Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-07-12
2001-07-17
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S113000, C523S115000, C523S117000, C524S700000, C524S789000
Reexamination Certificate
active
06262142
ABSTRACT:
The invention relates to a dental material useful in making artificial tooth enamel, inlays, onlays and veneers. The invention provides dental material preferably having an opacity less than 50 percent and a localized wear volume loss of less than 0.025 mm
3
, formed from material having a hardenable matrix and a filler. A method according to the invention includes shaping the dental enamel material. Preferably the refractive index of the resin matrix material used to make artificial tooth enamel is within 5 percent of the refractive index of the filler material. More preferably, the refractive index of the resin matrix material is within 1 percent of the refractive index of the filler material. Most preferably, the refractive index of the resin matrix material is within 0.5 percent of the refractive index of the filler material.
The appearance of a dental restoration is modified not only by the intensity and shade of the pigments employed therein but also by the degree of translucency or opacity of the other material in the restorative. This is especially true of dental enamel.
BACKGROUND OF THE INVENTION
In the dental enamel art, translucency (the inverse of opacity) is a characteristic which is essential and improvements of 5 percent or more are widely recognized as being significant improvements in the art particularly when accompanied by acceptable wear resistance.
It is greatly preferred that dental enamel material be effectively homogeneous such that air bubbles or structural discontinuities are substantially avoided from introduction into the tooth structure. Additionally, it is preferred that such materials be capable of deforming a matrix band during the course of tooth filling. Such materials should also be capable of withstanding the physical stresses extant in the posterior region of the mouth and not crumble, fracture or erode under such conditions.
Opacity as used herein refers to the percentage of impinging white light transmitted from a spectrophotometer through a 1 mm thick sample of material being tested. More specifically, as used herein opacity of the sample of material, which is not pigmented, is measured using a Macbeth Color Eye Spectrophotometer calibrated according to the manufacturer's calibration method CAL-030-95, with the spectrophotometer connected to a CompuAid 286 microcomputer.
Localized wear volume loss (also known as volume loss of localized wear) as used herein refers to the volume loss in mm from a sample of material being tested after 250,000 cycles in a Leinfelder in vitro wear testing device as described in Leinfelder et al in
An In Vitro Device for Predicting Clinical Wear,
Quintessence International, Volume 20, Number 10/1989, pages 755-761. Measurements may be made for example using a VCA 2500 Video Contact Angle System, sold by AST Products, Inc., Billerica, Mass., and a microcomputer with MicroSoft Windows software, in accordance with the AST products User's Manual. The wear pistons are calibrated with the return limit set to 8.3 mm, load set to 10Kg Maximum, (the load applied to the piston being from 7.6 to 8.0 Kg), Crosshead speed set to 200 mm/min. Such device is in use at University of Alabama, University of North Carolina, Creighton University and at DENTSPLY International Inc.
Localized extended wear volume loss as used herein refers to the volume loss in mm
3
from a sample of material being tested after 400,000 cycles in a Leinfelder in vitro wear testing device as described in Leinfelder et al in
An In Vitro Device for Predicting Clinical Wear,
Quintessence International, Volume 20, Number 10/1989, pages 755-761. Measurements may be made for example using a VCA 2500 Video Contact Angle System, sold by AST Products, Inc., Billerica, Mass., and a microcomputer with MicroSoft Windows software, in accordance with the AST products User's Manual. The wear pistons are calibrated with the return limit set to 8.3 mm, load set to 10 Kg Maximum, (the load applied to the piston being from 7.6 to 8.0 Kg), Crosshead speed set to 200 mm/min. Such device is in use at University of Alabama, University of North Carolina, Creighton University and at DENTSPLY International Inc.
In measuring material volume loss the sample from the Leinfelder University of Alabama wear machine is measured for wear in the Form Taysurf profilometer which employs a transversing stylus to construct a 3D topographic map of the worn area by means of an electronic interface unit linked to a host computer. A surface analyzer program installed in the host computer graphically depicts the worn area and calculates its volume. This volume, expressed in cubic millimeters, is regarded as the “wear volume loss” of the material tested. The higher the volume loss, the greater the material wears.
The index of refraction (or refractive index) for any substance is the ratio of the velocity of light in a vacuum (Air at one atmospheric pressure is commonly used in place of a vacuum) to its velocity in the material being tested.
Liquid refractive index as used herein refers to the refractive index of a liquid. Preferably liquid refractive index as used herein is measured by a refractometer-Abbe Model (manufactured by BAUSH & LOMB).
Filler refractive index as used herein refers to the refractive index of inorganic filler particles. Preferably filler refractive index as used herein is that provided by the manufacturer, and may be measured, for example using a microscope.
Contrast ratio of dental composite is the ratio between the daylight apparent reflectance of the specimen when backed by a black standard and the reflectance of the specimen when backed by a white standard. The translucency of composite material is dependent on the particle size, shape and the difference in refractive indices between the glass filler and resin matrix in which the glass powders are located. The substantially perfect match (effective equality) in the refractive indices between inorganic glass filler and organic resin matrix used in the material of the invention results in the improved translucency of the dental enamel material of the invention.
Ethoxylated Bisphenol A Dimethacrylate (EBPADMA) also known as 2,2-Bis[4-(2-methacryloxyethoxy)phenyl]propane has the structural formula:
and is used as a resin matrix.
Triethylene glycol dimethacrylate also known as 2,2′[Ethanediylbis(oxy)bisethyl-di-2-methyl-propenate has the structural formula:
and is used as resin matrix.
Cyclodi-2,2′-bis{4-[3-methacryloxy-2-(1,12-dioxa-2,11-dioxo-3,10-diazadodecane)propoxy]phenyl} Propane (NCO Monomer) has the structural formula:
and is used as a resin matrix.
1,7,7,Trimethylbicyclo[2.2.1]heptane-2,3 dione (camphorquinone or CQ).
Ethyl-(4-N,N-dimethylamino)benzoate (EDAB) is a VLC initiating system and has a structural formula:
Butylated Hydroxy Toluene (BHT) also known as 2,6-bis(1,1-dimethylethyl)-4-methylphenol is a stabilizer having the structural formula:
(2-Hydroxy-methoxyphenyl)phenyl Methanone is a UV stabilizer having the structural formula:
and sold by BASF Corporation as Uvinul M40.
Diethyl 2,5-dihydroxyterephthalate is a fluorescing agent having the structural formula:
and is sold by Riedel-de Haën AG as Lumilux® Blau LZ.
2,7,7,9,15-Pentamethyl-4,13-dioxo-3,14-dioxa-5,12-diaza-hexadecane-1,16-diyldimethacrylate (UDMA) has a structural formula:
THE OBJECTS OF THE INVENTION
It is an object of the present invention to provide a dental enamel material having an opacity less than 50 percent and a localized wear volume loss of less than 0.025 mm
3
.
It is a further object of the present invention to provide a polymerizable matrix forming liquid and inorganic filler particles, wherein the liquid comprises polymerizable material having a first refractive index, the filler comprises a plurality of particles having a second refractive index and having an average particle size of from about 0.1 to about 10 micrometers, and the first refractive index is within 5 percent of the second refractive index.
It is a further object of the present in
Hammesfahr Paul D.
Jefferies Steven R.
Silver Paul A.
Subelka John C.
Wang Xiuling
Bieber James B.
Dentsply Research & Development
Lovercheck Dale R.
Szekely Peter
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