and amalgam, fa voring the amalgam. Although there is a constant trend for Adap1114 ■ JADA, Vol. 89, November 1974
tic to receive better ratings in marginal adapta tion than amalgams of N ew True Dentalloy for each year after the base line, there is no signifi cant difference between the two materials in the Class I situation. Also, Addent consistently showed better ratings than the amalgam. The change in patient scores from the base line was more noticeable in the comparison of these two materials. Nevertheless, the difference was not statistically significant. N o significant differences were found between the composites and the amalgam in incidence of recurrent caries. ■ Study o f Class II restorations: The base line examinations were performed on 43 pairs of Class II restorations in 28 patients who were available for examination. Table 3 shows the rat ings for the characteristics evaluated at the base line and at subsequent recalls. As in the study of Class I restorations, the amalgam demonstrated superior retention of an atomic form as seen in the illustration. From the first-year recall through all following years, Velvalloy was statistically better, above the 95% confidence level (Table 4). The trend toward composite superiority in maintaining marginal integrity became statis tically significant at the same confidence level at the end of three years (Table 4). Again, no indication was found that recurrent caries was a problem of either material.
T a b le 5 ■ R a tin g s * for a n te rio r resto ra tio n s.
N o r e s t o r a t io n s
.
B a s e lin e (86) 4 3 A d a p t ic 4 3 M . Q . S ilic a t e O n e y r (88) 4 4 A d a p tic 4 4 M . Q . S ilic a t e T w o y r (70) 3 5 A d a p tic 3 5 M . Q . S ilic a t e T h r e e y r (56) 2 8 A d a p tic 2 8 M . Q . S ilic a t e
C o lo r M a r g in a l A n a t o m ic M a r g in a l m a tc h d is c o l o r a t io n fo r m a d a p ta tio n C a r ie s -------------------------------------------------------------------- ----------------------------------------------------------------------------------------------A B C O A B C A B C A B C D A B
N E N O
24 36
17 5
0
2 2
42 40
1 3
0 0
43 41
0 2
0 0
41 41
2 2
0 0
0 0
43 43
0 0
0 0
9 9
16 15
26 27
0 0
2 2
40 40
4 4
0 0
39 30
5 14
0 0
39 25
5 19
0 0
0 0
44 44
0 0
0 0
8 8
5 5
29 29
0 0
1 1
34 34
1 1
0 0
27 16
8 18
0 1
29 20
6 13
0 0
0 2
35 35
0 0
1 1
16 16
6 3
20 24
1 0
1 1
25 23
3 5
0 0
24 13
4 14
0 1
22 10
5 16
1 1
0 1
27 28
1 0
2 2
22 22
0
• R a t in g k e y . C o lo r m a tc h : A , r e s to r a tiv e m a te r ia l m a tc h e s t h e a d ja c e n t to o th s t r u c tu r e in c o lo r , s h a d e , a n d t r a n s tu c e n c y ; a m is m a tc h in c o lo r , s h a d e , o r tr a n s lu c e n c y w it h in th e n o r m a l ra n g e o f to o th c o lo r ; C , th e r e is a m is m a tc h n o r m a l ra n g e o f to o t h c o lo r ; O , t h e r e s t o r a t io n is n o t d ir e c t ly v is ib le a n d t h u s n o t ra te d . C a v o s u r fa c e m a r g in a l d is c o l o r a t io n : A , th e r e is n o d is c o lo r a t io n a n y w h e re o n t h e m a r g in b e tw e e n t h e a n d th e to o th s t r u c tu r e ; B , t h e r e is a d is c o lo r a t io n o n t h e m a r g in ; C , t h e d is c o lo r a t io n h a s p e n e tr a te d a lo n g in a p u lp a l d ir e c t io n . T h e r e m a in d e r o f th e k e y is th e s a m e a s f o r T a b le 1.
B , th e r e is o u ts id e th e r e s to r a tio n th e m a rg in
Table 6 ■ Changes in patient scores from the base line to latest recall periods favorable to specified materials, for anterior restorations. C h a r a c t e r is t ic s
2nd yr r e c a ll
3 rd yr re c a ll
A d a p tic C o lo r m a tc h M a r g in a l d is c o lo r a t io n A n a to m ic fo r m M a r g in a l a d a p ta tio n C a rie s
9* 2 6 9 0
2nd yr re c a ll
3 rd y r r e c a ll
2nd yr re c a ll
No change
M . Q . S ilic a t e 9* 3 9* 10 0
1 4 2 2 0
0 3 0 2 1
3 rd y r r e c a ll
8 13 11 8 1?
6 10 7 6 15
• S ig n if ic a n t d if fe r e n c e a t 9 5 % c o n f id e n c e le v e l in fa v o r o f t h is m a te r ia l.
■ Study o f anterior restorations: Table 5 gives the ratings of Class III, IV , and V restorations evaluated at the base line and after one, two, and three years for the criteria used. At the base line, only 43 of 51 pairs were evaluated since five pa tients were not available. A t subsequent recalls the remaining eight pairs were evaluated and the data recorded and included in the statistical work-up. The change in score for these eight pairs, as recorded in Table 6, was figured from the one-year evaluation. P ro m Table 5, the differences in color match between the silicate and composite restorations at the base line appeared to equalize at later ex aminations because of a significant change fav oring the composite. After three years, however, no significant difference was found between the two materials in color match. N o differences were found between the mater ials for the characteristics of marginal discolor ation and caries. However, the composite material demon strated consistently better ratings for anatomic' form and marginal adaptation at each recall ex amination as seen in the illustration. The com posite was statistically superior in anatomic form after three years, as seen in Table 6. The differ
ence in marginal adaptation after three years was close to a significant level (93.5% level of confi dence). Because a Class IV restoration is subjected to more stress and abrasion than either a Class III or Class V restoration and because nine of the ten Class IV restorations were composites, it might be assumed that the predominance of clin ical defects noted throughout the three-year study in anatomic form and marginal adaptation would come from this class. This was not true, however. The Class IV composite restorations evaluated after three years were rated mostly as alphas in the characteristics mentioned. The one Class IV silicate, as may have been expected, was a clinical failure after years. N o other differences were noted between class of prepara tion and material used. In none of the studies was the incidence of clinical failure of any of the materials great enough to be of significance.
Discussion During these few years of clinical study, we have observed two phenomena associated with com posite resins: the response elicited from the pulp
Eames— others: COMPOSITE, AMALGAM, SILICATE RESTORATIONS ■ 1115
Top, typical Class II Adaptic (left) and am algam (right) restorations at base-line examination. Center, after three years, same Adaptic restoration (left) exhibits better marginal integrity, but am algam restoration (right) maintains better anatom ic form. Bottom, figures show change in marginal adaptation and anatom ic form seen after two years in silicate restoration (left) in lateral incisor and Adaptic restoration (right) in central incisor.
and the loss of integrity of the surfaces of restor ations. ■ Pulp response: Pulp studies with primates at Emory University have shown that composites do not affect the pulp as adversely as was once thought. Initially, a mild to moderate inflam matory response may occur, which may remain for several weeks. When composite materials are placed adjacent to freshly cut dentin in teeth not previously restored, protective liners of cal cium hydroxide or polycarboxylate cements should be used as a precautionary measure. ■ Finishing: Although the finishing of compos ite restorations with ultrafine abrasives is impor tant for appearance and for the comfort of the patient, the ability to maintain a finished sur face over a period of time has not been demon strated. Clinical studies recently completed do not indicate more than slight improvement in reduction of accumulation of plaque. Although surface integrity as a category was not evaluated in this study, the examiners noted that the initial smooth surface seen after finish ing was not maintained. The surface became textured in the mouth environment in areas not ex posed to normal mastication. The cause of this attrition may be the loss of microscopic parti cles, but the cause of this phenomenon has yet to be identified.
Summary and conclusions In this three-phase investigation, composite den tal restoratives were compared clinically with amalgam in Class I and II restorations and with silicate in Class III, IV , and V anterior restora tions. In the study of Class I restorations, two composite materials were compared with an amalgam in a four-year period. In the study of Class II restorations, a composite was com pared with an amalgam for three years. In addi tion, a composite was compared with a silicate in
Class III, IV , and V restorations for three years. Amalgam is superior to the composites in its ability to retain its anatomic form, whereas the composites tend to be superior in marginal adap tation. This study also showed that the composite tested performed better than the silicate in main taining anatomic form and in marginal adapta tion. Gross surface deterioration, although evi dent, was less characteristic of the composite than of the silicate. Caries recurrence was not a problem asso ciated with any of the materials. Although this fact might serve only as a clinical exoneration of composite resins for some observers, it focuses attention on the degree and importance of micro leakage. Finally, anticipated fractures never manifested themselves as a clinical problem for either the amalgam or the composites.
This study was funded in part by National Institutes of Health Grant No. 5 R01 DE 03504-05. Dr. Eames is professor of operative dentistry and principle investigator of this study. Dr. Strain and Dr. Weitman are assis tant professors of operative dentistry, and Dr. Williams is asso ciate dean and professor of operative dentistry, Emory Univer sity School of Dentistry, 1462 Clifton Rd, NE, Atlanta, 30322. ♦Johnson & Johnson, New Brunswick, NJ 08903. tMinnesota Mining and Manufacturing Co., St. Paul, 55101. IS . S. White Dental Health Products, Pennwalt Corp., King of Prussia, Pa, 19406. §L. D. Caulk Co., Milford, Del 19963. 1. Phillips, R.W. Skinner's science of dental materials, ed 7. Philadelphia, W. B. Saunders Co., 1973, p 516. 2. Bowen, R.L. Properties of a silica-reinforced polymer for dental restoration. JADA 66:57 Jan 1963. 3. Phillips, R.W.-, and others. Observations on a composite resin for Class II restorations: three-year report. J Prosthet Dent 30:891 Dec 1973. 4. Osborne, J.W., and others. One and two year clinical eval uation of a composite resin versus amalgam. Abstracted, J Dent Res 52 (special issue):67 no. 35 Feb 1973. 5. Ryge, G.; McCune, R.J.; and Webber, R.L., Sr. Clinical com parison of two anterior restorative materials. Research protocol prepared by Dental Materials and Technology Program, May 1965. 6. McCune, R.J. and others. Clinical comparison of posterior restorative materials. Abstracted, IADR Program & Abstracts No. 546 March 1967.
Eames— others: COMPOSITE, AMALGAM, SILICATE RESTORATIONS ■ 1117
Clinical comparison of composite, amalgam, and silicate restorations W ilm e r B. E a m e s , DDS Jon D. S tra in , DDS R. T e rre ll W e itm a n , DDS A lfre d K. W illia m s , DDS, M S, A tlanta
The need for a dental restorative material that is durable, easily manipulated, and esthetic is read ily apparent. Amalgam possesses the first two characteristics, yet many find its appearance ob jectionable. The physical appearance of the sili cates is acceptable, but they tend to be soluble and are prone to leakage and discoloration. In addition, the high acidic nature of the silicates makes them a threat to the dental pulp.1 Within the past ten years the scope of restor ative dentistry has been expanded by the intro duction of composite resins. The earlier acrylic resins were deficient in hardness and strength, had a high coefficient of thermal expansion, and did not adapt well to the teeth. Many of these faults have been eliminated in a composite con sisting of silane-treated filler particles bonded to gether with dimethacrylate resin formed from an epoxy intermediate.2 Laboratory studies of the new composite resins have shown that they shrink less when setting, are harder and stronger, and have a significantly lower coefficient of ther mal expansion than the earlier resins. Although accurate clinical evaluation is diffi cult in view of subjective preferences of indi vidual evaluators, well-controlled clinical stud ies are necessary to determine the practical value of new materials. Concurrent studies have been reported.3,4 The Materials and Technology Branch, Divi sion of Dental Health, US Public Health Center has selected certain criteria to facilitate the eval
uation of composite resins. These criteria, as de scribed by Ryge and co-workers,5,6 were used in this study to evaluate and to compare the clin ical performance of composite resins. Certain factors that are directly related to the viability of a composite restoration as compared with that of silicate and amalgam restorations demanded attention. These included the extent, if any, of caries recurrence, the degree of sur face deterioration, the maintenance of marginal adaptation, the frequency of fracture, and the permanence of anatomic form. A priori objec tions relating to each of these factors have, per haps, impeded the effective use of composite resins in dentistry. The determination of the val idity of these objections was the goal of this study.
Materials and methods Composite materials were compared with stan dard dental restoratives in Class I, Class II, and anterior (Class III, Class IV , and Class V) res torations. In the study of Class I restorations, the clinical performances of a quartz-filled com posite (Adaptic*), a glass-filled composite (Addent 12t), and an amalgam (New True Dentalloyt) as a control were compared. In the evalua tion of Class II restorations, the performance of Adaptic was compared with that of an amalgam JADA, Vol. 89, November 1974 ■ 1111
prepared with Velvalloy.§ The final comparison was that of Adaptic and a conventional silicate cem ent (M. Q. Silicatet) in various classes of an terior restorations. Conservative cavity preparations were made following standard operative techniques. Man ipulation and insertion of the materials were in accordance with the manufacturer’s directions, and finishing procedures were standardized for all restorations according to accepted methods.
was applied to the surface of the dentin. After preparing a pair of cavities in a given patient, the dentist used a random statistical table to deter mine which restorative would be placed in each cavity. N o attempt was made to match tooth shades in the composite restorations. The res torations were examined at the base line and at recalls after one, two, and three years following the same criteria as those used in the study of Class I restorations.
■ Study o f Class I restorations: Twenty-four patients were chosen on the basis of their having at least three similar carious lesions. Each pa tient received three restorations, one each of A daptic, Addent, and New True Dentalloy, at the same sitting. A total of 34 sets of three were placed. (Some patients received more than one set.) One patient, however, received four restor ations, two of the composite materials and an amalgam control for each. Each patient was given a prophylaxis. When practical, a rubber dam was used to isolate the treated teeth; however, if it could not be used for one of the restorations in the set, it was not used for the others. After the placement of all test and control res torations, two examiners inspected the patients to establish base-line ratings on each of the res torations for three characteristics3,4: anatomic form, marginal adaptation, and caries. Each restoration was examined with a sharp no. 17 explorer, and each characteristic was rated “ al p ha,” “ bravo,” “ charlie,” or “ delta.” Alpha indicated the characteristic was superior, bravo m eant there were clinically detectable faults that did not require the replacement of the restora tion (except in the instance of caries), and Char lie or delta indicated an unacceptable character istic requiring replacement of the restoration. If disagreements occurred on independent exam inations, a final rating was determined in consul tation. Additional examinations were done at the three- and four-year recalls.
■ Anterior restorations, classes III, IV, and V: Twenty-nine patients who had at least two cari ous lesions or defective restorations of about the same size in anterior teeth were selected by screening. In each patient, a pair of cavity prep arations of similar size with comparable reten tion and resistance form was completed. The fa cial margin was made visible in most restora tions so that they could be viewed without a mir ror. On occasion, the incisal angle was involved in the preparation. In those restorations, resist ance and retention were achieved with lingual locks or placement of threaded pins. After completion of cavity preparations, a rubber dam was used to isolate the teeth in volved, and Dycal was placed as a base. A ran dom table was used to select the material, Adap tic or M. Q. Silicate, to be used for each prep aration. Because the manufacturer of the com posite material recommended it for use in stressbearing areas, it was used in all but one restora tion in which the incisal angle was involved. Fifty-one pairs of restorations were placed in the 29 patients. (Again, some patients had more than one pair of restorations placed.) O f the 102 restorations, 86 were Class III, 10 were Class IV , and 6 were Class V. In addition to the evaluation under the same three criteria as in the previous two studies, these anterior restorations were rated for color match and cavosurface marginal discoloration. Exam inations were conducted at the base line and at recalls after one, two, and three years.
■ Study o f Class II restorations: Thirty-one patients, each having one or more pairs of Class II lesions, were selected. F or each pair of teeth restored, one was filled with Velvalloy and the other with Adaptic. Forty-eight pairs of teeth were filled in the 31 patients. (Some patients had more than one pair of teeth restored.) T he cavities were prepared conservatively with proximal retentive grooves. If a base was required, a calcium hydroxide paste (Dycal§)
■ Evaluation procedures and statistical method: Each composite restoration in all of the clinical studies was considered the test restoration and was paired in the same oral environment with a control restoration of the same or comparable class. The study of Class I restorations was, in effect, two separate comparisons with one com mon control restoration. The two composite res torations in a set were compared independently with the same amalgam restoration. Thus, each
1112 ■ JADA, Vol. 89, November 1974
T a b le 1 ■ R a tin g s * fo r C la s s I resto ra tio n s. A n a t o m ic fo r m
D
A
B
NE
0 2
0 0
35 34
0 1
0 0
0 0
2
0
0
36
0
0
0
6 8
0 1
0 0
25 24
0 2
2 1
7 6
14
14
0
0
28
0
2
6
0 0
15 14
5 6
0 1
0 0
19 18
1 3
1 0
11 11
0
13
9
0
0
21
1
3
11
0 0
0 0
31 28
4 5
36
0
0
34
17 13
8 13
0 0
19 17
25
3
0
6 3
14 18
20
2
B ase 35 35 36
35 35
B
C a rie s
C
A
A
lin e (1 0 6) A d a p tic Addent N e w T ru e D e n ta llo y T h r e e y r (79) 2 5 A d a p tic 26 A d d e n t 2 8 N e w T ru e D e n ta llo y F o u r y r (63) 20 A d a p tic 21 A d d e n t 2 2 N e w T ru e D e n ta llo y
M a r g in a l a d a p ta tio n
C
N o . r e s t o r a t io n s
B
NO
• R a t in g ke y. A n a to m ic f o r m : A , r e s t o r a t iv e m a t e r ia l is c o n t in u o u s w ith e x is t in g a n a to m ic f o r m ; B, r e s t o r a t iv e m a t e r ia l is u n d e r c o n t o u r e d ; C , t h e r e is s u f f ic ie n t r e s t o r a t iv e m a t e r ia l m is s in g s o a s t o e x p o s e d e n t in o r b a s e . M a r g in a l a d a p t a t io n : A , r e s t o r a t iv e m a t e r ia l is c o n t in u o u s w ith t h e c a v o s u r fa c e m a r g in ; B , t h e r e is v is ib le e v id e n c e o f a m a r g in a l c r e v ic e in t o w h ic h t h e e x p lo r e r w il l p e n e t r a t e ; C , th e c r e v ic e is d e e p e n o u g h t o e x p o s e d e n t in o r b a s e ; D , th e r e s t o r a t io n is m o b ile , f r a c tu r e d , o r m is s in g in p a r t o r in to t a l. C a r ie s : A , t h e r e is n o e v id e n c e o f c a r ie s c o n t ig u o u s w it h th e r e s t o r a t io n ; B , t h e r e is e v id e n c e o f c a r ie s c o n t ig u o u s w it h t h e r e s t o r a t io n . N E , n o t e v a lu a te d (a r e s t o r a t io n o f a s e t o r p a ir h a d b e e n r e p la c e d ) . N O , n o t o b s e r v e d (th e p a t ie n t w a s n o t a v a ila b le f o r r e c a ll) .
Table 2 ■ Changes in patient scores from the base line to latest recall periods favorable to specified m aterials, for Class I restorations. C h a r a c t e r is t ic s
3 rd y r r e c a ll
4 th y r r e c a ll
A d a p tic A n a t o m ic fo r m M a r g in a l a d a p ta tio n C a r ie s
2 7 0
A n a t o m ic fo r m M a r g in a l a d a p ta tio n C a r ie s
2 7 1
3 rd y r r e c a ll
4 th y r re c a ll
3 rd y r r e c a ll
No change
N e w T r u e D e n t a llo y 0 5 1
Addent
6 2 0
9* 2 1
9 8 17
8 0 2
1 2* 0 2
5 7 12 No change
N e w T ru e D e n t a llo y 0 6 1
4 th y r r e c a ll
7 10 14
3 9 12
• S ig n if ic a n t d if fe r e n c e a t 9 5 % c o n f id e n c e le v e l in fa v o r o f t h i s m a te r ia l.
set of three restorations had two test-control pairs. The other two studies were strictly pair wise matched. On every examination, the ratings for each pair were recorded and tabulated according to the characteristics evaluated. For each charac teristic, the pair was scored plus if the test ma terial received a superior rating, minus if the con trol material was superior, or zero if the ratings for both materials were the same for the partic ular set of criteria used. The effect that different oral environments might have on one pair (set) versus multiple pairs (sets) of restorations per patient was minimized in that a patient score, summarizing the pair scores for every pair in an individual mouth, was determined for each characteristic rated. A ma jority of plus pair scores for a patient yielded a plus patient score. A majority of minus pair scores yielded a minus patient score. An equal number of plus and minus pair scores gave a zero patient score.
The patient scores were tested for significant difference in their change from the base line to subsequent recall examinations either in favor of the test material or in favor o f the control ma terial. The instances in which the patient scores from the base line to the recall did not change were split equally between those favoring the test and those favoring the control. A binomial test (two-tailed) was used to determine signifi cance beyond the 95% level of confidence.
Results
■ Study o f Class I restorations: The ratings for anatomic form, marginal adaptation, and caries of evaluated restorations of each material are given in Table 1, and the changes in patient scores from the base line to the latest recall per iods are shown in Table 2. These data are from patients available at the base-line, three-, and
Eames—others: COMPOSITE, AMALGAM, SILICATE RESTORATIONS ■ 1113
T a b le 3 ■ R a tin g s * fo r C la s s II resto ra tio n s. A n a t o m ic fo r m N o . r e s t o r a t io n s B a s e lin e (8 6 ) 4 3 A d a p tic 43 V e lv a llo y O n e y r (86) 4 3 A d a p tic 4 3 V e lv a llo y T w o y r (66) 3 3 A d a p tic 3 3 V e lv a llo y T h re e y r (60) 3 0 A d a p tic 3 0 V e lv a llo y
A
B
M a r g in a l a d a p ta tio n
C
A
B
C a r ie s
C
D
A
B
NE
NO
43 43
0 0
0 0
43 42
0 1
0 0
0 0
43 43
0 0
0 0
5 5
6 35
37 8
0 0
33 26
10 17
0 0
0 0
42 43
1 0
0 0
5 5
4 29
29 3
0 1
30 25
3 7
0 0
0 1
33 33
0 0
0 0
15 15
2 26
28 3
0 1
26 12
4 17
0 0
0 1
30 30
0 0
1 1
18 18
'R a t in g k e y , s a m e a s f o r T a b le 1.
Table 4 ■ Changes in patient scores from the base line to latest recall periods favorable to specified materials, for Class It restorations. C h a r a c t e r is t ic s
2nd y r r e c a ll
3 rd y r r e c a ll
2nd y r r e c a ll
1 11* 0
1 7* 1 0
A d a p tic A n a to m ic fo rm M a r g in a l a d a p ta tio n C a rie s
1 5 0
3 rd y r r e c a ll
2nd y r r e c a ll
V e lv a llo y
3 rd y r r e c a ll N o change
14* 0 0
3 15 21
4 8 19
• S ig n if ic a n t d if fe r e n c e a t 9 5 % c o n f id e n c e le v e l in f a v o r o f t h i s m a te r ia l.
four-year examinations. The number of restora tions evaluated at any recall period was depen dent on the number of patients available for re call and also on the number of test-control pairs within sets in those available patients. Restora tions in those patients not available for recall were included in the table as “ not observed.” Restorations that had been replaced between re call examinations were included as “ not eval uated.” I f the amalgam control restoration had been replaced, two pairs (the set) were lost from the study. Replacement of either composite restora tion caused the loss of only one test-control pair from the number evaluated. The remaining composite-amalgam pair of the set was included in the clinical comparison. As a general rule, if a clinical failure, denoted by an unacceptable rat ing on any criterion, had caused the replacement of any restoration, that rating was continued over to subsequent examinations and compared with the current rating of the remaining member of the pair. Table 1 shows a definite tendency for the amal gam to retain better anatomic form than either composite material. Also, an analysis of the change in patient scores from the base line to the fourth year, as seen in Table 2, reveals signifi cant differences beyond the 95% level of confi dence between the composites and amalgam, fa voring the amalgam. Although there is a constant trend for Adap1114 ■ JADA, Vol. 89, November 1974
tic to receive better ratings in marginal adapta tion than amalgams of N ew True Dentalloy for each year after the base line, there is no signifi cant difference between the two materials in the Class I situation. Also, Addent consistently showed better ratings than the amalgam. The change in patient scores from the base line was more noticeable in the comparison of these two materials. Nevertheless, the difference was not statistically significant. N o significant differences were found between the composites and the amalgam in incidence of recurrent caries. ■ Study o f Class II restorations: The base line examinations were performed on 43 pairs of Class II restorations in 28 patients who were available for examination. Table 3 shows the rat ings for the characteristics evaluated at the base line and at subsequent recalls. As in the study of Class I restorations, the amalgam demonstrated superior retention of an atomic form as seen in the illustration. From the first-year recall through all following years, Velvalloy was statistically better, above the 95% confidence level (Table 4). The trend toward composite superiority in maintaining marginal integrity became statis tically significant at the same confidence level at the end of three years (Table 4). Again, no indication was found that recurrent caries was a problem of either material.
T a b le 5 ■ R a tin g s * for a n te rio r resto ra tio n s.
N o r e s t o r a t io n s
.
B a s e lin e (86) 4 3 A d a p t ic 4 3 M . Q . S ilic a t e O n e y r (88) 4 4 A d a p tic 4 4 M . Q . S ilic a t e T w o y r (70) 3 5 A d a p tic 3 5 M . Q . S ilic a t e T h r e e y r (56) 2 8 A d a p tic 2 8 M . Q . S ilic a t e
C o lo r M a r g in a l A n a t o m ic M a r g in a l m a tc h d is c o l o r a t io n fo r m a d a p ta tio n C a r ie s -------------------------------------------------------------------- ----------------------------------------------------------------------------------------------A B C O A B C A B C A B C D A B
N E N O
24 36
17 5
0
2 2
42 40
1 3
0 0
43 41
0 2
0 0
41 41
2 2
0 0
0 0
43 43
0 0
0 0
9 9
16 15
26 27
0 0
2 2
40 40
4 4
0 0
39 30
5 14
0 0
39 25
5 19
0 0
0 0
44 44
0 0
0 0
8 8
5 5
29 29
0 0
1 1
34 34
1 1
0 0
27 16
8 18
0 1
29 20
6 13
0 0
0 2
35 35
0 0
1 1
16 16
6 3
20 24
1 0
1 1
25 23
3 5
0 0
24 13
4 14
0 1
22 10
5 16
1 1
0 1
27 28
1 0
2 2
22 22
0
• R a t in g k e y . C o lo r m a tc h : A , r e s to r a tiv e m a te r ia l m a tc h e s t h e a d ja c e n t to o th s t r u c tu r e in c o lo r , s h a d e , a n d t r a n s tu c e n c y ; a m is m a tc h in c o lo r , s h a d e , o r tr a n s lu c e n c y w it h in th e n o r m a l ra n g e o f to o th c o lo r ; C , th e r e is a m is m a tc h n o r m a l ra n g e o f to o t h c o lo r ; O , t h e r e s t o r a t io n is n o t d ir e c t ly v is ib le a n d t h u s n o t ra te d . C a v o s u r fa c e m a r g in a l d is c o l o r a t io n : A , th e r e is n o d is c o lo r a t io n a n y w h e re o n t h e m a r g in b e tw e e n t h e a n d th e to o th s t r u c tu r e ; B , t h e r e is a d is c o lo r a t io n o n t h e m a r g in ; C , t h e d is c o lo r a t io n h a s p e n e tr a te d a lo n g in a p u lp a l d ir e c t io n . T h e r e m a in d e r o f th e k e y is th e s a m e a s f o r T a b le 1.
B , th e r e is o u ts id e th e r e s to r a tio n th e m a rg in
Table 6 ■ Changes in patient scores from the base line to latest recall periods favorable to specified materials, for anterior restorations. C h a r a c t e r is t ic s
2nd yr r e c a ll
3 rd yr re c a ll
A d a p tic C o lo r m a tc h M a r g in a l d is c o lo r a t io n A n a to m ic fo r m M a r g in a l a d a p ta tio n C a rie s
9* 2 6 9 0
2nd yr re c a ll
3 rd y r r e c a ll
2nd yr re c a ll
No change
M . Q . S ilic a t e 9* 3 9* 10 0
1 4 2 2 0
0 3 0 2 1
3 rd y r r e c a ll
8 13 11 8 1?
6 10 7 6 15
• S ig n if ic a n t d if fe r e n c e a t 9 5 % c o n f id e n c e le v e l in fa v o r o f t h is m a te r ia l.
■ Study o f anterior restorations: Table 5 gives the ratings of Class III, IV , and V restorations evaluated at the base line and after one, two, and three years for the criteria used. At the base line, only 43 of 51 pairs were evaluated since five pa tients were not available. A t subsequent recalls the remaining eight pairs were evaluated and the data recorded and included in the statistical work-up. The change in score for these eight pairs, as recorded in Table 6, was figured from the one-year evaluation. P ro m Table 5, the differences in color match between the silicate and composite restorations at the base line appeared to equalize at later ex aminations because of a significant change fav oring the composite. After three years, however, no significant difference was found between the two materials in color match. N o differences were found between the mater ials for the characteristics of marginal discolor ation and caries. However, the composite material demon strated consistently better ratings for anatomic' form and marginal adaptation at each recall ex amination as seen in the illustration. The com posite was statistically superior in anatomic form after three years, as seen in Table 6. The differ
ence in marginal adaptation after three years was close to a significant level (93.5% level of confi dence). Because a Class IV restoration is subjected to more stress and abrasion than either a Class III or Class V restoration and because nine of the ten Class IV restorations were composites, it might be assumed that the predominance of clin ical defects noted throughout the three-year study in anatomic form and marginal adaptation would come from this class. This was not true, however. The Class IV composite restorations evaluated after three years were rated mostly as alphas in the characteristics mentioned. The one Class IV silicate, as may have been expected, was a clinical failure after years. N o other differences were noted between class of prepara tion and material used. In none of the studies was the incidence of clinical failure of any of the materials great enough to be of significance.
Discussion During these few years of clinical study, we have observed two phenomena associated with com posite resins: the response elicited from the pulp
Eames— others: COMPOSITE, AMALGAM, SILICATE RESTORATIONS ■ 1115
Top, typical Class II Adaptic (left) and am algam (right) restorations at base-line examination. Center, after three years, same Adaptic restoration (left) exhibits better marginal integrity, but am algam restoration (right) maintains better anatom ic form. Bottom, figures show change in marginal adaptation and anatom ic form seen after two years in silicate restoration (left) in lateral incisor and Adaptic restoration (right) in central incisor.
and the loss of integrity of the surfaces of restor ations. ■ Pulp response: Pulp studies with primates at Emory University have shown that composites do not affect the pulp as adversely as was once thought. Initially, a mild to moderate inflam matory response may occur, which may remain for several weeks. When composite materials are placed adjacent to freshly cut dentin in teeth not previously restored, protective liners of cal cium hydroxide or polycarboxylate cements should be used as a precautionary measure. ■ Finishing: Although the finishing of compos ite restorations with ultrafine abrasives is impor tant for appearance and for the comfort of the patient, the ability to maintain a finished sur face over a period of time has not been demon strated. Clinical studies recently completed do not indicate more than slight improvement in reduction of accumulation of plaque. Although surface integrity as a category was not evaluated in this study, the examiners noted that the initial smooth surface seen after finish ing was not maintained. The surface became textured in the mouth environment in areas not ex posed to normal mastication. The cause of this attrition may be the loss of microscopic parti cles, but the cause of this phenomenon has yet to be identified.
Summary and conclusions In this three-phase investigation, composite den tal restoratives were compared clinically with amalgam in Class I and II restorations and with silicate in Class III, IV , and V anterior restora tions. In the study of Class I restorations, two composite materials were compared with an amalgam in a four-year period. In the study of Class II restorations, a composite was com pared with an amalgam for three years. In addi tion, a composite was compared with a silicate in
Class III, IV , and V restorations for three years. Amalgam is superior to the composites in its ability to retain its anatomic form, whereas the composites tend to be superior in marginal adap tation. This study also showed that the composite tested performed better than the silicate in main taining anatomic form and in marginal adapta tion. Gross surface deterioration, although evi dent, was less characteristic of the composite than of the silicate. Caries recurrence was not a problem asso ciated with any of the materials. Although this fact might serve only as a clinical exoneration of composite resins for some observers, it focuses attention on the degree and importance of micro leakage. Finally, anticipated fractures never manifested themselves as a clinical problem for either the amalgam or the composites.
This study was funded in part by National Institutes of Health Grant No. 5 R01 DE 03504-05. Dr. Eames is professor of operative dentistry and principle investigator of this study. Dr. Strain and Dr. Weitman are assis tant professors of operative dentistry, and Dr. Williams is asso ciate dean and professor of operative dentistry, Emory Univer sity School of Dentistry, 1462 Clifton Rd, NE, Atlanta, 30322. ♦Johnson & Johnson, New Brunswick, NJ 08903. tMinnesota Mining and Manufacturing Co., St. Paul, 55101. IS . S. White Dental Health Products, Pennwalt Corp., King of Prussia, Pa, 19406. §L. D. Caulk Co., Milford, Del 19963. 1. Phillips, R.W. Skinner's science of dental materials, ed 7. Philadelphia, W. B. Saunders Co., 1973, p 516. 2. Bowen, R.L. Properties of a silica-reinforced polymer for dental restoration. JADA 66:57 Jan 1963. 3. Phillips, R.W.-, and others. Observations on a composite resin for Class II restorations: three-year report. J Prosthet Dent 30:891 Dec 1973. 4. Osborne, J.W., and others. One and two year clinical eval uation of a composite resin versus amalgam. Abstracted, J Dent Res 52 (special issue):67 no. 35 Feb 1973. 5. Ryge, G.; McCune, R.J.; and Webber, R.L., Sr. Clinical com parison of two anterior restorative materials. Research protocol prepared by Dental Materials and Technology Program, May 1965. 6. McCune, R.J. and others. Clinical comparison of posterior restorative materials. Abstracted, IADR Program & Abstracts No. 546 March 1967.
Eames— others: COMPOSITE, AMALGAM, SILICATE RESTORATIONS ■ 1117