Dentistry – Prosthodontics
Reexamination Certificate
2001-09-04
2003-07-15
Manahan, Todd E. (Department: 3732)
Dentistry
Prosthodontics
C523S115000, C433S199100
Reexamination Certificate
active
06592369
ABSTRACT:
DETAILED DESCRIPTION
The invention relates to wax-like polymerizable materials. The invention provides wax-like polymerizable dental materials, and methods of forming dental products of high strength dental polymeric material. This wax-like polymerizable dental material is quickly and easily reshaped. It is reshaped by warming, and shaping while warm and then allowing it to cool to room temperature. The shaped wax-like polymerizable dental material is cured to form dental products. These dental products have superior strength compared to products formed from prior wax-like polymerizable materials. Prior wax-like polymerizable materials do not form strong enough polymeric material for making dentures. High strength dentures are made by positioning artificial teeth in wax-like polymerizable dental material of the invention. The disclosures of U.S. patent application Ser. No. 09/670,364 filed Sep. 26, 2000 now abandoned and U.S. provisional patent application Serial No. 60/237,523 filed Oct. 4, 2000 are incorporated herein by reference in their entirety.
Volkel et al in U.S. Pat. No. 6,057,383 (and Canadian Patent Application 2207351), assigned to Ivoclar, disclose wax-like polymerizable material for making entire dental products. The prior art does not disclose a wax-like polymerizable material for forming dentures or other high strength products.
The invention provides a high strength dental polymeric material formed from wax-like polymerizable dental material. High strength dental polymeric dental products include partial dentures and full dentures.
Working wax-like polymerizable dental material, often includes molding, shaping, and/or carving. When heated, wax-like polymerizable dental material softens. In its softened state, it is believed to be partially crystalline and have a flowable amorphous phase, which allows some flowability of the material. Preferably, wax-like polymerizable dental material is dimensionally stable below 24° C. and softened at and above 24° C. More preferably it is softened at and above 30° C. By heating from its dimensionally stable condition, wax-like polymerizable dental material of the invention undergoes a rapid transition to being freely flowable. By cooling from its softened state, wax-like polymerizable dental material of the invention undergoes a rapid transition to being dimensionally stable. Small volumes of wax-like polymerizable dental material may be worked, while being warmed on the dental device. They may be dispensed from a heated syringe-type dispensing device, spatula, electric spatula, disposal dropper or other mechanical or electrical dispenser. To make a denture, wax-like polymerizable dental material is positioned on a polymeric base plate made from an impression of a patient's mouth. Artificial teeth are positioned in the wax-like polymerizable dental material, which is then shaped by melting and resolidifying. Then the wax-like polymerizable dental material is polymerized to form a denture. Thus the denture is formed without applying inorganic plaster to the artificial teeth and without positioning artificial teeth in a mold as required by conventional lost wax or other similar prior art methods of forming a denture. Compounds, which are readily partially crystallizable and useful in wax-like polymerizable dental material of a preferred embodiment of the invention, include methacrylate (or acrylate) compounds prepared for example by reaction of a urethane pre-oligomer with hydroxylalkymethacrylate. Preferably such compounds have a structure within the scope of one of general formulas I-V below. Preferably the urethane pre-oligomer is linear, comprises isocyanate end groups and has a structure within the scope of general formula I:
OCN—(R
1
—NH—CO—O—R
2
—O—OC—NH)
m
—R
1
—NCO I
wherein R
1
and R
2
are either an alkyl having from 1 to 14 carbon atoms or containing at least an aromatic group having from 6 to 14 carbon atoms, m is an integer from 0 to 20, the value of m in the oligomer depends on the molar ratio of diisocyanate to diol used, and the value of m increases as this molar ratio decreases. The diisocyanate portion has the structure OCN—R
1
—NCO and the diol portion has the structure HO—R
2
—OH.
Alternatively, urethane pre-oligomer is formed by reaction of at least one diol with excess, at least one diisocyanate to yield a urethane pre-oligomer having a structure within the scope of one or more of general formulas:II-IV
General Formulas: II-IV
OCN—(R
1
—NH—CO—O—R
2
—O—OC—NH)
m
—
II
(R
1
—NH—CO—O—R′
2
—O—OC—NH)
n
—R
1
—NCO
OCN—(R
1
—NH—CO—O—R
2
—O—OC—NH)
m
—
III
(R″
1
—NH—CO—O—R
2
—O—OC—NH)
n
—R′
1
—NCO
OCN—(R
1
—NH—CO—O—R
2
—O—OC—NH)
m
—
IV
(R″
1
—NH—CO—O—R′
2
—O—OC—NH)
n
—R′
1
—NCO
wherein R
1
, R′
1
, R
2
and R′
2
each independently is an alkyl having from 1 to 14 carbon atoms or at least an aromatic group having from 6 to 14 carbon atoms, n and m are each independently integers from 0 to 20, the sum of n and m in the oligomer depends on the molar ratio of diisocyanates to diols used, and the value of the sum of n and m increases as this molar ratio decreases. The diisocyanates have the structures OCN—R
1
—NCO and OCN—R′
1
—NCO and the diols have the structures HO—R
2
—OH and HO—R′
2
—OH. The more complex structures of urethane pre-oligomer are constructed from at least two different diols and at least two different diisocyanates.
Reaction of the urethane pre-oligomer with the ethylenically unsaturated monomer as defined below yields a polymerizable compound having the structure within the scope of the general formula V:CH═C(R
3
)—CO
2
—R
4
—CO—NH—(R
1
—NH—CO—O—R
2
—O—OC—NH)
n
—R
1
—NH—CO—R
4
—O
2
C—C(R
3
)═CH
2
V wherein R
3
is hydrogen, or an alkyl, such as a methyl group, and R
4
is an alkyl group having from 1 to 14 carbon atoms, and n is an integer from 0 to 20. The typical ethylenically unsaturated monomer is a hydroxyalkyl (meth) acrylate, e.g. 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, caprolactone 2-(methacryloyloxy) ethyl ester, etc.
Preferred mechanical properties of cured resin and the adequate handling properties of compositions, polymerizable compound, are present when the value of n in the compound is not greater than 10; more preferably n is not greater than 5. The preferred value of n in the compound largely depends on the requirements of the specific application. The most preferable value of n in the compound for aromatic ring based diol is between 1 and 3. Therefore, the molar ratio of diisocyanate to diol for aromatic ring based diol is most preferable between 1.33 and 2. The most preferable value of n in the compound for alkyl based diol is between 1 and 4. Therefore, the molar ratio of diisocyanate to diol for alkyl based diol is most preferable between 1.25 and 2.
Catalysts known in the art may be used to accelerate the formation of the isocyanate-ended pre-oligomer and end-capped ethylenically unsaturated monomer, for examples, tertiary amines and metal salts, e.g. stannous octoate and in particular dibutyl tin dilaurate. Preferred stabilizers used in this invention are butylated hydroxytoluene (BHT) and the methyl ether of hydroquinone (MEHQ).
Preferably compounds of the invention are difunctional methacrylates including reaction products of bisphenol A propoxylate, 1,6-diisocyanatohexane and 2-hydroxyethyl methacrylate, reaction products of bisphenol A propoxylate, trimethyl-1,6-diisocyanatohexane and 2-hydroxyethyl methacrylate, a series of reaction products of bisphenol A, trimethyl-1, 6-diisocyanatohexane and 2-hydroxylethyl methacrylate, a series of reaction products of bisphenol A, 1,6-diisocyanatohexane and 2-hydroxylethyl methacrylate, a series of reaction products of trimethyl-1,6-diisocyanatohexane, 2,5-dimethyl-2,5-hexanediol and 2-hydroxyethyl methacrylate, a series of reaction products of trimethyl-1,6-diisocyanatohexane, 1,6-diisocyanatohexane, 2,5-dimethyl-2,5-hexanediol and 2-hydroxyethyl methacrylate, a series of reaction products of trimethyl-1,6-diisocyanatohexane, 1,6-diisocyanat
Lichkus Andrew M.
Sun Benjamin J.
Bieber James B.
Dentsply Research & Development Corp.
Lovercheck Dale R.
Manahan Todd #E.
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