Alginate-based power composition for dental impressions.

p0001The present invention relates to a powdery composition for the production of dental impressions, alginate, the characteristics of wettability, fluidity and dustiness are improved compared to conventional products.

p0002commonly used for making dental prints, composed essentially of at least one hydrosoluble alginate, a gelling agent of the alginate solutions, a regulating agent of the gelation, and powdered mineral fillers.

p0003The water-soluble alginate may be an alkali alginate, ammonium alginate, alkanolamine or a mixture thereof; the gelling agent may be a metal salt: metal salt of fatty acid such as calcium oleate, zinc laurate, stearate iron or a metal inorganic acid salt such as an iron or zinc sulfate or, preferably, a calcium sulfate hydrate; the regulating agent of the gelation can be selected from phosphates, pyrophosphates, silicates, alkali metal carbonates or citrates and mixtures thereof. The charges which are introduced into the mixture to improve its consistency and resistance, are generally diatomaceous earths, silica, talc, perlite or mixtures thereof.

p0004The powder mixture components is kneaded with water by the practitioner just prior to taking the impression, which is performed by applying the paste obtained, using an impression tray over the area of ​​the jaw patient which is to record the morphology, to prepare a prosthesis or make a model; when the paste is gelled, the footprint due to its elasticity can be removed from the mouth to be cast in plaster. This plaster model is subsequently used to prepare a prosthesis or to make a study Dentofacial Orthopedics.

p0005Reference may be made to the work of EW and RW SKINNER. PHILIPS - Science of dental materials - published by Julien PRELAT, Paris gives the product type composition for alginate impressions.

p0006The addition is also proposed various compounds in these conventional compositions to improve the properties of the product, and in particular the malleability of the pulp by addition of plasticizers such as alcohols, mineral or vegetable oils; or the accuracy of the impression, for example by the addition of fluorides, preferably with oxides or alkali hydroxides to also improve the stability of the powder and the strength of the gel, as described in US 3,291,668 or by the addition of polyacrylamide in the mixture as described in EP 198 131 or by addition of polymers to the pulp prior to its use as described in US 3,620,778.

p0007Colorants, flavorings and preservatives may also be introduced in the product.

p0008More recently it has proposed dental impression compounds whose implementation is accompanied by a low dust generation. Indeed, it is common that during storage the mixture becomes heterogeneous, the denser components tend to settle in the bottom of the box, and the practitioner has a habit of shaking the container before you take the amount of powder needed to prepare a paste for cavity, resulting in the opening of the box, the dispersion in the air of fine particles, that is, without a doubt, unpleasant for the persons present in the room, but can also be toxic.

p0009Thus, patent application EP-A-0058203 discloses a powdery composition for dental impressions which a part at least of the constituents has been coated with a product easy to wet, disperse or to dissolve in water; Among these products are cited dispersant polymers, such as xanthan gum, alkali polyalginates, ethers and cellulose esters, and surface active polymers, such as polyalkylene glycols or even molecules of low massemoléculaire, such as polyols, esters glycerol, alkanolamines, and laurylsulfates.

p0010In the Patent Application JP 58-98021, the grains of the powder coating is recommended with a nonionic surfactant and a hydrophobic liquid having a vapor pressure lower than 3.15 mmHg at 20 ° C while in FR-A- 2,553,999, is added to the powder thus coated with polyvinylpyrrolidone to improve stability of the product during storage and the plaster cast of the surface state to be prepared from the alginate impression.

p0011In patent application EP-A-0217 270, it calls for the introduction of an isoparaffin, such as 2,2,4,4,6,6,8-heptamethylnonane or 2,2,4,4, 6,6,8,8,10-nonaméthylundecane in a classic mixture to reduce the release of volatile dust.

p0012Finally, in patent application DE-A-35 11 721, it is recommended the granulation of the entire mixture with a polymer such as hydroxypropylcellulose or polyvinylpyrrolidone.

p0013The products of the present invention do not release dust when they are implemented; moreover, they flow well and are not tacky as can the products treated by liquids and they get wet easily by water, in contrast to products treated with hydrophobic compounds or granules, which makes the preparation and the homogenization of the dough easier.

p0014According to the present invention, the fillers introduced into an article for dental impressions based on conventional composition alginate, are previously coated with a hydrolysed gelatin, water soluble.

p0015The fillers are coated with a film of hydrolyzed gelatin, by spraying, dipping or by spraying the charge powder with an aqueous solution of hydrolysed gelatin in a coating turbine, a planetary mixer, a mixer granulator, a granulating sieve or in a fluidized bed for example in a spray granulator, and then the coated grains are dried by the action of a hot air stream at a temperature between 20 ° C and 80 ° C in a suitable apparatus, such as a drying tunnel or in the unit where took place the coating if it were a coating pan or a fluidized air bed apparatus.

p0016Hydrolysed gelatin film is from 1 to 10% by weight of loads weight and more particularly from 3 to 6%.

p0017The hydrolysed gelatin is prepared by action of an acid, a base, heat or an enzyme on a conventional gelatin resulting from the acidic or alkaline hydrolysis of the collagen present in bones, skin or tendons cattle, pigs or sheep. The starting gelatin has a molecular weight generally between 60 000 and 300 000, whereas the hydrolysed gelatin has an average molecular weight between 500 and 30,000 and preferably between 5000 and 10 000. The hydrolysed gelatin is soluble in water, at room temperature, that is to say around 20 ° C and shows no measurable gel strength in the conditions defined by the "British Standards", the concentration of 6.67% ( w / v) in water after 17 hours at 10 ° C.

p0018The gelatin hydrolysis methods are well known to those skilled in the art; reference may be ref anaging including patents FR-A-2099777 and US 4130555 or documents published by Novo (Denmark) and including NOVO Enzyme Information ref: 163b.

p0019Hydrolyzed gelatins are commercially available; mention may be made of gelatin having the SPG reference or reference DSF, marketed by MERO ROUSSELOT SATIA become SANOFI BIO INDUSTRY (France) and gelatin called Crotein A, marketed by Croda (Great Britain).

p0020In the following describes examples of implementation of the invention, and comparing results obtained with those compositions not having the features of the invention.

EXAMPLE 1

p0021The feed used is a diatomaceous earth, called Clarcel, it is coated with hydrolyzed gelatin, marketed by MERO ROUSSELOT SATIA Company under the GSP reference.

p0022In a granulator fluidized air bed Uniglatt type sold by Glatt (Germany) was charged with 400 g of Clarcel and 320 ml of an aqueous 5% (w / v) gelatin GSP (Mero Rousselot SATIA). The mass of powder being suspended in the air, under pressure is sprayed, the binder solution onto the fluidized powder bed.

p0023There is thus obtained a granular powder Clarcel coated tablet, containing 4% of gelatin, which flows freely and whose characteristics, compared with the starting product, are shown in Table I. <tables id="tabl0001" num="0001"><table frame="all"><title>TABLE I</title><tgroup cols="3" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" colsep="0" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="left">Clarcel</entry><entry namest="col3" nameend="col3" align="center">Clarcel coated</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Apparent volume:</entry><entry namest="col2" nameend="col2" align="char" char=",">4 m³ / kg</entry><entry namest="col3" nameend="col3" align="char" char=",">5.36 m³ / kg</entry></row><row><entry namest="col1" nameend="col1" align="left">Bulk density:</entry><entry namest="col2" nameend="col2" align="char" char=",">0.25 kg / m³</entry><entry namest="col3" nameend="col3" align="char" char=",">0.186 kg / m³</entry></row></tbody></tgroup><tgroup cols="3" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" colsep="0" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" align="left">Granulometry :</entry><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" /></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left"><500 microns</entry><entry namest="col2" nameend="col2" align="char" char=",">0.16%</entry><entry namest="col3" nameend="col3" align="char" char=",">1.4%</entry></row><row><entry namest="col1" nameend="col1" align="left"><250 microns</entry><entry namest="col2" nameend="col2" align="char" char=",">1.1%</entry><entry namest="col3" nameend="col3" align="char" char=",">10.64%</entry></row><row><entry namest="col1" nameend="col1" align="left"><100 microns</entry><entry namest="col2" nameend="col2" align="char" char=",">24.2%</entry><entry namest="col3" nameend="col3" align="char" char=",">61.54%</entry></row><row><entry namest="col1" nameend="col1" align="left"><40 microns</entry><entry namest="col2" nameend="col2" align="char" char=",">46.62%</entry><entry namest="col3" nameend="col3" align="char" char=",">23.04%</entry></row><row><entry namest="col1" nameend="col1" align="left">> 40 microns</entry><entry namest="col2" nameend="col2" align="char" char=",">27.92%</entry><entry namest="col3" nameend="col3" align="char" char=",">3.38%</entry></row></tbody></tgroup></table></tables>

p0024The composition for imprint is prepared by dry mixing in a fast ploughshare mixer, available from Lödige, the following products: <tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Clarcel coated ...</entry><entry namest="col2" nameend="col2" align="char" char=",">64.2 g</entry></row><row><entry namest="col1" nameend="col1" align="left">Laminar seaweed alginate potassium form ...</entry><entry namest="col2" nameend="col2" align="char" char=",">15.1 g</entry></row><row><entry namest="col1" nameend="col1" align="left">calcium sulfate dihydrate ...</entry><entry namest="col2" nameend="col2" align="char" char=",">1 g</entry></row><row><entry namest="col1" nameend="col1" align="left">potassium fluorotitanate ...</entry><entry namest="col2" nameend="col2" align="char" char=",">4.6 g</entry></row></tbody></tgroup></table></tables>

p0025The composition is then canning. At the opening of it after shaking, there is no release of powders in the air.

p0026then mixed 10 g of this product with 21 ml of water, a spatula in a small semi-rigid plastic bowl; the powder is wet very quickly and water is easily incorporated, the dough is ready in 30 seconds and it takes 3 minutes at 20 ° C.

p0027The powder mixture prepared in the same conditions but with Clarcel untreated releases particles in the air after shaking the box and the preparation of the dough is more difficult: the powder is less wet, and the incorporation of all of the water in the longest pulp.

p0028Both products give the same time of gelation and the gel allows, in both cases, to reproduce fine detail on the order of 35 m.

p0029Another powder mixture was prepared in the same conditions but with the ordinary Clarcel coated with a gelatin having a gel strength of 80 blooms measured according to British Standards. The shaken mixture does not release dust, but you can not prepare a paste with this composition suitable for fingerprinting: the beans are difficult to wet and do not crash with a spatula and is finally obtained a gel granular.

EXAMPLE 2

p0030It uses the same laminated load as in Example 1, but to prepare a powder for fingerprints giving a smooth paste, apply to the distribution of syringe:

p0031The mixture consists of: <tables id="tabl0003" num="0003"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">granulated Clarcel ......</entry><entry namest="col2" nameend="col2" align="char" char=",">63 g</entry></row><row><entry namest="col1" nameend="col1" align="left">Laminar seaweed alginate potassium form ......</entry><entry namest="col2" nameend="col2" align="char" char=",">6.5 g</entry></row><row><entry namest="col1" nameend="col1" align="left">Cloustonii alginate sodium form ......</entry><entry namest="col2" nameend="col2" align="char" char=",">6.5 g</entry></row><row><entry namest="col1" nameend="col1" align="left">calcium sulfate ......</entry><entry namest="col2" nameend="col2" align="char" char=",">3.7 g</entry></row><row><entry namest="col1" nameend="col1" align="left">potassium fluorotitanate ......</entry><entry namest="col2" nameend="col2" align="char" char=",">2 g</entry></row><row><entry namest="col1" nameend="col1" align="left">magnesium oxide ......</entry><entry namest="col2" nameend="col2" align="char" char=",">1 g</entry></row></tbody></tgroup></table></tables>

p0032This mixture does not release the dust shaking.

p0033Preparing a slurry with 7 g of powdery mixture and 21 ml of water.

p0034This dough takes gel in 4 minutes at 20 ° C. The mixture prepared with plain Clarcel releases dust and it is more difficult to prepare a slurry, with the homogeneous mixture according to the invention. The setting time, the smoothness of the resulting gel and the ability to reproduce fine details are not altered with the product according to the invention.