SE450547B - POLYMERIZABLE DENTAL COMPOSITION WITH ACCELERATED CURE SPEED - Google Patents

Description

20 25 30 450 547 Fast and complete curing are thus highly desirable goals. To some extent, increased catalyst concentration improves the cure rate; however, a corresponding increase in degree of hardening does not necessarily follow from this. In fact, high catalyst concentrations often impair the degree of cure and thus give a relatively higher percentage of soluble and leachable components in the finished polymer. In addition, larger amounts of peroxycatalyst increase the risk of prepolymerization of methacrylate monomer, ie before contact with reducing agents, and often necessitate the use of additives in unusually large amounts with a retarding effect on stabilization or polymerization. However, such retarding effects inevitably manifest themselves to some extent in contact with monomer oxidant-reducing agent, whereby the cure rate is attenuated and so does the degree of cure.

A primary object of the present invention is to provide polymerizable dental compositions in which said and associated disadvantages are eliminated or at least reduced to a considerable degree.

Another object of the invention is to provide polymerizable dental compositions which are capable of curing rapidly to give a polymer with a relatively high amount of insoluble component.

A further object of the invention is to provide such a composition with good structural stability in the environment of the human oral cavity.

Another object of the present invention is to provide a composition in which the requirement to use higher catalyst concentrations to achieve effective speed (degree of curing and degree of curing is eliminated.

According to a further object of the invention, such compositions are provided with previously described advantageous properties despite the absence of fillers and / or coupling agents and the like.

A further object of the present invention is to provide such compositions in which, according to a particularly effective embodiment, the stability of the monomer in the presence of peroxy catalyst is effectively improved.

According to a further object of the present invention, there is provided a process for using such compositions to prepare a high quality polymer.

Other objects and advantages of the invention will become apparent from the following description.

The foregoing and related objects are achieved according to the invention which in its broader form provides a polymerizable dental composition and a process for the use of this composition, and which composition exhibits accelerated cure rate and high cure rate and includes at least one methacrylate monomer having 2 to 4 polymerizable double bonds, from about 0 to 400%, calculated on the monomer, inorganic particulate filler, from about 0 to 5%, calculated on the monomer, silane coupling agent, an effective catalyst activating amount of accelerator comprising copper (II ion and from about 0.5 to 5%, based on the monomer, of a compound selected from (a) free radical generating polymerization catalyst (b) reducing agent for the peroxy compound and (c) mixtures of tor comprising an organic peroxy compound, ( a) and (b), wherein the concentration (b) does not exceed 450 547 about 40% of the total amount of (a) and (b), which composition is characterized in that said copper ( II) ion is dispersed in the monomer and is selected from the group of copper (II) acetate, copper (II) acetylacetonate, copper (II) chloride and mixtures thereof.

In addition, copper (I) ions may be present with those mentioned, although the copper (II) compounds have generally been found to be more effective in achieving both a high degree of cure and a high cure rate. Accordingly, it is particularly preferred herein that copper (II) ion Cu ++ constitute at least about 50% of the total amount of copper ion used. However, as will be shown below, the use of only copper (I) salts provides significant improvements over test experiments performed completely without the addition of copper ion. Whether this is due to the presence of copper (II) ions, which are always present in available copper (I) salts, or due to the copper (I) ion or the combination thereof, has not been clearly established.

The amount of copper ion present in the monomer composition is extremely small, usually in the range from about 5 to 100 ppm and preferably 8 to 50 ppm based on total monomer. In other words, the amount of copper ion is at least the amount required to produce effective catalyst activating or accelerating action.

The term "total monomer", as used herein, refers to the total amount of monomer present at the time the polymerization actually takes place. Thus, according to a preferred embodiment, peroxy catalyst, monomer and optionally filler are included in a first paste composition called "oxidant" paste and the reducing agent for this peroxy catalyst is included in a second "reducing agent" paste, which preferably includes the same components as the first paste except for the peroxy catalyst. The pastes are mixed together shortly before the dental use, whereby the polymerization is initiated. The copper ion can be added to either or both of the pasta compositions, with its presence in the oxidation composition being preferred. In any case, the copper ion concentration in this embodiment refers to the total amount of monomer present in both the oxidizing and reducing agent pastes. Calculated on the catalyst, the concentration of copper ion is from about 0.02 to 0.4% of the peroxy compound. It is usually preferred to add the copper compound to the liquid monomer system (without filler) which is to be the oxidant paste.

The copper compound can be added to the composition by dispersing in the normally liquid component comprising one or more monomers. The required dispersion can be achieved by adding the copper compound to the monomer in the form of a solution in a solvent, preferably a polar organic solvent with a low boiling point such as ether or lower alkanol, for example methanol.

Since the solvent is only a carrier for the copper compound, it is most desirable that it has a high volatility so that in general the largest amount and not even the whole amount of solvent is removed in subsequent handling steps, for example mixing, etc. The amount of solvent used is thus low to give 80 ppm Cu ++ and using only a 1% solution in methanol, the volume of solvent becomes only 12.5% of the monomer volume and 2.5% of a suitable paste, calculated on a weight basis. Alternatively, the copper compound may be sorbed onto the filler component, for example silica if such material is used, for mixing with the monomer component (s).

In addition to the copper compound, preferred compositions according to the invention are as follows: parts by weight of monomer (s) 100 inorganic particulate filler 0 -400 silane coupling agent 0.5- 5.0 peroxy catalyst 0.5- 5.0 reducing agent 0.3-2.0 The methacrylate monomer is selected from having at least two and preferably two to four polymerizable double bonds per molecule so that the cured composite product becomes crosslinked and thus better suited for use in the oral cavity. The most preferred monomers are those with two polymerizable double bonds per molecule. Desirable properties of such monomers include low polymerization shrinkage, low exothermic reaction during polymerization, low water sorption, and ability to cure rapidly and completely in the mouth. It is also desirable that the monomers have low volatility and do not irritate the pulp of the tooth.

Particularly useful methacrylate monomers for the invention are those represented by the following general formulas: M - A - oco) 2Ar I II _ __ _ 3 (MA) m CRP MZR '(MA OCO - NH) 2R III IV V CH 2 - M 1 CH - M 'CH 2 ~ M VI wherein M is methacryloyloxy, ie CH 2 = C (CH 3) COO-, M' is methacryloyloxy or hydroxyl, A is alkylene having 1 to 3 carbon atoms, for example methylene, propylene, isopropylene, hydroxyalkylene with 1 to 3 carbon atoms, such as hydroxymethylene, 2-hydroxypropylene or acetoxyalkylene having 3 to 5 carbon atoms in the alkylene group such as 2-acetoxypropylene, 3-acetoxyamylene, etc., n has the value 1 to 4, preferably 1 or 2, m has the value 2 or 3 and p has the value 1 or 2 provided that the sum of m and p is equal to 4, R represents hydrogen, methyl, ethyl or -AM, wherein A and M have the previously indicated meaning, Ar represents phenylene, for example o -phenylene, m-phenylene or p-phenylene, alkyl-substituted phenylene, for example tolylene or 5-t-butyl-m-phenylene or cycloaliphatic group p with 6 to 10 carbon atoms such as, for example, 1,3-cyclohexylene, B denotes R4 wherein R4 and R5 independently of each other denote hydrogen, alkyl, for example C1 to C4 , or substituted alkyl and R 'represents alkylene having 2 to 1 carbon atoms such as ethylene, dodecylene, etc. or -R 2 (O-R 2) X OR 2 - wherein R 2 represents alkylene having 2 to 3 carbon atoms such as ethylene, propylene or isopropylene. , x has the value zero to 5 and R 3 represents phenylene, tolylene, methylene-bis-phenylene or alkylene having 2 to 12 carbon atoms.

Monomers with the above formulas are well known and commercially available materials. Alternatively, they can be readily obtained by conventional syntheses, for example by reacting a phenolic compound such as diphenolic acid, phloroglucinol or bisphenol A with glycidyl methacrylate in the presence of various tertiary amines or by reacting methacrylic acid with an epoxide-containing compound of diglycidyl ether. and bisphenol. Some of these monomers can also be prepared by reacting appropriate alcohols with methacrylic acid, methacrylyl chloride or methacrylic anhydride.

Illustrative monomers having these formulas include: cH2 = c (cH3) coocH2cH2-oco - {::: r-coocH2cH2ococ (cH3) = cH2; cH2 = c (cH3) -coo:} ::: ï: -cH2oco: ï ::: 1: -ococ (CH3) = cH2 'Ho CH3 CH3 oH _ c [bH2ococ (cn3) = cH2] 4; cH3cH2c 4 cH2-o-ceí = fi H2) 3; 0 CH3 450 547 CH2 = C (CH3) CO0 (CH2) 4OCOC (CH3) = CH2 CH = C (CH 2 COOCH CH OCH CH 3) 2 2 2 cH2 = c (C143) coocazcn (oH) cH2- -cf12- cr1 (or1) cr12 OCOC (CH3) = CH cH2 = c (C213) coo - @ - c (C113) 2 - @ - o-coc (çH3) = cH2; cn2 = c (cn3) coo-cnzca (om cH2-o ~ --- @ __ _ OCH2CH (OH) CH2OCOC (CH3) = CH OCH2CH (OH) OCOC (CH3) = CH 0CH2CH OCOC (CH2) = CH2; 2 2 2 CH CH2 = C (CH3) COO-CH2CH2OCONH NHCOOCH2CH2OCOC (CH3) = CH2 CH I CH2 = C (CH3) C00-CH2? H ~ OCONH-CHZCH2? -E-ç ~ CHëNHCOO? H-CH2- CH CH CH CH 2 CO-C (CH 3) = CH 2 Monomers of formulas I, II, III and IV are preferred in the practice of the invention, among which monomers I, II and III are particularly preferred, and monomers IV are more often used in admixture with one or more of monomers I, II and III Other useful methacrylate monomers suitable for use in the practice of the invention include those having the following formulas wherein M and Ar are as previously defined: 10 450 547 10 (MR 4 OAr) 2 C (CH 3) 2 wherein R 4 is isopropylene; (MR 5 OAr) 2 and (MR 5 O) 2 Ar wherein R 5 is Z-hydroxypropylene; Ma RGM wherein R 6 is cyclohexyl and A is 2-hydroxyethylene and is hydroxycyclopentyl or hydroxy M R 8 wherein R 8 is: 2 (A) CH _. c _ _, @ I 3 @ | cn3 '(13) (C) -CH2- ~ O -CHZ- or -CH2- ~ CH2- Details for preparation of several of these monomers are given in U.S. Pat. Nos. 3,066,112, 3,721,644, 3,730,947, 3,770,881 and 3,774,305. A tertiary eutectic monomer mixture, also useful in the invention, is described in U.S. Pat. patent specification 3,539,526. The entire contents of all cited patents are hereby incorporated into the present text.

It is to be understood that a mixture of two or more suitable methacrylate monomers is within the scope of the invention. In fact, depending on the monomer choice, a mixture is often highly desirable to optimize the properties of the resulting dental composition. Thus, it is preferred that the monomer or monomer mixture exhibit a viscosity of from about 100 to 10,000 cP as determined on a Brookfield viscometer at 20 rpm and room temperature.

The inorganic particulate or finely divided filler used in the compositions of the present invention includes molten silica, quartz, crystalline silica, amorphous silica, soda glass beads, glass rods, ceramic oxides, particulate silicate glass, radiopaque glassware (barium) and stratum glass. and synthetic minerals such as beta-eucryptite (LiAlSiO 4), which later have a negative coefficient of thermal expansion. It is also convenient to use comminuted materials and powdered hydroxylapatite, although materials which react with silane coupling agent are preferred. Colloidal or submicron silicas coated with polymer can also be used as fillers.

Small amounts of pigment to match the color of the composition to different tooth enamel shades can be included. Suitable pigments include iron oxide black, cadmium yellow and cadmium orange pigments, fluorescent zinc oxides, titanium dioxide, etc. The filler particles should generally be less than about 50 microns in diameter and preferably less than 30 microns. It should be noted that the filler is an arbitrary ingredient, and non-filler-containing mixtures are used when the dental composition is to be used as a coating, cantilever for amalgam restorations or as a binder. 10 15 20 25 450 547 12 The silane coupling agents or silane locking agents are compounds containing at least one polymerizable double bond to react with the methacrylate monomers. Examples of suitable coupling agents are vinyltrichlorosilane, tris- (acetoxy) vinylsilane, 1N (vinylbenzylaminoethyl) aminopropyltrimethoxysilane-3 or 3-methacryloxypropyltrimethoxysilane, the latter material being preferred for use with methacrylate-like monomers. Peroxy catalysts capable of initiating the polymerization of the methacrylate monomer (s) are well known in the art and include, without limitation, conventional peroxy as well as hydrogen peroxy compounds such as cumin hydrogen peroxide, p-methane hydrogen peroxide, diisopropylbenzene hydrogen peroxide and t-butoxide.

The hydrogen peroxides are the preferred compounds of organic peroxy polymerization catalyst, with cumin hydrogen peroxide (CHP) being particularly preferred. If desired, peroxide stabilizers such as ascorbic acid, maleic acid and the like can be added in small amounts.

Reducing agents useful in the invention generally include any material capable of reacting with the peroxy compound to form polymerization-initiating free radical compounds known in the art. Particularly preferred according to the invention is a substituted thiourea of the formula: wherein X represents H or Y and Y represents alkyl having 1 to 8 carbon atoms, for example methyl, butyl, octyl, cycloalkyl having 5 or 6 carbon atoms such as cyclopentyl, cyclohexyl, m. Chloro-, hydroxy- or mercapto-substituted alkyl having 1 to 8 carbon atoms such as chloroethyl, mercaptoethyl, hydroxymethyl and chlorooctyl, alkenyl having 3 to 4 carbon atoms, for example allyl or metallyl, aryl having 6 to 8 carbon atoms 8 'carbon atoms such as phenyl or xylyl and chloro-, hydroxy-, methoxy- or sulfonyl-substituted phenyl such as chlorophenyl, phenylsulfonyl, hydroxyphenyl and methoxyphenyl, acyl having 2 to 8 carbon atoms such as acetyl, butyryl, octanoyl, chloro- or methoxy-substituted acyl such as chloroacetyl, V chlorobenzoyl, chlorotoluoyl and methoxybenzoyl, aralkyl having 7 to 8 carbon atoms such as benzyl or chloro- or methyl-substituted aralkyl, for example methoxybenzyl and Z represents NH 2, NHX or NX 2. Examples of illustrative compounds suitable for the practice of the present invention are methylthiourea, isopropylthiourea, butylthiourea, octylthiourea, benzylthiourea, acetylthiourea, benzoylthiourea, octanoylthiourea, cyclohexylthioamide thiolabylthioamthiophthylamide trialkylthiolthiophthylurea . thiourea, 1- (hydroxymethyl) -3-methylthiourea, 1,1-dibutylthiourea, 1,3-dibutylthiourea, 1- (p-chlorophenyl) -3-methylthiourea, 1-butyl-3-butyrylthiourea, 1-acetyl -3-phenyl-thiourea, 1-methyl-3- (p-vinylphenyl) -thiourea, 1-methyl-3-O-tolyl-thiourea-1-methyl-3-pentylthiourea, 3-methyl-1,1-diphenylthiourea and 1-acetyl-3- (2-mercaptoethyl) thiourea. Although any of the mentioned thioureas can be used in the practice of the present invention, the monosubstituted thiouramides are preferred, i.e. those of the above formula wherein X is H and Z is NH 2. Particularly preferred are phenylthiourea, acetylthiourea and allylthiourea. Preferably, the composition contains about 0.5 to about 1% by weight of reducing agent.

The following examples are given for illustrative purposes only and do not limit the invention.

Example l - 14 Radiopaque reducing agent pastes with the following compositions_prepared: 450 547 l5 mnwnmm flfl ocmuwš fl muw cwm flflfi øcmannmñonoš uumma fifl w # muwum ^ HHvHmmmox bm Enow HI oo fl _wH ~ mm wöHo vo. mm ww. fl w oo fi vH ~ mm ww_Hw mmoO.o NNoo.o mw.o mo.H ßN.oH ¶> ~ .oH wm «_Q mQ.H> N.oH ß ~. @ ~ h ^ mH-w: fl z¶mHø = HHHHv w fl xo fl ø fi ww fl x munen mmHHm fi Noumå fl uu fiämonmwxoH> HMmwmE | NI um fi wuxmßwå fi ø fi o fi wmmxw fl lm.HI OOH «fl« m. Nwoooa | 1 1 1> oQ m «_ @ m« .Q m «.om« _o mo.H mo.H mo.H ~ ° .H ß ~ .oH> ~ »oH> ~ .oH« N.oH> ~ .oH ß ~ .oH> ~ _oH «~. ° H mmmm N IPVHH? .mw fl HQn-.UWWCMGH-âw oo fl «H.wm mæ.Av mw.c mo.H bN.o fl ßN ~ oH w Amø fl nnouv mm fi wåä fi nmn | l ffi <2 'LO KO Ådäüv mmH nl QHMUOB wwßß wz fi zmouw OHIÉ QHwSHm ++ 5Uv wuæm flfl nnoxmm v fl emnumxo fl p fl æpwom WSS fi amine QEQEEN QOQDZH Hwww fifi mßmwm 10 15 20 25 450 547 16 Radiopaque oxidationsmedelspastor with the following compositions down prepared: Composition in wt% ingredient 1 Q NÜPoL p 9.94 9.78 HMDMA 9.94 9.78 A - 174 0.99 0.98 maleic acid _ - 0.41 ascorbic acid 0.07 - hydrocarbon peroxia (so%) 1.05 1.65 IMSIL A-10 41, 93 41.79 CORNING 7724 36.06 36.22 A total of 100 in 100 The oxidizing and reducing agent pastes are mixed in a 1: 1 weight ratio, as set forth in the following examples. Curing times are given in minutes and include the time required for mixing to be approximately 30 seconds.

The completed curing reaction is determined by the fact that the material can no longer be nibbled with a spatula. It can also be determined by measuring the percentage of methanol insoluble polymer when the curing reaction is completed. Samples of the polymer-forming mass are taken at certain time intervals during the curing reaction, its termination being indicated by the point at which the percentage of insoluble material remains substantially constant. The results are summarized as follows: f: 10 15 20 450 547 l7 oxide-reduction- ppm Cu ++ tion- in reduction-curing ex. average- average- average- time temp. no pasta pasta pasta min. OC 1 JC 2.2 3.5-4.3 21 2 "D 4.4 2.8-3.2 23 3" E 11.0 l, 8É2.2 - 23 4 "F 22.0 l, 7 -2.2 20.5. 5 "G 33.0 1.5-1.8 21.5 6" H 44.0 l, 3 ~ 1, 8 23 7 "A inga 4.0-5.0 27 8 IC 2.2 3.3 -3.8 21 9 "D 4.4 2.7-3.5 22.5, io" E 11.0 1, s-2.2 23 ll '"F 22.0 l, 7-2.0 20.5 12 "G 33.0 1.3-1.7 21 13 _" H 44.0 1.25-1.6 23 14 AA none 3, 3-4, o '21 In each experiment the curing is carried out in air, ie in a ++ open vessel. increased concentration of Cu results in faster curing.

In comparison with Examples 7 and 14, without a copper accelerator, the data show a clear improvement in cure rate for the present invention. Similar combinations (1: 1) of the reducing agent paste B with I and J give comparable results.

Examples 15 ~ 17 The procedure of the previous example is repeated but using a NUPOL: HMDMA (71:29) monomer mixture, by weight, in each of the oxidation and reduction compositions.

Fillers are omitted entirely in each of the examples.

Copper ions are supplied by the following compounds: Example no. Accelerator 15 copper (II) acetate 16 copper (II) chloride 17 copper (II) acetonylacetonate (no solvent) In all cases improved curing rate is obtained compared to identical control experiments without the copper compound.

Examples 18 - 20 The procedure of Examples 15 - 17 is repeated but using the following materials as accelerators. HQ 10 15 20 450 547 19 Example No. Accelerator (weight ratios) 18 copper (II) acetate / copper (II) chloride (50:50 ) 19 copper (II) acetate / copper (I) chloride (50:50) 20 copper (II) chloride / copper (I) chloride (50:50) The results are similar to those obtained in the previous examples.

Example Gel 21 - 34 Each And one of Examples 1 - 14 is repeated except that the copper (II) acetate is sorbed onto the filler and then the monomer composition is added. Similar improvement is obtained by the curing rate when compared with control experiments without the copper compound- 'Example 35 - 37 The following reducing agent-containing and oxidizing agent-containing compositions are prepared: Composition in% by weight § QQ NuPoL 9.9 9.9 9.9 HMDMA 9 .9 9.9 9.9 acetylthiourea 0.45 0.45 0.45 eu ”9 o, ooo2 o, ooo5 o, oo1o coRmNe 7724a 36.25 35.25 36.25 msn, A-loa 42.25 42 , 42.25 colloidal silica 1.30 1.30 1.30 a. silanized 10 15 20 450 547 20 OXIDATOR COMPOSITION - N ingredient composition in% by weight NUPoL '9.325 HMDMA 9.325 CHP (80%) 1.05 coRNING 77245' 36.25 msn. A-loa 42.25 colloidal silica 1.80 a. . silanized The oxidizing agent paste is mixed on a clean glass plate with each of the three reducing agent pastes in a ratio of 1: 1. The curing times for each of the three mixtures are determined by the time required for the mixed material to become resistant to chipping or marking with a plastic spatula. The results are summarized as follows: oxide-reduction- ppm Cu ++ in _ tion- reduction- hardening- ex. mean- mean- mean- time no pasta pasta pasta min l NK 2 4.2-5.0 2 NL 5 2.5-3.0 3 NM 10 2.3-2.8 H 10 450 547 "21 In each and in one of the above experiments the curing is carried out in air. (Shorter curing times would be obtained under glass or in a cavity covered by adhesive strip.) It is clear that increasing the concentration of Cu ++ results in shorter curing time.

Similar results are obtained when repeating the foregoing examples, but using, within the foregoing limits, the following peroxy catalysts and reducing agent compounds - peroxy catalysts: p-methane hydrogen peroxide, diisopropylbenzene hydrogen peroxide and t-butyl hydrogen peroxide; reducing agents: allylthiourea, phenylthiourea and 3-allyl-1,1-diethylthiourea.

Claims (11)

450 547 22 P a t e n t k r a v An accelerated cure rate polymerizable dental composition comprising at least one methacrylate monomer having from 2 to 4 polymerizable double bonds, from about 0 to 400% based on the monomer, inorganic, particulate filler, from about 0 to 5%, based on the monomer, silane coupling agent, an effective catalyst activating amount of accelerator comprising copper (II) ion and from about 0.5 to 5.0%, based on the monomer, of a compound selected from (a) free radical generating polymerization catalyst containing an organic peroxy compound, (b ) reducing agents for the peroxy compound and (c) mixtures of (a) and (b), wherein the concentration of (b) does not exceed about 40% of the total amount of (a) and (b), characterized in that said copper (II) ion is dispersed in the monomer and is selected from the group of copper (II) acetate, copper (II) acetylacetonate, copper (II) chloride and mixtures thereof. 2. A composition according to claim 1, characterized in that the ratio between (a) and (b) is about 2: 1. 3. A composition according to claim 1, characterized in that the reducing agent comprises a substituted thiourea compound. 4. A composition according to claim 3, characterized in that the reducing agent comprises an allyl-substituted or acetyl-substituted thiourea. 5. A composition according to claim 4, characterized in that the peroxy compound comprises hydrocarbon peroxide and the reducing agent is acetylthiourea. H: v '450 547 ä3 6. A composition according to claim 4, characterized in that the peroxy compound comprises hydrocarbon peroxide and that the reducing agent comprises allylthiourea. Composition according to claim 1, characterized in that the concentration of copper (II) ion is from about 5 to 100 ppm, calculated on the monomer. Composition according to Claim 1, characterized in that at least about 40% of the monomer consists of the reaction product between glycidyl methacrylate and bisphenol A. Composition according to Claim 8, characterized in that up to 60% of the monomer consists of 1,6-hexanediol dimethacrylate. 10. A composition according to claim 1, characterized in that it includes up to 50% by weight of copper (I) ion based on the weight of copper (II) ion. 11. A composition according to claim 1, characterized in that it has a paste-like consistency. __..., _.___..._ ,, v ,,,,., ._..... ._. m .. ........_ ._ _.__.._._.._....__ .., i ___., _