ARTICLES
Properties of m icrofilled an d visible light-cured com posite resins C. N. R aptis, DDS, MS P. L. F an, PhD J. M. P ow ers, PhD
Depth o f indentation, therm al expansion, w ater sorption, modulus of elasticity, and fille r content were evaluated in fo u r commercial m icrofilled composite resins, a visible light-cured composite resin, and a conventional composite resin.
c^ - J o m p o s i t e
resin s are u sed as di re c t resto rativ e m aterials for reestab lish in g th e e s th e tic a p p e a ra n ce o f a n te rio r teeth . E ssen tially , th ey co n sist of a resin m atrix th at bonds to in o rg an ic filler p articles co ated w ith silan e. C o n v en tio n al co m p osite re s i n s c o m p r i s e 7 0 % to 8 0 % , b y w eig h t, glass or q uartz p articles sev eral m icro n s in size. In co rp o ratio n of in o rg a n ic filler p articles in th e resin g iv e s c o m p o s i t e r e s in s d iffe r e n t p ro p e rtie s th an u n filled d ire c t r e storativ e m a te ria ls .1’6 M ore recen tly , co m p o site resin s of d ifferent co m p o sitio n s h ave been in tro d u ced . T hese in clu d e m icro filled co m p o sites (re sin s w ith p articles of silica sm aller th an 1 /xm) th at are d esig n ed to give s m o o th e r te x tu re s of th e fin ish ed su rface an d co m p o site resin s th at are c u r e d by v is ib le l i g h t .7,8 In th is stu d y, th e p h y sical and m ech an ical p ro p erties o f several n ew com p osite re sin s are co m p ared w ith th ose of a c o n v en tio n al co m p o site resin.
M a te r ia ls a n d m e th o d s T h e co m p o site resin s u sed w ere four c o m m e rc ia l m icro filled co m p o sites, Iso ca p ,* Isop ast,* S ila r.t and Superf ilt; a visib le lig h t-cu red co m p o site, F o to fil§ ; an d a con v en tio n al co m p o site, C o n c is e .t Isop ast, Superfil, Silar, an d C o n cise are tw o -p aste sys tem s, Isocap is an en cap su lated sy s
tem , an d F o tofil is a on e-p aste sy s tem . F o r th e tw o -p a s te s y s te m s , th e sam p les w ere p rep ared a cco rd in g to m a n u fa c tu re rs ’ in s tru c tio n s an d p ack ed into stain less steel m o ld s of ap p ro p riate d im en sio n s. Isocap w as m ix e d w ith a m e ch a n ica l trituratoiD as in d ic a te d b y th e m a n u fa c tu re r and p ack ed into m olds. Fo tofil w as p rep ared by p ack in g th e co m p o site resin in to m o ld s, co v erin g th e m olds w ith glass slid es, and c u rin g them u n d e r a tu n g s te n -h a lo g e n lig h t* * w ith a blue filter. Glass m o ld s and p lastic m o ld s w ere also used w ith F o tofil. A ll sam p les w ere stored in 3 7 C d istilled w ater for 24 h ou rs b e fore all tests e x c e p t th e w ater sorp tio n test. T h e p h y s ic a l an d m e c h a n ic a l p ro p erties in vestig ated , m eth od s of m e a s u r e m e n t, d im e n s io n s o f th e s a m p le s , an d n u m b e r o f s a m p le s te ste d for e a ch m aterial w ere: — In o r g a n ic f ille r c o n te n t. T h e p e rc e n t by w eig h t of th e in o rg an ic f ille r c o n te n t w as m e a su re d g r a v im e tr ic a lly .tt F iv e sam p les (3 .7 m m in d iam eter, 7.7 m m in length) w ere w eigh ed before and after ig n i tio n at 5 0 0 C to co n stan t w eigh t. — D iam etral ten sile stren gth . Five sam p les (6 .0 m m in d ia m e te r, 3 .0 m m in th ick n ess) w ere sub jected to d ia m e tra l lo ad in g a t a ra te o f 1.5 m m /m in in a testin g m a c h in e .i t
— C o m p re s siv e s tre n g th . F iv e sam p les ( 6.0 m m in d iam eter, 12.0 m m in le n g th ) w e re s u b je c te d to ax ia l lo ad in g at a rate of 0.2 m m /m in in a testin g m a c h i n e .tt S am p les of F o to fil w ere of sm aller d im en sio n s (3 .0 m m in d ia m e te r, 2 .7 m m in len gth ). — M o d u lu s o f e la s tic ity . F iv e sam p les ( 6.0 m m in d iam eter, 12.0 m m in le n g th ) w e re s u b je c te d to a x ia l lo ad in g at a rate of 0.2 m m /m in in a te s tin g m a c h i n e .t t D is p la c e m e n ts u n d e r lo ad w ere m e a su re d w ith u se of an o p tic a l s tra in g a u g e .§ § — W ater sorp tion . The am o u n t of w ater ab sorb ed by th e sam p les (20.0 m m in d iam eter, 1.0 in th ick n ess) a fte r se v e n d a y s in 3 7 C d istille d w a te r w as m e a su re d g r a v im e t r i c a l l y .t t T h e m in im u m n u m b er of sam p les tested w as three. — R e s ista n c e to in d e n ta tio n an d re c o v e ry . S am p les (2 0 .0 m m in d i am eter, 2.0 m m in th ick n ess) w ere tested in a su p erficial h ard n ess testerlin w ith a stain less steel ball ind e n te r (1 2 .5 m m in d iam eter). R esis ta n c e to in d e n ta tio n an d re c o v e ry w e re m e a s u re d fo r th re e s a m p le s w ith u se o f a m ajor load o f 3 0 kg an d a m in o r load of 3 k g .9 — L in e a r th e rm a l c o e f f ic ie n t of exp an sio n . E xp an sio n of s ix sam p les (3 .7 m m in d ia m e te r, 7 .7 m m in len gth ) w as m easu red in a th e rm o m e c h a n ic a l a n a ly z e r* * * b etw een 0 an d 6 0 C as d escrib ed by P ow ers, H o s te tle r, an d D e n n is o n .10 L in e a r c o e ff ic ie n ts o f th e rm a l e x p a n s io n w ere ca lcu la te d b etw een 1 0 an d 4 5 C.
R e su lts In v e s tig a te d p ro p e rtie s o f th e s ix c o m p o s ite re s in s are liste d in th e T ab le. M ean valu es of th e p rop erties
(ADA, Vol. 99, October 1979 ■ 631
ARTICLES
Table • Physical and mechanical properti es of composite resins.
Pro perty Inorga ni c filler cont ent, % by w eiyht Diametra tensile strength, MPa:j::j: Compressive strength, MPa Modulus of elasticity, GPa§§ Depth of inde ntation, µm Recovery from indenta tion ,
33.2tt 30" 221· 3.711 · '>
82 83.3'
%
Water sorption, mg /c m' Linear coe ffi c ie nt of thermal expa nsion (10-45 C), 10- "
c -·
1.26' 64.9'
SD
Mea n va lu e
0.1
37.3
2 17
36"·" 280"
SD
Mean va lue
0.3
35.1
2 31
56 240" ·"
SD
Mea n va lu e
0.4
49.7
10 10
30" 284"
Concise
Fotofil
S ilar
Superfil
Isopast
lsoca p Mean value
SD
Mean valu e
SD
0.7
77.7
0.2
4 13
4 25
39" 21 6"
Mean value
SD
76.7
0.1
47 220"
2 18
Sche ff e interval * 0.7
7t
52
0.1 1
89
0.2 3
3.2' 86"
0.3 1
5.4 73
0.6 1
7.1 52
2 1
13.7 57
2.9 1
0.6:j: 1§
0.3 0.09
79.3" 1.3'
0.9 0.16
82.7' 2.2
0.7 0.6
80.2" 1.76
0.8 0.12
83.7' 0.26
0.7 0.04
79.1 0.65
1.8 0.07
2.1 1 0.31* *
0.7
65.3"
1.8
69.8
1.1
46. 3
0.6
25.1
0.7
34.2
1.2
2.5
3. 911
*In computing the Scheffe inte rvals, th e following data were excluded as indicated beca use th e va ri a nces were too large: Superfilt. Fotofil and Concise,i Isopast,§ Concise. Wa nd Superfil. •• ttFor eat: h property. values with the sa me superscript s (a. b) a re not statisti calJ y different a t th e 95% level of co nfid ence. HMega Pascal. §§Giga Pascal.
were analyzed by a one-way analysis of variance 11 and were compared with use of Scheffe intervals at the 95% level of confidence. 12
Discussion INORGANIC FILLER CONTENT. Con-
cise and Fotofil had the highest percent of weight of inorganic filler; they were followed by Silar and then by Isocap, Isopast, and Superfil. Differences observed in the properties of these composite resins could be closely related to differences in inorganic filler content. MECHANICAL PROPERTIES. The
diametral tensile strength of Superfil was the highest of the tested materials ; it was followed by Concise. The other filled resins had similar values of diametral tensile strength, but all were lower than that of Concise. The compressive strengths of Isopast and Silar were the highest of the composite resins tested. Isocap, Superfil, Fotofil, and Concise had similar values. Moduli of elasticity of the four microfilled composite resins (Isocap , Isopast, Superfil, and Silarl were less than 50% of that of Concise. This results from the lower content of inorganic filler of the microfilled composite resins. The moduli of elasticity, however, were higher than those of an unfilled acrylic restorative material (2 .34 GPa-giga Pascall. 5 The modulus of elasticity of Fotofil was lower than that of Concise. This may result from the use of a urethane resin and the choice of filler in Fotofil. 8 632 • JADA, Vol. 99, October 1979
Concise and Fotofil had values of depth of indentation considerably less than the microfilled composite resins. Silar had an intermediate value of depth of indentation and also an intermediate amou:rft of inorganic filler. Although depths of indentation were significantly different among materials, the percent of recovery after removal of the major load was similar for all the composite resins (approximately 80%l. WATER SORPTION. Fotofil showed
the lowest values of water sorption after seven days in 37 C distilled water . Superfil showed the highest values of water sorption. Isocap, Isopast, and Silar showed higher values of water sorption than Concise. In composite resins, water is absorbed by the resin matrix. The low sorption of water in Fotofil may have resulted from the urethane resin used in its formulation. 8 The other composite resins are based on a BIS-GMA resin. Their water sorption would be influenced by the resin content. Concise, with the highest content of inorganic filler, had less resin per sample available for water sorption and had an apparently lower value of water sorption. Water sorption of composite resins can result in dimensional changes in composite restorations and can thereby alter marginal integrity. LINEAR COEFFICIENT OF THERMAL EXPANSION. Thermal dimensional
changes in composite restorations depend on the coefficient of thermal expansion of the composite resins
and the size of the restoration. To minimize marginal leakage and to maintain marginal integrity, the thermal expansion of composite restorations should be similar to that of tooth structure (11.4 x 10- 6 c- 11.13 ·of the investigated composite resins, Fotofil had the lowest linear coefficient of thermal expansion. Yet, it was more than twice that of tooth structure . lsocap , lsopast , Superfil, and Silar showed higher values of thermal expansion than Concise and other conventional composite resins 10 but lower values than those of an unfilled acrylic resin (92.0 x 10- 6 c- 11.s The clinical performance of a composite restoration is complexly related to its physical and mechanical properties. A material should be chosen for clinical use after many of its properties, rather than a specific one, have been carefully considered.
Conclusion Physical and mechanical properties of four commercial micro-filled composite resins, a visible lightcured composite resin, and a conventional composite resin were investigated. Isocap, Isopast, and Superfil were similar in most properties. Compartid with Concise, they had lower values of inorganic filler content and modulus of elasticity and higher values of water sorption, depth of indentation , and linear coefficient of thermal expansion. The properties of Silar were between those of Concise and the other microfilled composite resins. Fotofil had lower values of modulus of elas-
A R T IC L E S
t i c i ty , w a te r s o r p tio n , an d lin e a r c o e f f i c i e n t o f th e r m a l e x p a n s io n th an C o n cise.
* Is o c a p (1 1 -7 9 ), I s o p a s t (b a s e - 1 4 1 2 7 7 , catalyst-2811 7 7 ), V iv a d en t, S ch aan , L ie c h te n stein. tP a s te A , M PP-501-B 7; p a ste B, M PP-397-B7, 3M C o., St. P a u l, M in n . ♦ U n iv e rs a l, 8 0 3 3 8 , c a ta ly s t, 8 0 3 2 9 , H . J. B o sw o rth Co., Sk o k ie, 111. §F3762, ADM , 44092/76, Im p e rial C h em ical In d u s trie s , In c ., M a c c le sfie ld , C h esh ire , E n glan d . H Silam et, Ju sti-W illiam s, B uffalo, NY. ** R ilu m a b u lb , Q u a rry , In c ., A n n A rb o r, M ich. t tM e ttle r b a la n c e H 14, M e ttle r In stru m e n t, P rin c e to n , NJ. i t R i e h l e te s tin g m a c h in e , A m e ric a n M a c h in e a n d M etals, E ast M o lin e , 111. § § T u k e rm a n , A m e r ic a n I n s tr u m e n t C o., S ilv er S p rin g s, M d. H IR ockw ell s u p e rfic ia l h a rd n e s s te ster, W il s o n In s tru m e n ts D iv., A m e ric a n C h a in a n d C able Co., In c., N e w York. ***M odel 941, In s tru m e n t P ro d u c ts D iv., E. I. d u P o n t d e N e m o u rs a n d C o ., In c ., W il m in g to n , Del.
T h is in v e stig a tio n w as s u p p o rte d in p a rt b y R ese arch G ra n t D E-3416 a n d b y S e rv ic e A w ard D E-07057 fro m th e N a tio n a l In s titu te o f D e n tal R e s e a rc h , N a tio n a l I n s titu te s o f H e a lth , B eth esd a, M d 20014. T h e c o o p e ra tio n o f th e 3M C o m p a n y in p ro v id in g a c o m m e rc ial p ro d u c t is a c k n o w le d g e d . T h e a u th o rs th a n k Dr. W. J. O 'B rie n fo r d is c u s sio n s. Dr. R ap tis is in th e g ra d u a te p ro g ram , d e p a rtm e n t o f d e n ta l m a te ria ls; Dr. F a n is a ss is ta n t re s e a rc h sc ie n tis t, d e p a rtm e n t of d e n ta l m a te ria ls; a n d Dr. P o w e rs is a sso c iate p ro fes so r, d e p a rtm e n t o f d e n ta l m a te ria ls, S c h o o l of D e n tistry , U n iv e rsity o f M ich ig an , A n n A rbor, 4 8 1 0 9 . A d d re s s re q u e s ts fo r r e p r in ts to Dr. Pow ers. 1. B o w e n , R .L . P r o p e r t i e s o f a s i l i c a re in fo r c e d p o ly m e r fo r d e n ta l re s to ra tio n s . JADA 6 6 (l):5 7 -6 4 , 1963. 2. B o w en , R.L. E ffect of p a rtic le s h a p e a n d size d is trib u tio n i n a re in fo rce d p o ly m er. JADA 6 9 (4 ):4 8 1 -4 9 5 ,1964. 3. P e t e r s o n , E .A .; P h i l l i p s , R .W .; a n d S w a rtz , M .L. A c o m p a ris o n o f th e p h y s ic a l p r o p e r tie s o f f o u r re s to ra tiv e re s in s . JAD A 73(6J:1324-1336, 1966.
4. M acch i, R.L., a n d C raig, R.G. P h y sic a l a n d m e c h a n ic a l p ro p e rtie s o f c o m p o site re s to ra tiv e m a te ria ls. JADA 7 8 (2 ):3 2 8 -3 3 4 ,1969. 5. D e n n iso n , J.B., a n d C raig, R.G. P h y sic al p ro p e rtie s a n d fin ish e d su rfa c e te x tu re o f com p o s ite re sto ra tiv e re sin s. JADA 85(1):101-108, 1972. 6. H a n n a h , C. M cD onald, a n d C om be, E.C. M ec h a n ic al p ro p e rtie s o f c o m p o site re sto ra tiv e m ate ria ls. B r D e n t J 1 4 0 (5 ):1 6 7 -1 7 3 ,1976. 7. P e rd e n t GMBH, B ritish p a te n t 1488403, 1977. 8. Im p e rial C h em ical In d u s trie s , Inc. B ritish p a te n t 1 4 6 5 8 9 7 ,1 9 7 5 . 9. C o u n cil o n D en tal M ate rials a n d D evices. N ew A m e ric a n D en tal A sso c ia tio n S p e c ific a tio n N o. 27 fo r D irect F illin g R esin s. JADA 94(6):1191-1194, 1977. 10. P o w ers, J.M .; H o stetler, R.W.; a n d D en n is o n , J.B. T h e rm a l e x p a n s io n o f c o m p o site re s in s a n d s e a la n ts . J D en t R es 58(2):584-587, 1979. 11. U n iv e rsity o f M ich ig an , S ta tis tic a l Re sea rc h Laboratory. A m a n u a l of e le m e n ta ry sta tis tic s u s in g M ID A S. A n n A rbor, S ta tistic a l Re s e a rc h L aboratory, 1975. 12. G u e n th e r, W .C. A n a ly s is o f v a ria n c e . E n g lew o o d C liffs, NJ, P ren tice -H a ll, 1964. 13. S o u d e r, W .H ., a n d P a ffe n b a rg e r, G.C. P h y s ic a l p ro p e rtie s o f d e n ta l m a te ria ls, N a tio n a l B u re au o f S ta n d a rd s C irc u la r no. C433. W ash in g to n , DC, U S G o v e rn m e n t P rin tin g O f fice, 1942.
R a p U s -F a n -P o w e rs : M IC RO FILLED A N D LIG HT-CU RED C O M PO SITE R ESIN S a 633
Properties of m icrofilled an d visible light-cured com posite resins C. N. R aptis, DDS, MS P. L. F an, PhD J. M. P ow ers, PhD
Depth o f indentation, therm al expansion, w ater sorption, modulus of elasticity, and fille r content were evaluated in fo u r commercial m icrofilled composite resins, a visible light-cured composite resin, and a conventional composite resin.
c^ - J o m p o s i t e
resin s are u sed as di re c t resto rativ e m aterials for reestab lish in g th e e s th e tic a p p e a ra n ce o f a n te rio r teeth . E ssen tially , th ey co n sist of a resin m atrix th at bonds to in o rg an ic filler p articles co ated w ith silan e. C o n v en tio n al co m p osite re s i n s c o m p r i s e 7 0 % to 8 0 % , b y w eig h t, glass or q uartz p articles sev eral m icro n s in size. In co rp o ratio n of in o rg a n ic filler p articles in th e resin g iv e s c o m p o s i t e r e s in s d iffe r e n t p ro p e rtie s th an u n filled d ire c t r e storativ e m a te ria ls .1’6 M ore recen tly , co m p o site resin s of d ifferent co m p o sitio n s h ave been in tro d u ced . T hese in clu d e m icro filled co m p o sites (re sin s w ith p articles of silica sm aller th an 1 /xm) th at are d esig n ed to give s m o o th e r te x tu re s of th e fin ish ed su rface an d co m p o site resin s th at are c u r e d by v is ib le l i g h t .7,8 In th is stu d y, th e p h y sical and m ech an ical p ro p erties o f several n ew com p osite re sin s are co m p ared w ith th ose of a c o n v en tio n al co m p o site resin.
M a te r ia ls a n d m e th o d s T h e co m p o site resin s u sed w ere four c o m m e rc ia l m icro filled co m p o sites, Iso ca p ,* Isop ast,* S ila r.t and Superf ilt; a visib le lig h t-cu red co m p o site, F o to fil§ ; an d a con v en tio n al co m p o site, C o n c is e .t Isop ast, Superfil, Silar, an d C o n cise are tw o -p aste sys tem s, Isocap is an en cap su lated sy s
tem , an d F o tofil is a on e-p aste sy s tem . F o r th e tw o -p a s te s y s te m s , th e sam p les w ere p rep ared a cco rd in g to m a n u fa c tu re rs ’ in s tru c tio n s an d p ack ed into stain less steel m o ld s of ap p ro p riate d im en sio n s. Isocap w as m ix e d w ith a m e ch a n ica l trituratoiD as in d ic a te d b y th e m a n u fa c tu re r and p ack ed into m olds. Fo tofil w as p rep ared by p ack in g th e co m p o site resin in to m o ld s, co v erin g th e m olds w ith glass slid es, and c u rin g them u n d e r a tu n g s te n -h a lo g e n lig h t* * w ith a blue filter. Glass m o ld s and p lastic m o ld s w ere also used w ith F o tofil. A ll sam p les w ere stored in 3 7 C d istilled w ater for 24 h ou rs b e fore all tests e x c e p t th e w ater sorp tio n test. T h e p h y s ic a l an d m e c h a n ic a l p ro p erties in vestig ated , m eth od s of m e a s u r e m e n t, d im e n s io n s o f th e s a m p le s , an d n u m b e r o f s a m p le s te ste d for e a ch m aterial w ere: — In o r g a n ic f ille r c o n te n t. T h e p e rc e n t by w eig h t of th e in o rg an ic f ille r c o n te n t w as m e a su re d g r a v im e tr ic a lly .tt F iv e sam p les (3 .7 m m in d iam eter, 7.7 m m in length) w ere w eigh ed before and after ig n i tio n at 5 0 0 C to co n stan t w eigh t. — D iam etral ten sile stren gth . Five sam p les (6 .0 m m in d ia m e te r, 3 .0 m m in th ick n ess) w ere sub jected to d ia m e tra l lo ad in g a t a ra te o f 1.5 m m /m in in a testin g m a c h in e .i t
— C o m p re s siv e s tre n g th . F iv e sam p les ( 6.0 m m in d iam eter, 12.0 m m in le n g th ) w e re s u b je c te d to ax ia l lo ad in g at a rate of 0.2 m m /m in in a testin g m a c h i n e .tt S am p les of F o to fil w ere of sm aller d im en sio n s (3 .0 m m in d ia m e te r, 2 .7 m m in len gth ). — M o d u lu s o f e la s tic ity . F iv e sam p les ( 6.0 m m in d iam eter, 12.0 m m in le n g th ) w e re s u b je c te d to a x ia l lo ad in g at a rate of 0.2 m m /m in in a te s tin g m a c h i n e .t t D is p la c e m e n ts u n d e r lo ad w ere m e a su re d w ith u se of an o p tic a l s tra in g a u g e .§ § — W ater sorp tion . The am o u n t of w ater ab sorb ed by th e sam p les (20.0 m m in d iam eter, 1.0 in th ick n ess) a fte r se v e n d a y s in 3 7 C d istille d w a te r w as m e a su re d g r a v im e t r i c a l l y .t t T h e m in im u m n u m b er of sam p les tested w as three. — R e s ista n c e to in d e n ta tio n an d re c o v e ry . S am p les (2 0 .0 m m in d i am eter, 2.0 m m in th ick n ess) w ere tested in a su p erficial h ard n ess testerlin w ith a stain less steel ball ind e n te r (1 2 .5 m m in d iam eter). R esis ta n c e to in d e n ta tio n an d re c o v e ry w e re m e a s u re d fo r th re e s a m p le s w ith u se o f a m ajor load o f 3 0 kg an d a m in o r load of 3 k g .9 — L in e a r th e rm a l c o e f f ic ie n t of exp an sio n . E xp an sio n of s ix sam p les (3 .7 m m in d ia m e te r, 7 .7 m m in len gth ) w as m easu red in a th e rm o m e c h a n ic a l a n a ly z e r* * * b etw een 0 an d 6 0 C as d escrib ed by P ow ers, H o s te tle r, an d D e n n is o n .10 L in e a r c o e ff ic ie n ts o f th e rm a l e x p a n s io n w ere ca lcu la te d b etw een 1 0 an d 4 5 C.
R e su lts In v e s tig a te d p ro p e rtie s o f th e s ix c o m p o s ite re s in s are liste d in th e T ab le. M ean valu es of th e p rop erties
(ADA, Vol. 99, October 1979 ■ 631
ARTICLES
Table • Physical and mechanical properti es of composite resins.
Pro perty Inorga ni c filler cont ent, % by w eiyht Diametra tensile strength, MPa:j::j: Compressive strength, MPa Modulus of elasticity, GPa§§ Depth of inde ntation, µm Recovery from indenta tion ,
33.2tt 30" 221· 3.711 · '>
82 83.3'
%
Water sorption, mg /c m' Linear coe ffi c ie nt of thermal expa nsion (10-45 C), 10- "
c -·
1.26' 64.9'
SD
Mea n va lu e
0.1
37.3
2 17
36"·" 280"
SD
Mean va lue
0.3
35.1
2 31
56 240" ·"
SD
Mea n va lu e
0.4
49.7
10 10
30" 284"
Concise
Fotofil
S ilar
Superfil
Isopast
lsoca p Mean value
SD
Mean valu e
SD
0.7
77.7
0.2
4 13
4 25
39" 21 6"
Mean value
SD
76.7
0.1
47 220"
2 18
Sche ff e interval * 0.7
7t
52
0.1 1
89
0.2 3
3.2' 86"
0.3 1
5.4 73
0.6 1
7.1 52
2 1
13.7 57
2.9 1
0.6:j: 1§
0.3 0.09
79.3" 1.3'
0.9 0.16
82.7' 2.2
0.7 0.6
80.2" 1.76
0.8 0.12
83.7' 0.26
0.7 0.04
79.1 0.65
1.8 0.07
2.1 1 0.31* *
0.7
65.3"
1.8
69.8
1.1
46. 3
0.6
25.1
0.7
34.2
1.2
2.5
3. 911
*In computing the Scheffe inte rvals, th e following data were excluded as indicated beca use th e va ri a nces were too large: Superfilt. Fotofil and Concise,i Isopast,§ Concise. Wa nd Superfil. •• ttFor eat: h property. values with the sa me superscript s (a. b) a re not statisti calJ y different a t th e 95% level of co nfid ence. HMega Pascal. §§Giga Pascal.
were analyzed by a one-way analysis of variance 11 and were compared with use of Scheffe intervals at the 95% level of confidence. 12
Discussion INORGANIC FILLER CONTENT. Con-
cise and Fotofil had the highest percent of weight of inorganic filler; they were followed by Silar and then by Isocap, Isopast, and Superfil. Differences observed in the properties of these composite resins could be closely related to differences in inorganic filler content. MECHANICAL PROPERTIES. The
diametral tensile strength of Superfil was the highest of the tested materials ; it was followed by Concise. The other filled resins had similar values of diametral tensile strength, but all were lower than that of Concise. The compressive strengths of Isopast and Silar were the highest of the composite resins tested. Isocap, Superfil, Fotofil, and Concise had similar values. Moduli of elasticity of the four microfilled composite resins (Isocap , Isopast, Superfil, and Silarl were less than 50% of that of Concise. This results from the lower content of inorganic filler of the microfilled composite resins. The moduli of elasticity, however, were higher than those of an unfilled acrylic restorative material (2 .34 GPa-giga Pascall. 5 The modulus of elasticity of Fotofil was lower than that of Concise. This may result from the use of a urethane resin and the choice of filler in Fotofil. 8 632 • JADA, Vol. 99, October 1979
Concise and Fotofil had values of depth of indentation considerably less than the microfilled composite resins. Silar had an intermediate value of depth of indentation and also an intermediate amou:rft of inorganic filler. Although depths of indentation were significantly different among materials, the percent of recovery after removal of the major load was similar for all the composite resins (approximately 80%l. WATER SORPTION. Fotofil showed
the lowest values of water sorption after seven days in 37 C distilled water . Superfil showed the highest values of water sorption. Isocap, Isopast, and Silar showed higher values of water sorption than Concise. In composite resins, water is absorbed by the resin matrix. The low sorption of water in Fotofil may have resulted from the urethane resin used in its formulation. 8 The other composite resins are based on a BIS-GMA resin. Their water sorption would be influenced by the resin content. Concise, with the highest content of inorganic filler, had less resin per sample available for water sorption and had an apparently lower value of water sorption. Water sorption of composite resins can result in dimensional changes in composite restorations and can thereby alter marginal integrity. LINEAR COEFFICIENT OF THERMAL EXPANSION. Thermal dimensional
changes in composite restorations depend on the coefficient of thermal expansion of the composite resins
and the size of the restoration. To minimize marginal leakage and to maintain marginal integrity, the thermal expansion of composite restorations should be similar to that of tooth structure (11.4 x 10- 6 c- 11.13 ·of the investigated composite resins, Fotofil had the lowest linear coefficient of thermal expansion. Yet, it was more than twice that of tooth structure . lsocap , lsopast , Superfil, and Silar showed higher values of thermal expansion than Concise and other conventional composite resins 10 but lower values than those of an unfilled acrylic resin (92.0 x 10- 6 c- 11.s The clinical performance of a composite restoration is complexly related to its physical and mechanical properties. A material should be chosen for clinical use after many of its properties, rather than a specific one, have been carefully considered.
Conclusion Physical and mechanical properties of four commercial micro-filled composite resins, a visible lightcured composite resin, and a conventional composite resin were investigated. Isocap, Isopast, and Superfil were similar in most properties. Compartid with Concise, they had lower values of inorganic filler content and modulus of elasticity and higher values of water sorption, depth of indentation , and linear coefficient of thermal expansion. The properties of Silar were between those of Concise and the other microfilled composite resins. Fotofil had lower values of modulus of elas-
A R T IC L E S
t i c i ty , w a te r s o r p tio n , an d lin e a r c o e f f i c i e n t o f th e r m a l e x p a n s io n th an C o n cise.
* Is o c a p (1 1 -7 9 ), I s o p a s t (b a s e - 1 4 1 2 7 7 , catalyst-2811 7 7 ), V iv a d en t, S ch aan , L ie c h te n stein. tP a s te A , M PP-501-B 7; p a ste B, M PP-397-B7, 3M C o., St. P a u l, M in n . ♦ U n iv e rs a l, 8 0 3 3 8 , c a ta ly s t, 8 0 3 2 9 , H . J. B o sw o rth Co., Sk o k ie, 111. §F3762, ADM , 44092/76, Im p e rial C h em ical In d u s trie s , In c ., M a c c le sfie ld , C h esh ire , E n glan d . H Silam et, Ju sti-W illiam s, B uffalo, NY. ** R ilu m a b u lb , Q u a rry , In c ., A n n A rb o r, M ich. t tM e ttle r b a la n c e H 14, M e ttle r In stru m e n t, P rin c e to n , NJ. i t R i e h l e te s tin g m a c h in e , A m e ric a n M a c h in e a n d M etals, E ast M o lin e , 111. § § T u k e rm a n , A m e r ic a n I n s tr u m e n t C o., S ilv er S p rin g s, M d. H IR ockw ell s u p e rfic ia l h a rd n e s s te ster, W il s o n In s tru m e n ts D iv., A m e ric a n C h a in a n d C able Co., In c., N e w York. ***M odel 941, In s tru m e n t P ro d u c ts D iv., E. I. d u P o n t d e N e m o u rs a n d C o ., In c ., W il m in g to n , Del.
T h is in v e stig a tio n w as s u p p o rte d in p a rt b y R ese arch G ra n t D E-3416 a n d b y S e rv ic e A w ard D E-07057 fro m th e N a tio n a l In s titu te o f D e n tal R e s e a rc h , N a tio n a l I n s titu te s o f H e a lth , B eth esd a, M d 20014. T h e c o o p e ra tio n o f th e 3M C o m p a n y in p ro v id in g a c o m m e rc ial p ro d u c t is a c k n o w le d g e d . T h e a u th o rs th a n k Dr. W. J. O 'B rie n fo r d is c u s sio n s. Dr. R ap tis is in th e g ra d u a te p ro g ram , d e p a rtm e n t o f d e n ta l m a te ria ls; Dr. F a n is a ss is ta n t re s e a rc h sc ie n tis t, d e p a rtm e n t of d e n ta l m a te ria ls; a n d Dr. P o w e rs is a sso c iate p ro fes so r, d e p a rtm e n t o f d e n ta l m a te ria ls, S c h o o l of D e n tistry , U n iv e rsity o f M ich ig an , A n n A rbor, 4 8 1 0 9 . A d d re s s re q u e s ts fo r r e p r in ts to Dr. Pow ers. 1. B o w e n , R .L . P r o p e r t i e s o f a s i l i c a re in fo r c e d p o ly m e r fo r d e n ta l re s to ra tio n s . JADA 6 6 (l):5 7 -6 4 , 1963. 2. B o w en , R.L. E ffect of p a rtic le s h a p e a n d size d is trib u tio n i n a re in fo rce d p o ly m er. JADA 6 9 (4 ):4 8 1 -4 9 5 ,1964. 3. P e t e r s o n , E .A .; P h i l l i p s , R .W .; a n d S w a rtz , M .L. A c o m p a ris o n o f th e p h y s ic a l p r o p e r tie s o f f o u r re s to ra tiv e re s in s . JAD A 73(6J:1324-1336, 1966.
4. M acch i, R.L., a n d C raig, R.G. P h y sic a l a n d m e c h a n ic a l p ro p e rtie s o f c o m p o site re s to ra tiv e m a te ria ls. JADA 7 8 (2 ):3 2 8 -3 3 4 ,1969. 5. D e n n iso n , J.B., a n d C raig, R.G. P h y sic al p ro p e rtie s a n d fin ish e d su rfa c e te x tu re o f com p o s ite re sto ra tiv e re sin s. JADA 85(1):101-108, 1972. 6. H a n n a h , C. M cD onald, a n d C om be, E.C. M ec h a n ic al p ro p e rtie s o f c o m p o site re sto ra tiv e m ate ria ls. B r D e n t J 1 4 0 (5 ):1 6 7 -1 7 3 ,1976. 7. P e rd e n t GMBH, B ritish p a te n t 1488403, 1977. 8. Im p e rial C h em ical In d u s trie s , Inc. B ritish p a te n t 1 4 6 5 8 9 7 ,1 9 7 5 . 9. C o u n cil o n D en tal M ate rials a n d D evices. N ew A m e ric a n D en tal A sso c ia tio n S p e c ific a tio n N o. 27 fo r D irect F illin g R esin s. JADA 94(6):1191-1194, 1977. 10. P o w ers, J.M .; H o stetler, R.W.; a n d D en n is o n , J.B. T h e rm a l e x p a n s io n o f c o m p o site re s in s a n d s e a la n ts . J D en t R es 58(2):584-587, 1979. 11. U n iv e rsity o f M ich ig an , S ta tis tic a l Re sea rc h Laboratory. A m a n u a l of e le m e n ta ry sta tis tic s u s in g M ID A S. A n n A rbor, S ta tistic a l Re s e a rc h L aboratory, 1975. 12. G u e n th e r, W .C. A n a ly s is o f v a ria n c e . E n g lew o o d C liffs, NJ, P ren tice -H a ll, 1964. 13. S o u d e r, W .H ., a n d P a ffe n b a rg e r, G.C. P h y s ic a l p ro p e rtie s o f d e n ta l m a te ria ls, N a tio n a l B u re au o f S ta n d a rd s C irc u la r no. C433. W ash in g to n , DC, U S G o v e rn m e n t P rin tin g O f fice, 1942.
R a p U s -F a n -P o w e rs : M IC RO FILLED A N D LIG HT-CU RED C O M PO SITE R ESIN S a 633
