Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23G—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF
  • A23G4/00—Chewing gum
  • A23G4/06—Chewing gum characterised by the composition containing organic or inorganic compounds
  • A23G4/064—Chewing gum characterised by the composition containing organic or inorganic compounds containing inorganic compounds
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/15—Compositions characterised by their physical properties
  • A61K6/17—Particle size
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/20—Protective coatings for natural or artificial teeth, e.g. sealings, dye coatings or varnish
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/60—Preparations for dentistry comprising organic or organo-metallic additives
  • A61K6/69—Medicaments
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
  • A61K6/831—Preparations for artificial teeth, for filling teeth or for capping teeth comprising non-metallic elements or compounds thereof, e.g. carbon
  • A61K6/838—Phosphorus compounds, e.g. apatite
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
  • A61K8/20—Halogens; Compounds thereof
  • A61K8/21—Fluorides; Derivatives thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
  • A61K8/24—Phosphorous; Compounds thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/02—Inorganic materials
  • A61L27/12—Phosphorus-containing materials, e.g. apatite
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/28—Materials for coating prostheses
  • A61L27/30—Inorganic materials
  • A61L27/32—Phosphorus-containing materials, e.g. apatite
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q11/00—Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B25/00—Phosphorus; Compounds thereof
  • C01B25/16—Oxyacids of phosphorus; Salts thereof
  • C01B25/26—Phosphates
  • C01B25/32—Phosphates of magnesium, calcium, strontium, or barium
  • C01B25/322—Preparation by neutralisation of orthophosphoric acid
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B25/00—Phosphorus; Compounds thereof
  • C01B25/16—Oxyacids of phosphorus; Salts thereof
  • C01B25/26—Phosphates
  • C01B25/455—Phosphates containing halogen

Definitions

• Rod-shaped apatite crystals with a certain length-to-width ratio Rod-shaped apatite crystals with a certain length-to-width ratio
• the invention relates to rod-shaped apatite crystals which have a length-to-width ratio> 5 and in which the ratio of hydroxide ions to fluoride ions based on the total amount of crystals can be varied easily.
• the invention further relates to dispersions which contain such rod-shaped apatite crystals, and to a process for producing the dispersions or the apatite crystals.
• the tooth enamel like human bones, consists predominantly of hydroxyapatite.
• Mechanical stress on the teeth e.g. when eating or brushing teeth
• caries develops in bacteria in the cracks or in the pores, which is widely known as a very dangerous dental disease.
• a mineral protective film forms quickly on the teeth, which over time becomes slowly identical to the enamel due to slow dissolution in the mouth and adsorption of the fluoride-containing compounds also contained in the toothpastes, smoothes the enamel and effectively closes the cracks or pores.
• WO 00/37033 describes suspensions of sparingly water-soluble calcium phosphates, calcium fluorides and calcium fluorophosphates and their use in dentifrices.
• the calcium salts contained in the suspensions are produced by precipitation in an alkaline medium, the calcium salts being obtained in the form of crystals (primary particles) with thicknesses (diameters) of 0.005 to 0.05 ⁇ m and lengths of 0.01 to 0.15 ⁇ m.
• the calcium salts are precipitated in the presence of agglomeration inhibitors, such as water-soluble surfactants or water-soluble polymeric protective colloids.
• WO 01/01930 describes composite materials which comprise calcium salts which are sparingly soluble in water, such as calcium phosphates and calcium fluorophosphates, and a protein component.
• the calcium salts which also include hydroxylapatite, fluoroapatite and fluorodoped hydroxylapatite, are produced by being precipitated in an alkaline medium in the presence of the protein component. If necessary, the calcium salts (at least partially) also have rod-shaped structures, a large number of crystals with a length-to-width ratio of 1 to 2 being produced due to the also overlapping length and width values of the calcium salt crystals produced using this method. The crystals are deposited on the surface of the high-molecular protein component used, so to a certain extent they depict the spatial structure of the protein component.
• composite materials can be used for so-called biomineralization (mineral crystallization in a protein matrix), ie protein and calcium salt crystals are built into the protein matrix of the teeth or cooking. Consequently, the 3-dimensional structure of the composite materials is applied to the previous (tooth) surface, while, as mentioned above, hydroxyapatite crystals form sheet-like, 2-dimensional layers on the (tooth) surface.
• biomineralization process is comparatively slow and leads to composite materials applied to the (tooth) surface, the mechanical properties of which can differ considerably from those of the pure crystals.
• WO 98/18719 describes a process for the elongation of rod-shaped hydroxylapatite crystals in suspensions and the adjustment or concentration of the solids content of hydroxylapatite crystals in these suspensions.
• the original crystal length can be increased from 0.05 to 0.1 ⁇ m to 0.1 to 0.5 ⁇ m with a constant width of 0.01 to 0.02 ⁇ m, on the other hand, a solids content of 7 to 96% of hydroxyapatite crystals in the suspension can be set.
• the process is complex due to the numerous stirring and filtering steps, and it is also restricted exclusively to suspensions of hydroxyapatite crystals.
• the crystal length also appears to depend on the solids content in the suspension.
• the object is achieved by a process for producing dispersions which contain the rod-shaped apatite crystals described above.
• the method according to the invention has the following steps:
• step b) optionally, after step b), at least one fluoride-containing compound is added to the mixture present as a dispersion in the autoclave and mixed with this dispersion over a period of at least 1 hour.
• the pure apatite crystals can be isolated from the dispersions obtained in this way by subjecting the dispersions to drying, in particular spray drying, in an additional process step.
• the advantage of the solution according to the invention is in particular that a new method is provided with which apatite crystals can be produced which are exclusively rod-shaped.
• the method is not only limited to the production of hydroxyapatite crystals, but also mixtures of rod-shaped hydroxylapatite crystals and rod-shaped fluorapatite crystals or rod-shaped mixed crystals of hydroxylapatite and fluoroapatite can be produced.
• the rod-shaped apatite crystals produced by the process according to the invention have a length-to-width ratio of> 5. This means that in the "worst case" the crystals have a length-to-width ratio of 5, but there is also a significant number of crystals that have a length-to-width ratio have significantly greater than 5, for example 8 to 15. In contrast, most processes according to the prior art, as already mentioned, produce a large number of crystals with a length-to-width ratio of 1 to 2.
• Another advantage of the method according to the invention can be seen in the simple handling of the setting of the fluoride ion concentration.
• the hydroxyapatite crystals are already produced in rod form; in the second stage of the process, a defined number of hydroxide ions can be replaced by fluoride ions in an ion exchange process without changing the rod shape of the crystals.
• This process in which both pure fluorapatite crystals and mixed crystals of fluorapatite and hydroxylapatite are produced, provides a total amount of apatite crystals which contains a defined, freely adjustable amount of fluoride ions.
• the process according to the invention is suitably carried out in an autoclave, in particular a stirred autoclave.
• an autoclave in particular a stirred autoclave.
• Vessels or devices known to those skilled in the art can be used which can withstand the reaction conditions under elevated pressure.
• a mixture for example in the form of a suspension, is produced from the starting materials and water in an autoclave.
• Calcium hydroxide as a component containing calcium and phosphoric acid as a component containing phosphorus are suitable as educts. If necessary, additives such as calcium chloride, calcium nitrate (tetrahydrate), ammonium hydrogen phosphate or diammonium hydrogen phosphate can also be added to the reaction. Calcium hydroxide and phosphoric acid are particularly suitable; the latter is preferably used in 85% by weight form.
• water is understood to mean, in particular, fully demineralized water, but if appropriate the water can also have a residual content, for example of hydroxide ions and / or protons.
• demineralized water is placed in the autoclave and calcium hydroxide is added to the autoclave with stirring at room temperature.
• the suspension thus obtained is heated to 40 to 50 ° C and the phosphoric acid, which is optionally diluted with deionized water, is allowed to run into the autoclave with stirring over a suitable period of time.
• a temperature of at least 100 ° C. and a pressure> 1 bar is generated in the interior of the autoldaven; these conditions are maintained for at least 1 hour, preferably 5 to 16 hours, maintained.
• the second process step is preferably carried out at pressures between 1.5 and 6 bar, particularly preferably between 2 and 5 bar.
• Preferred temperature ranges are 105 ° C to 150 ° C, particularly preferred are 110 ° C to 130 ° C. If necessary, temperature gradients can also be used, temperature changes also causing pressure changes.
• the conditions of the second process step are maintained for 10 to 14 hours with stirring.
• the second process step can also be carried out in less than 1 hour.
• the second process step gives dispersions which contain rod-shaped hydroxylapatite crystals and which are preferably homogeneous.
• the solids content of these dispersions is 5 to 70% by weight, preferably 10 to 40% by weight, particularly preferably 15 to 30% by weight, of hydroxyapatite crystals; if appropriate, the solids content can also be ⁇ 5% by weight.
• the hydroxylapatite crystals produced in this way have (almost all) a rod-like shape, the length-to-width ratio of the (individual) crystals being> 5, but only> 20 in exceptional cases. A length-to-width ratio of 8 to 15, particularly preferably 9 to 12, is preferred.
• rod-shaped hydroxylapatite crystals having a length of 0.1 to 0.2 ⁇ m and a width of 0.01 to 0 can be produced , 02 ⁇ m, each based on the individual crystals.
• the thickness (ie the 3rd dimension) of the crystals corresponds to their width. It can thus be seen that the crystals produced by the method according to the invention only have a length-to-width (or thickness) ratio of 5 in the "worst case". This occurs with a crystal length of 0.1 ⁇ m and a crystal width
• the thickness-to-width ratio can also be a maximum of 20 (length: 0.2 ⁇ m; width: 0.01 ⁇ m).
• the length-to-width ratio of the individual Crystals can be controlled in the second process step using the parameters pressure, temperature and reaction time.
• the rod-shaped hydroxyapatite crystals can also be isolated from the dispersion.
• the dispersant can be removed by simple evaporation, if necessary with the aid of vacuum.
• the dispersion can also be subjected to freeze-drying to isolate the apatite crystals.
• the rod-shaped hydroxylapatite crystals produced by the process according to the invention are preferably isolated from the dispersion by spray drying, the apparatus necessary for this and the implementation of the spray drying being known to the person skilled in the art.
• the isolated hydroxyapatite crystals can be redispersed in water to give homogeneous dispersions without any problems.
• organic compounds such as water-soluble, lower alcohols and glycols, polyethylene glycols, glycerol and mixtures of the aforementioned organic compounds with one another and / or with water can also be used as dispersants for redispersion.
• a third process step (c) the hydroxide ions can be (partially) exchanged for fluoride ions in the hydroxyapatite crystals produced according to the invention become.
• at least one fluoride-containing compound is added to the dispersion produced in the second process step.
• Sodium fluoride, calcium fluoride, potassium fluoride and ammonium fluoride are suitable as fluoride-containing compounds; sodium fluoride is preferably suitable.
• the mixture thus obtained is mixed over a period of at least one hour, preferably 10 to 14 hours. Stirring is preferably carried out at room temperature; if appropriate, higher temperature values and / or shorter mixing times than 1 hour can also be used.
• the third process step is presumably based on an ion exchange mechanism.
• the calcium ions of the rod-shaped apatite crystals can be partially substituted by the cations originating from the fluoride-containing compound.
• those rod-shaped apatite crystals in which the calcium ions are partially replaced by the cations derived from the fluoride-containing compounds are also to be recorded by the formula Ca 5 (PO 4 ) (OH) x F y .
• the thickness of the crystals corresponds to their width. Any values for y from 0 to 1 can be set; this is controlled by the amount of fluoride-containing compounds added, the temperature values and the duration of the mixing process in the third process step.
• the rod-shaped apatite crystals of the formula Ca 5 (PO) 3 (OH) x F y contained in the dispersion can be encased by one or more surface modification agents.
• Surface modification agents are understood to mean substances which physically adhere to the surface of the crystals but do not react chemically with them.
• Surface modifiers are to be understood in particular as dispersants; the latter are also known to the person skilled in the art, for example, under the terms emulsifiers, protective colloids, wetting agents or detergents. Suitable surface modification agents are described, for example, in WO 01/01930. Antiallergics and / or anti-inflammatory agents can also be used as surface modification agents.
• the surface modification agents are applied to the surface of the rod-shaped apatite crystals by processes known to those skilled in the art.
• the apatite crystals of the formula Ca 5 (PO 4 ) (OH) x Fy produced by the process according to the invention are suitable in isolated form and / or in the form of dispersions for use as a remineralizing component for teeth and / or bones.
• the apatite crystals can be present both in cleaning and care formulations and in formulations for the treatment of tooth and bone defects.
• tooth gels, tooth pastes (or tooth creams), mouthwash (or mouth rinses) and chewing gums are mentioned.
• the apatite crystals according to the present invention are used as a constituent of formulations for inducing or promoting the formation of new bone tissue and for coating implants. The invention is further illustrated by the following examples.
• the autoclave was then closed and the temperature increased to 100 ° C.
• the hydroxyapatite obtained consisted of columnar crystals of prismatic cross section with widths and thicknesses of 0.01 to 0.02 ⁇ m and lengths of 0.1 to 0.2 ⁇ m.
• the specific surface was 49.4 qm g.
• Example 2 was carried out analogously to Example 1. After the dispersion containing the hydroxyapatite had cooled to room temperature, 0.168 kg of sodium fluoride were added to the autoclave and the dispersion was stirred for a further 12 hours at room temperature.
• the suspension was then drained from the autoclave.
• the X-ray diffractogram of a dried sample showed that approx. 20 mol% of the
• Example 2 was repeated with the difference that the reaction content was heated to 150 ° C. after 20 min at 100 ° C. and the reaction time was reduced to 4 h at this temperature. The pressure was 4.5 bar under these conditions. After the dispersion containing the hydroxyapatite cooled to room temperature, 0.067 kg of sodium fluoride was added.
• the X-ray diffractogram of the dried sample showed that approximately 8 mol% of the hydroxide ions, based on the total amount of crystals, were replaced by fluoride ions.
• the specific surface area was 46.8 m 2 g, the Ca / P ratio was 1.65, and the shape and dimensions of the crystals corresponded to those from Example 1.
• reaction mixture was stirred for a further 2 h at 70 ° C. and then cooled to room temperature.
• the X-ray diffractograms of the crystals isolated from the dispersion showed the diffraction reflections of hydroxyapatite.
• the hydroxyapatite had the shape of irregular spheres with a diameter of 0.4 to 5 ⁇ m.

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• 2002
  • 2002-06-20 US US10/480,809 patent/US20040171471A1/en not_active Abandoned
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