Note: Descriptions are shown in the official language in which they were submitted.
CA 02254649 1998-11-19
Ion-releasinq com~osite material
The in~en.ti2n -el2t2s to composite mater als on the basis of one
or mo=e ncn-ac d, non-ion-c, hycrophilic c=osslinke-.,.onomers and
one or mor~ non-acid, non-ionic, hydrconilic dilu~-cr. monomers
ha~ing a viscosity of < 1 Pas, which are suitable in ?zrticula-
as denta mzterizls.
Der.tal materi2ls which are capable of releasin ions, such as for
e.Y2mple fluorice, calcium or hydr~xide ions, in the oral c~vity
are inc=e2singly of interes~ because o~ their remine~ai zing,
bioactive and cariostatic action.
~estorati~e dental materials which display a c2ries-inhibiting
action because they contain sources of fluoride, such as special
chlorohexidine-fluoride compounds, are known e.g. f-om U. Salz,
Philli~ Journal 14 (19g7) 296.
Further examoles of ion-releasing dental materials are glass
ionomer c~ments and compomers whose organic matri:~ is made up at
least in part from acid monomers, ollgomers or polymers (A.D.
Wilson, J r,~. McLe2n, Glasionomer Cement, Quintessence ~ublishers,
Chic2go lS88; J. Nicholson, ~. Anstice, Trends Polym. Sci. 2
CA 022~4649 1998-11-19
(l~g4) 272; R. ~ickel, L. Kremers, C. Haffner, Quintessenz 47
~1996) 1581).
Glzss ionomer cements are water-containing, two-component cements
on the basis of polymeric organic acids such as for example
poly(acrylic acid) and powdery, solid bases such as calcium-
fluoride-aluminium silicate glasses. The curing of the cement
takes place through ionic reaction between polymer-bound COOH
groups and the calcium or aluminium ions emerging from the
filler, so that the components of the glass ionomer cement can
be mixed only shortly before use. This is laborious, and moreover
the inclusion of air is unavoidable in most cases, which
adversely affects the strength of the material. Because of their
poor bending strength, glass ionomer cements are not suitable for
occlusion-bearing fillings.
The term compomers is taken to mean compositions which are
composed of polymerizable acid monomers and ion-releasing glass
particles. They are anhydrous single-component systems which cure
through radical polymerization of the monomer matrix. Acid-base
reaction takes place to a small extent only when water is
absorbed in.3 the ~illing via saliva. The non-cu_ed materials are
moisture-sensitive, and uncontrolled contact with water, for
example during production or storage, leads to a premature curing
which makes the material unusable. Compomers have a greater
mechanical strength than glass ionomer cements, but frequently
display a smaller ion release.
Both glass ionomer cements and compomers generally display a high
ion-release capacity when the matrix of the materials has an
adequate hydrophilic character which encourages absorption of
water. In the case of glass ionomer cements, the matrix is formed
by polyalkene acids, whereas in the case of compomers it is above
all carboxylic acid-containing monomers that are used as matrix
CA 022~4649 1998-11-19
-- 3 --
materials. However, since a high water content or a high water
absorption has a disadvantageous effect on the mechanical
properties of polymers, it was not previously possible to produce
materials having a high ion-release capacity which simultaneously
display a hish mechanical strength.
EP 0 449 399 B1 discloses as underfilling materials suitable
composites on the basis of ion-releasing fillers and a mixture
of customary dental monomers, such as e.g. the dimethacrylate of
ethoxylated bisphenol-A, a hydrophobic dimethacrylate; with the
urethane dimethacrylate comprising 2-hydroxyethyl methacryla.e
and 2,2,4-trimethyl hexamethylene diisocyanate, which do not
contain acid monome-s but do display only a small ion release.
The object of the invention is to provide composite materials
ha~ing a high ion-release capacity and high mechanical strength
capacity which are storage-stable in the uncured state even under
moist conditions and whose mechanical properties are not
substantially impaired after curing by the addition of water.
This object is achieved by composite materials on the basis of
polymerizable mor.omers which a_e characterized in that the
material contains a mixture of
(a) at least one non-acid, non-ionic, hydrophilic crosslinker
monomer,
(b) at least one non-acid, non-ionic, hydrophilic dilution
monomer having a viscosity of < 1 Pas and
(c) at least one ion-releasing filler.
The term crosslinker monomers is taken to mean monomers which
contain at least two, preferably 2 to 4 groups capable of
polymerization per monomer molecule.
CA 022~4649 1998-11-19
The monome~s are hydrophilic, i.e. they are capable of hydro-
philic interactions with the filler. Monomers are preferred which
contain one or more, preferably 1 to 2 urethane and/or OH groups,
preferably OH groups. It was also found that these groups promote
ion transport or ion emission.
The term non-acid compounds is taken to mean monomers which carry
no strongly acidic groups such as carboxyl, phosphoric acid,
phosphonic acid, phosphinic acid or sulphonic acid groups and
which preferably also contain no weakly acid groups such as
phenolic OH groups or SH groups or CH-acid groups such as ~-
diketone or ~-diketoester groups.
Non-ionic monomers within the meaning of this invention are those
which contain no ionic groups such as cationic ammonium or
sulphonium groups or anionic acid residue groups of the strongly
acid groups named above.
Preferred crosslinker monomers are 2,2-bis-4-(3-methacryloxy-2-
hydroxypropyl)-phenylpropane) (bis-GL~), i.e. the reaction
product of glycidyl methacrylate and bisphenol-A (containing OH
groups), ~.c 7,7,9-t_-methyl-4,13-dioxo-3,14-diox2-5,12-d aza-
hexadecan-1,16-diyl-dimethacrylate (UD~A), i.e. the urethane
dimethacrylate comprising 2 moles of 2-hydroxyethyl methacrylate
(HEMA) and l mole of 2,2,4-trimethyl hexa-methylene diisocyanate
(containing urethane groups). Also preferred as crosslinker
monomers are reaction products of glycidyl methacrylate with
other bisphenols, such as e.g. bisphenol-B (2,2'-bis-(4-hydroxy-
phenyl)-butane), bisphenol-F (2,2~-methylene diphenyl) or 4,4'-
dihydroxydiphenyl)~ as well as reaction products of 2 mol HEMAor 2-hydroxypropyltmeth)-acrylate preferably with l mole of known
diisocyanates, such as e.g. hexamethylene diisocyanate, m-
xylylene diisocyanate or toluylene diisocyanate.
CA 022~4649 1998-11-19
The term dilution monomers is ta~en to mean monomers having a
viscosity of < l Pas, preferably < 100 mPas, ~Jhich are suitable
for diluting the generally highly viscous cross-linker monomers
and thus permit the production of composites with a high filler
content. The viscosity data relate to a temperature of 23~C.
The viscosity is measured by means of a plate or rotation
viscometer in accordance with DIN 53018.
The dilution monomers likewise contain at least two, preferably
two to three groups capable of polymerization and at least one,
preferably 1 to 2 OH and/or urethane groups, preferably OH
groups. They are non-ionic and non-acid compounds.
A particularly preferred dilution monomer is glycerol dimeth-
acrylate (GDMA). Other preferred dilution monomers can beproduced by reaction of low-viscosity di- or triepoxides, such
as for example ethylene glycol diglycidyl ethers, glycerol
triglycidyl ethers or trimethylolpropane triglycidyl ethers with
(meth)acrylic acid. Further preferred are also the reaction
products of 2 or 3 moles of methacrylic acid with glycerol
triglycidyl ether or trimethylolpropane triglycidyl ether. The
ter~ low-viscosity~l is taken to mean subs~ances having a
viscosity of < 200 mPas, preferably < 100 mPas (23~C).
Preferred groups capable of polymerization are, in the case of
both crosslinker monomers and dilution monomers, methacryl and/or
acryl groups, in particular methacryl groups.
To produce composite materials, crosslinker monomers and dilution
monomers are mixed with fillers, initiators for radical
polymerization and optionally other auxiliaries. Single-
component composite materials, i.e. composite materials which
contain all the necessary components, are preferred.
CA 022~4649 1998-11-19
The composite materials according to the invention preferably
have the following composition:
(a) 1 to 40 wt.-%, particularly preferably 10 to 30 wt.-% and
quite particularly preferably 15 to 25 wt.-% crosslinker
monomer;
(b) 2 to 40 wt.-%, particularly preferably 2 to 30 wt.-% and
quite particularly preferably 5 to 20 wt.-% dilution
monomer;
(c) 30.0 to 94.0 wt.-% filler;
(d) 0.01 to 5 wt.-%, particularly preferably 0.1 to 2.0 wt.-%
of an initiator for radical polymerization as well as
optionally other additives.
The filler content depends crucially on the intended use of the
composite material and is preferably 30 to 60 wt.-%, particularly
preferably 40 to 60 wt.-%, in the case of securing cements, and
60 to 94 wt.-%, preferably 70 to 85 wt.-%, in the case of filling
composites.
The composite materials preferably contain at least 5 wt.-%,
particularly preferably at least 10 wt.-% of hydr~xyl group-
containing monomers, i.e. monomers having at least one hydroxyl
group per monomer molecule.
The uncured materials can contain up to 1.0 wt.-% water without
the stability in storage of the materials or the mechanical
properties of the cured materials being impaired. This consider-
ably facilitates both the production and the processing of the
materials by the dentist or dental technician.
CA 022~4649 1998-11-19
The materials according to the invention preferably contain as
a maximum 2 wt.-~ of monofunctional monomers, i.e. ~onomers
having only one unsaturated group capable of polymerization, such
as for example 2-hydroxyethyl(meth)acrylate.
The known initiators for cold, hot and photocuring are suitable
as initiators for radical polymerization. Suitable initiators are
described for example in the Encyclopedia of Polymer Science and
Engineering, Vol. 13, ~iley-Intersci. Pub., New York etc. 1988,
pp. 754 et seq.
Preferred initiators are azo-compounds, such as azobis(iso-
butyronitrile) (AIBN) or azobis(4-cyanovaleric acid) or perox-
ides, such as dibenzoyl peroxide, dilauroyl peroxide, tert.-butyl
peroctoate,tert.-butylperbenzoateordi-(tert.-butyl)-peroxide.
Benzpinacol and 2,2'-di(C!-C8-alkyl)benzpinacols are particularly
suitable as initiators for hot curing.
Suitable photoinitiators for the W or visible range are
described by J.P. Fouassier, J.F. Rabek (Pub.), Radiation Curing
in Poly~er Science and Technolosy, Vol. II, Elsevier Applied
Science, London and New York 1993, pages 155 to 237. Preferred
photoinitiators are benzoin ethers, dialkyl benzil ketals,
dialkoxyacetophenones, acylphosphonic oxides, a-diketones, such
as 10-phenanthrene~uinone, diacetyl, furil, anisil, 4,4'-
dichlorobenzil and 4,4'-dialkoxybenzil and camphor quinone.
Dibenzoyl peroxide, camphor quinone and acylphosphinic oxides are
preferred for the production of dental materials.
Suitable as fillers are all the ion-releasing fillers known for
the production of glass ionomer cements. Fillers releasing Ca2,
F and/or OH ions, such as are described in the publications
CA 022~4649 1998-11-19
named above or in DE 39 41 629 and in US-A-4,814,362, are
preferred.
Particularly preferred fillers a~e glass powders of fluoro-
aluminium silicate glasses with an average particle size of 0.05to 15 ~m, preferably 0.5 to 5.0 ~m, which contain as principal
constituents silicon oxide, aluminium oxide and calcium oxide
(cf. A.D. ~ilson, J.W. ~cLean, Glasionomerzement, Quintessence
Verlags GmbH, Berlin 1988, pages 21 et seq.).
Preferred glasses are obtained by melting 25 to 45 wt.-~ SiOz, 15
to 40 wt.-% Al203, 0 to 10 wt.-~ AlF3, 0 to 30 wt.-% CaO, 0 to 10
wt.-% Na2O, 0 to 15 wt.-% CaF2, 0 to 15 wt.-% NaF and 0 to 25
wt.-% AlPO4.
A particularly preferred glass has the following composition: 25
wt.-% SiO2, 16.2 wt.-% Al20~, 8.8 wt.-% AlF3, 12.8 wt.-% NaF, 13
wt.-% CaF2 and 24.2 wt.-% AlPO~.
Dental materials which release calcium hydroxide or fluoride have
proved themselves in dentistry. Through the controlled emission
of calcium hydroxide and fluoride, the formatiGn of secondary
dentin is promoted and an alkalizing action vis-à-vis the pulpa
is achieved, which protects the latter against acids and
bacterial attacks.
Fillers which release alkaline ions are not compatible with acid
monomers, however, and bring about a spontaneous curing of the
matrix. Single-component composites which release calcium
hydroxide are therefore either not stable or display only a small
ion release when non-acid monomers are used.
The monomers used according to the invention contain no acid
groups and can therefore be combined with alkaline fillers
CA 022~4649 1998-11-19
without problems. They allow the production for the first time
of single-component composites which rele2se calcium hydroxide
and have a high ion-release capacity.
The term alkaline fillers is taken to mean fillers with alkaline
components such as CaO, Ca(OH) 2 or NazO which display an alkaline
reaction in comoination with water.
Preferred alkaline fillers are calcium hydroxide, calcium oxide
and in particular calcium hydroxide-releasing glasses, i.e.
glasses with a high calcium oxide content.
Glasses with a CaO content of at least 20 wt.-%, preferably 40
to 75 wt.-% and in particular 45 to 60 wt.% are preferred.
A preferred glass powder with a high calcium oxide content is
described in EP 0 449 399 B1 and contains 40 to 75 wt.-~,
preferably 45 to 60 wt.-% calcium oxide, 5 to 30 wt.-%, preferab-
ly 15 to 28 wt.-% boron oxide and 5 to 35 wt.-%, preferably 10
to 30 wt.-% silicon dioxide. The average particle size (weight
average) of the glass powder lies between 1 and 100 ~m, preferab-
ly 10 and 30 ~m.
Further preferred are transparent glasses with a high calcium and
fluoride ion emission, which contain the following components:
Component wt.-%
SiO2 24.0 to 56.0
CaO 26.0 to 57.0
F 4.0 to 14Ø
The transparent glasses used according to the invention preferab-
ly contain in addition at least one of the following components
CA 022~4649 1998-11-19
-- 10 --
.
Com~onent wt.-~
Na20 1.0 to 9.0
Bz03 1.0 to 14.0
~gO 1.0 to 14.0
SrO 1.0 to 12.0
ZnO 1.0 to 7.0
Alz03 0.5 to 5.0
ZrOz 0.5 to 4Ø
Preferred quantity ranges exist for the individual components of
the transparent glasses. These can be chosen independently of one
another and are as follows
ComPonent wt.-~
SiOz 30.0 to 54.0
in particular 36.0 to 54.0
CaO 32.0 to 50.0
F 5.0 to 12.0
Na20 1.0 to 8.0
B203 1.0 to 12.0
MgO 1.0 to 10.0
SrO 1.0 to 10.0
ZnO 1.0 to 5.0
Alz03 0.5 to 4.0
Zr~2 0.5 to 4Ø
Particularly preferred quantity ranges of the components of the
transparent glass, which can be chosen independently of one
another, are as follows
CA 022~4649 1998-11-19
-- 11 --
,
Com~onent wt.-%
SiO2 45.0 to 54.0
CzO 35.0 to 50.0
F 6.0 to 12.0
Na2O 4.0 to 7.0
Bz03 1.0 to 12.0
MgO 1.0 to 10.0
SrO 1.0 to 10.0
ZnO 1.0 to 5.0
Al2O~ 0.5 to 4.0
Zr~2 0.5 to 4Ø
All the quantities that are given above and in the following in
the description and in the claims of the components of the
transparent fluoride-containing glasses are to be understood as
values which were obtained as follows. The quantities of the
oxides were ascertained by quantitative determination of the
corresponding cations, i.e. Si, Ca, Na, B, Mg, Sr, Zn and Al, by
means of X-ray fluorescence analysis and conversion of the
obtained values into the quantities of corresponding oxides. Thus
the level of a cation serves as a basis for deducing the level
of the corresponding oxides. In contrast to this, the quantity
of F is determined directly by means of an electrode which is
selective for fluoride ions after the glass had been su~jected
to a soda-potash dissolution.
As a result of the high F-contents of the transparent glasses,
there is formation to a noticeable extent of fluorides, such as
e.g. CaF2, in the glass. Therefore, the calculated oxide
contents and accordingly the absolute oxygen content of the glass
are too high, and the sum of the components exceeds 100%. The
portion going beyond 100% is therefore shown as so-called
fluorine-equivalent oxygen~. This is customary for silicate
CA 022~4649 1998-11-19
- 12 -
glasses containing f'uoride and is described at length e.g. in
J. Lange "Rohstoffe der Glasindustrie", Deutscher Verlag fur
Grundstoffindustrie, Leipzig, Stuttgart (1933), pp. 221-223.
It is generally customary in glass manufacture to add small
quantities of fluoride as flux in order to improve the melting
behaviour of the glass in question. ~owever, the overall
structure of the glasses is not substantially changed by these
small portions of fluoride.
In contrast to thls, a high fluoride portion of at least 4,0 wt.-
% incorporated into the tr~nsparent glass used according to the
invention, which substantially changes the basic structure of the
glass compared with corresponding glasses which are free from
fluoride or have only small fluoride contents as a result of the
use of flux. A marked degradation of the SiO4 tetrahedron
network structure of the glass occurs because of this high
fluorine content and the simultaneous incorporation of other
network transfor~er ions, such as e.g. Ca or Na . A glass
structure forms which can no longer be explained by the classical
network theory. The glass structure comes close to a new glass
structure which is called "inverted glass structure". The ter~
inverted glass is taken to mean a glass which has less than 50
mol.-% network-former material.
As a result of the changed structure, it is above all the
refractive index of the glass which changes, and surprisingly an
emission of fluorine ions with a simultaneous emission of calcium
ions from the glass is also possible. When the composite material
is used in the dental field, the desired alkaline action can
therefore be brought about in the oral cavity by the calcium ions
together with carbonate in the saliva, and, through the fluorine
ions, their known remineralizing action. Calcium ions also
promote the remineralization process.
CA 022~4649 1998-11-19
- 13 -
Furthermore, the high fluoride content of the glass brings about
a marked reduction in its refractive index to values below 1.60
and preferably below 1.56. The organic matrix of the composite
forming th-ough curing of the polymerizable monomer hzs a very
similar refractive index, for which reason the whole composite
material can li~ewise be translucent or even transparent. This
is naturally of particular advantage if the composite material
is to be used for the production of visible dental restorations,
which naturally are to have similar optical properties to
translucent natural dental material.
To produce the transparent glass used according to the invention,
suitable raw materials, in particular oxides, carbonates and
fluorides, are mixed and melted at temperatures of in particular
1000 to 1500 ~C to form a glass. The glass melt that for~s is
then quenched by being poured into water. The obtained transpar-
ent glass frit is then ground, dried and can be combined with
polymerizable monomer to give the polymerizable composite
material according to the invention.
The glass is customarily used as powder, the average size of the
particles customarily being 1 to 100 ~m and preferably 10 to 30
~m relative to the number of particles.
The ion-releasing fillers named above can be combined with other
fillers, the proportion of ion-releasing fillers being at least
5 w..-%, preferably 15 to 70 wt.-%.
Particularly suitable as further filler components are amorphous,
spherical materials on the basis of mixed oxides from SiO2, ZrO2
and/or TiO~ having an average particle size of 0.005 to 2.0 ~m,
preferably of 0.1 to 1 ~m, such as are disclosed for example in
DE-PS 32 47 800, microfine fillers, such as pyrogenic silica or
precipitation silica as well as macro- or mini-fillers, such as
CA 022~4649 1998-11-19
- 14 -
quartz, glass ceramic or glass powder having an average particle
size of 0.01 to 20 ~m, p_efe=ably 0.5 to 5 ~m, as well as X-ray-
opaque fillers, such as ytterbium fluoride. The term mini-fillers
is taken to mean fillers having a particle size of 0.5 to 1.5 ~m
and the term macro-fillers to describe fillers having a particle
size of 10 to 20 ~m.
In addition, the compositions according to the invention can, in
case of need, contain further auxiliaries, in particular
stabilizers, W absorbers, dyestuffs, pigments and/or slip
agents. The term stabilizers is taken to mean those substances
which prevent a premature polymerization and thus above all
increase the stability in storage of monomer mixtures and
composites, without however impairing the properties of the cured
materials. Preferred stabilizers are hydroquinone mono-methyl
ether (MEHQ) and 2,6-di-tert.-butyl-4-methylphenol (BHT).
It was surprisingly found that, through the simultaneous use of
the crosslinker and dilution monomers named above, compositions
having a high ion-release capacity can be obtained which are
storage-stable in the uncured state even in moist conditions and
whose mechanical properties are not significantly worsened by the
addition of water. The monomer mixtures according to the
invention can be processed without problems with alkaline fillers
to produce single-component composites.
The invention is described further in the following with
reference to embodiments.
CA 02254649 1998-li-19
-- 15 --
ExamPles 1 to 5
As starting materials for the production of hydrophilic compos-
ites, monomer mixtures having the compositions given in Table 1
were produced and then processed to give the single-component
composite pastes shown in Table 2.
Table 1
Composition of the monomer mi~tures
Monomer M~xture (in mass-Z)
1 2') 3 4) 5
.
bis-G~A!) 39.0 42.0 42.0 42.0 42.0
UDMA2) 30.0 37.1 27.8 27.8 27.8
GDMA3) 30.0 _ 29.4
TEGDMA~) - 20.1 - 29.4
HE~As) _ _ _ - 29.4
Initiator/ 1.0 0.8 0.8 0.8 0.8
additives 6)
30 ) Comparative example
1) Bisphenol-A-glycidyl methacrylate (Esschem)
2) 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5,12-diazahexadecan-1,16-diyl-
dimethacrylate (Ivoclar)
3) Glycerol dimethacrylate (Rohm)
~) Triethylene glycol dimethacrylate (Esschem)
5) 2-hydroxyethyl methacrylate (Rohm)
6) Initiator:camphorquinone;accelerator:N-(2-cyanoethyl)-N-methylani
ine; inhibitor: hydroquinone monomethyl ether
. ~ . . . .
CA 022~4649 1998-11-19
Table 2
Composition of the composite pastes
Monomer Composlte (in mass-')
1 2') 3 4~) 5~)
~onomer mixturel) 22.0 22.1 22.3 22.3 22.3
Alkali glass, sil.2) 48.0 52.2
SP-2034, sil.3) 11.0 - 60.1 60.1 60.1
YbF74) 12.0 10.0 11.6 11.6 11.6
Aerosil-OX-50~, 4.0 3.8
silanized:)
Spharosil ~ sil .6) _ _ 6.0 6.0 6.0
HDK-20007) 3.0 2.4
8a-glass sil.a) - 9.5 - - -
(G~ 27884)
) The monomer mixtures listed in Table 1 were used. Composite 1 is based
on monomer mixture 1, etc.
2) Silanized alkaline glass with 47.4 wt.-Z SiO2, 39.8 wt.-~ CaO, 8.4 wt.-~
NazO, 7.6 wt.-Z F.
3) Silanized glass ionomer-fluorine-calcium-aluminium-silicate glass,
average grain slze 1.6 ~m.
4) Ytterbium fluoride (Rhdne-Poulenc)
s) Silanized pyrolysis silica (Degussa) primary particle size 40 nm, BET
surface 50 m2/g
6) Silanized Si02-ZrO2 mixed oxide (Tokoyama Soda), secondary particle size
< 7 ~m
7) Highly-dispersed precipitation silica (Wacker)
3) Silanized barium aluminium silicaee glass powder (Schatt), proportion
with a grain size of < 7 ~m: 99Z
CA 022~4649 1998-11-19
Testpieces were formed from the composite pastes in accordance
with ISO standard 4049 (1988), cured by irradiation with light
of a wavelength of 400-500 nm (2 x 3 minutes) and their mechan-
ical properties were then determined.
To establish the fluoride-release capacity, cured testpieces
(diameter = 20 mm, H = 1.5 mm) were stored in 30 ml of buffer
solution at 37~C in the agitator and the amount of released
fluoride was measured after specific intervals using a fluor-
electrode.
The results summarized in Table 3 show that the hydrophiliccomposite l, which contains no acid or ionic monomer components,
releases about ten times more fluoride ions within 28 days than
does Compoglass~, a compomer customary in the trade that is based
on COO~-acid monomers (filler: SP-2034 and YbF3). The fluoride-
ion release of composite 1 is thus of the same order as that of
glass ionomer cements (cf. e.g. Vivaglass~, glass ionomer cement
based on polyacrylic acid, filler: SP-2034 and YbF3).
However, composite 1 displays clearly better mechanical prop-
erties and a higher resistance to water than do the compomer and
the glass ionomer cement. Even six days' storage in water
followed by 24-hour boiling scarcely impair the mechanical
properties.
Uncured composite l was storage-stable under moist conditions
(30~ atmospheric humidity) over the 8-week investigation period.
If the hydrophilic GD~ in composite 1 is replaced by the
hydrophobic TEGDMA (composite 2), a clearly smaller fluoride
release is measured, although composite 2 contained, instead of
SP-2034, a greater proportion of alkaline glass which displays
a clearly higher fluoride release than SP-2034.
.. , . .,. . ,, _
CA 022~4649 l998-ll-l9
- 18 -
Composite 3 contains exclusively SP-2034 as ion-rele2sing filler.
Its fluoride release is comparable with that of Compoglzss~ but,
unlike Compoglass~, composite 3 is storage-st2ble in the uncured
state even under moist conditions.
s
In composite 4, GDMA was replaced by TEGDMA. As in the case of
composites 1 and 2, this replacement brings about a clear
reduction in fluoride release.
In composite 5, the hydrophilic but multifunctional ~E~A was used
instead of GDMA. Although composite 5 displays a clearly higher
fluoride release than does composite 4, the mechanical properties
are unsatisfactory after the addition of water.
Table 3
Mechanical properties of c~red coolposites
Propl!rly¦ Ca-posil: 1 ¦ CL.:poslle Z ¦ C~nposite 3 C~llposite 4 ¦ Ca posile S ¦ Calpo~l.ss~l ¦ Viy:gl~ssZ~ ¦
llend i ng s t reng t h3~
24 h - - 85 MPa 112 MPa 111 MPa - -
24 h H20 storage 122 MPa 136 MPa 92 MPa 100 MPa 100 MPa 91 MPa 28 0 MPa
L d llj~b stor:ge ~ 2411 boiling117 MP~ IôS IlPa - - - 73 PP- - o
7 d H20 slorage - - 75 MPa 103 MPa 77 MPa
Oending E-modulus31
24 h - - 11 3 GPa 9 7 GPa 10 6 GPa - -
24 h 1120 storage 11 4 GPa 11 1 GPa 11 5 GPa 9 3 GPa 9 5 Gl'a 8 6 CPa 2 0 GPa
6 d 1120 storage t 24 h boiling 11 3 GPa 8 2 GPa - - - 10 l GPa
7d 1120 storage - - 9 7 GPa 9 7 GPa 7 8 GPa
E rele.se'l ¦ 2185l ¦ 124 1 ¦Ib 9-1 ¦3 Iq ¦~2 2 1 ¦ 22q ¦ 24
,,
CA 02254649 1998-11-19
- 20 -
,
I) Compomer on acid monomer basis, filler SP-2034, silanized (Vivadent)
2) Glass ionomer cement on the basis of polyacrylic acid, filler SP-2034
~Vivadent)
3) Determined in accordance with IS0 standard 4049(1988) after the times
given in the table
Cumulative fluorlde release after 28 days, given in ~glcm2
S) Measured in lactate buffer, 37~C
6) Measured in tris buffer, 37~C
