Clinical evaluation of a composite resin system with bonding agent for restoration of permanent posterior Q-year study Michael W. Roberts, DDS, MSCD,~ John Folio, DDS, Joseph P. Moffa, DDS, MSD,C and Albert D. Guckes,
MS,b DDS,
a dentin teeth: A
MSD,d
University of North Carolina-Chapel Hill, Department of Pediatric Dentistry, Chapel Hill, N.C.; National Institute of Dental Research, National Institutes of Health, Bethesda, Md.; and University of California-San Francisco, Department of Restorative Dentistry, San Francisco, Calif. This study evaluated the clinical performance of a visible light-cured small particle bimodally filled hybrid condensable composite resin system that included a dentin bonding agent compared with an amalgam alloy in class II restorations of permanent teeth. A total of 108 restorations were placed in 34 patients. Fifty-three composite resin and 55 amalgam restorations were inserted. Each restoration was evaluated immediately after placement and then on an annual basis for a 3-year period using the Public Health Service (PHS) criteria. In addition, the MoffaLugassy scale was used to measure the loss of material on the occlusal surface of these materials. One hundred percent of the resin and amalgam restorations were evaluated, measured, and reasons for replacement were recorded over the 3-year period. There was no significant difference (p > 0.05) in the clinical performance of the composite resin and the amalgam when evaluated by the PHS criteria. Analyses of wear at each of the three annual recall periods did not reveal any significant difference (p > 0.05) between the two restorative materials when measured by the Moffa-Lugassy scale.(J PROSTHET DENT1992;67:301-6.)
T
he dental profession in the United States uses approximately 200,900 pounds of mercury per year.l Al-
resin than amalgam was purchased by dentists in the
though the effects of chronic exposure to low levels of elemental mercury are unknown, they are not believed to be significant. However, physiologic symptoms have been recognizedfor long-term high levelsof organicmercury.2 In spite of the fact that elemental mercury hasfew suspected
formance of composite resins in posterior teeth has not been optimal becauseof accelerated wear, marginal leakage, and caries susceptibility. This study evaluated the clinical performance of a small particle, bimodally filled, visible light-cured composite resin systemthat included a dentin bonding agent, Herculite Condensableand Bondlite (Kerr/Division of Sybron Corporation, Romulus, Mich.). This composite resin system wascomparedwith that of an amalgamalloy, Dispersalloy (Johnson& JohnsonDental Products Company, East Windsor, N.J.), in classII restorations of permanent premolarsand molarsand wasevaluated for a period of 3 years.
or known
toxic cumulative
properties,
there has been con-
siderableinterest recently regarding possiblemercury-oriented health hazards.3 Other clinical
concerns,
such as esthetics
and marginal
integrity, have stimulated the dental professionto seekan alternative to silver amalgam as a direct restorative material. Composite resins are currently used in 95 % of all direct esthetic restorations,4 and in 1985 more composite
Supported in part by Interagency Agreement 2YOl-DE-4001-04 between the National Institute of Dental Research and the U.S. Army Medical Research and Development Command. aAssociate Professor, Department of Pediatric Dentistry, University of North Carolina-Chapel Hill. bSenior Staff-Orthodontics, Clinical Investigations and Patient Care Branch, National Institute of Dental Research, National Institutes of Health. CClinical Professor, Department of Restorative Dentistry, University of California-San Francisco. dDeputy Clinical Director, Clinical Investigations and Patient Care Branch, National Institute of Dental Research, National Institutes of Health.
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States.5 Unfortunately,
the long-term
clinical
per-
METHODS Thirty-four patients, 19men and 15women,with a mean ageof 57.9years, were usedin the study. Each patient was given a thorough soft and hard tissueexamination prior to inclusion into the study and again after 1, 2, and 3 years. Where indicated clinically, intraoral radiographswere obtained.
A total of 108 restorations was included in the study. Fifty-three classII compositeresinand 55classII amalgam restorations were placed in conventional G.V. Black amalgam class II cavity design preparations
(Table
I).
The materials were manipulated in accordancewith the respective manufacturer’s instructions. A rubber dam was employed
10/l/32695
THE
United
during
cavity preparation
and placement
of the
301
ROBERTS
ET AL
Fig. 1. The Moffa-Lugassy scaleusesa seriesof calibrated standardsto determine indirectly the amount of material wear.
Table
Distribution of restorations
I.
Teeth Material
Premolars
Compositeresin Amalgam
Surfaces Molars
2
3
4
18 28
31 30
18 20
3 5
35 27
II. Evaluation of color match using PHS criteria
Table
Material
Baseline
12 mo
24 mo
36
85%
88% (44/50)
91% (43/47)
mo
Composite resin Alpha
79% (42/43) 21%
Bravo Charlie Amalgam N/A,
Not
applicable;
(44/52) 15%
10%
9%
W/53)
@/52) -
G/50) 2% (l/50)
(4147) -
N/A
N/A
N/A
PHS,
United
States
Public
Health
N/A Service;
mo,
months.
restorative material. A calcium hydroxide base,Improved Dycal (L. D. Caulk Division, Dentsply International Inc., Milford, Del.), wasplaced when indicated. After eachcavity preparation wascompleted, a random number table was employed to select the material (resin or amalgam)to restore the tooth. The enamel of the teeth restored with compositeresin was etched with a gel containing 507%phosphoric acid for 1 minute, rinsed thoroughly with water for a minimum of 15 seconds,dried, and the bonding agent wasplacedon the exposed dentin and enamel margins. A celluloid matrix, held with a Tofflemire matrix holder (Teledyne Dental Products, Elk Grove, Ill.), wasadapted and wedgedforcibly into the interproximal spacesprior to insertion of the composite resin. A Centrix composite syringe (Centrix Inc., Stratford, Conn.) and Teflon-coated compositeresin hand instruments were used for resin material placement and
302
condensation.The resin was condensedand polymerized incrementally into the cavity preparation and wascovered with Saran wrap (Dow Chemical Co., Dow Plastics, Midland, Mich.) during final curing. Anatomic carving wasaccomplishedwith compositefinishing points. Interproximal carbide finishing knives (Brasseler USA Inc., Savannah, Ga.) and aluminum oxide strips were usedto finish interproximal margins. Aluminum oxide disks (Sof-Lex, 3M Dental Products Division, St. Paul, Minn.) were used to finish proximal margins. Final polishing was completed with a compositefinishing compound,Luster Paste (Kerr/ Division of Sybron Corp.). The cavity preparations for amalgam restorations received an application of Copalite varnish (H.J. Bosworth Co., Skokie, Ill.) prior to material insertion. Green stones, rubber wheelsand cups, pumice, and tin oxide were used to finish and polish the restorations 48 or more hours after amalgamplacement. All restorations were evaluated independently by two previously calibrated evaluators at baseline,and at 12, 24, and 36 months using the United States Public Health Service (PHS) criteria6 for color match, cavosurfacemarginal discoloration, anatomic form, marginal adaptation, and caries. In the event of disagreementbetween the evaluators, a consensusrating was obtained by conference. In addition, impressionswith a vinyl polysiloxane, type I low and high viscosity material (Mirror 3, Kerr/Division of Sybron Corp.) were madeof the restored teeth and were poured in dental stone.The castswereusedin the indirect measurementof material wear using the Moffa-Lugassy scale7of accurately calibrated standards,rangingfrom 0 to a maximum of 1000pm, asshown in Fig. 1. All castswere independently examined by two calibrated evaluators. Disagreementswere resolved by conference. RESULTS Over the 3-year period we evaluated, measured,and recordedthe reasonfor replacementof 1007%of the 108resin and amalgamrestorations placed.
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Table V. Evaluation of marginal adaptation using PHS criteria
Table III. Evaluation of cavosurface marginal discoloration using PHS criteria Material Composite Alpha
12 mo
24 mo
36 mo
70%
50%
42%
34%
(37153) 30% (16/53) N/A
(‘X/52)
(21/W
W/47)
50%
58%
(26/52)
(29/50) N/A
66% (31/47) N/A
Baseline
Composite Alpha
resin
Bravo Amalgam Abbreviations
N/A
Baseline
Material
Charlie
Material
Baseline
Composite Alpha
36
mo
96% (51/53) 4% (2/53)
90% (47152) 10% (5/52) -
100% (55/55)
Bravo Charlie
-
Abbreviations as in Table II. *Chi square, p > 0.05, no significant
96%
W.52) 2% 2%
(l/52) (l/52)
91%
96% (48/50) 4% (2/50) -
(43/47) 9% (4/47) -
96% (50/52) 2% (l/52) 2% (l/52)
98% (50/51) 2% (l/51) -
difference.
match
Cavosurface
marginal
discoloration
Seventy percent of the resin restorations showed no cavosurface marginal discoloration (alpha rating) at baseline, while 50% were rated alpha at 12 months, 42% were so rated at 24 months, and 34% were so categorized after 36 months (Table III).
Anatomic
form
No loss of anatomic form (alpha rating) was detected in 96 % of the resins and in 100 % of the amalgam restorations at baseline. Ninety percent of the resins and 96% of the amalgam restorations had no loss in anatomic form at 12 months. Ninety-six percent of the resins and the amalgam restorations were observed to have no loss in anatomic form after 24 months. After 36 months, 91% of the resin and 98 % of the amalgam restorations were still rated as alpha, which was not statistically significant, being at the p > 0.05 level (Table IV).
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91%
98%
92%
85%
W/W
(44/52)
6% 2%
(48/50) 4% (2/50)
(3/52) (l/52)
9%
(43/47) (4/47)
84% (43/51) 14% (7/51) 2% (l/51)
13% (7/52) 2% (l/52)
difference.
Table VI. Evaluation of caries using PHS criteria Material
Composite Alpha
12 mo
24 mo
100% (53/53) -
100% (53/53) -
96%
100% (55/55) -
100% (52/52) -
Baseline
36 mo
resin*
Bravo Amalgam* Alpha Bravo
Abbreviations as in Table II. *Chi square, p > 0.05, no significant
Marginal
According to the PHS criteria, 79 % of the resin restorations initially matched the surrounding tooth structure (alpha rating). Eighty-five percent matched after 12 months, 88% matched after 24 months, and 91% matched after 36 months (Table II).
96%
92% (48152) 8% (4/52)
Abbreviations as in Table II. *Chi square, p > 0.05, no significant
resin*
Bravo Charlie Amalgam* Alpha
Color
24 mo
12 mo
36 mo
96% (51/53) 4% (2/53)
(54/55) 2% (l/55) -
Bravo
Table IV. Evaluation of anatomic form using PHS criteria
24 mo
resin*
Bravo Amalgam* Alpha
as in Table II.
12 mo
W/50) 4%
(2/50) 98%
W/52) 2%
(l/52)
98% (46147) 2% (l/47) 100% (51/51) -
difference.
adaptation
Excellent marginal adaptation (alpha rating) was observed in 96% of the resin and in 98% of the amalgam restorations at baseline. After 12 months, 92% of restorations exhibited excellent margin adaptation for both the resins and amalgams. Ninety-six percent of the resins and 85 % of the amalgams were found to have alpha ratings after 24 months. After 36 months, 91% of the resin restorations and 84% of the amalgam restorations were rated alpha (Table VI.
Caries No carious lesions that could be related to the performance of either restorative material were observed at the first annual recall period. Ninety-six percent of the resins and 98% of the amalgams remained free of associated caries after 24 months. At the 36-month recall, 98% of the resins and 100% of the amalgams, remained caries-free (Table VI).
Moffa-Lugassy
wear
evaluation
For each individual restoration, the margin demonstrating the greatest loss of restorative material on the thirdyear cast was marked and this location was transferred to the baseline and earlier recall casts to standardize the lo-
ROBERTS
ET AL
Mean Wear (Microns) 120.0 -.-..
110.0
--.-I Cowite
Am%gam
i
,, 6’
100.0 90.0 60.0
r-
, WEAR
= 39.458
X YEARS
0.731
70.0
60.0 50.0 40.0 30.0 20.0
10.0 0.0
i Years
Fig. 2. A regression analysis curve provides a graphic representation of the projected wear characteristics of the restorative materials at the end of 4 years.
VII. Measure of wear in Moffa-Lugassy units (M-L unit = 25 pm)
scale
Table
Material Composite Mean Corrected
Baseline
mean
t Test:
36 mo
1.83
2.85
3.60
4.52
(46 w? -
(71 ctm) 1.25
(90 pm) 2.10
(113 rm) 3.13
2.15 0.30
(31 wlb 1.13 0.16
(53 m)C 1.80 0.25
(78 dd 2.52 0.37
3.44
5.02
6.08
7.04
(86 da
(126 pm)
(152 rm)
1.58
2.60
(176 d 3.54
(40 rdb 2.07 0.28
(65 IrmY
mean
SD SEM
2.41 0.32
SD, Standard
24 mo
resin
SD SEM Amalgam Mean Corrected
12mo
deviation;
Qxnparison
SEM,
standard
error
of means at baseline,
difference. bComparison of corrected icant difference. CComparison of corrected icant difference. dComparison of corrected
(89 w-dd 3.36 0.47
3.31 0.45 of the mean.
p < 0.001,
very
significant
means
at 12 months
p = 0.31, no signif-
means
at 24 months
p = 0.34,
no signif-
means
at 36 months
p = 0.50,
no signif-
icant difference.
cation employed for the quantification of occlusal wear. The initial lossof material at baseline causedby carving and polishing had a meanvalue of 46 pm in the composite resinsand 86 pm in the amalgams.This difference wassignificant statistically (t test, p < O.OOl),suggestingthat a better initial occlusal adaptation was obtainable with the compositeresinthan with the amalgam.Since there wasan occlusaldefect present at baselinefor both restorative materials, this value was subtracted from the observabledefects seenat later recall periods to arrive at a “corrected” 304
value of actual wear. The mean corrected difference at the end of 3 years from baselinewas78 pm for the composite resin and 89pm for the amalgamrestorations. Observation of the data presented in Table VII revealed that at each yearly interval there waslessocclusallossof resin than of amalgam.However, there wasno significant statistical difference (p > 0.05) between the two materials at any of the three annual recall periods. A regression analysis was performed to determine whether there was an orderly relationship between time and the corrected wear valuesfor both materials. The correlation coefficients (R2)for the compositeresin and amalgam were 0.9943769and 0.9998148,respectively, which showed a highly significant curvilinear relationship between observable wear and time that followed a typical power function of Y = aXb. The derived equation for the composite resin curve was Wear = 30.799X years 0.826, and the correspondingequation for the amalgamwasWear = 39.458x years 0.731 (Fig. 2). Cold hypersensitivity wasreported involving three composite resin restorations (6%). Two of these restorations were self-limiting and resolved spontaneously within 2 weeks.However, one restoration persistedwith hypersensitivity and required removal of the filling material and placement of a palliative intermediate restoration. No temperature hypersensitivity associatedwith the amalgam restorations was reported. During the 3-year courseof this study, five composite restorations required replacement for reasonsthat were attributable to restorative material failure-that is, a 9.4% failure rate. The reasonsfor replacement were: caries-2 each;fracture-2 each;hyperemia-1 each. During the same time interval, two amalgamrestorations required replacement for related reasons-that is, a 3.6% failure rate. One instance of recurrent cariesand one fracture were the reasons for failure of the amalgam restorative material. MARCH
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Frequency 25 ,
7
Y
-1
0
1
2
3
4
5
6
10
M-L Wear Values Fig.
3. Frequency versus wear for all restorations evaluated at l-year recall.
Frequency 15 r
10
1
i -2
0
1
2
3
4
5
7
s
9
10
12
16
M-L Wear Values Fig.
4. Frequency versus wear for all restorations evaluated at 2-year recall.
Therefore caries and fracture were the prime causesof failure for both the compositeresin and amalgamalloy used in this study. DISCUSSION A slight improvement in color match of the composite resin to surrounding tooth structure wasobserved at each annual evaluation when comparedwith baseline.Composite resin restorations tended to be lighter in color than the approximating dental enamelat the time of insertion, even though several shadeswere available for selection by the dentist. However, this difference in color becamelessapparent as the resin darkened with age. The marginal staining observed at annual recall associated with the composite resin restorations was not of the penetrating type (Charlierating). This staining could have been caused by the discoloration of the bonding agent rather than by marginal leakage. THE
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The distribution of two, three, and four surface restorations between the two restorative materials was almost equal. However, a larger number of compositeresin restorations wereplacedin premolarsthan in molars,while more amalgamrestorations were placed in molars than in premolars.This would appear to placethe amalgamat greater risk for wear and may account for the greater lossof material on the occlusal surfaces of amalgam restorations compared with the compositeresin restorations. It should be emphasizedthat the wear recorded in this study wasa “worst case”representation of the performance of the two restorative materials. Therefore the wear may appear higher than that seenin other clinical studies that integrate wear along the entire margins and report mean wear for each restoration. Current American Dental Association (ADA) guidelines for the Acceptance Programsfor compositeresin materials as posterior restorations permit a maximum of 50 pm of 305
ROBERTS
ET AI.
Frequency 15
101
-1
0
1
2
3
4
5
6
7
6
9
13
14
M-L Wear Values Fig.
5. Frequency versus wear for all restorations evaluated at 3-year recall.
wear at 2 years and no more than 100 pm at 4 years for composite resinsin the unrestricted category. The evaluated compositeresin in this study had 53 pm of wear at 2 years and, on the basisof the regressionanalysis, a projected wear of 97pm at the end of 4 years (Fig. 2). The ADA guideline-required graphs of frequency versuswear for all restorations seenat recall are shown in Figs. 3 through 5. The clinical performance of the compositeresin, Herculite Condensable, used with a dentin bonding agent, Bondlite, compared favorably with the amalgam in this study. The data imply that this composite resin system may be used for classII restorations in permanent teeth, especially when esthetics are a consideration. SUMMARY
AND
CONCLUSIONS
During the 3 years of observation the composite resin, Herculite Condensable,demonstratednosignificant change in color match, loss of surface material, deterioration in marginal adaptation, or incidence of caries,as assessed by the PHS criteria. An increase in marginal staining was noted in the composite resin group. During this same 3-year evaluation period, a control amalgamalloy, Dispersalloy, demonstrated no significant changein marginal adaptation, lossof surfacematerial, or incidence of caries, as assessed by the samePHS Criteria. However, quantification of surface material wear using the Moffa-Lugassy scale revealed a significant difference betweenthe two restorative materials at the baselineevaluation period. The composite resin showedlesslossof occlusal material than the amalgam alloy at the baseline evaluation period. Finishing and polishing techniques could have affected baseline values. The compositeresin
306
continued to showlessocclusallossthan the amalgamrestorations in the 3 subsequentyears. However, when the observablelossof material at baseline wassubtracted from that seenat the 3 later years,there wasno statistically significant difference in the wear of the compositeresin and the control amalgamalloy. REFERENCES 1. Huggins HA. Systemic reactions to silver amalgam filling. Workshop on biocompatibility of materials in dentistry. Chicago: National Institute of Dental Research and the American Dental Association, July 11-13. Chicago: Council on Dental Materials, American Dental Association, 1984:201-64. 2. Klaassen CD. Heavy metal and heavy metal antagonists. In: Gilman AG, Goodman LS, Gilman A, eds.: The pharmacological basis of therapeutics, 7th ed. New York: MacMillan Publishing Company, Inc, 1985:160521. 3. Berman E. Toxic metals and their analysis. Philadelphia: Heyden and Sons, Ltd, 1980:149-60. 4. Leinfelder KF, Roberson TM. Clinical evaluation of posterior composite resins. Gen Dent 1983,31:276-80. 5. Leinfelder KF. Evaluation of criteria used for assessing the clinical performance of composite resins in posterior teeth. Quintessence Int 1987;18:531-6. 6. Cvar JF, Ryge G. Criteria for the clinical evaluation of dental restorative materials. USPHS Publication No. 790.244. San Francisco: U.S. Government Printing Office, 1971. 7. Lugassy AA, Moffa JP. Laboratory model for the quantification of clinical occlusal wear. J Dent Res 1985;64(special issue):lSl. 8. Guidelines for submission of composite resin materials for posterior restorations. Council on Dental Materials, Instruments and Equipment. American Dental Association, November 1, 1989.
Reprint requests to: DR. MICHAEL W. ROBERTS DEPARTMENT OF PEDIATRIC DENTISTRY S~HOOI. OF DENTISTRY, CB# 7450 UNIVERSITY OF NORTH CAROLINA-CHAPEL CHAPEL HILL, NC 27599.7450
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