Ascorbic acid is a famous natural reducing agent or antioxidant.
Chem. Jabs et al. It is utilized in combination with an oxidizing agent in nonaqueous dental systems. It is well recognized that ascorbic acid is easily oxidized, especially in aqueous solution, and in its oxidized or partially oxidized form exhibits a yellowish to yellow/brown coloration. Generally. Did you hear of something like that before? The specific complexes discussed were highly colored compounds. Actually, metal complexes of ascorbic acid was prepared and characterized.
Jabs et al. Inorganica Chimica Acta. Fourier Transform infrared and 13 C nuclear magnetic resonance spectroscopic analysis of Ai, La and Pb ascorbates as solids and in solution. OisopropylideneLascorbic acid. Generally, tajimirRiahi in Journal of Inorganic Biochemistry.
Ascorbic acid in its complexed form is prepared for use in medicinal and cosmetic compositions.
The complexes are almost 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. Complexed ascorbic acid has also been incorporated in dental compositions to inhibit the formation and growth of calculus on oth enamel.
Pat. The complex compound is a brownish solid used to treat diseases which present an abnormal blood picture. 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. Various alkali metal and alkaline earth metal salts are listed as suitable ascorbic acid derivatives. Lots of info can be found by going on the internet preferred metal oxides include barium oxide, calcium oxide, magnesium oxide and zinc oxide.
The filler can be subjected to a surface treatment, if desired.
Preferably, the filler represents less than about 90%, more preferably about 25% to about 85percent, and most preferably about 75% to about 85percentage by weight of the unset tal weight cement components. With that said, filler amount could be sufficient to provide a cement having desirable mixing and handling properties before cure and good cement performance after cure. That is interesting. Suitable surface treatments include acid washing, treatment with phosphates, treatment with chelating agents such as tartaric acid, treatment with a silane coupling agent.
The glass second component ionomer invention cement is an acidic, water miscible polymer.
Suitable polymers are also available from a wide variety of commercial sources, and many are found in ‘currently available’ glass ionomer cements. Need not be entirely water soluble it does not undergo substantial sedimentation when combined with the cement liquid ingredients because, the acidic polymer going to be at least sufficiently water miscible. Actually, 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 will be appreciated by those skilled in the art, the polymer should have a molecular weight sufficient to provide good storage.
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. As a result, preferably the ethylenically unsaturated moiety is present on the acidic polymer. Remember, acidic polymers in which about 10 to about 30% of the acidic groups been replaced with ethylenically unsaturated groups are preferred. Other monomers, oligomers and polymers may also be present. Although, the ethylenically unsaturated moiety and the acidic polymer might be present as separate components or as a mixture of components. Just keep reading. 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.
Optionally, the glass ionomer cement may contain stabilizers. Also, stabilizers incorporation serves to further improve the color stability of metal complexed ascorbic acid containing paste. Suitable stabilizers include oxalic acid, sodium metabisulfite, metaphosphoric acid, sodium bisulfite, sodium thiosulfate, and combinations thereof. Oftentimes oxalic acid and sodium metabisulfite are preferred stabilizers. Stabilizers are particularly useful for paste.
The invention cements can contain adjuvants such as pigments, nonvitreous fillers, inhibitors, accelerators, viscosity modifiers, medicaments and other ingredients that will be apparent to those skilled in the art, if desired. All parts and percentages are by weight unless otherwise indicated. The invention will be further clarified by following consideration nonlimiting examples, which are intended to be purely exemplary of the invention.
Ascorbic acid was dissolved in 150 methanol ml. 100 ethyl ml acetate was added to precipitate aluminum ascorbate. The mixture was stirred for 30 minutes with some precipitate observed, after addition was complete. Water was then added and the solution stirred for 2 hours. The infrared spectrum showed that the carbonyl peak had shifted from 1675 ‘cm 1’ for unmodified ascorbic acid to 1625 ‘cm1’ for the aluminum ascorbate. Aluminum butoxide in 10 isopropanol ml was added slowly to the ascorbic acid. The aluminum ascorbate was filtered, washed with water and then methanol.
Ascorbic acid was dissolved in 200 methanol ml.
5 water ml was added to the resultant solution to catalyze hydrolysis and condensation of zirconium npropoxide to zirconium oxide, right after addition was complete. Normally, ascorbic acid was dissolved in 50 methanol ml. It’s a well the solution was stirred for 1 hour before the methanol was distilled off. Basically, the whitish powder was dried in a 45° oven under vacuum for 24 hours. With that said, the methanol was distilled off to yield zirconium ascorbate as an almost white powder. Zirconium ‘npropoxide’ was slowly added to the ascorbic acid. The precipitate was filtered and washed with water to remove any free ascorbic acid. Furthermore, zirconium npropoxide was slowly added to the ascorbic acid. The mixture was stirred for 30 minutes with some precipitate observed, after addition was complete. The powder was dried in a 45° oven for 24 hours.
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. Known ascorbic acid was dissolved in 600 methanol ml. 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. With that said, the mixture was stirred for 10 minutes with some precipitate observed, after addition was complete. Make sure you after a comment about it. Zirconium n propoxide was slowly added to the ascorbic acid.
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 singlephase 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. The slurry was poured into a ‘plasticlined’ 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. Each Paste I formulation was handloaded into an opaque polyethylene syringe and aged at 45° for 14 days. 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 an almost white paper towel. For instance, the data in TABLE IIa show that, upon visual inspection, the Paste Ia formulation containing zirconium ascorbate.
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.
The Paste set times Ia. Paste IIa compositions were measured in accordance with ISO specification The average set time of all samples prepared immediately after formulation and before aging was 1’30” to 1’40”. 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. Anyany disk was removed from the water, blotted dry with a paper wel and color coordinates immediately measured. 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 formulations were formed into 1 mm thick disks by pressing each Paste Ia. Each cured disk was removed from the mold and placed in a 37° /95percentage relative humidity chamber for 15 to 30 minutes. Paste IIa mixture into a 1 mm thick×2 cm diameter steel mold. Basically, anyevery disk was removed from the chamber and stored in deionized water at room temperature for 15 to 60 minutes.
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 syringe containing Paste remainder Ia was aged at 45° for various time intervals. On p of this, anyany 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. It is the L, a and b reflection color coordinates were obtained using the standard white color tile in the reflection sample port.
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. 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. Normally, paste Ia, the Paste set time Ia. Now please pay attention. Paste IIa composition. The ΔE ab values are reported in TABLE Set out below in TABLE V are the run no.
The data in TABLE V show the improvement in color stability without significant change in set time of a dental composition containing metal complexed ascorbic acid as well as stabilizers.
Even after 9 days at 45°, Run composition no. Certainly, additionally, both Paste Ie and Paste If contained both 1 g oxalic acid and 1 g sodium metabisulfite 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.
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 percentage 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 as pointed out by Example procedure 1 of Pat, as a comparison.
The three Paste I formulations were independently hand loaded into opaque polyethylene syringes and degassed. Each Paste I was independently mixed with an equal quantity of Paste IIb which was formed by combining the ingredients set out below in TABLE VIII. Paste Ii PREPARATORY aluminum ascorbate EXAMPLE 1 was substituted for the unmodified ascorbic acid.
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.
The Paste Ii composition contained the aluminum ascorbate, whereas the Paste Ih composition contained the allantoin ascorbate. Essentially, the data in TABLE IX show that both the Paste Ih. Oftentimes paste IIb and the Paste Ii. You can find more info about it on this site. Paste IIb composition continued to exhibit excellent color stability. Actually, paste IIb composition had noticeably yellowed. On p of this, by day 10, only the Paste Ii. Whenever failing to maintain its preaged consistency, On day 5, it was observed that the Paste Ih composition contained localized areas wherein the composition had gelled. Paste IIb compositions exhibited excellent color stability after 5 days aging at 45° Already by day 5, the Paste Ig.
On day 6, the Paste Ij formulation was removed from the oven and mixed with an equal percentage of Paste IIc. Paste IIc composition. Set out below in TABLE XII are the Paste Ij. For example, 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. 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.
Even after 14 days at 45°, the composition maintained excellent color stability. PREPARATORY EXAMPLE 1 as the reducing agent and cumene hyaftereroxide as the oxidizing agent. The data in TABLE XII show the excellent color stability of a paste. PREPARATORY EXAMPLE 1 as the reducing agent and cumene hyaftereroxide as the oxidizing agent. Needless to say, even after 14 days at 45°, the composition maintained excellent color stability.