WO1993016675A1 - Dental cement - Google Patents

Dental cement Download PDF

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Publication number
WO1993016675A1
WO1993016675A1 PCT/GB1993/000272 GB9300272W WO9316675A1 WO 1993016675 A1 WO1993016675 A1 WO 1993016675A1 GB 9300272 W GB9300272 W GB 9300272W WO 9316675 A1 WO9316675 A1 WO 9316675A1
Authority
WO
WIPO (PCT)
Prior art keywords
cement composition
composition according
acid
pvpa
glass
Prior art date
Application number
PCT/GB1993/000272
Other languages
English (en)
French (fr)
Inventor
Ademola Olaseni Akinmade
Julian Hugh Braybrook
Original Assignee
British Technology Group Ltd.
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 British Technology Group Ltd. filed Critical British Technology Group Ltd.
Priority to EP93903260A priority Critical patent/EP0626842B1/en
Priority to DE69310150T priority patent/DE69310150T2/de
Priority to US08/256,265 priority patent/US5411584A/en
Priority to JP5514611A priority patent/JPH07503967A/ja
Publication of WO1993016675A1 publication Critical patent/WO1993016675A1/en

Links

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 a dental cement made from a polymeric phosphonic acid and a glass, other metal oxide or cermet, to a method of making the cement and to materials for use in making the cement.
  • a cement composition comprises an intimately blended mixture of a water-containing liquid, at least 30% by weight of the composition being a cation-catalysed cross-linkable polymeric add containing on average one phosphonic acid group per one to three backbone carbon atoms, such as poly(vinyl phosphonic acid) PVPA optionally containing poly(acrylic acid), and a metal oxide (e.g.
  • aluminosllicate (preferably fluoroaluminoslHcate) glass powder preferably containing SiO 2 and AI 2 O 3 in the mass proportions (0.6 to 3.0):1 such as (1 to 2):1, preferably (1% to 2):1, in the proportions (1 minus ⁇ )g phosphonic add: 1 to 5g glass: ⁇ g liquid, where ⁇ is from 0.3 to 0.7, characterised in that the acid has been pre-reacted in aqueous solution at elevated temperature with a fluoride and/or phosphate of preferably a divalent or trivalent metal e.g. of Zn, Sn, Mg, Ca, Al or B, or a mixture, e.g. ZnF 2 + BPO 4 , preferably amounting to Z1 ⁇ 2 to 121 ⁇ 2%
  • the glass powder is preferably two-phase and preferably consists of particles substantially all of which are smaller than 100 microns, preferably smaller than 60 microns. If it is desired to reduce its reactivity with the acid, the glass powder may be heat-treated, for example at at least 400°C (preferably 450 - 600°C) for at least 40 minutes (preferably at least 55 minutes). While a glass rapidly quenched from a high temperature will usually be translucent, certain heat treatments yield an opaque glass, and hence an opaque cement, which may be acceptable in appropriate cases. The glass may alternatively.be de-activated by washing in a dilute acid such as acetic add, typically in a 21 ⁇ 2% weight concentration for 1 hour.
  • the glass is admixed (e.g.
  • MgO deactivated at at least 900°C may be used.
  • the solvent is preferably aqueous, i.e. water, and preferably dissolves the acid, the glass being kept separate until use.
  • the add may be dried (optionally freeze-dried but more preferably spray-dried) and mixed with the glass; the invention extends to this mixture, and to a pack of dried acid plus glass, preferably packed in a sealed capsule (PVPA being hygroscopic) and which is made into cement by adding the said liquid.
  • the acid may be accompanied by a desiccant such as hydrophobic silica.
  • the glass may be replaced by a metal oxide such as ZnO or MgO, preferably heat-treated, preferably of dense powder morphology, or by a cermet.
  • a cermet is a metallised glass powder, typically formed by fusing (by sintering) a metal powder (e.g. silver or tin) onto the surface of a glass powder, and may offer lower friction when burnished and greater wear resistance than glass in these cements.)
  • a chelating agent e.g. a chelating phosphonic acid is preferably present, in a preferred amount of 10 to 20% by mass.
  • the invention extends to a pack comprising two pastes which when mixed form a cement composition as set forth above; the first paste may be the pre-reacted acid(s) plus water, and the second paste may be the glass or oxide powder suspended in aqueous thickening agent e.g. methylcellulose.
  • aqueous thickening agent e.g. methylcellulose.
  • Ordinary aqueous PVPA with optional complexant is a solution and therefore not entirely satisfactory as a paste, but pre-reacted PVPA as set forth above forms a gel and thus a true paste. If the two pastes have been formulated to appropriate concentrations, one could in use squeeze out equal lengths of paste from two tubes, or scoop out equal numbers of spoonfuls from two tubs, as an easy way to ensure that the mixture is of the correct composition.
  • composition may further contain acid-neutralising agents such as zinc oxide or aluminium phosphate or both, in a total amount of up to 10% by mass based on the acid solution, and/or complexing agents such as phosphonic-add-based materials.
  • acid-neutralising agents such as zinc oxide or aluminium phosphate or both
  • complexing agents such as phosphonic-add-based materials.
  • the invention also extends to a pack comprising the components of the cement composition set forth above, so packed that when unpacked and mixed they form the cement.
  • ingredients of a cement composition according to the invention comprise glass, glass modifier, acid (PVPA), prereactant, desiccant, complexant, and solvent. These will be considered in turn.
  • Glass Three compositions of glass were used, referred to for convenience as G4, G5 and G6.
  • G4 and G5 are prepared by mixing together 424 parts by weight silica, 32 parts by weight alumina, 18 parts by weight calcium fluoride, 24 parts by weight cryolite Na3AlF 6 and 8 parts by weight aluminium phosphate.
  • G4 is fired at 1330°C, held for 70 minutes, then quenched (poured) straight into water.
  • G5 is fired at 1280-1300°C, held for 90 minutes, poured out of the furnace onto a metal plate and held there as a melt for 30 seconds before being quenched in water.
  • the metal plate causes a relatively slow cooling, during which some crystallisation (typically of fluoride) takes place, yielding ultimately a less reactive glass.
  • G6 is prepared by mixing together 441 parts by weight silica, 232 parts alumina, 130 parts calcium fluoride, 65 parts lithium fluoride, 72 parts aluminium fluoride and 60 parts aluminium phosphate. This is fired at 1300°C, held for 60 minutes, poured onto a metal plate and held there as a melt for 30 seconds before being quenched in water. The resulting glass in each case is ground and sieved, and the fraction of particle size less than 45 microns is deactivated by heating in a furnace at 450°C for 90 minutes.
  • Glass modifier Boron phosphate BPO 4 was used in varying concentrations as a glass modifier. It is commercially available in "General Purpose Reagent" grade. It was sieved and the fraction of particle size less than 45 microns was ball-milled with the (previously milled) glass powder for 6 hours to obtain a homogeneous mixture.
  • Prereactant The PVPA was mixed with a prereactant.
  • the prereactant was incorporated into aqueous solutions of the PVPA by simply heating the PVPA solutions to ⁇ 80°C on a hot plate and then gradually stirring the prereactant portions into the solutions with the aid of a magnetic stlrrer.
  • the white prereactant powder gels up within a few minutes before finally dissolving to result in a homogeneous solution. These solutions were then spray dried and could be stored in resealable bags. Seven different prereactants were tried.
  • Boron phosphate improved the compressive strength of the resulting cement. It was however found that, if used instead as a glass modifier, boron phosphate had the additional benefit of. lengthening the working time of the cement. Therefore, while boron phosphate is a possible prereactant, we have (when glass is used) preferred to exploit it more fully, as a glass modifier.
  • Zinc phosphate Zinc phosphate
  • Metal ions appear to crosslink PVPA and hence increase its effective molecular weight or chain length. This in turn Improves the compressive strength. Phosphate Ions in general improve the working time, giving the cement a longer opportunity to wet the surface on which it has been placed, and hence can improve adhesive strength.
  • F- appears to enhance the compressive strength and, by decreasing the surface energy of the cement, improves the wetting power of the newly mixed cement components, hence improving the quality of mixing, hence Improving the strength of the cements.
  • Fluoride also desensitises the tooth, and achieves the creation of a new species, conveniently referred to hereafter as PVPA/F, wherein the F- ions are believed to 'graft' onto the backbone of the PVPA chains.
  • Possible advantages of PVPA/F include the controlled (slow) release of F- ions and its reduced solubility in water and its 'deactivation' with regards to its reaction with glass to form cements,
  • Divalent metals such as Sn(II) have been found generally better than trivalent. Tin shortens working time (but not excessively) and setting time while improving compressive strength,
  • Desiccant A problem encountered with all of these formulations is that even spray-dried PVPA readily takes up water from the atmosphere, resulting in inconsistencies unless the PVPA is used within a short space of time. For this reason silica e.g. untreated or preferably hydrophoblc silica R972 by Degussa (Milmslow, Cheshire) was incorporated into PVPA in an attempt to increase its stability and translucency and to improve the handling properties of the cement. The R972 was added as a given percentage of the total PVPA mass. For example if 0.175g R972 were added to 3.5g (dry weight) of PVPA then this would be expressed as 5% R972. The desiccant was added directly to the PVPA and mixed using a pestle and mortar.
  • a chelating phosphonic acid in freeze-dried form was added to the cement mix (glass + dry PVPA) with the aid of a pestle and mortar.
  • a suitable complexant was Dequest 2010 (trade mark), which is 1-hydroxyethylidene-1,1-diphosphonic acid. This was most successfully handled in freeze-dried form, unlike PVPA. Inadequate chelating phosphonic add will inadequately lengthen the working time, while excess chelating phosphonic acid will compete with the polymeric phosphonic acid in forming a reaction cement with the glass, the cement formed by "chelating" acid being a source of potential weakness.
  • Solvent Distilled water. This would normally be added to the acid, prereactant, dessicant and complexant just before the full cement composition was made up, but other sequences of addition are possible. The relative proportions of these components are significant, as the following examples will show, and are defined herein according to the following conventions:
  • the powder:liquid (p/l) ratio is defined as
  • any of the divisor components (apart from the solvent) can in practice be mixed with the glass powder in the solid phase.
  • the % strength of acid (e.g. "50% PVPA”) is defined as
  • the % strength of complexant (e.g. "15% D2010") is defined as
  • mass of glass powder includes the mass of glass modifier (BPO 4 ). Where we talk (as in the following examples) of, say, "14g glass/5%BPO 4 ", we thus mean 100 parts (13.333g) of the product of (silica + alumina + calcium fluoride + cryolite + aluminium phosphate) and 5 parts (0.667g) of boron phosphate.
  • the mass of the glass/5% BPO 4 is altered, while keeping all other parameters constant. For example in a 3:1 p/l ratio, 21g of glass is used.
  • a cement may thus be identified, for example, as la/2:1/G5.
  • the results obtained were as follows:-
  • R972 incorporation up to an optimum value of 5% also increases the compressive strength, after which the effect is less.
  • the opacity is unaffected by R972 except at higher concentrations.
  • Freeze-dried PVPA is less stable than spray-dried PVPA and gives lower compressive strength and working times.
  • Zinc phosphate used in 7% and 10% concentrations give better working times than 5% or 15%, but 10% gives a quicker set. Compressive strength was however best at 12%%.
  • bracketed numbers represent the standard deviations of six cement specimens for each formulation.
  • the results are average values of three cement samples.
  • the modified PVPA was prepared by adding ZnF 2 to an aqueous solution of PVPA (40% by mass) to give a ZnF 2 level of 5% on PVPA. This mixture was heated at 80°C until all of the ZnF 2 had dissolved (approximately 2 hrs), then cooled and the solid product obtained by spray-drying. This solid was then blended with an appropriate amount of freeze-dried D2010 and glass powder in a pestle and mortar. Cements were prepared by adding sufficient water to create an equivalent powder/liquid ratio of 1.4:1.
  • the resulting cement had the following propertles:- Working time: 174 seconds
  • Example 2 used magnesium fluoride MgF 2 .
  • the compressive strengths of the resulting cements were as follows:
  • Example 1 was repeated but using aluminium fluoride AIF 3 in place, of ZnF 2 .
  • Increasing AIF 3 led to increasing strength but cements with AIF 3 greater than 5% were not tested due to the difficulty encountered in mixing such cement formulations.
  • Cements having 15% D2010 concentration also show an improvement in compressive strength compared with 10% D2010 variant.
  • AlF 3 -modified PVPA cements with 60% PVPA are weak.
  • the compressive strength could be improved to 137MPa using.5% AIF 3 , but at the cost of a working time cut to 108 seconds and an ST/WT of 2.1.
  • This Example shows the use of ZnO rather than glass.
  • the brick was ground for as short a period as possible and sieved to obtain -45 microns powder; it was preferred to lose oxide on the sieve than to grind for so long that an excess of submicron powder resulted, as such submicron powde ⁇ would have been too reactive.
  • This zinc oxide powder was reacted in p:1 ratio of 1.5:1 with aqueous PVPA of 50% strength with 13.8% D2010, the PVPA having been pre-reacted with 10% BPO 4 .
  • This cement should be capable of releasing fluoride ions, which is known to be clinically beneficial.
  • This Example shows a two-paste system. Using 10% Zn 3 (PO 4 ) 2 -modified PVPA (40g), and a commercial 60% aqueous solution of D2010 (13.15g), and 4g added water, made into a solution, a thick tacky paste was formed by letting the solution stand for 3 weeks. The overall weight composition, after allowing for the fact that 40% of the 13.15g component was itself water, worked out at 70.0% PVPA + 13.8% D2010 + 16.2% water. Hydrophobic silica could also be added. This unusually concentrated PVPA helped to achieve a thick paste with plenty of active ingredient and also compensated for the presence of water in the glass paste, which is now described.
  • G5 glass (not deactivated by heat-treatment or acid washing) was mixed with 0.11g carboxymethylcellulose thickener and 6.89g water. These were the least quantities of thickener and of water that allowed the glass to be presented as a paste; larger quantities of thickener and/or of water led to a weaker cement; but possibly de-activated G5 glass would need less water.
  • a cement was made using a glass:polymer ratio of 2.5:1 and had a compressive strength of 48MPa.
  • the BF 3 and also the SnF 2 improved working time, setting time and compressive strength compared with the non-pre-reacted PVPA.
  • the PVPA was pre-reacted as in the previous examples, but note that BF 3 was used in the form of BF 3 .2H 2 O, which is a liquid.

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  • Health & Medical Sciences (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Veterinary Medicine (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Plastic & Reconstructive Surgery (AREA)
  • Dental Preparations (AREA)
  • Chemical & Material Sciences (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
PCT/GB1993/000272 1992-02-19 1993-02-10 Dental cement WO1993016675A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP93903260A EP0626842B1 (en) 1992-02-19 1993-02-10 Dental cement
DE69310150T DE69310150T2 (de) 1992-02-19 1993-02-10 Dentalzement
US08/256,265 US5411584A (en) 1992-02-19 1993-02-10 Dental cement
JP5514611A JPH07503967A (ja) 1992-02-19 1993-02-10 歯科用セメント

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9203510A GB2264498A (en) 1992-02-19 1992-02-19 Dental cement
GB9203510.4 1992-02-19

Publications (1)

Publication Number Publication Date
WO1993016675A1 true WO1993016675A1 (en) 1993-09-02

Family

ID=10710666

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1993/000272 WO1993016675A1 (en) 1992-02-19 1993-02-10 Dental cement

Country Status (7)

Country Link
US (1) US5411584A (en, 2012)
EP (1) EP0626842B1 (en, 2012)
JP (1) JPH07503967A (en, 2012)
DE (1) DE69310150T2 (en, 2012)
GB (1) GB2264498A (en, 2012)
IN (1) IN184301B (en, 2012)
WO (1) WO1993016675A1 (en, 2012)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6818682B2 (en) 2001-04-20 2004-11-16 3M Innovative Properties Co Multi-part dental compositions and kits

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5681953A (en) * 1992-11-19 1997-10-28 E. I. Du Pont De Nemours And Company Fluoroaluminate (AlF4) compounds
US6391286B1 (en) 1995-11-17 2002-05-21 3M Innovative Properties Company Use of metallofluorocomplexes for dental compositions
CN101351183A (zh) * 2005-12-29 2009-01-21 3M创新有限公司 包含水清除剂的牙科用组合物
DE102008030326A1 (de) * 2008-06-30 2009-12-31 S&C Polymer, Silicon- und Composite Spezialitäten GmbH Polyalkenoat-Zemente mit verbesserten Eigenschaften
JP6734659B2 (ja) * 2016-02-15 2020-08-05 株式会社松風 根管充填用シーラー組成物

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0225706A2 (en) * 1985-10-25 1987-06-16 Btg International Limited Cement-forming compositions
EP0340016A2 (en) * 1988-04-27 1989-11-02 Btg International Limited Poly-vinylphosphonic acid and metal oxide or cermet or glass ionomer cement
EP0431740A1 (en) * 1989-10-26 1991-06-12 Btg International Limited Poly(vinylphosphonic acid) glass ionomer cement

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59122411A (ja) * 1982-12-29 1984-07-14 Tokuyama Soda Co Ltd 歯科用セメント組成物

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0225706A2 (en) * 1985-10-25 1987-06-16 Btg International Limited Cement-forming compositions
EP0340016A2 (en) * 1988-04-27 1989-11-02 Btg International Limited Poly-vinylphosphonic acid and metal oxide or cermet or glass ionomer cement
EP0431740A1 (en) * 1989-10-26 1991-06-12 Btg International Limited Poly(vinylphosphonic acid) glass ionomer cement

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6818682B2 (en) 2001-04-20 2004-11-16 3M Innovative Properties Co Multi-part dental compositions and kits

Also Published As

Publication number Publication date
IN184301B (en, 2012) 2000-08-05
EP0626842B1 (en) 1997-04-23
JPH07503967A (ja) 1995-04-27
GB2264498A (en) 1993-09-01
GB9203510D0 (en) 1992-04-08
US5411584A (en) 1995-05-02
DE69310150D1 (de) 1997-05-28
DE69310150T2 (de) 1997-08-28
EP0626842A1 (en) 1994-12-07

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