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Ascorbic acid is a well known natural reducing agent or antioxidant. The specific complexes discussed were highly colored compounds. Although. Jabs et al. It was utilized in combination with an oxidizing agent in nonaqueous dental systems. Metal complexes of ascorbic acid been prepared and characterized. It is well recognized that ascorbic acid is easily oxidized, especially in aqueous solution, and in its oxidized or partially oxidized form exhibits a dark yellow to yellow/brown coloration. Yes, that’s right! Allg.
Jabs et al.
TajimirRiahi in Journal of Inorganic Biochemistry. Fourier Transform infrared and 13 C nuclear magnetic resonance spectroscopic analysis of Ai, La and Pb ascorbates as solids and in solution. You can find a lot more info about it on this site. Inorganica Chimica Acta. Therefore, lascorbic acid and ’56 O isopropylidene L ascorbic’ acid.
Ascorbic acid in its complexed form was prepared for use in medicinal and cosmetic compositions. Complexed ascorbic acid has also been incorporated in dental compositions to inhibit the formation and growth of calculus on oth enamel. Although, the complexes are white powders and are reported to be stable in dry form and solutions and are not sensitive to heat. Mecca disclose allantoin ascorbic acid complexes for use in medicinal and cosmetic compositions.
Various alkali metal and alkaline earth metal salts are listed as suitable ascorbic acid derivatives. The complex compound is a brownish solid used to treat diseases which present an abnormal blood picture. Certainly, they are reported to exhibit a reduced tendency to discolor upon storage and exposure to air, when the compositions further contain a stannous compound. Marstrand discloses a compound which comprises a complex combination of ascorbic acid, trivalent titanium and divalent copper. Fact. For instance, riley discloses oral compositions such as othpastes which contain Vitamin C or a derivative thereof and a copper compound such as copper sulphate.
Pat. The compositions are reported to inhibit the formation and growth of calculus on dental enamel. Metal incorporation complexed ascorbic acid provides a composition that exhibits improved color stability. Of course, putt et al. Ascorbic acid is listed, along with other carboxylic acids, as a stable preferred complexing carboxylic acid. Generally.
Applicants have surprisingly found that when ascorbic acid is present as a metal complex in curable dental compositions, the resultant compositions are color stable without excellent loss reducing capabilities of ascorbic acid.
In a preferred embodiment, a tri cure glass ionomer cement, the threeway cure mechanism facilitates thorough, uniform cure and retention of good clinical properties. The curable dental invention compositions can be mixed and clinically applied using conventional techniques. Whenever luting of metallic crowns or other light impermeable prosthetic devices to teeth, and other restorative applications in inaccessible mouth areas, Such applications include deep restorations, large crown ‘buildups’, endodontic restorations. The compositions have general applicability as restoratives, liners, bases, cements, sealants and as dental or orthodontic adhesives. Consequently, have particular utility in clinical applications where cure of a conventional light curable composition might be difficult to achieve, the invention cements provide utility for all the applications enumerated above.
Two part paste. This is observed when the ΔE ab value of a cured composition containing metal complexed ascorbic acid is less than that of a similar composition containing unmodified ascorbic acid.
a material color stability is evaluated by measuring in reflection the L, a and b color coordinates of a cured sample containing complexed ascorbic acid and a similar sample containing unmodified ascorbic acid.
The color coordinates are obtained by the CIELAB. The sample is considered to exhibit color stability if the ΔE ab cured value sample after aging at 45° for 5 days is less than the ΔE ab value of a similar sample containing unmodified ascorbic acid. The ΔE ab values are obtained using the CIELAB color difference equation set out in Billmeyer Saltzman. As a result, the ΔL, Δa and Δb values are obtained by subtracting the L, a and b values of a cured aged sample material containing the complexed ascorbic acid from the L, a and b values of a cured sample of identical material immediately after it is formulated.
The curable dental invention composition, in the broadest embodiment, contains three components. Of the many materials mentioned, water miscible or water soluble acrylates and methacrylates such as 2 hydroxyethyl methacrylate, hydroxymethyl methacrylate, ‘2hydroxypropyl’ methacrylate, tetrahydrofurfuryl methacrylate, glycerol mono or dimethacrylate, trimethylol propane trimethacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, urethane methacrylates, acrylamide, methacrylamide, methylene bis acrylamide or methacrylamide, and diacetone acrylamide and methacrylamide are preferred. The ethylenically unsaturated moiety can be present as a single component or as a mixture of components. If desired, the ethylenically unsaturated moiety can be present as a separate ingredient or it can, be present as a group on another ingredient. However, additional monomers, oligomers and polymers may also be present. The dental first component invention composition is an ethylenically unsaturated moiety. The components are an ethylenically unsaturated moiety, an oxidizing agent and metal complexed ascorbic acid. In a preferred embodiment, the ethylenically unsaturated moieties are present as groups on the acidic polymer, as described in more detail below. You should take it into account. Mixtures of ethylenically unsaturated moieties can be used if desired. This is the case.
The second and third components of the invention dental composition are an oxidizing agent and metal complexed ascorbic acid reducing agent.
The oxidizing agent and the metal complexed ascorbic acid should also preferably be sufficiently soluble and present in an amount sufficient to permit an adequate free radical reaction rate. This can be evaluated by combining the ethylenically unsaturated moiety, the oxidizing agent and the metal complexed ascorbic acid and observing whether or not a hardened mass is obtained. The oxidizing agent should react with or otherwise cooperate with the metal complexed ascorbic acid reducing agent to produce free radicals capable of initiating ethylenically polymerization unsaturated moiety. Let me tell you something. The oxidizing agent and the metal complexed ascorbic acid are the redox catalyst system that enable the dental composition to cure via a redox reaction. The oxidizing agent and the metal complexed ascorbic acid preferably are sufficiently shelf stable and free of undesirable coloration to permit their storage and use under typical dental conditions.
Suitable oxidizing agents include persulfates such as sodium, potassium, ammonium and alkyl ammonium persulfates, benzoyl peroxide, hydroperoxides such as cumene hydroperoxide, ‘tert butyl’ hydroperoxide, tert amyl hydroperoxide and ’25dihydroperoxy25dimethylhexane’, salts of cobalt and iron, hydroxylamine, perboric acid and its salts, salts of a permanganate anion, and combinations thereof.
It is particularly preferred to use the oxidizing agent in an encapsulated form as described in Pat. Although it may, hydrogen peroxide can also be used, in some instances, interfere with the photoinitiator, if one is present.
Metal complexed ascorbic acid is the reducing agent. The desired metal complexed ascorbic acid is preferably prepared using a suitable metal alkoxide or metal salt. Preferred metals include the transition metals and metals of group IA, IIA, and IIIB. It’s a well the metal complexed ascorbic acid provides a dental composition that exhibits color stability and maintains the ascorbic catalytic potency acid. It is preferred to add the metal complexed ascorbic acid in its powdered form. I’m sure you heard about this. Particularly preferred complexing metals are zirconium and aluminum with aluminum being most preferred. That is interesting right? Any metallic ion that can form stable complexes with ascorbic acid can be used. Of course the metal complexed ascorbic acid can be added to the dental composition in its powdered form or it can be precipitated as a coating on a filler, zirconium oxide, silica, ceramic fillers and fluoroaluminosilicate glass.
The metal amounts complexed ascorbic acid reducing agent and the oxidizing agent may be sufficient to provide the desired degree and rate of ethylenically polymerization unsaturated component.
Optionally, the curable dental composition may contain a photoinitiator. The preferred amount for metal each complexed ascorbic acid and the oxidizing agent is about 01 to about 10percent, more preferably about 02 to about 5percentage, based on the uncured tal weight composition. The photoinitiator preferably is water soluble or water miscible. That’s where it starts getting really entertaining, right? Visible light photoinitiators are preferred. Typically it is used in combination with a suitable donor compound or a suitable accelerator, the photoinitiator frequently can be used alone. I’m sure it sounds familiar.|Doesn’t it sound familiar?|Sounds familiar?|does it not? It also preferably is sufficiently shelf stable and free of undesirable coloration to permit its storage and use under typical dental conditions. The photoinitator might be capable of promoting free radical ethylenically crosslinking unsaturated moiety on exposure to light of a suitable wavelength and intensity. Photoinitiators bearing polar groups usually have a sufficient degree of water solubility or water miscibility.
Preferred visible ‘light induced’ initiators include camphorquinone, diaryliodonium simple or metal complex salts, ‘chromophoresubstituted’ halomethylstriazines and halomethyl oxadiazoles. Preferred commercially available ultraviolet lightinduced polymerization initiators include ’22dimethoxy2phenylacetophenone’ and benzoin methyl ether, both from ‘Ciba Geigy’ Corp. Notice, preferred ultraviolet lightinduced polymerization initiators include ketones such as benzyl and benzoin, and acyloins and acyloin ethers. With or without additional hydrogen donors, particularly preferred visible lightinduced photoinitiators include combinations of an alphadiketone. And a diaryliodonium salt. Bromide, iodide or hexafluorophosphate.
The photoinitiator might be present in an amount sufficient to provide photopolymerization desired rate.
The curable dental invention composition optionally can contain nonreactive fillers, reactive fillers, water, stabilizers, pigments, coupling agents, viscosity modifiers, accelerators, inhibitors, medicaments, and other ingredients that should be apparent to those skilled in the art. Typically, the photoinitiator components going to be present at a tal weight of about 01 to about 5%, more preferably from about 1 to about 5percentage, based on the composition tal weight. This amount gonna be dependent in part on the light source, the layer thickness to be exposed to radiant energy, and the extinction photoinitiator coefficient.
Unmodified ascorbic acid is present as the reducing agent in a dental cement composition disclosed in Pat.
The redox incorporation initiated curing mechanism provides a cement that cures well in thick layers and can be used without a dental curing light or with a light that is weak or defective. The ascorbic acid in combination with an oxidizing agent provides a tricure cement, a cement having three curing modes, namely a redox initiated curing mechanism in addition to an acidfiller ionic curing mechanism and a photoinitiated free radical crosslinking curing mechanism. Anyways.
The aforementioned cement is commercially available as a powder.
The powder contains ascorbic acid which is microencapsulated to ensure its stability prior to admixture with the liquid. In particular, for restorative applications, a relatively plenty of a somewhat flocculent powder must be hand spatulated with a quite small percentage of liquid. So, the desire to provide the practitioner with a paste. This should be not only inconvenient but also time consuming for a busy dental practitioner. While powder.
The invention cements are not limited to paste. Other useful configurations could be familiar to those skilled in the art. Generally, deionized water is preferred. Traditional powder. Loads of info can be found easily by going on the web. Water amount might be sufficient to provide adequate handling and mixing properties and to permit the transport of ions in the filleracid reaction. The water can be distilled, deionized or plain tap water. Eventually, these formulations generally are ‘twopart’ systems and are prepared by hand spatulating the parts together. Preferably, water represents at least about 1%, more preferably about 3% to about 25percentage, and most preferably about 5% to about 20% of ingredients tal weight used to form the cement. The glass ionomer invention cement contains water.
The glass ionomer invention cement is ionically hardenable.
When combined, by this is meant that it contains ingredients that can react via an ionic reaction to produce a hardened mass. The glass first component ionomer cement is finely divided reactive filler. It can be conveniently mixed with the other ingredients and used in the mouth since The filler going to be sufficiently finely divided. More preferably about 1 to 10 micrometers, preferred average particle diameters for the filler are about 2 to about 15 micrometers for instance, a sedimentation analyzer. Have you heard about something like that before? The ionic reaction occurs between acid groups on the polymer and ‘acidreactive’ groups on the filler.
Preferred fillers are acidreactive.
Mixtures of fillers can be used if desired. Fluoroaluminosilicate glasses are particularly preferred. Anyway, suitable fillers can be obtained from lots of commercially available glass ionomer cements, such as GC Fuji LC cement and Kerr XR ionomer cement. Suitable ‘acidreactive’ fillers include metal oxides, metal salts and glasses. Preferred metal oxides include barium oxide, calcium oxide, magnesium oxide and zinc oxide. Now let me tell you something. Suitable fillers are also available from various commercial sources familiar to those skilled in the art. Preferred metal salts include salts of multivalent cations, for the sake of example aluminum acetate, aluminum chloride, calcium chloride, magnesium chloride, zinc chloride, aluminum nitrate, barium nitrate, calcium nitrate, magnesium nitrate, strontium nitrate and calcium fluoroborate. Preferred glasses include borate glasses, phosphate glasses and fluoroaluminosilicate glasses.
The filler can be subjected to a surface treatment, if desired. Suitable surface treatments include acid washing, treatment with phosphates, treatment with chelating agents such as tartaric acid, treatment with a silane coupling agent. Generally, filler amount might be sufficient to provide a cement having desirable mixing and handling properties before cure and good cement performance after cure. On p of that, preferably, the filler represents less than about 90percent, more preferably about 25% to about 85percent, and most preferably about 75percentage to about 85% by weight of the unset tal weight cement components.
The glass second component ionomer invention cement is an acidic, water miscible polymer. Preferred acidic polymers include homopolymers and copolymers of alkenoic acids such as acrylic acid, itaconic acid and maleic acid. Suitable acidic polymers include those listed at column 2, line 62 through column 3, line 6 of Pat. Whenever handling and mixing properties, as might be appreciated by those skilled in the art, the polymer should have a molecular weight sufficient to provide good storage. Suitable polymers are also available from a wide types of commercial sources, and many are found in currentlyavailable glass ionomer cements. Need not be entirely water soluble it does not undergo substantial sedimentation when combined with the cement liquid ingredients since, the acidic polymer might be at least sufficiently water miscible.
The glass third component ionomer invention cement is an ethylenically unsaturated moiety as discussed above.
Preferably, acid numbers groups and ethylenically unsaturated groups are adjusted to provide an appropriate balance of properties in the cement, both during the setting reaction and after the cement has hardened. The ethylenically unsaturated moiety and the acidic polymer might be present as separate components or as a mixture of components. Acidic polymers in which about 10 to about 30percent of the acidic groups are replaced with ethylenically unsaturated groups are preferred. Other monomers, oligomers and polymers may also be present. Preferably the ethylenically unsaturated moiety is present on the acidic polymer. Suitable ethylenically unsaturated acidic polymers are described in Pat.
Acidic amount polymer in the cement should also be sufficient to provide a desired balance of physical properties. Stabilizers are particularly useful for paste. Oxalic acid and sodium metabisulfite are preferred stabilizers. Optionally, the glass ionomer cement may contain stabilizers. Suitable stabilizers include oxalic acid, sodium metabisulfite, metaphosphoric acid, sodium bisulfite, sodium thiosulfate, and combinations thereof. Stabilizers incorporation serves to further improve the color stability of metal complexed ascorbic acid containing paste.
The invention cements can contain adjuvants such as pigments, nonvitreous fillers, inhibitors, accelerators, viscosity modifiers, medicaments and other ingredients that could be apparent to those skilled in the art, if desired.
The invention may be further clarified by following consideration nonlimiting examples, which are intended to be purely exemplary of the invention. All parts and percentages are by weight unless otherwise indicated.
Ascorbic acid was dissolved in 150 methanol ml.
The infrared spectrum showed that the carbonyl peak had shifted from 1675 cm 1 for unmodified ascorbic acid to 1625 cm 1″ for the aluminum ascorbate. The mixture was stirred for 30 minutes with some precipitate observed, after addition was complete. A well-known fact that is. The aluminum ascorbate was filtered, washed with water and later methanol. It is 100 ethyl ml acetate was added to precipitate aluminum ascorbate. Aluminum butoxide in 10 isopropanol ml was added slowly to the ascorbic acid. Water was then added and the solution stirred for 2 hours.
Ascorbic acid was dissolved in 200 methanol ml. The almost white powder was dried in a 45° oven under vacuum for 24 hours. The methanol was distilled off to yield zirconium ascorbate as an almost white powder. Nonetheless, the precipitate was filtered and washed with water to remove any free ascorbic acid. With all that said. Ascorbic acid was dissolved in 50 methanol ml. 5 water ml was added to the resultant solution to catalyze hydrolysis and condensation of zirconium npropoxide to zirconium oxide, after addition was complete. The mixture was stirred for 30 minutes with some precipitate observed, after addition was complete. Zirconium npropoxide was slowly added to the ascorbic acid. The powder was dried in a 45° oven for 24 hours. Zirconium ‘n propoxide’ was slowly added to the ascorbic acid. Nevertheless, the solution was stirred for 1 hour before the methanol was distilled off.
Except 28 ml instead of 56 ml of zirconium ‘n propoxide’ was added to the ascorbic acid, REPARATORY procedure EXAMPLE 3 was repeated.
The zirconium ascorbate deposited on the zirconium oxide and was isolated by filtration and washed with water. Certainly, 60 water ml was added and the resultant mixture stirred for 2 hours at which time 100 g of zirconium oxide was added and the resultant mixture stirred overnight. Ascorbic acid was dissolved in 600 methanol ml. Zirconium npropoxide was slowly added to the ascorbic acid. The mixture was stirred for 10 minutes with some precipitate observed, right after addition was complete.
The ingredients set out below in TABLE I were mixed, melted in an arc furnace at about 1350°-1450°, poured from the furnace in a thin stream and quenched using chilled rollers to provide an amorphous single phase fluoroaluminosilicate glass. The mixture was stirred magnetically for 30 minutes at ambient temperature, added to 50 glass parts powder and slurried for 5 hours at ambient temperature. Also, the slurry was poured into a ‘plastic lined’ tray and dried for 20 hours at 45° The silanol treated dried powder was sieved through a 74 micron mesh screen.
Four Paste I formulations, Ia, Ib, Ic and Id, were independently prepared using the metal complexed ascorbic acid set out below in TABLE IIa.
The formulation maintaining color greatest degree stability was prepared with zirconium ascorbate having a molar ratio of ascorbic acid. The data in TABLE IIa show that, upon visual inspection, the Paste Ia formulation containing zirconium ascorbate. Each Paste I formulation was handloaded into an opaque polyethylene syringe and aged at 45° for 14 days. Notice that on day 14, the syringes were removed from the oven and a sample of each aged paste and its corresponding unaged paste were syringed side by side on a whitish paper towel.
Paste Ia formulations from TABLE IIa were prepared with 65 addition g sodium metabisulfite and/or 65 g oxalic acid stabilizers as well as without the addition of stabilizer. Paste IIa compositions were measured according to ISO specification The average set time of all samples prepared immediately after formulation and before aging was 1’30” to 1’40”. The Paste set times Ia. Nevertheless, the resultant Paste Ia formulations were mixed with an equal quantity of a Paste II designated Paste IIa, prepared by combining the ingredients set out below in TABLE IV.
The Paste Ia.
Each cured disk was removed from the mold and placed in a 37° /95percentage relative humidity chamber for 15 to 30 minutes. Each disk was cured with a VISILUX 2″ dental curing light using a 60 second exposure to each sample side, and a 1 cm distance between the light output end guide and the sample. Paste IIa mixture into a 1 mm thick×2 cm diameter steel mold. Needless to say, anyevery disk was removed from the chamber and stored in deionized water at room temperature for 15 to 60 minutes. Everyany disk was removed from the water, blotted dry with a paper wel and color coordinates immediately measured. Paste IIa formulations were formed into 1 mm thick disks by pressing each Paste Ia.
The color coordinates for standard daylight conditions were measured for each disk using a DINO MATCH SCAN II color computer with a 25 mm diameter sample port. Each Paste Ia formulation was mixed with an equal quantity of Paste IIa, disks were prepared and color coordinates measured as detailed for the samples prepared immediately after formulation. The L, a and b reflection color coordinates were obtained using the standard white color tile in the reflection sample port. Each syringe containing Paste remainder Ia was aged at 45° for various time intervals.
The ΔL, Δa and Δb values were obtained by subtracting the L, a and b values of a cured aged sample material from the L, a and b values of a cured sample of identical material immediately after it had been formulated.
The ΔE ab values are reported in TABLE Set out below in TABLE V are the run no. Paste IIa composition. Also, paste IIa compositions at 37° time length the Paste Ia formulations were aged at 45° and the ΔE ab color value for each Paste Ia. Paste Ia, the Paste set time Ia.
The data in TABLE V show the improvement in color stability with no significant change in set time of a dental composition containing metal complexed ascorbic acid as well as stabilizers. Two Paste I formulations were prepared as in TABLE II except that 32 instead g metal complexed ascorbic acid, 8 g of PREPARATORY aluminum ascorbate EXAMPLE 1 was incorporated in Paste Ie and 6 the zirconium g ascorbate coated on zirconium oxide of PREPARATORY EXAMPLE 5 was incorporated in Paste If. Even after 9 days at 45°, Run composition no. Additionally, both Paste Ie and Paste If contained both 1 g oxalic acid and 1 g sodium metabisulfite stabilizers.
Paste Ie and Paste If were then aged at 45° for 6 and/or 9 days.
Aged Paste Ie and Paste If were independently mixed with an equal quantity of Paste IIa of TABLE IV, disks were prepared and color coordinates measured as detailed in EXAMPLE The data in TABLE VI show that the paste color stability.
Two additional Paste I formulations, Paste Ih and Paste Ii, were prepared by combining the ingredients set out in TABLE VII, except that for Paste Ih allantoin ascorbate (prepared according to Example procedure 1 of Pat, as a comparison. Each Paste I was independently mixed with an equal percentage of Paste IIb which was formed by combining the ingredients set out below in TABLE VIII. Oftentimes paste Ii PREPARATORY aluminum ascorbate EXAMPLE 1 was substituted for the unmodified ascorbic acid. The three Paste I formulations were independently ‘handloaded’ into opaque polyethylene syringes and degassed.
Disks of each Paste IIb formulation were prepared and color coordinates measured as described in EXAMPLE the syringes containing Paste remainder Ig, Paste Ih and Paste Ii were placed in a 45° oven.
On day 5, the Paste I formulations were removed from the oven and independently mixed with an equal quantity of Paste IIb. Disks of each composition were prepared and color coordinates measured as detailed in EXAMPLE each remainder Paste I formulation was returned to the 45° oven and the procedure of disk preparation and color coordinate measurement repeated on day 10.
Set out below in TABLE IX are the Paste I formulations, days number the Paste I formulation was aged at 45°, the L, a and b reflection color coordinates and the ΔE ab color value for each Paste IIb composition. Paste IIb composition had noticeably yellowed. That said, paste IIb and the Paste Ii. The Paste Ii composition contained the aluminum ascorbate, whereas the Paste Ih composition contained the allantoin ascorbate. Ok, and now one of the most important parts. Paste IIb compositions exhibited excellent color stability after 5 days aging at 45° Already by day 5, the Paste Ig. Paste IIb composition continued to exhibit excellent color stability. This is the case. Whenever failing to maintain its pre aged consistency, On day 5, it was observed that the Paste Ih composition contained localized areas wherein the composition had gelled. By day 10, only the Paste Ii. The data in TABLE IX show that both the Paste Ih.
On day 6, the Paste Ij formulation was removed from the oven and mixed with an equal percentage of Paste IIc.
Set out below in TABLE XII are the Paste Ij. Paste IIc formulation, days number the Paste Ij formulation was aged at 45°, the L, a and b reflection color coordinates and the ΔE ab color value for the Paste Ij. Paste IIc composition. Disks were prepared and color coordinates measured as detailed in EXAMPLE Paste remainder Ij was returned to the 45° oven and the procedure of disk preparation and color coordinate measurement repeated on day 14.
The data in TABLE XII show the excellent color stability of a paste. PREPARATORY EXAMPLE 1 as the reducing agent and cumene hydroperoxide as the oxidizing agent. PREPARATORY EXAMPLE 1 as the reducing agent and cumene hydroperoxide as the oxidizing agent. Even after 14 days at 45°, the composition maintained excellent color stability. The data in TABLE XII show the excellent color stability of a paste. Anyway, even after 14 days at 45°, the composition maintained excellent color stability.