Clinical evaluation of four anterior composite resins over five years

Dent Mater 8:246-251, July, 1992

Clinical evaluation of four anterior composite resins over five years R. J. Smales, D. C. Gerke Department of Dentistry, The University of Adelaide, Adelaide, South Australia

Abstract. Four hundred and thirty nine chemical-cured composite resin restorations were placed in the anterior teeth of 86 patients treated in aprivate dental practice. Four anterior resinswere used, and placement was performed with acid etching and appropriate enamel bonding resins. Assessments were made of the handling characteristics, condition of the gingiva, surface staining, marginal staining, color deterioration, and of the longevity of the four materials. Clinical deterioration rates and failures of the different types of composites were evaluated over periods of up to five years. Although all the assessed clinical factors deteriorated with time, there were very few unsatisfactory rating scores. Most of the composite restorations performed well over the study. Eight per cent of the restorations failed during the study. Class IV preparations showed the highest restoration failure rates, INTRODUCTION Clinical investigations of anterior composite restorative materials have increased during the past few years. However, many of the recent studies of light-cured materials have evaluated either few restorations (Doering and Jensen, 1986; Heymann et al., 1988; van der Veen et al., 1989), or have been for short durations (Doering and Jensen, 1986; Osborne et al., 1986; Vanherle et al., 1986; Tyas, 1987; Heymann etal., 1988; van der Veen et al., 1989). The present study of four chemical-cured composites was initiated before the modernlight-cured composites were introduced commercially to the dental profession. However, the general comparison ofvarious composite types (conventional, microfilled, and hybrid) is relevant for all current composite materials, Therefore, the purpose of the present studywastocompare the handling and finishing, the deterioration of several clinical characteristics, and the longevity of four anterior composites placed under controlled conditions and assessed over long periods in a private dental practice. The long-term results presented provide usefulinformation for allpractitioners, and update the findings of an earlier brief report (Smales and Gerke, 1987). MATERIALS AND METHODS A total of 439 composite restorations were placed from January 1980 to June 1984 in conventional preparations and finished in the same manner to a high standard in the anterior teeth of 86 patients treated in a private dental practice by one operator (DCG). The four paste-paste, chemical-cured cornposite materials (Table 1) were inserted by bulk filling, 246 Smales & Gerke/Evaluation of four anterior resins

TABLE 1: MATERIALSUSEDIN THE STUDY Material Concise Silar Estic Miradapt

Manufacturer 3M DentalProducts, St Paul,MN, USA 3M DentalProducts, Kulzer& Co GmbH, Bad Homberg,GFR Johnson& Johnson, EastWindsor,NJ, USA

Type, Fillerw/o Conventional quartz,78 MicrofilledSi% 52 MicrofilledSi% 51 HybridBaglass, 73 SiO27

following acid etching of enamel and dentin, and using appropriate bonding resins, but no surface glazes (Gerke, 1981). Restorations were assessed immediately after placement and then at around six monthly intervals for adjacent gingivitis, surface staining, marginal staining, and color mismatch. Assessments were made clinically and from Ektachrome 35mm color transparencies (Eastman Kodak Co., Rochester, NY, USA) taken at 1:1 magnification, which were matched under magnification against four standard sets of 2x enlarged color transparencies. Each of the clinical factors for the restorations was rated against a ranked ordinal scale 0 to 3, 0 representing no detection of any deterioration; 1, slight changes from ideal; 2, obvious changes; and 3, severe changes requiring some form of treatment. The photographic method and the related clinical criteria have been reported (Smales, 1977, 1983a). Each of the four clinical factors was analyzed separately using a mixed model analysis ofvariance. This model included a random effects term for patients, a co-variate effect for restoration age, and a fixed effect for each material or class of cavity preparation whose significance was determined by a likelihood ratio test. Statistical analyses used the BMDP program 3V on a minicomputer (Dixon, 1990). Significant differences between the scored means over the study were assumed to exist when there was an alpha probability value of 0.01 or less. The longevity or survival rates of the different restorations over the study period with respect to material and class of cavity preparation were analyzed using the BMDP actuarial life table program 1L.

RESULTS The 439 restorations were placed according to the classification of the preparations shown in Table 2. The numbers of

TABLE 2: CAVITY CLASSIFICATIONS

t.5

Classes

~

Con¢ls,

Illll'lll

S[lar

Material

III

IV

V

Concise

96

9

16

.~

Silar

99

17

31

f])8 1.0 .~.,,~w~,E~ti¢

Estic

67

6

11

-~

Miradapt

78

6

3

340

38

61

Totals

Microfll

,~

= 18.287, df = 6, p < 0.01

=~

....• ....... d,p,

0.5

TABLE 3: RESTORATION DISTRIBUTION OVER STUDY PERIOD Material

0-1

Yearly Intervals 1-2 2-3

3-4

4-5

Concise Silar

121 147

105 121

69 83

49 53

28 23

Estic

84

69

40

19

6

Miradapt

87

74

46

23

10

439

369

238

144

67

Totals

= 12.749, df = 12, p > 0.10.

o.o .

.

.

1.

.

Age

.

2

.

.

.

3

of Restoration

4

5

Years

"

Fig. I. Gingivitis adjacent to restorations with time by material (linear regressions).

--

1.5

~ , , O

Concise

restorations available for assessment at each yearly interval over the study are shown in Table 3. The numbers decreased over the study, not because of restoration failures, but mainly from patient "dropouts" and observation periods less than five years. The materials were similarly distributed between the patients and the dental arches. However, most of the restorations were placed in the maxillary arch (81%) and in the 21to 40-year-old age group (63%). Mixes of Estic tended to be dry and stiff, while those of Miradapt were somewhat sticky and runny and when set, the latter restorations were sometimes difficult to finish. Some restorations were also contaminated by minute plastic shavings scraped from the material containers by sharp-edged plastic spatulas, which was most obvious (blue) for Miradapt. Although Concise restorations had a rougher surface texture than the other three materials, there were no significant clinical differences found for the level of gingivitis adjacent to the restorations, p=0.92 (Fig.l). Silar restorations showed the least surface staining, p<0.01 (Fig.2), Miradapt and Concise restorations the least marginal staining, p=0.03 (Fig.3), and Miradapt and Concise restorations the best color matchings, p<0.001 (Fig.4). The mean scores for the clinical factors and asymptotic t-test results for the materials are shown in Table 4. Although there was more gingivitis associated with the restored Class IV preparations, this was not significant, p=0.46 (Fig.5). However, the least amount of surface staining was observed with Class V preparations, p<0.001 (Fig.6), while Class III preparations showed the least marginal staining, p=0.01 (Fig.7) and the best color matching, p<0.001 (Fig.8), The mean scores for the clinical factors and asymptotic t-test results for the classes are shown in Table 5. All clinical factors deteriorated with the age of the restorations, p<0.001. However, there were very few instances of unsatisfactory (scores of 3) ratings given for any of the clinical factors; for gingivitis adjacent to restorations, results ranged from 1.3-3.3%, for surface staining from 1.0-3.0%, for marginal staining from 0.0-1.5%, and for

,.,.," "'"

....• ........ ~ 1.o ,.,,,.o............... ~ ....• ........... ~ ~- ~

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~

,,,,,,,, ,,m"

,:j,""

~ o.5

,d" ,.,'~ J,""

o.o! o

1

2

3

Age of Restoration

4

5

Years

-

Fig.2. Surface staining with lime by material (linear regressions).

1.5 -.o- c...... ...." ........ ~ 1.0 .......° ................... .~

,"'•

.... " . . . . . . . . . "'

~ ~ ~

"'"" "~""

0.5

,e '''~

....., ..........

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,.,.,,,......... .,,,,.~........ °°o

;

~

3

i

Age of Restoration Years Marginalstaining withtime by material(linear regressions). -

Fig.3.

Dental Materials~July

1992

247

TABLE 4: MEAN SCORES OVER 5 YEARS FOR THE CLINICAL FACTORS, AND ASYMPTOTIC T-TESTS BY MATERIALS FOR THE PREDICTED CELL MEANS* Material Concise Silar Estic Clinical factor, with mean t-test scores over 5 years Silar 1.18 Estic -0.07 -1.11 Miradapt 1.17 0.14 p = 0.92 Silar -127 Estic 1.23 2.93 Miradapt 1.53 3.22 p
1.14

Gingivitis adjacent Estic Conc Silar 0.18 0.19 0.23

1.s] . - o - c...... ....,,.. s,,,r _

~, Mira 0.24

~, t.o .~

./~,,,,,,~

,,,,..o,................. • , , , o ,I,

,,1,~''~''1'*'6

Mlradapt

,,,,,,,....

,~

0.27

Surface staining Silar Conc 0.36 0.44

Estic 0.49

Mira 0.50

-2.30

Marginal staining Mira Conc 0.26 0.27

Silar 0.33

Estic 0.37

,,,e......

~ o.s o

" ...... ,,,•.....

o.o

!

2

Age

Silar 2.43 Color mismatch Estic 2.50 0.42 Mira Conc Silar Estic Miradapt-1.48 -3.67 -3.69 0.44 0.53 0.63 0.65 p < 0.001+ • Values of 2.0 or greater considered to be of statistical significance. +Significant differences present between materials at the 1% probability level. Materials connected by horizontal lines are not significantly different.

of

3

Restoration

4

5

Years

-

Fig.4. Color mismatch with time by material (linear regressions).

a..D. .......... Class IV

TABLE 5: MEAN SCORES OVER 5 YEARS FOR THE CLINICAL FACTORS, AND ASYMPTOTIC T-TESTS BY CLASSES FOR THE PREDICTED CELL MEANS* Class III IV Clinical factor, with t-test mean scores over 5 yrs IV V

IV V

IV V

IV V

1.03 - 1.05 p < 0.46

- 1.56

0.39 - 9.84 - 6.75 p < 0.001+ 2.43 2.27 p = 0.01+

- 0.56

7.61 6.17 -2.37 p < 0.001+

Gingivitis adjacent V III 0.05 0.22

IV 0.24

Surface staining V IV 0.02 0.47

III 0.50

Marginalstaining Ill V 0.25 0,39

IV 0,44

Color mismatch III V 0.46 0.81

IV 1.01

o ~ g

2

....• ..........

o

1

~

........~;,;,~ .... ~=~ .... o .... ~ 1

2 Age of

3

4

Restoration

-

s

Years

Fig.5. Gingivitis adjacent to restorations with time by class of preparation (linear regressions). 3.

• Values of 2.0 or greater considered to be of statistical significance. + Significant differences present between classes at the 1% probability level. Materials connected by horizontal lines are not significantly different.

..o.. c,~=,,,, ~ ,~

- , , - c.... 2- ""'"' ~'=v

c

color mismatch from 0.6-3.4%. There were 35 restoration failures during the five-year study period, or 8% of the total restorations originally placed. There were no instances of recurrent caries, and the failed restorations were replaced by different types of materials in only five instances. Life table survivals for the four materials and the three classes of preparations, expressed as the cumulative proportion of survivors, are illustrated in Figs. 9 and 10. Although Silar restorations had the highest failure rates, these were not statistically significant, p>0.01. However, the Class IV" p r e p a r a t i o n s h a d s i g n i f i c a n t l y h i g h e r r e s t o r a t i o n f a i l u r e s t h a n d i d t h e o t h e r t w o c]asses, p
=~ ~

i

~

~ .o..... ....

..... "~

,.~ ..... o.~....... ~,-" . .............. ..................................° ..................° o=........~.........1: . .2 . . 3 . . .4 . 5 Aoe of Restoration Y e a r s Fig.6. Surface staining with time by class of preparation (linear regressions). -

3-

1 ==(3,=

( la~s]11

0

{

==

....~P=,,,Concise ~ ~ilsr ~~ ,,,,I.,, Estl¢Microfil ~,. 0.5" .,.,0,., Miradapt ~o

2" e,=,O,i, v (']ass

"E

~,

,,,o0

..,C]''""1 o-°G'°'''.'''C.''''° o-"'D'°''*'O''...c '

~

omE~ 0 . 0

Mantel-Cox

p=O.07

1

0 0

~

-~ .>

Class IV

"~.~ ~

.

1

2

3

4

Age Age

of

Restoration

2

3

4

5

5 of

Restoration

- Years

- Years

Fig.7. Marginal staining with time by class of preparation (linear regressions).

Fig.9. Life table cumulative survival by material,

31.0 I h l l t ~ ~ ~ , o , , w , o o . . i . _ ..

o

..........

• ,,,0,.*

(n

(]lass ~

~

> -

,.,.,~I',,.,, Class III

~

~

classiv

,,,,I,,,

C~as$v

= o i .=E

o o

0.5-

~-

I '

:t

~,~lT, ,

.......................

[]

=E

J

0

1

2

Age

of

Restoration

3

4

5

- Years

fqg.8. Color mismatch with time by class of preparation (linear regressions). DISCUSSION

The different handlingcharacteristics of the four materials did not appear to significantly affect the clinical results. Although acid etching of both the enamel and dentine with phosphoric acid was used to enhance restoration retention and marginal sealing, there were no adverse pulpal responses found in a long-term clinical follow-up of the restored teeth (Gerke, 1988), a findingsupportedbyshort-termanimalstudies(Fuks et al., 1990) and as discussed elsewhere (Hume and Massey, 1990; Kanca, 1990). No significant differences were found among the four materials for gingival tissue response (Fig. 1), which agrees with the findings from another study over 3-4 years of lightcure conventional, microfilled and hybrid resins (van Dijken et al., 1987). The present study and that by van Dijken et al. (1987) confirmed earlier reports ofprogressivelyworse gingival tissue responses to composite restorations with time (Smales, 1975; 1977). In the present study, gingivitis was also seenmorefrequentlywiththelargerClass IVrestoredpreparations (Fig.5), possibly because of their more extensive

0.0

1

2

Age

of

3

Restoration

4

5

- Years

Fig.lO. Life table cumulative survival by class of preparation.

gingival tissue contact, and associated problems with inserting and finishing the margins of chemical-cured materials. (Smales, 1983b). Silar, a microfilled composite, showed the least surface staining (Fig.2), which was usually confined to the interproximal and occasionally the lingual surfaces of the restorations. Despite its rougher surfaces, Concise restorations did not stain significantly more than did the other materials; similar results have also been reported between anterior hybrid and microfilled materials (van der Veen et al., 1989). Significantly less surface staining was found with Class V preparations (Fig.6), which was probably related to the ease of cleaning the restorations. Miradapt, a hybrid composite, showed the least marginal staining (Fig.3). Differences in the marginal quality between bonded hybrid and microfilled restorations have been reported by some authors (Osborne et al., 1987), but not by others for several different composite materials (van Dijken et al., 1985;DavisandMayhew, 1986; Heymannetal., 1988). In the present study, the two microfilled materials showed more Dental Materials~July 1992 249

marginal staining than did the conventional large particle and hybrid materials. A five-year study of Class III restorations, where enamel etching but no bonding resin was used, also found that microfills exhibited more marginal staining than did a large particle composite (Crumpleret al., 1988). The least marginal staining was found with the Class III preparations (Fig.7), possibly because oftheir smaller sizes and the inability to assess the proximal gingival margins of the restorations. Miradapt and Concise restorations showed the best color matchings (Fig.4), while the microfilled materials were often lighter and more translucent than the adjacent tooth structure, as has been noted by others (van der Veen et al., 1989). The much poorer color matching and stability of the two microfills when compared with Concise restorations has also been reported elsewhere (Crumpler et al., 1988). The best initial colormatching was seen with the Class III restorations (Fig.8), as the larger and/or more obvious Class IV and V restorations posed more critical color matching problems. Interestingly, the Class V preparations appeared to show more color stability than did the other two classes, an observation also reported by others (Loeys et al., 1982). As was expected, all four materials deteriorated at slightly different rates for different clinical factors with time. But there were very few unsatisfactory rating scores for any ofthe materials, and most of the changes were slight (scores of 1). Restorations placed in differentcavity preparations also deteriorated at varying rates over the five-year period, depending on their sizes, sites, and accessibility for cleaning. Although the actuarial life table cumulative survival findings did not reveal any significant differences among the four materials (Fig.9), the Class IV restorations had much lower survival rates than did the other two classes (Fig.10). After five years, 57% of Class IV restorations had survived, but it should be noted that there were relatively few restorations placed in the Class IV preparations. Microfilled materials appear to be unsuited to high tensile and flexural stress situations (Goldman, 1985), which is supported by the findings of the present study and by other clinical studies involving Class IV restorations (Dogon et al., 1987; Tyas, 1990). Cohesive chip fractures associated with the larger microfilled resins were noticed in the present study and have alsobeenreportedbyothers(LambrechtsandVanherle, 1983; Tyas, 1990). A six-year study of several types of anterior composites reported that 24.9% of the restorations were replaced (van Dijken, 1986), compared with only 8% ofthe total restorations originally placed in the present five-year study, and very few failures were found in another five-year study (Crumpler et al., 1988). One other three-year study of Silar restorations reported that 47.3% of the restorations were replaced, nearly all because of bulk discoloration (Dogon et al., 1985). Such obvious colorchanges were not foundin the present study. The cumulative survival rates of Class III and V restorations in the present study were also slightlybetter than those reported for several anterior chemical-curedcomposites over the same time in another general practice study (van Noort et al., 1988). In summary, the four different chemical-cured composites comprising conventional, microfilled and hybrid materials showed few failures or unsatisfactory restorations over periods of up to five years, Although there were some handling differences among the materials, this variable did not have a significant effect on the results of the present study. Dispensing the materials from 250 Smales & Gerke/Evaluation of four anterior resins

their containers by using sharp-edged plastic spatulas caused minute plastic shavings contamination of some restorations. The microfilled restorations showed more marginal staining and poorer color matchings, while Class IV preparations had the highest restoration failures and color mismatches.

ACKNOWLEDGMENTS We would like to thank Mr. P. Leppard and Mr. D. Webster, respectively, for their advice and assistance in the statistical analyses and for the computer processing required. The provision ofdental products from the manufacturers was also appreciated.

ReceivedMay 16, 1990/Accepted January 20, 1992 Address correspondence and reprint requests to: Dr R.J. Smales Departmentof Dentistry The UniversityofAdelaide

G.P.O.Box498 Adelaide,SouthAustralia 5001

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Dental Materials/July 1992 251