Ultrasonic Curing of Dental Filling Materials

a technology of dental filling and ultrasonic curing, which is applied in the field of composite materials, can solve the problems of secondary caries or discoloration of plastic filling, rise to shrinkage, and small cracks between teeth and fillings

Inactive Publication Date: 2008-05-22
DENTOFIT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007]The present invention provides an elegant solution to the above-mentioned shrinkage problems, in particular the shrinkage problems known from dental composite materials.

Problems solved by technology

This can give rise to shrinkage when the plastic dental filling material is polymerised.
This means that a small micro-crack is opened between the tooth and the filling.
The crack can cause secondary caries or discoloration of the plastic filling.
Micro-cracks give rise to a degradation of the mechanical properties of the composite material.
This can also give rise to degradation of the mechanical properties and failure of implants.
In the field of impression materials, shrinkage can cause dimension problems which can lead to misfit.

Method used

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Examples

Experimental program
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embodiments

[0145]In order to obtain zirconia particles that could undergo a fast phase transformation, a large surface area, e.g. 10-250 m2 / g or even better 50-200 m2 / g, of the particles is preferred and also obtainable by the means described herein.

[0146]Thus, a further aspect of the present invention relates to a population of zirconia particles having an average particle size in the range of 50-2000 nm and a BET surface area of in the range of 10-250 m2 / g, said particles being present in a metastable first phase and being able to undergo a martensitic transformation to a stable second phase.

[0147]Preferably, this population of zirconia particles allows for a martensitic transformation to be effected to an extent of at least 80% within 300 sec when tested in the “Zirconia Particle Transformation Test” defined herein.

[0148]As mentioned above, the average particle size is typically in the range of 50-2000 nm, such as in the range of 50-1000 nm, in particular 100-600 nm.

[0149]Although the parti...

example 1

Tetragonal Nano-Sized Zirconia

[0203]A method of making the tetragonal nano-sized zirconia (ZrO2) is described in the following. A solution of 0.5 M ZrOCl2 was made from ZrOCl2.8H2O and pure water. The amorphous zirconia ZrOx(OH)4−2x is precipitated with 1.5 M NH3 at a constant pH of 10. The mixture was left with magnetic stirring for 10 days. The precipitate was then washed with pure water and the filter cake was then heated to 120° C. overnight. The cake was then ground to a fine white powder and put in an oven with dry atmosphere at 450° C.

example 2

Tetragonal Nano-Sized Zirconia

[0204]A method of making the tetragonal nano-sized zirconia (ZrO2) is described in the following. A solution of 0.5 M ZrOCl2 is made from ZrOCl2.8H2O and pure water. The amorphous zirconia ZrOx(OH)4−2x is precipitated with 1.5 M NH3 at a constant pH of 8.5. The mixture is left with mechanical stirring for 10 days. The precipitate is then washed with pure water until no chloride ions was detected and finally with 96% ethanol. The filter cake is then dried in an oven 60° C. overnight. The cake is then ground to a fine white powder. To obtain particles, that can undergo a fast phase transformation, a large surface area e.g. 250-550 m2 / g better 350-550 m2 / g of the powder is preferred. The powder is then heated in an oven with dry atmosphere for 2 h. with a ramp of 4 h. to the temperature of the crystal formation temperature (460° C. for this batch) of the amorphous zirconia powder. The crystal formation temperature is determined by DSC of the amorphous zirc...

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Abstract

The present invention relates to a composite material exhibiting a low or even negligible volumetric shrinkage upon curing, or even a small expansion (e.g. up to 0.5%), in particular composite materials in the form of dental filling materials. The present invention also relates to a method of controlling volumetric shrinkage of a composite material upon curing, and to a method of reconstructing a tooth. The present invention also relates to ultrasonic curing of dental filling materials. The present invention further relates to a population of zirconia particles and methods for preparing such zirconia particles (e.g. zirconia in the tetragonal phase or zirconia in the cubic phase). The martensitic transformation of the filler ingredients is, e.g., triggered by application of ultrasound or by a chemical trigger.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a composite material exhibiting a low or even negligible volumetric shrinkage upon curing, or even a small expansion (e.g. up to 0.5%), in particular composite materials in the form of dental filling materials. The present invention also relates to a method of controlling volumetric shrinkage of a composite material upon curing, and to a method of reconstructing a tooth. The present invention also relates to ultrasonic curing of dental filling materials. The present invention further relates to a population of zirconia particles and methods for preparing such zirconia particles.BACKGROUND OF THE INVENTION[0002]In general, when polymerizable resin bases (e.g. monomers or monomer mixtures) are polymerized, shrinkage occurs. As it has been pointed out in, e.g., “Ring-Opening Polymerization with Expansion in Volume” by William J. Bailey et al, ACS Symposium 59, No. 4, pages 38-59 (1977), most of the critical shrinkage occurs a...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61K6/08A61K6/027A61K6/083A61K6/884A61K6/891A61K6/893
CPCA61K6/0073A61K6/083A61K6/09A61K6/0002C08L33/10C08L75/16A61K6/15A61K6/71A61K6/893A61K6/887
Inventor VAN LELIEVELD, ALEXANDERALMDAL, KRISTOFFERLINDEROTH, SORENSORENSEN, BENT
Owner DENTOFIT
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