Classifications

• • 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
  • A61K6/884—Preparations for artificial teeth, for filling teeth or for capping teeth comprising natural or synthetic resins
  • A61K6/887—Compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • A61K6/889—Polycarboxylate cements; Glass ionomer cements

Definitions

• This invention relates to the use of lining materials for use with composite restorative materials by the "sandwich technique".
• the application of composites alone has produced microleakage at the gingival margin, which is probably caused by polymerisation shrinkage forces of the composite creating a channel between the composite and the gingival margin which allows access to bacteria.
• shrinkage forces are greater than the forces of adhesion between the composite and dentine, necessitating the development of either a new technique or other material to eliminate the channel.
• Previous workers have utilised glass ionomer cements as a primary layer at the cavity floor or gingival wall prior to the placement of the composite.
• Glass ionomers adhere strongly to dentine, and their curing mechanism does not create shrinkage forces as great as those for the setting of composites, so reducing the likelihood of microleakage. Moreover, the use of glass ionomers as linings has the desirable effect of continuous fluoride release into adjacent tooth structure, especially relevant in cases of high caries rate and susceptibility.
• Ceramic/acrylic fillings are transparent to X-rays. As a result, it is impossible for the dentist to inspect restorations, and to detect decalcified dentine, caries, overhanging margins, defects and voids when examining radiographs of teeth restored with non-metallic fillings.
• the first three problems can be overcome by using a glass ionomer/acrylic cement containing a filler to confer radiopacity, such as barium glass or barium sulphate.
• the glass ionomer cement would minimiue dontine decalcification and secondary caries if a high fluoride ion-leachable glass were used, together with its constituent calcium salt content.
• a radiopaque cement should enable detection of defects and voids, it is desirable to reduce their occurrence as far as possible.
• Other desirable criteria which this liner should meet include:
• the glass ionomer cement of this invention comprises an ionleachable fluoroaluminosilicate glass together with 15 to 30%, preferably about 20% by weight of barium glass or other suitable radiopaquer agents, to provide radiopacity. Blended with the glass is 0.1 to 10.0%, suitably 3 to 5% by weight of an organic peroxide, preferably benzoyl peroxide. Both glasses are in the form of fine powders, having a wet film thickness of less than about 15 ⁇ when dispersed in water.
• the frit of the ion-leachable glass has a ternary oxide composition consisting of chemically combined oxides of calcium, aluminium and silicon, wherein:
• alumina comprises 15-30% by weight of the total glass composition
• (b) calcium oxide comprises up to 50% by weight of the total glass composition
• silica comprises from 10-65% by weight of the total glass composition
• the glass comprises less than 14% by weight of fluorine, introduced by the addition of aluminium fluoride, calcium fluoride and/or fluorine containing minerals such as cryolite.
• the composition of the glass helps to control the setting time of the cement, which should be between one and ten minutes, and preferably two to five minutes, to allow the dentist adequate working time to mould the cement into the desired shape.
• BIS-GMA bisphenol A and glycidyl methacrylate usually referred to as BIS-GMA;
• aqueous solution of a polycarboxylic acid preferably poly (acrylic acid), of concentration 30-50% by weight
• the polycarboxylic acid solution should contain a maximum of 5% by weight of an amine activator.
• Representative amines include N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine, N,N-dihydroxyethyl-p-toluidine, N,N-dimethyl-3,5-xylldine and p-(dimethylamino) phenylacetic acid, with N,N-dihydroxyethyl-p-toluidine being the preferred activator. Setting occurs by two mechanisms, namely:
• An alternative embodiment of this invention is the subsitution of the chemical curing agents with a visible light curing systemo
• a suitable photosensitising system comprises two components, namely an ⁇ -diketone photosensitive species together with an amine reducing agent.
• Representative ⁇ -diketones include biacetyl, camphoroquinone, 2,2' - furil, p-toluil, ⁇ -and ⁇ -naphthil, benzil, phenanthraquinone and naphthoquinone, with camphoroquinone being the preferred photoinitiator.
• amines include tripropylamine, tributylamine, N-alkyl dialkanolamines and 2-(dimethylamino) ethyl methacrylate with the latter being the most preferred.
• Either or both components may be incorporated into either or both pastes, although it is preferred that both pastes contain both components.
• the quantity of both ingredients is carefully controlled within the range 0.01 to 0.2% by weight of the paste, and most preferably within the range 0.03 to 0.08% by weight.
• hardening should occur in 5 to 60 seconds, and suitably in 10 to 20 seconds.
• the set glass ionomer cement of this invention is acid-etched with a 30-40% by weight aqueous solution of orthophosphoric acid for 30 to 60 seconds, washed with water and dried. It is then optionally treated with a dentinal bonding agent prior to the application of a composite restoration.
• Suitable composites include two-paste chemically cured or single paste visible light cured formulations for the restoration of either anterior or posterior teeth.
• the two components are thoroughly blended by spatulation for about 30 seconds and immediately placed on the glass ionomer liner, shaped, and allowed to set.
• the composite With light cured composites, the composite is shaped in the lined cavity, and exposed to an intense beam of light of wavelength 420-450nm for 10 to 60 seconds preferably 10 to 20 seconds, to induce hardening.
• the composite adhered fairly strongly to the glass ionomer liner as separation was difficult.

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• Health & Medical Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Plastic & Reconstructive Surgery (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Dental Preparations (AREA)

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• 1987
  • 1987-02-04 EP EP87901094A patent/EP0312525A1/de not_active Withdrawn
  • 1987-02-04 WO PCT/GB1987/000085 patent/WO1988005651A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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