SEM and elemental Hiroyasu Shigehisa Tokyo
analysis of composite resins
Hosoda, D.D.S., PhD.,+ Toshimoto Inokoshi, D.D.S., Ph.D.**
Medical
and
Dental
University,
School
Yamada,
of Dentistry,
Tokyo,
D.D.S., Ph.D.,**
and
Japan
Twenty-four chemically cured, 21 light-cured anterior, three light-cured anterior/ posterior, and 18 light-cured posterior composite resins were examined using scanning electron microscopy, and the elemental composition of their filler particles was analyzed with an energy dispersive electron probe microanalyzer. According to the results obtained, the composite resins were divided into 5ve groups (traditional, micro5lled type, submicro5lled type, hybrid type, and semihybrid), with two additional hypothetical categories (microfilled and hybrid). Characteristics of each type were described with clinical indications for selective guidance of respective composite resins for clinical use. (J PROSTHET DENT 1990;64:669-76.)
R
estorative composite resins have been widely used by most dentists for restoring anterior cavitities.The use of these materials in posterior teeth has spread dramatically in the past few years because patients and dentists have sought better esthetics, and concern about mercury pollution has reduced the use of amalgam restorations. In the past two decades, composite resin therapy has advanced as a result of acid-etching, improvement in filler particles and base resins, bonding agents, and polymerization methods.1*10 As a result of these developments and improvements, the American Dental Association (ADA) described two categories of direct filling resins in specification No. 27.” The Federation Dentaire Internationale (FDI) also proposed a classification in IS0 4049.12 These classifications do not provide information for predicting the clinical performance of composite resins. Lutz et all3 and Lutz and Phillips14 have proposed a more detailed classification based on the current state of the art. They presented data for selecting a composite resin based on existing research results This classification, however, was primarily for anterior composite resins, since the posterior composite resins were just emerging. Some composite resins not yet commercially available were also studied. This study examined composite resins by scanning electron microscopy (SEM) and by qualitative analysis (EDX) in order to obtain an understanding for the appropriate selection of composite resins for clinical use.
The composite resin specimens used for EDX analysis were repolished with diamond paste to remove the carbon coating. After vapor-coating with gold, the polished surfaces were examined in the SEM with the back-scattered electron images under 500 power magnification.
MATERIAL AND METHODS Composite resins examined
RESULTS Weight filler contents of resins
Sixty-six commercially available composite resins were used, which included 24 chemically-cured composite resins (Table I), 21 light-cured anterior composite resins, three
The filler contents of the composite resins are listed in Tables IV through VI. The traditional composite resins showed high inorganic contents ranging from 70% to 80 % . The microfilled composite resins indicated relatively looser quantities around 50%. The heavily filled composite resins exhibited approximately 85 % inorganic contents. The filler contents of the others varied from 60% to 80%.
*Professor **Lecturer,
and Chairman, Department
Department of Operative
of Operative Dentistry.
10/l/21276
TEE
JOURNAL
OF PROSTHETIC
DENTISTRY
Dentistry.
light-cured anterior and posterior composite resins (Table II), and 18 light-cured posterior composite resins (Table III). The weight filler contents were determined for individual materials by ashing at 570” C in air.
Qualitative
analysis
The composite resin specimens, 5 mm in diameter and 2 mm thick, made according to the manufacturer’s instructions, were partially embedded in a cold-curing epoxy resin and stored in water at 37” C for 1 week. The surfaces of the composite resins were finished with water-proof siliconecarbide paper and were polished with diamond paste. After vapor-coating with carbon, the surfaces were qualitatively analyzed with EDX (SED-880, Seiko EG & G, Tokyo, Japan) under 500 power magnification for various elements, heavier than Ne, present on the surfaces of the specimens. When a few filler particles, different in shape and shade, were observed under the SEM, the energy spectra of elements present in the individual fillers were obtained under 3000 through 5000 power magnification.
SEM observation
669
HOSODA,
Table
I.
Anterior
name
Adaptic before 1982* Adaptic Radiopaque* before 1982 Adaptic after 1982 Adaptic Radiopaque after 1982 Bell Feel Anterior Clearfil Clear61 Clearfil Concise Concise
F* FII F3 before 1982* after 1982
Miradapt
Posterior
Bell
Bond
Feel
Anterior
& posterior
products
Elements
are not currently
Posterior
INOEOSHI
St. Paul,
Minn.
Tokyo,
Japan
Post-ComII*
Microrest Palfique
Tokuyama Soda, Tokuyama, Japan
commercially
AP
available
GC, Tokyo,
CU-2422, CC-2322 FU-1222, FC-1122 TJU-412, TJC-412 lM75, lN75 4MlH, 4J2H 025185 3D906 AUOl, AC01 3H1,3Jl 17348 PU-2229, PC-2129 KC-0102, KU-0202 5604.83, 5704.83 2272,2002 PUO2, PC01 840917PPU 84083OPPC
Kuraray Kuraray Vivadent 3M Sankin Pentron,
AG
Wallingford,
No.
4GO42 SA102,8B102 4B002,4COO2 4M303 lDF61
Kanebo
Conn.
Japan
080341 ASlO, C368
in Japan.
of fillers
The elements detected in the polished composite resin surfaces and filler particles that differed in shape and shade are shown in Tables IV through VI. Only Si appeared in the traditional composite resins (except for Adaptic Radiopaque, J&J, East Windsor, N.J.) and the microfiller-filled composite resins. Al, Ba, Zr, La, Ti, Zn, and/or Yb appeared in the other resins. The filler particles having radiopacity contained Ba, Al, Zr, Zn, and/or Yb.
Composition
J&J, East Windsor, N.J. J&J J&J J&J Kanebo, Tokyo, Japan Kuraray, Osaka,Japan Kuraray Kuraray
Sankin, 3M
Clearfil Posterior Clearfil Posterior 3 Isomolar P-10 Pyrofil Bond Posterior
Anterior
Lot
Vivadent AG, Schasn,Liechtenstein Bayer AG, Leverkusen, W. Germany J&J
Lumicon* Pyrofil Silar
Manufacturer
3M, 3M
Isopast
SEM images
The composition SEM images of the polished surfaces produced by using back-scattered electrons were divided into the five groups according to the filler type and their distribution. One of the traditional composite resins is presented in Fig. 1, A. Angular quartz filler particles, both large and small, were distributed in the matrix. One of the microfiller-filled composite resins is shown in Fig. 1, B. The angular-splintered microfiller complexes of various sizes were incorporated in a microfiller-reinforced matrix. In Fig. 1, C, the angular-splintered prepolymerized complexes making up spherical submicron-filler particles are added to a submicron-filler reinforced organic matrix.15 670
AND
Chemically-cured composite resins examined Brand
*These
YAMADA,
In Fig. 1, D and E, the angular-splintered prepolymerized or agglomerated microfilled complexes and the inorganic filler particles of various sizes are distributed in a microfiller-reinforced composite resin matrix. In Fig. 1, F, the spherical microfilled complexes and the inorganic filler particles are observed in a microfiller-reinforced matrix. In Fig. 2, macrofillers of various sizes of identical or different composition were admixed with an organic matrix reinforced by pyrogenic silica. The size of macrofillers tended to decrease, as shown in Fig. 2. This is most noticeable in Fig. 2, D, where the sizes of macrofillers are approximately or less than 1 pm.
DISCUSSION The composite resins in this study were divided into five groups, with an additional two hypothetical categories, by precisely observing the filler particle shape and its distribution, as exhibited on the SEM composition images. Another categorization approach was to review data of the manufacturing technique (Fig. 3 and Table VII).
Traditional
composite
resin
A schematic representation of traditional composite resin structure is shown in Fig. 3, A through C. The traditional macrofiller particles are mechanically made from DECEMBER
1990
VOLUME
64
NUMBER
6
SEM STUDY
Table
II.
OF COMPOSITE
Light-cured
RESINS
anterior
and anterior Brand
Anterior
Anterior
*This tThis
Table
& posterior
product product
III.
Manufacturer
JOURNAL
Lot
Bell Feel LX Bis-Fil M Brilliant Lux Command Ultrafine Durafil Fotofil* Glar Heliosit Lite-Fil A Lumifor Opalux Panagraf LCR Pekalux PhotoClearfil Bright Plurafil Super? Prisma-Fil Pyrofil Light Bond Anterior Silux Starfil Valux Visio-Dispers
Kanebo, Tokyo, Japan Bisco, Lombard, Ill. Coltene, Altstiten, Switzerland Kerr, Romulus, Mich. Kultzer, Friederichsdorf, W. Germany J&J, East Windsor, N.J. Teledyne-Getz, Elk Grove Village, Ill. Vivadent AG, Schaan, Liechtenstein Shofu, Kyoto, Japan Bayer AG, Leverkusen, W. Germany I.C.I. Macclesfield, Cheshire, U.K. Den-Mat, Santa Maria, Calif. Bayer AG Kuraray, Osaka, Japan Litema, Baden-Baden, W. Germany L.D. Caulk, Milford, Del. Sankin, Tokyo, Japan 3M, St. Paul, Minn. Kultzer 3M Espe GmbH, Seefeld/Oberbayern, W. Germany
6110-l
Palfique Light Palfique Light-S PhotoClearfil A
Tokuyama Soda, Tokuyama, Japan Tokuyama Soda Kuraray
LL402
Light-cured
posterior
composite
No.
082985 310784-16 63175 124 7G803 25095 030682 018401
659012-260885 AH130DEC85 3006 60250 100181 20586 4BCl 170 6G2 0055
us201 1050
resins examined
name
Manufacturer
are not currently
commercially
J&J, East Windsor, N.J. Bisco, Lombard, Ill. Kultzer, Friederichsdorf, W. Germany L.D. Caulk, Milford, Del. Vivadent AG, Schaan, Liechtenstein Vivadent AG Kerr, Romulus, Mich. Shofu, Kyoto, Japan I.C.I. Macclesfield, Cheshire, England I.C.I. Macclesfield Pentron, Wallingford, Conn. 3M, St. Paul, Minn. 3M 3M Kuraray, Osaka, Japan Sankin, Tokyo, Japan Teledyne-Getz, Elk Grove Village, Ill. Espe GmbH, Seefeld/Oberbayern, W. Germany available
OF PROSTHETIC
DENTISTRY
Lot
No.
5H5101 053185 169 0411862 341801 336501 61219 98301 LHC6 BOO33197 010485-41
4MlP 6P30 72P HPS-1001 177-806 40666 0002
in Japan
larger blocks of quartz and/or glass containing heavy radiopaque metals. The size of the filler particles ranges from 100 to 1 Mm. The currently used traditional composite resins show a definite trend to use smaller and rounded macrofiller particles. With modern resins of this type, the TEE
resins examined
name
Adaptic 2* Bis-Fil 1 Estilux Posterior Ful-Fil Heliomolar Heliomolar Radiopaque Cavifil Herculite Condensable Lite-Fil P Occlusin Qar) Occlusin (syringe) Post-Corn11 LC* P-30 (jar) P-30 (syringe) P-50 Clearfil PhotoPosterior Pyrofil Light Bond Posterior Sinter Fil P Visiomolar products
composite
is not currently commercially available. is visible and ultraviolet light-cured.
Brand
*These
and posterior
average particle size is generally range of 30 to 5 pm to about 5 macrofiller particles still results in spite of the change in filler With Adaptic and Concise
reduced from the original to 1 prn.15 Incorporation of in an unsatisfactory finish size. (3M Co., St. Paul, Minn.) 671
HOSODA,
Fig. 1. SEM images of composite Clearfil Posterior. E, Visio-Dispers.
Table
IV.
Type, elements
detected, Brand
Anterior
Posterior
Anterior
672
& posterior
and filler
resins. A, Adaptic F, Pekalux.
contents
name
of chemically Type
YAMADA,
after 1982. B, Silar. C, Palfique.
cured composite Elements detected
Adaptic before 1982 Adaptic Radiopaque before 1982 Adaptic after 1982 Adaptic Radiopaque after 1982 Bell Feel Anterior Clearfil F Clearfil FII Clearfil F3 Concise before 1982 Concise after 1982 Isopast Lumicon Miradapt Pyrofil Bond Anterior Silar
Macro Macro Macro Macro Semihybrid Macro Macro Hybrid type Macro Macro MFR type Semihybrid Semihybrid Semihybrid MFR type
Si Si, Si Si, Si Si Si Si Si Si Si Si, Si, Si Si
Bell Feel Posterior Clearfil Posterior Clearfil Posterior 3 Isomolar P-10 Pyrofil Bond Posterior Post-Corn11
Semihybrid Hybrid type Hybrid type MFR type Semihybrid Semihybrid Semihybrid
Si, Si, Si, Si Si Si Si,
Microrest AP Palfique
MFR type SFR type
Si SI, Ti
AND
D,
resins Elements detected in each filler
Weight content
(Si) Al, Ba Al, Ba
Al Al, Ba
Zr Al, Zr, La Al, Zr, La
Al, Ba
INOKOSHI
(Si) (Si) (Si) W (Si) (Si) (Si) (Si) (Si) (Si) (Si) (Si, (Si) (Si)
filler (70)
78.4 77.3 75.4
(Si, Al, Ba) (Si, Al, Ba)
17.5
(Si) (Si)
78.5 74.8 76.2 74.4
(Si, Al) Al, Ba)
80.4 37.4 77.5 81.2
79.3
(8%) (Si, (Si) (Si) (8%) (Si) (Si) W (Si) (Si) (Si,
7‘9.4 49.4 Zr) (Si, Al, Zr, La) (Si, Al, Zr, La)
80.3 80.2 83.0 62.2 83.3 83.1 75.4
Al, Ba)
(Si) (Si, Ti) DECEMBER
46.4 65.8
lSS0
VOLUME
64
NUMBER
6
SEM STUDY
OF COMPOSITE
RESINS
Fig. 2. SEM images of composite Herculite Condensable.
Table
V. Type,
elements
detected, Brand
Anterior
Anterior
& posterior
and filler
resins. A, Miradapt.
contents
name
of light-cured
THE
JOURNAL
anterior
Bell Feel LX Bis-Fil M Brilliant Lux Command Ultrafine Durafil Fotofil Glar Heliosit Lite-Fil A Limifor Opalux Panagraf LCR Pekalux PhotoClearfil Bright Plurafil Super Prisma-Fil Pyrofil Light Bond Anterior Silux Starfil Valux Visio-Dispers
Semihybrid Hybrid type Semihybrid Semihybrid Hybrid type Semihybrid Semihybrid MFR type Semihybrid Semihybrid Semihybrid Semihybrid Hybrid type Hybrid type Hybrid type Semihybrid Semihybrid MFR type Semihybrid Semihybrid Hybrid type
Si Si, Si, Si, Si Si, Si, Si Si Si, Si, Si, Si, Si Si, Si, Si Si Si, Si Si,
Palfique Light Palfique Light-S PhotoClearfil A
SFR type SFR type Semihybrid
Si, Ti Si, Zr Si
OF PROSTHETIC
DENTISTRY
and anterior
Elements detected
TYPO
composite resins after 1982, microfiller particles, presumed to be fumed silica dispersed in a matrix phase, are not clear on the SEM composition images obtained in this study. Lutz et a1.13 and Lutz and PhillipsI have previously reported the presence of this element. However, some composite resins with the same name differ from country to country and from one time to another.
B, PhotoClearfil
Al Al, Ba Al, Ba Al, Ba, Zn Al, Ba
Al, Ba Al Al, Ba Al Al, Ba Al, Ba
Al, Ba, Zn, Zr Al
Microfilled
A. C, P-50. D,
and posterior
composite
Elements detected in each filler
(Si) (Si) (Si, Al) (Si, Al, Ba) (Si, Al, Ba) (Si) (Si) (Si, Al, Ba) (Si) (Si, Al, (Si) (Si) (Si, Al, Ba) (Si, Al) (Si, Al) (Si, (Si) (Si, Al) (Si) (Si) (Si, Al, Ba) (Si, Al, Ba) (Si) (Si) (Si, Al, Ba) CW (Si) (Si, Al)
Weight content
(Si, Al, Zn) Ba)
Al, Ba)
(Si, Al, Zn, Zr)
(Si, Ti) (Si, Zr) (Si)
composite
resins filler (%)
80.6 65.2 74.2 75.1 56.2 80.0 79.9 37.3 80.8 75.9 85.1 78.8 33.3 66.6 60.7 75.6 80.0 52.6 74.8 76.8 60.0 66.7 67.5 83.2
resin
(MFR)
A schematic presentation of this type of composite resin is shown in Fig. 3, D. Such a resin is called a homogeneous microfilled resin by Lutz and Phillips.i4 In this type, microfiller particles of fumed silica are dispersed homogeneously in the organic phase; however, this type of composite resin has ceased to be further developed, remaining
HOSODA,
YAMADA,
AND INOKOSHI
Fig. 3. Schematicillustration of structure of composite resins. A, B, and C, “Traditional.” D, “Microfilled.” E, “Microfilled type.” F, “Submicrofilled type.” G, H, and I, “Hybrid.” J and K, “Hybrid type.” L and M, “Semihybrid” (heavily-filled).
Table
VI.
Type, elements Brand
detected,
name
Adaptic 2 Bis-Fil 1 Estilux Posterior Ful-Fil Heliomolar Heliomolar Radiopaque Cavifil Herculite Condensable Lite-Fil P Qcclusin (jar) Occlusin (syringe) Post-Corn11 LC P-30 (jar) P-30 (syringe) P-50 Clearfil PhotoPosterior Pyrofil Light Bond Posterior Sinter Fil P Visiomolar
674
and filler
contents
Type
Semihybrid Semihybrid Semihybrid Semihybrid MFR type Hybrid type Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Hybrid type Semihybrid
of light-cured
posterior
Elements detected
Si, Si, Si, Si, Si Si, Si, Si, Si, Si, Si, Si, Si, Si, Si, Si Si, Si
Al, Ba Al Al, Ba, Zr Al, Ba Yb Al, Al, Al, Al, Al, Al, Al, Zr Al,
Ba Ba, Zn Ba Ba Ba Ba, Zn Ba, Zn Ba
Al, Ba
composite
resins
Elements detected in each filler
(Si, (Si, (Si, (Si, (Si) W (Si, (Si, (Si, (Si, (Si) (Si, (Si, (Si, (Si) (Si) (Si) (Si)
Weight content
Al, Ba) Al) Al, Ba) (Si, Al, Zr) Al, Ba) W-9 Al, Ba) Al, Ba, Al, Ba) Al, Ba) (Si, Al, Al, Ba, Al, Ba, Zr) (Si, Al,
81.1 81.8 76.4 72.8 60.1 62.1 74.7 81.8 85.3 85.9 75.3 84.2 85.0 84.9 84.0 81.0 65.5 87.2
Zn) (Si, Al, Zn)
Ba) Zn) Zn) Ba)
(Si, Al, Ba)
DECEMBER
1990
filler (W)
VOLUME
64
NUMBER
6
8EM
STUDY
OF COMPOSITE
RESINS
in the experimental stage. This is because the incorporation of microfillers ranging from 0.06 to 0.04 pm into the organic phase is necessarily limited, and also because these microfillers increase the viscosity of the resin. This type of resin has not yet appeared on the market.i6 Its presumed pattern is shown in this study.
Microfilled type)
type
composite
resin
(MFR
A schematic representation of this pattern is shown in Fig. 3, E. This type was designated a heterogeneous microfilled composite resin with prepolymerized particles.13* l4 In this context, the authors call this type of resin “MFR type.” MFR and MFR type composite resins are thought to be similar, but are actually different. The filler particles are made of fumed silica dispersed in the organic phase and in prepolymerized complexes. The organic complexes appear to play the role of macrofiller particles as in traditional composite resins. They correct the disadvantages of decreasing filler content and increasing viscosity. The MFR type composite resins provides the best polishability of the composite resins. This type of composite resin should be indicated for class III and V cavities and for cervical lesions without occlusal loading. This type of composite resin is subcategorized into two groups due to the manufacturing method of producing organic complexes, splintered, and agglomerated prepolymerized complexes. SubmicrofilZed type composite resin (SFR type). A schematic structure of this type is presented in Fig. 3, F. The authors13* l4 decided to call this type of composite resin “SFR type,” since the filler particles are made up of spherical submicrofillers ranging from 0.3 to 0.2 lrn in size and splintered prepolymerized complexes that were made from the identical spherical submicronfillers.15 The splintered prepolymerized complexes appear to serve as macrofillers, with the same rationale as in the MFR type. This type of composite resin exhibits better polishability, indicating its use for class III and V cavities and cervical lesions.
Hybrid
composite
resin
A schematic presentation of the hybrid composite resin is given in Fig. 3, G through I. The first marketed brand of this type appears to be Miradapt composite resin (J & J, East Windsor, N. J.) (Fig. 2, A). The original meaning of “hybrid” is a cross between inorganic macrofillers and microfillers. Since most modern composite resins are loaded with microfiller particles to a greater or lesser degree, they must be hybrid. l7 The purpose of dispersion of the microfiller particles into the organic phase is to increase wear resistance by shortening the interparticle spaces and to protect sedimentation of heavier macrofiller particles. In the first materials such as Miradapt, untreated fumed silica with silane binders was probably used, but presently both
TEE
JOURNAL
OF PROSTHETIC
DENTISTRY
Table
VII.
Proposed categories of composite resins
1. Traditional composite resin (macro) (Fig. 3, A through C)
Traditional macrofiller 2. Microfilled composite resin (MFR) (Fig. 3, D)
Microfiller (0.06 to 0.04 pm) 3. Microfilled type composite resin (MFR type) (Fig. 3, E) a. Microfiller (0.06 to 0.04 km) Splintered microfilled complex b. Microfiller (0.06 to 0.04 pm) Agglomerated microfiller complex Submicrofilled type composite resin (SFR type) (Fig. 3,F) Submicrofiller (0.3 to 0.2 pm) Splintered submicrofilled complex Hybrid composite resin (Fig. 3, G through n Traditional macrofiller Microfiller (0.06 to 0.04 Frn) Hybrid type compositeresin a. Traditional macrofiller (Fig. 3, JI Microfiller (0.06 to 0.04 pm) Splintered microfilled complex b. Traditional macrofiller (Fig. 3, K) Microfiller (0.06 to 0.04 pm) Sphericalmicrofilled complex c. Traditional macrofiller Microfiller (0.06 to 0.04 pm) Agglomerated microfiller complex 7. Semihybrid or heavily-filled composite resin a. Traditional microfiller (50 to 0.1 rm) (Fig. 3, L) b. Traditional
small filler (6.5 to 0.1 pm) (Fig. 3, M)
untreated and treated fumed silica seem to be loaded together. Of the SEM composition images, fumed silica was not clearly demonstrated as a “hybrid composite” in Adaptic and Concise composite resins after 1982. Miradapt composite resin also falls into this category.
Hybrid
type composite
resin
A schematic structure of this type of composite resin is shown in Fig. 3, J and K. Since modern composite resins contain fumed silica particles, current composite resins must be hybrid, but microfiller particles cannot be clearly demonstrated on the SEM images of most composite resins. The prepolymerized microfiller complex particles can easily be demonstrated on the SEM pictures. Therefore the present investigators decided to call the resins making up both prepolymerized microfiller complexes and inorganic macrofiller particles “hybrid type;” this is demonstrated in Fig. 1, D through F. This type of composite resin is subcategorized into the three groups of splintered prepolymerized complex, spherical prepolymerized complex, or agglomerated microfiller complex. Representative products are Clearfil Posterior (Kuraray, Osaka, Japan), Visio-Dispers (Espe GmbH,
675
HOSODA,
Seefeld, W. Germany), and Pekalux (Bayer AG, Leverkusen, W. Germany). The Visio-Dispers composite resin was classified as a heterogeneous microfilled composite resin with agglomerated microfiller complexes. l4 In our study we observed the inorganic filler particles, dispersed in the matrix with agglomerated microfiller complexes (Fig. 1, E). This type may apparently be classified as a hybrid type composite resin. Pekalux was classified as a hetrogenous microfilled composite resin with spherical prepolymerized particles.14 In our study, inorganic filler particles were demonstrated in the spherical particles and in the matrix. This type should thus be classified as a hybrid type composite resin. The polishability of this type of composite resin falls between modern traditional and MFR type composite resins. Therefore this type of composite resin might be indicated for class II and IV cavities.
Semihybrid resin
or heavily-filled
composite
A schematic presentation of the structure of semihybrid composite resins appears in Fig, 3, L and M. With the development of manufacturing techniques to crush or pulverize the larger pieces of inorganic materials, the size of filler particles has become smaller, as can be appreciated in Fig. 2, A through D. In this composite resin, smaller filler particles apparently assume the role of microfiller particles. This type may be called “semihybrid composite resin” or “heavily-filled composite resin.” This composite resin may be divided into two groups based on the size and distribution of the filler particles: traditional macrofillers ranging from 50 to 0.1 pm, and traditional small fillers ranging from 6 or 5 to 0.1 pm. Most current posterior composite resins conform to this pattern. The composite resins used in this study were divided into seven categories. The resin types are listed in Tables IV through VI.
Weight
of fillers
Weight of the filler contents of most traditional composite resins was generally less than 80% ; weight of the filler contents of the MFR type was around 50% ; the weight of the filler contents of the SFR type was around 65%. With the hybrid type, weight of the filler contents was relatively high in comparison with the MFR type composite resins, but varied depending upon the individual filler components. With semihybrid, weight of the filler contents of posterior composite resins was higher than 80%. The higher content provides a higher wear resistance compared with the anterior composite resins of this type.
676
YAMADA,
AND
INOKOSHI
With respect to the elemental composition of filler particles, only Si was detected in quartz, prepolymerized microfiller complexes, and in some kinds of glass. Other heavy metal elements were detected in some kinds of glass and ceramic filler particles; their purpose was to create radiopacity.
CONCLUSION Current commerically available composite resins were examined with the SEM and the elemental composition of their filler particles was analyzed with the EDX. Based on these results, the composite resins have been divided into seven groups (Fig. 3, Table VII). Characteristics of each group are described, with clinical indications for selective use of respective composite resins in clinical applications.
REFERENCES 1. Buonocore MG. A simple method of increasing the adhesion of acrylic filling materials to enamel surface. J Dent Res 1955;34:849-53. 2. Craig RG. Chemistry, composition, and properties of composite resins. Dent Clin North Am 1981;25:219-39. 3. Fusayama T, Nakamura M, Kurosaki N, Iwaku M. Non pressure adhesion of a new adhesive restorative resin. J Dent Res 1979;58:1364-70. 4. Nakabayashi N. Bonding of restorative materials to dentin: the present status in Japan. Int Dent J 1985;35:145-54. 5. Bowen RL. Bonding of restorative materials to dentin: the present status in the United States. Int Dent J 1985;35:155-9. 6. Asmussen E, Munksgaard EC. Bonding of restorative resins to dentin promoted by aqueous mixtures of aidehydes and active monomers. Int Dent J 1985;35:160-5. 7. Norden R. Bonding of restorative materials to dentin: the present status in the Federal Republic of Germany. Int Dent J 1985;35:166-72. 8. Stanford JW. Bonding of restorative materials to dentin. Int Dent J 1985;35:133-8. 9. Stanford JW, Sabri Z, Jose S. A comparison of the effectiveness of dentin bonding agents. Int Dent J 1985;35:139-44. 10. Yearn JA. Factors affecting cure of visible light activated composite. Int Dent J 1985;35:218-25. 11. American Dental Association. Specification No. 27 for direct filling resins. J Am Dent Assoc 1977;94:1191-4. 12. Federation Dent&e Internationale. Dental resin-based restorative materials (IS0 4049). 1985. 13. Lutz F, Setcos JC, Phillips RW, RouIet JF. Dental restorative resinstypes and characteristics. Dent Clin North Am 1983;27:697-712. 14. Lutz F, Phillips RW. A classification and evaluation of composite resin. J PROSTHEZ DENT 1983;50:430-8. 15. Tani Y. Posterior composite resin dental restorative materials. Utrecht, The Netherlands: Peter SzuIc Publishing Co, 1985:185-97. 16. Asmussen E, Jorgensen KD. Fatique strength of some resinous materials. Stand J Dent Res 1982;90:76-9. 17. Craig RG. Posterior composite resin dental restorative materials. Utrecht, The Netherlands: Peter SzuIc Publishing Co, 1985:199-2X Reprint
requests
to:
DR. H. HOSODA TOKYO MEDICAL AND DENTAL UNIVERSITY FACULTY OF DEWTISTFIY ~-CHOWS, 5-45, YUSHIMA, BIJNKYO-KU TOKYO 113 JAPAN
DECEMBER
lB90
VOLUME
64
NUMBER
6
analysis of composite resins
Hosoda, D.D.S., PhD.,+ Toshimoto Inokoshi, D.D.S., Ph.D.**
Medical
and
Dental
University,
School
Yamada,
of Dentistry,
Tokyo,
D.D.S., Ph.D.,**
and
Japan
Twenty-four chemically cured, 21 light-cured anterior, three light-cured anterior/ posterior, and 18 light-cured posterior composite resins were examined using scanning electron microscopy, and the elemental composition of their filler particles was analyzed with an energy dispersive electron probe microanalyzer. According to the results obtained, the composite resins were divided into 5ve groups (traditional, micro5lled type, submicro5lled type, hybrid type, and semihybrid), with two additional hypothetical categories (microfilled and hybrid). Characteristics of each type were described with clinical indications for selective guidance of respective composite resins for clinical use. (J PROSTHET DENT 1990;64:669-76.)
R
estorative composite resins have been widely used by most dentists for restoring anterior cavitities.The use of these materials in posterior teeth has spread dramatically in the past few years because patients and dentists have sought better esthetics, and concern about mercury pollution has reduced the use of amalgam restorations. In the past two decades, composite resin therapy has advanced as a result of acid-etching, improvement in filler particles and base resins, bonding agents, and polymerization methods.1*10 As a result of these developments and improvements, the American Dental Association (ADA) described two categories of direct filling resins in specification No. 27.” The Federation Dentaire Internationale (FDI) also proposed a classification in IS0 4049.12 These classifications do not provide information for predicting the clinical performance of composite resins. Lutz et all3 and Lutz and Phillips14 have proposed a more detailed classification based on the current state of the art. They presented data for selecting a composite resin based on existing research results This classification, however, was primarily for anterior composite resins, since the posterior composite resins were just emerging. Some composite resins not yet commercially available were also studied. This study examined composite resins by scanning electron microscopy (SEM) and by qualitative analysis (EDX) in order to obtain an understanding for the appropriate selection of composite resins for clinical use.
The composite resin specimens used for EDX analysis were repolished with diamond paste to remove the carbon coating. After vapor-coating with gold, the polished surfaces were examined in the SEM with the back-scattered electron images under 500 power magnification.
MATERIAL AND METHODS Composite resins examined
RESULTS Weight filler contents of resins
Sixty-six commercially available composite resins were used, which included 24 chemically-cured composite resins (Table I), 21 light-cured anterior composite resins, three
The filler contents of the composite resins are listed in Tables IV through VI. The traditional composite resins showed high inorganic contents ranging from 70% to 80 % . The microfilled composite resins indicated relatively looser quantities around 50%. The heavily filled composite resins exhibited approximately 85 % inorganic contents. The filler contents of the others varied from 60% to 80%.
*Professor **Lecturer,
and Chairman, Department
Department of Operative
of Operative Dentistry.
10/l/21276
TEE
JOURNAL
OF PROSTHETIC
DENTISTRY
Dentistry.
light-cured anterior and posterior composite resins (Table II), and 18 light-cured posterior composite resins (Table III). The weight filler contents were determined for individual materials by ashing at 570” C in air.
Qualitative
analysis
The composite resin specimens, 5 mm in diameter and 2 mm thick, made according to the manufacturer’s instructions, were partially embedded in a cold-curing epoxy resin and stored in water at 37” C for 1 week. The surfaces of the composite resins were finished with water-proof siliconecarbide paper and were polished with diamond paste. After vapor-coating with carbon, the surfaces were qualitatively analyzed with EDX (SED-880, Seiko EG & G, Tokyo, Japan) under 500 power magnification for various elements, heavier than Ne, present on the surfaces of the specimens. When a few filler particles, different in shape and shade, were observed under the SEM, the energy spectra of elements present in the individual fillers were obtained under 3000 through 5000 power magnification.
SEM observation
669
HOSODA,
Table
I.
Anterior
name
Adaptic before 1982* Adaptic Radiopaque* before 1982 Adaptic after 1982 Adaptic Radiopaque after 1982 Bell Feel Anterior Clearfil Clear61 Clearfil Concise Concise
F* FII F3 before 1982* after 1982
Miradapt
Posterior
Bell
Bond
Feel
Anterior
& posterior
products
Elements
are not currently
Posterior
INOEOSHI
St. Paul,
Minn.
Tokyo,
Japan
Post-ComII*
Microrest Palfique
Tokuyama Soda, Tokuyama, Japan
commercially
AP
available
GC, Tokyo,
CU-2422, CC-2322 FU-1222, FC-1122 TJU-412, TJC-412 lM75, lN75 4MlH, 4J2H 025185 3D906 AUOl, AC01 3H1,3Jl 17348 PU-2229, PC-2129 KC-0102, KU-0202 5604.83, 5704.83 2272,2002 PUO2, PC01 840917PPU 84083OPPC
Kuraray Kuraray Vivadent 3M Sankin Pentron,
AG
Wallingford,
No.
4GO42 SA102,8B102 4B002,4COO2 4M303 lDF61
Kanebo
Conn.
Japan
080341 ASlO, C368
in Japan.
of fillers
The elements detected in the polished composite resin surfaces and filler particles that differed in shape and shade are shown in Tables IV through VI. Only Si appeared in the traditional composite resins (except for Adaptic Radiopaque, J&J, East Windsor, N.J.) and the microfiller-filled composite resins. Al, Ba, Zr, La, Ti, Zn, and/or Yb appeared in the other resins. The filler particles having radiopacity contained Ba, Al, Zr, Zn, and/or Yb.
Composition
J&J, East Windsor, N.J. J&J J&J J&J Kanebo, Tokyo, Japan Kuraray, Osaka,Japan Kuraray Kuraray
Sankin, 3M
Clearfil Posterior Clearfil Posterior 3 Isomolar P-10 Pyrofil Bond Posterior
Anterior
Lot
Vivadent AG, Schasn,Liechtenstein Bayer AG, Leverkusen, W. Germany J&J
Lumicon* Pyrofil Silar
Manufacturer
3M, 3M
Isopast
SEM images
The composition SEM images of the polished surfaces produced by using back-scattered electrons were divided into the five groups according to the filler type and their distribution. One of the traditional composite resins is presented in Fig. 1, A. Angular quartz filler particles, both large and small, were distributed in the matrix. One of the microfiller-filled composite resins is shown in Fig. 1, B. The angular-splintered microfiller complexes of various sizes were incorporated in a microfiller-reinforced matrix. In Fig. 1, C, the angular-splintered prepolymerized complexes making up spherical submicron-filler particles are added to a submicron-filler reinforced organic matrix.15 670
AND
Chemically-cured composite resins examined Brand
*These
YAMADA,
In Fig. 1, D and E, the angular-splintered prepolymerized or agglomerated microfilled complexes and the inorganic filler particles of various sizes are distributed in a microfiller-reinforced composite resin matrix. In Fig. 1, F, the spherical microfilled complexes and the inorganic filler particles are observed in a microfiller-reinforced matrix. In Fig. 2, macrofillers of various sizes of identical or different composition were admixed with an organic matrix reinforced by pyrogenic silica. The size of macrofillers tended to decrease, as shown in Fig. 2. This is most noticeable in Fig. 2, D, where the sizes of macrofillers are approximately or less than 1 pm.
DISCUSSION The composite resins in this study were divided into five groups, with an additional two hypothetical categories, by precisely observing the filler particle shape and its distribution, as exhibited on the SEM composition images. Another categorization approach was to review data of the manufacturing technique (Fig. 3 and Table VII).
Traditional
composite
resin
A schematic representation of traditional composite resin structure is shown in Fig. 3, A through C. The traditional macrofiller particles are mechanically made from DECEMBER
1990
VOLUME
64
NUMBER
6
SEM STUDY
Table
II.
OF COMPOSITE
Light-cured
RESINS
anterior
and anterior Brand
Anterior
Anterior
*This tThis
Table
& posterior
product product
III.
Manufacturer
JOURNAL
Lot
Bell Feel LX Bis-Fil M Brilliant Lux Command Ultrafine Durafil Fotofil* Glar Heliosit Lite-Fil A Lumifor Opalux Panagraf LCR Pekalux PhotoClearfil Bright Plurafil Super? Prisma-Fil Pyrofil Light Bond Anterior Silux Starfil Valux Visio-Dispers
Kanebo, Tokyo, Japan Bisco, Lombard, Ill. Coltene, Altstiten, Switzerland Kerr, Romulus, Mich. Kultzer, Friederichsdorf, W. Germany J&J, East Windsor, N.J. Teledyne-Getz, Elk Grove Village, Ill. Vivadent AG, Schaan, Liechtenstein Shofu, Kyoto, Japan Bayer AG, Leverkusen, W. Germany I.C.I. Macclesfield, Cheshire, U.K. Den-Mat, Santa Maria, Calif. Bayer AG Kuraray, Osaka, Japan Litema, Baden-Baden, W. Germany L.D. Caulk, Milford, Del. Sankin, Tokyo, Japan 3M, St. Paul, Minn. Kultzer 3M Espe GmbH, Seefeld/Oberbayern, W. Germany
6110-l
Palfique Light Palfique Light-S PhotoClearfil A
Tokuyama Soda, Tokuyama, Japan Tokuyama Soda Kuraray
LL402
Light-cured
posterior
composite
No.
082985 310784-16 63175 124 7G803 25095 030682 018401
659012-260885 AH130DEC85 3006 60250 100181 20586 4BCl 170 6G2 0055
us201 1050
resins examined
name
Manufacturer
are not currently
commercially
J&J, East Windsor, N.J. Bisco, Lombard, Ill. Kultzer, Friederichsdorf, W. Germany L.D. Caulk, Milford, Del. Vivadent AG, Schaan, Liechtenstein Vivadent AG Kerr, Romulus, Mich. Shofu, Kyoto, Japan I.C.I. Macclesfield, Cheshire, England I.C.I. Macclesfield Pentron, Wallingford, Conn. 3M, St. Paul, Minn. 3M 3M Kuraray, Osaka, Japan Sankin, Tokyo, Japan Teledyne-Getz, Elk Grove Village, Ill. Espe GmbH, Seefeld/Oberbayern, W. Germany available
OF PROSTHETIC
DENTISTRY
Lot
No.
5H5101 053185 169 0411862 341801 336501 61219 98301 LHC6 BOO33197 010485-41
4MlP 6P30 72P HPS-1001 177-806 40666 0002
in Japan
larger blocks of quartz and/or glass containing heavy radiopaque metals. The size of the filler particles ranges from 100 to 1 Mm. The currently used traditional composite resins show a definite trend to use smaller and rounded macrofiller particles. With modern resins of this type, the TEE
resins examined
name
Adaptic 2* Bis-Fil 1 Estilux Posterior Ful-Fil Heliomolar Heliomolar Radiopaque Cavifil Herculite Condensable Lite-Fil P Occlusin Qar) Occlusin (syringe) Post-Corn11 LC* P-30 (jar) P-30 (syringe) P-50 Clearfil PhotoPosterior Pyrofil Light Bond Posterior Sinter Fil P Visiomolar products
composite
is not currently commercially available. is visible and ultraviolet light-cured.
Brand
*These
and posterior
average particle size is generally range of 30 to 5 pm to about 5 macrofiller particles still results in spite of the change in filler With Adaptic and Concise
reduced from the original to 1 prn.15 Incorporation of in an unsatisfactory finish size. (3M Co., St. Paul, Minn.) 671
HOSODA,
Fig. 1. SEM images of composite Clearfil Posterior. E, Visio-Dispers.
Table
IV.
Type, elements
detected, Brand
Anterior
Posterior
Anterior
672
& posterior
and filler
resins. A, Adaptic F, Pekalux.
contents
name
of chemically Type
YAMADA,
after 1982. B, Silar. C, Palfique.
cured composite Elements detected
Adaptic before 1982 Adaptic Radiopaque before 1982 Adaptic after 1982 Adaptic Radiopaque after 1982 Bell Feel Anterior Clearfil F Clearfil FII Clearfil F3 Concise before 1982 Concise after 1982 Isopast Lumicon Miradapt Pyrofil Bond Anterior Silar
Macro Macro Macro Macro Semihybrid Macro Macro Hybrid type Macro Macro MFR type Semihybrid Semihybrid Semihybrid MFR type
Si Si, Si Si, Si Si Si Si Si Si Si Si, Si, Si Si
Bell Feel Posterior Clearfil Posterior Clearfil Posterior 3 Isomolar P-10 Pyrofil Bond Posterior Post-Corn11
Semihybrid Hybrid type Hybrid type MFR type Semihybrid Semihybrid Semihybrid
Si, Si, Si, Si Si Si Si,
Microrest AP Palfique
MFR type SFR type
Si SI, Ti
AND
D,
resins Elements detected in each filler
Weight content
(Si) Al, Ba Al, Ba
Al Al, Ba
Zr Al, Zr, La Al, Zr, La
Al, Ba
INOKOSHI
(Si) (Si) (Si) W (Si) (Si) (Si) (Si) (Si) (Si) (Si) (Si, (Si) (Si)
filler (70)
78.4 77.3 75.4
(Si, Al, Ba) (Si, Al, Ba)
17.5
(Si) (Si)
78.5 74.8 76.2 74.4
(Si, Al) Al, Ba)
80.4 37.4 77.5 81.2
79.3
(8%) (Si, (Si) (Si) (8%) (Si) (Si) W (Si) (Si) (Si,
7‘9.4 49.4 Zr) (Si, Al, Zr, La) (Si, Al, Zr, La)
80.3 80.2 83.0 62.2 83.3 83.1 75.4
Al, Ba)
(Si) (Si, Ti) DECEMBER
46.4 65.8
lSS0
VOLUME
64
NUMBER
6
SEM STUDY
OF COMPOSITE
RESINS
Fig. 2. SEM images of composite Herculite Condensable.
Table
V. Type,
elements
detected, Brand
Anterior
Anterior
& posterior
and filler
resins. A, Miradapt.
contents
name
of light-cured
THE
JOURNAL
anterior
Bell Feel LX Bis-Fil M Brilliant Lux Command Ultrafine Durafil Fotofil Glar Heliosit Lite-Fil A Limifor Opalux Panagraf LCR Pekalux PhotoClearfil Bright Plurafil Super Prisma-Fil Pyrofil Light Bond Anterior Silux Starfil Valux Visio-Dispers
Semihybrid Hybrid type Semihybrid Semihybrid Hybrid type Semihybrid Semihybrid MFR type Semihybrid Semihybrid Semihybrid Semihybrid Hybrid type Hybrid type Hybrid type Semihybrid Semihybrid MFR type Semihybrid Semihybrid Hybrid type
Si Si, Si, Si, Si Si, Si, Si Si Si, Si, Si, Si, Si Si, Si, Si Si Si, Si Si,
Palfique Light Palfique Light-S PhotoClearfil A
SFR type SFR type Semihybrid
Si, Ti Si, Zr Si
OF PROSTHETIC
DENTISTRY
and anterior
Elements detected
TYPO
composite resins after 1982, microfiller particles, presumed to be fumed silica dispersed in a matrix phase, are not clear on the SEM composition images obtained in this study. Lutz et a1.13 and Lutz and PhillipsI have previously reported the presence of this element. However, some composite resins with the same name differ from country to country and from one time to another.
B, PhotoClearfil
Al Al, Ba Al, Ba Al, Ba, Zn Al, Ba
Al, Ba Al Al, Ba Al Al, Ba Al, Ba
Al, Ba, Zn, Zr Al
Microfilled
A. C, P-50. D,
and posterior
composite
Elements detected in each filler
(Si) (Si) (Si, Al) (Si, Al, Ba) (Si, Al, Ba) (Si) (Si) (Si, Al, Ba) (Si) (Si, Al, (Si) (Si) (Si, Al, Ba) (Si, Al) (Si, Al) (Si, (Si) (Si, Al) (Si) (Si) (Si, Al, Ba) (Si, Al, Ba) (Si) (Si) (Si, Al, Ba) CW (Si) (Si, Al)
Weight content
(Si, Al, Zn) Ba)
Al, Ba)
(Si, Al, Zn, Zr)
(Si, Ti) (Si, Zr) (Si)
composite
resins filler (%)
80.6 65.2 74.2 75.1 56.2 80.0 79.9 37.3 80.8 75.9 85.1 78.8 33.3 66.6 60.7 75.6 80.0 52.6 74.8 76.8 60.0 66.7 67.5 83.2
resin
(MFR)
A schematic presentation of this type of composite resin is shown in Fig. 3, D. Such a resin is called a homogeneous microfilled resin by Lutz and Phillips.i4 In this type, microfiller particles of fumed silica are dispersed homogeneously in the organic phase; however, this type of composite resin has ceased to be further developed, remaining
HOSODA,
YAMADA,
AND INOKOSHI
Fig. 3. Schematicillustration of structure of composite resins. A, B, and C, “Traditional.” D, “Microfilled.” E, “Microfilled type.” F, “Submicrofilled type.” G, H, and I, “Hybrid.” J and K, “Hybrid type.” L and M, “Semihybrid” (heavily-filled).
Table
VI.
Type, elements Brand
detected,
name
Adaptic 2 Bis-Fil 1 Estilux Posterior Ful-Fil Heliomolar Heliomolar Radiopaque Cavifil Herculite Condensable Lite-Fil P Qcclusin (jar) Occlusin (syringe) Post-Corn11 LC P-30 (jar) P-30 (syringe) P-50 Clearfil PhotoPosterior Pyrofil Light Bond Posterior Sinter Fil P Visiomolar
674
and filler
contents
Type
Semihybrid Semihybrid Semihybrid Semihybrid MFR type Hybrid type Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Semihybrid Hybrid type Semihybrid
of light-cured
posterior
Elements detected
Si, Si, Si, Si, Si Si, Si, Si, Si, Si, Si, Si, Si, Si, Si, Si Si, Si
Al, Ba Al Al, Ba, Zr Al, Ba Yb Al, Al, Al, Al, Al, Al, Al, Zr Al,
Ba Ba, Zn Ba Ba Ba Ba, Zn Ba, Zn Ba
Al, Ba
composite
resins
Elements detected in each filler
(Si, (Si, (Si, (Si, (Si) W (Si, (Si, (Si, (Si, (Si) (Si, (Si, (Si, (Si) (Si) (Si) (Si)
Weight content
Al, Ba) Al) Al, Ba) (Si, Al, Zr) Al, Ba) W-9 Al, Ba) Al, Ba, Al, Ba) Al, Ba) (Si, Al, Al, Ba, Al, Ba, Zr) (Si, Al,
81.1 81.8 76.4 72.8 60.1 62.1 74.7 81.8 85.3 85.9 75.3 84.2 85.0 84.9 84.0 81.0 65.5 87.2
Zn) (Si, Al, Zn)
Ba) Zn) Zn) Ba)
(Si, Al, Ba)
DECEMBER
1990
filler (W)
VOLUME
64
NUMBER
6
8EM
STUDY
OF COMPOSITE
RESINS
in the experimental stage. This is because the incorporation of microfillers ranging from 0.06 to 0.04 pm into the organic phase is necessarily limited, and also because these microfillers increase the viscosity of the resin. This type of resin has not yet appeared on the market.i6 Its presumed pattern is shown in this study.
Microfilled type)
type
composite
resin
(MFR
A schematic representation of this pattern is shown in Fig. 3, E. This type was designated a heterogeneous microfilled composite resin with prepolymerized particles.13* l4 In this context, the authors call this type of resin “MFR type.” MFR and MFR type composite resins are thought to be similar, but are actually different. The filler particles are made of fumed silica dispersed in the organic phase and in prepolymerized complexes. The organic complexes appear to play the role of macrofiller particles as in traditional composite resins. They correct the disadvantages of decreasing filler content and increasing viscosity. The MFR type composite resins provides the best polishability of the composite resins. This type of composite resin should be indicated for class III and V cavities and for cervical lesions without occlusal loading. This type of composite resin is subcategorized into two groups due to the manufacturing method of producing organic complexes, splintered, and agglomerated prepolymerized complexes. SubmicrofilZed type composite resin (SFR type). A schematic structure of this type is presented in Fig. 3, F. The authors13* l4 decided to call this type of composite resin “SFR type,” since the filler particles are made up of spherical submicrofillers ranging from 0.3 to 0.2 lrn in size and splintered prepolymerized complexes that were made from the identical spherical submicronfillers.15 The splintered prepolymerized complexes appear to serve as macrofillers, with the same rationale as in the MFR type. This type of composite resin exhibits better polishability, indicating its use for class III and V cavities and cervical lesions.
Hybrid
composite
resin
A schematic presentation of the hybrid composite resin is given in Fig. 3, G through I. The first marketed brand of this type appears to be Miradapt composite resin (J & J, East Windsor, N. J.) (Fig. 2, A). The original meaning of “hybrid” is a cross between inorganic macrofillers and microfillers. Since most modern composite resins are loaded with microfiller particles to a greater or lesser degree, they must be hybrid. l7 The purpose of dispersion of the microfiller particles into the organic phase is to increase wear resistance by shortening the interparticle spaces and to protect sedimentation of heavier macrofiller particles. In the first materials such as Miradapt, untreated fumed silica with silane binders was probably used, but presently both
TEE
JOURNAL
OF PROSTHETIC
DENTISTRY
Table
VII.
Proposed categories of composite resins
1. Traditional composite resin (macro) (Fig. 3, A through C)
Traditional macrofiller 2. Microfilled composite resin (MFR) (Fig. 3, D)
Microfiller (0.06 to 0.04 pm) 3. Microfilled type composite resin (MFR type) (Fig. 3, E) a. Microfiller (0.06 to 0.04 km) Splintered microfilled complex b. Microfiller (0.06 to 0.04 pm) Agglomerated microfiller complex Submicrofilled type composite resin (SFR type) (Fig. 3,F) Submicrofiller (0.3 to 0.2 pm) Splintered submicrofilled complex Hybrid composite resin (Fig. 3, G through n Traditional macrofiller Microfiller (0.06 to 0.04 Frn) Hybrid type compositeresin a. Traditional macrofiller (Fig. 3, JI Microfiller (0.06 to 0.04 pm) Splintered microfilled complex b. Traditional macrofiller (Fig. 3, K) Microfiller (0.06 to 0.04 pm) Sphericalmicrofilled complex c. Traditional macrofiller Microfiller (0.06 to 0.04 pm) Agglomerated microfiller complex 7. Semihybrid or heavily-filled composite resin a. Traditional microfiller (50 to 0.1 rm) (Fig. 3, L) b. Traditional
small filler (6.5 to 0.1 pm) (Fig. 3, M)
untreated and treated fumed silica seem to be loaded together. Of the SEM composition images, fumed silica was not clearly demonstrated as a “hybrid composite” in Adaptic and Concise composite resins after 1982. Miradapt composite resin also falls into this category.
Hybrid
type composite
resin
A schematic structure of this type of composite resin is shown in Fig. 3, J and K. Since modern composite resins contain fumed silica particles, current composite resins must be hybrid, but microfiller particles cannot be clearly demonstrated on the SEM images of most composite resins. The prepolymerized microfiller complex particles can easily be demonstrated on the SEM pictures. Therefore the present investigators decided to call the resins making up both prepolymerized microfiller complexes and inorganic macrofiller particles “hybrid type;” this is demonstrated in Fig. 1, D through F. This type of composite resin is subcategorized into the three groups of splintered prepolymerized complex, spherical prepolymerized complex, or agglomerated microfiller complex. Representative products are Clearfil Posterior (Kuraray, Osaka, Japan), Visio-Dispers (Espe GmbH,
675
HOSODA,
Seefeld, W. Germany), and Pekalux (Bayer AG, Leverkusen, W. Germany). The Visio-Dispers composite resin was classified as a heterogeneous microfilled composite resin with agglomerated microfiller complexes. l4 In our study we observed the inorganic filler particles, dispersed in the matrix with agglomerated microfiller complexes (Fig. 1, E). This type may apparently be classified as a hybrid type composite resin. Pekalux was classified as a hetrogenous microfilled composite resin with spherical prepolymerized particles.14 In our study, inorganic filler particles were demonstrated in the spherical particles and in the matrix. This type should thus be classified as a hybrid type composite resin. The polishability of this type of composite resin falls between modern traditional and MFR type composite resins. Therefore this type of composite resin might be indicated for class II and IV cavities.
Semihybrid resin
or heavily-filled
composite
A schematic presentation of the structure of semihybrid composite resins appears in Fig, 3, L and M. With the development of manufacturing techniques to crush or pulverize the larger pieces of inorganic materials, the size of filler particles has become smaller, as can be appreciated in Fig. 2, A through D. In this composite resin, smaller filler particles apparently assume the role of microfiller particles. This type may be called “semihybrid composite resin” or “heavily-filled composite resin.” This composite resin may be divided into two groups based on the size and distribution of the filler particles: traditional macrofillers ranging from 50 to 0.1 pm, and traditional small fillers ranging from 6 or 5 to 0.1 pm. Most current posterior composite resins conform to this pattern. The composite resins used in this study were divided into seven categories. The resin types are listed in Tables IV through VI.
Weight
of fillers
Weight of the filler contents of most traditional composite resins was generally less than 80% ; weight of the filler contents of the MFR type was around 50% ; the weight of the filler contents of the SFR type was around 65%. With the hybrid type, weight of the filler contents was relatively high in comparison with the MFR type composite resins, but varied depending upon the individual filler components. With semihybrid, weight of the filler contents of posterior composite resins was higher than 80%. The higher content provides a higher wear resistance compared with the anterior composite resins of this type.
676
YAMADA,
AND
INOKOSHI
With respect to the elemental composition of filler particles, only Si was detected in quartz, prepolymerized microfiller complexes, and in some kinds of glass. Other heavy metal elements were detected in some kinds of glass and ceramic filler particles; their purpose was to create radiopacity.
CONCLUSION Current commerically available composite resins were examined with the SEM and the elemental composition of their filler particles was analyzed with the EDX. Based on these results, the composite resins have been divided into seven groups (Fig. 3, Table VII). Characteristics of each group are described, with clinical indications for selective use of respective composite resins in clinical applications.
REFERENCES 1. Buonocore MG. A simple method of increasing the adhesion of acrylic filling materials to enamel surface. J Dent Res 1955;34:849-53. 2. Craig RG. Chemistry, composition, and properties of composite resins. Dent Clin North Am 1981;25:219-39. 3. Fusayama T, Nakamura M, Kurosaki N, Iwaku M. Non pressure adhesion of a new adhesive restorative resin. J Dent Res 1979;58:1364-70. 4. Nakabayashi N. Bonding of restorative materials to dentin: the present status in Japan. Int Dent J 1985;35:145-54. 5. Bowen RL. Bonding of restorative materials to dentin: the present status in the United States. Int Dent J 1985;35:155-9. 6. Asmussen E, Munksgaard EC. Bonding of restorative resins to dentin promoted by aqueous mixtures of aidehydes and active monomers. Int Dent J 1985;35:160-5. 7. Norden R. Bonding of restorative materials to dentin: the present status in the Federal Republic of Germany. Int Dent J 1985;35:166-72. 8. Stanford JW. Bonding of restorative materials to dentin. Int Dent J 1985;35:133-8. 9. Stanford JW, Sabri Z, Jose S. A comparison of the effectiveness of dentin bonding agents. Int Dent J 1985;35:139-44. 10. Yearn JA. Factors affecting cure of visible light activated composite. Int Dent J 1985;35:218-25. 11. American Dental Association. Specification No. 27 for direct filling resins. J Am Dent Assoc 1977;94:1191-4. 12. Federation Dent&e Internationale. Dental resin-based restorative materials (IS0 4049). 1985. 13. Lutz F, Setcos JC, Phillips RW, RouIet JF. Dental restorative resinstypes and characteristics. Dent Clin North Am 1983;27:697-712. 14. Lutz F, Phillips RW. A classification and evaluation of composite resin. J PROSTHEZ DENT 1983;50:430-8. 15. Tani Y. Posterior composite resin dental restorative materials. Utrecht, The Netherlands: Peter SzuIc Publishing Co, 1985:185-97. 16. Asmussen E, Jorgensen KD. Fatique strength of some resinous materials. Stand J Dent Res 1982;90:76-9. 17. Craig RG. Posterior composite resin dental restorative materials. Utrecht, The Netherlands: Peter SzuIc Publishing Co, 1985:199-2X Reprint
requests
to:
DR. H. HOSODA TOKYO MEDICAL AND DENTAL UNIVERSITY FACULTY OF DEWTISTFIY ~-CHOWS, 5-45, YUSHIMA, BIJNKYO-KU TOKYO 113 JAPAN
DECEMBER
lB90
VOLUME
64
NUMBER
6
