EP0258241A1 - Zusammensetzung zur zahnärztlichen behandlung - Google Patents

Zusammensetzung zur zahnärztlichen behandlung

Info

Publication number
EP0258241A1
EP0258241A1 EP86902853A EP86902853A EP0258241A1 EP 0258241 A1 EP0258241 A1 EP 0258241A1 EP 86902853 A EP86902853 A EP 86902853A EP 86902853 A EP86902853 A EP 86902853A EP 0258241 A1 EP0258241 A1 EP 0258241A1
Authority
EP
European Patent Office
Prior art keywords
hydroxy apatite
paste
particles
dentine
calcium phosphate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP86902853A
Other languages
English (en)
French (fr)
Inventor
Brian Edward 38 St. John's Rise CAUSTON
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National Research Development Corp UK
Original Assignee
National Research Development Corp UK
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Research Development Corp UK filed Critical National Research Development Corp UK
Publication of EP0258241A1 publication Critical patent/EP0258241A1/de
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • 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

Definitions

  • This invention relates to a composition for use in dental treatment and also to dental treatment using such composition.
  • Dentine contains tubules which contain living cell processes and nerve fibres. These dentine tubules run perpendicularly from the surface of the tooth and directly to the pulp. Exposure of the dentine tubules to saliva and its cytotoxins can result in secondary caries, pulpitis, abscess formation, all of which cause pain to the patient and require additional removal of tooth structure.
  • the dentist will normally expose dentine and remove all the dentine which has deteriorated before a filling is applied. It is desirable to maintain as much dentine as possible to cut down on the time for cavity preparation with a view to making dental treatment less unpleasant by reducing the use of the drill. This is particularly important in the treatment of difficult or hypersensitive patients. In addition as much dentine as possible should be conserved since it has no equal as a material for constructing the inner parts of teeth (certainly better than composites or amalgams) .
  • Deterioration of the remaining dentine may also result from leakage of e.g. saliva around the margins and under the filling. Again if this occurs it is necessary for the filling and the newly deteriorated dentine to be removed and a larger filling is then applied.
  • filling material will bond more strongly to enamel than it will to dentine.
  • Filling adhesives used generally wet the more hydrophobic enamel material more than the dentine.
  • a storage stable paste comprising: (i) an aqueous phase containing Ca 2+ and PO.3- and having a pH between 5 and 7; and
  • the paste according to the present invention has sufficient stability to be stored, e.g. on a dentist's shelf, for prolonged periods. In the presence of dentine, however, the paste becomes unstable and a mineralising layer of hydroxy apatite is deposited from the paste on to the tooth to occlude dentine tubules and hypermineralise the dentine to provide a pseudo-enamel layer to which filling material bonds more strongly than to the dentine itself.
  • the paste according to the invention can be applied by a dentist as a thin layer, e.g. about 1mm thick, over the surface of a dental cavity of a patient after drilling and the tooth is filled.
  • the paste can act as a buffer and neutralises any acid leaking from the oral cavity or any acid biproducts of dental materials.
  • the dentist may be able to leave some damaged dentine, to be remineralised, rather than having to remove all deteriorated dentine as he would conventionally have had done. This means that using the paste according to the invention it is unnecessary for the dentist to remove as much damaged dentine as with conventional treatments.
  • the invention also provide a method for preparing a storage stable paste for use in dental treatment which method comprises contacting particles of hydroxy apatite with a saturated aqueous solution comprising calcium phosphate having a pH of between 4.6 and 8.5 whereby a protective layer comprising calcium phosphate forms on the surface of the particles, and, after protective layer has formed, if desired, removed an excess liquid, e.g. by decanting, to give a paste.
  • the paste according to the present invention is a metastable system. It has storage stability but becomes unstable in the presence of dentine. While it is not wished in any way to be bound by theory, it is believed that the composition and behaviour of the paste according to the present invention derives from the complex structures and behaviour of the calcium phosphates themselves.
  • the hydroxy apatite in the particles of the present paste is in a form which, in the presence of dentine, deposits hydroxy apatite.
  • a particle material which is too insoluble even in the presence of dentine the particles themselves will not dissolve in the aqueous phase of the paste and will not accordingly deposit hydroxy apatite on the dentine.
  • the hydroxy apatite material used according to the present invention will be a high solubility one having a higher water solubility than the exactly stoichiometric material.
  • Particularly suitable for use in the paste according to the present invention is water deficient, preferably highly crystalline, hydroxy apatite.
  • This known material is deficient in water of crystallisation and may be prepared by dehydration of hydroxy apatite under dehydration conditions (see for example Verbeeck et al. Caries Res. 14; 311-314 (1980)). Crystals of the water deficient material under X-ray crystallography are shown to be highly crystalline and apatite in structure with normal apatite dimensions except for one reduced dimension.
  • the water deficient material generally has a slightly higher solubility than normal stoichiometric crystalline hydroxy apatite.
  • the water deficient material may be prepared by heating the stoichiometric material at a temperature at which water of crystallisation is lost, generally between 900°C and 1200°C.
  • a temperature at which water of crystallisation is lost generally between 900°C and 1200°C.
  • it may be prepared by compacting industrial hydroxy apatite powder, and heating in a tube furnace at temperatures between 900°C and 1200"C and flushed with atmospheric carbon dioxide-scrubbed steam. The material thus sintered is then ground to a fine powder.
  • the sinter may contain some tricalcium phosphate but this is lost under aqueous conditions.
  • the paste according to the invention may be prepared by contacting the particles of hydroxy apatite with a saturated aqueous solution of calcium phosphate having a pH between 4.6 and 8.5 whereby a protective layer of calcium phosphate forms on the particles, and, after the protective layer has formed, removing any excess liquid to give a paste.
  • the addition of the hydroxy apatite particles to the saturated aqueous solution of calcium phosphate causes calcium phosphate to crystallise on to the particle surfaces. In this way a protective layer is formed over the hydroxy apatite. After the protective layer has formed any excess liquid can be removed, e.g. decanted off.
  • the composition of the calcium phosphate protective layer obtained in this way appears to depend for example on its age.
  • the protective layer obtained after some storage will normally comprise a mixture of at least octacalcium phosphate crystals and tricalcium phosphate crystals.
  • the initial protective layer should not be formed on the hydroxy apatite particles too slowly. Firstly of course if the process is too slow, preparation of the paste itself becomes a drawn out matter. In addition water deficient hydroxy apatite has a tendency to take up water from an aqueous environment to make up for its deficiency. Once the calcium phosphate protective layer has built up on the particles this does not happen. Thus the protective layer should be formed at a sufficient rate to prevent any appreciable gain of water.
  • the speed of formation of the initial calcium phosphate layer will depend upon several factors. Most particularly it will depend upon the degree of saturation of the aqueous calcium phosphate solution. The higher the degree of super saturation of the solution, then the faster will be the formation of the protective layer. Of course the higher the degree of super saturation, in addition the less stable will the aqueous solution itself be and it will have a tendency for calcium phosphate to precipitate out. Thus for practical purposes there is often a short concentration range which can be used bounded on one side by those solutions which are so highly concentrated that they are so metastable that they cannot practically be used and those solutions of lower concentration which have too slow a growth rate of dicalcium phosphate dihydrate crystals to be practical.
  • the aqueous solution will contain F , the presence of F ⁇ being desirable to ensure adequate speed of formation of the protective layer.
  • F should not be present in too great a quantity.
  • the F ⁇ may adversely affect the behaviour of the paste itself and impair the formation of the hydroxy apatite mineralising layer.
  • the F concentration will be of the order of 5 to lOOppm, suitably 5 to 20ppm.
  • the pH of the starting aqueous calcium phosphate solution is also an important factor. It is preferred that the aqueous solution used be isotonic and has a pH of approximately 7.4. The tonality of this solution may be achieved by addition of sodium chloride, pH being adjusted with sodium hydroxide. The pH of the solution will be between 4.6 and 8.5. However this pH also affects the speed at which the calcium phosphate protective layer is formed. Below pH 4.6 the speed is too slow to be practical while above pH 8.5 the solution obtained is so unstable that again it is impractical.
  • the aqueous solution may contain an agent for preventing algal growth though of course that agent must not interfere with the dynamics of the mineralising solution.
  • a suitable such agent is chloroform, preferably present at approximately 1.5% by weight concentration.
  • the aqueous solution should preferably contain Ca and P in the hydroxy apatite stoichiometric ratio i.e. they should preferably be present in the ratio of approximately 1.67. Departure from this ratio may lead to a tendency for the mineralising hydroxy apatite layer formed using the paste to have for example calcium deficiency.
  • the amount of hydroxy apatite which is added to the calcium phosphate solution is not critical and excess liquid can be decanted off. Generally speaking 10 to 50% by weight of hydroxy apatite will be added to the solution.
  • the hydroxy apatite is suitably used in the form of a fine powder having a particle size not exceeding 350 microns. Preferably the average particle size is approximately 100 microns.
  • Part I represents the time after water deficient, highly crystalline hydroxy apatite powder has been added to an isotonic, stoichiometric aqueous calcium hydroxide solution. There is seen a drop in pH as the crystals of calcium phosphate form on the surface of the hydroxy apatite particles.
  • Part II of the plot shows the paste obtained when being stored at 25 ⁇ C.
  • Part III shows the changes which occur when the paste is brought into contact with dentine. There is a rise in pH and, as will be seen, a loss of Ca 2+ from solution; the lost Ca 2+ having been deposited as hydroxy apatite mineralising layer on the dentine.
  • the compacting was carried out in a sturdy stainless steel cylinder with a heavy screw down gasketted top which was filled with oil and the pressure in the cylinder raised by means of a hydraulic pump.
  • the resulting pellet was easy to handle being of similar consistency and strength as a stick of chalk.
  • the pellets were then weighed and placed in a quartz boat which in turn was placed in a tube furnace having a fused silica liner and being flushed with atmospheric C0 2 /steam.
  • the heating cycle was as follows: When the quartz boat was introduced into the furnace the temperature was 500 ⁇ C. The temperature was raised at the rate of 35°C for 10 minutes to 1200 ⁇ C and then held at 1000°C overnight. Temperature was then reduced at the rate of 35°C per 10 minutes to 500 ⁇ C at which point the sintered material was withdrawn, over a period of the next hour.
  • Preparation of paste The hydroxy apatite powder was then added to the mineralising solution. A protective layer of initially dicalcium phosphate dihydrate was deposited on the powder particles. After maturing the protective layer was found to contain predominantly octacalcium phosphate crystals and subsequently tricalcium phosphate crystals. Any excess liquid was then decanted off to leave a paste. use A cavity was cut into a patient's tooth through the enamel and into the dentine. The cavity was irrigated first as a precaution with a broad spectrum antibiotic or a non-irritant bactericide.
  • a thin layer (about 1mm) of paste was spread over the exposed dentine and over adjacent enamel. The remaining exposed enamel was etched and the tooth was then filled.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Veterinary Medicine (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Birds (AREA)
  • Epidemiology (AREA)
  • Dental Preparations (AREA)
  • Cosmetics (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
EP86902853A 1985-04-23 1986-04-22 Zusammensetzung zur zahnärztlichen behandlung Ceased EP0258241A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8510310 1985-04-23
GB858510310A GB8510310D0 (en) 1985-04-23 1985-04-23 Dental treatment

Publications (1)

Publication Number Publication Date
EP0258241A1 true EP0258241A1 (de) 1988-03-09

Family

ID=10578058

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86902853A Ceased EP0258241A1 (de) 1985-04-23 1986-04-22 Zusammensetzung zur zahnärztlichen behandlung

Country Status (4)

Country Link
EP (1) EP0258241A1 (de)
JP (1) JPS62502547A (de)
GB (2) GB8510310D0 (de)
WO (1) WO1986006274A1 (de)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4861590A (en) * 1986-09-25 1989-08-29 Colgate-Palmolive Company Sustained release fluoride and calcium composition
US4859467A (en) * 1986-09-25 1989-08-22 Colgate-Palmotive Company Sustained release fluoride composition
GB8623643D0 (en) * 1986-10-02 1986-11-05 Unilever Plc Oral products
JPS646213A (en) * 1987-06-27 1989-01-10 Sangi Kk Composition for preventing denting caries
JP2711393B2 (ja) * 1988-05-31 1998-02-10 日本ゼオラ株式会社 口腔用組成物
JPH089530B2 (ja) * 1988-10-19 1996-01-31 株式会社サンギ 歯磨材
US6579516B1 (en) * 1995-06-13 2003-06-17 Zahra Mansouri Methods of delivering materials into the skin, and compositions used therein

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1487181A (en) * 1974-10-30 1977-09-28 Colgate Palmolive Co Sintered ceramics
US4342741A (en) * 1981-04-27 1982-08-03 Dental Chemical Co., Ltd. Dentifrice compositions
US4518430A (en) * 1982-04-29 1985-05-21 American Dental Association Health Foundation Dental resptorative cement pastes

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8606274A1 *

Also Published As

Publication number Publication date
GB8609791D0 (en) 1986-05-29
JPS62502547A (ja) 1987-10-01
GB2174301A (en) 1986-11-05
WO1986006274A1 (en) 1986-11-06
GB2174301B (en) 1989-07-12
GB8510310D0 (en) 1985-05-30

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Inventor name: CAUSTON, BRIAN, EDWARD38 ST. JOHN'S RISE