Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2003-03-05
2004-03-09
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
C556S013000, C556S055000, C556S105000, C556S131000, C556S133000, C556S150000, C558S070000, C560S221000, C562S571000, C562S575000, C534S015000
Reexamination Certificate
active
06703518
ABSTRACT:
This invention pertains to compositions useful in dental composites or in other composite materials, particularly to compositions that release fluoride ion and that may be recharged with additional fluoride ion.
Fluoride is the most widely used agent to prevent dental caries (tooth decay). Tooth decay can occur on the margins of dental restorations. Such recurring caries is a frequent cause for failure of dental restorations. Fluoride-releasing restorative materials have been used to try to reduce recurrent caries at restoration margins. The effectiveness of such fluoride-releasing materials varies widely. Fluoride-releasing materials generally fall into one of four categories: glass ionomers, resin-modified glass ionomers, compomers, and fluoride-releasing composite resins. In general, materials with higher levels of fluoride release tend to have poorer mechanical properties (e.g., a lower compressive strength) High fluoride-releasing materials have therefore been used clinically primarily to restore decayed, but non-biting areas.
Glass ionomers and resin-modified glass ionomers release fluoride as a by-product during acid-base reactions between the ion-leachable fluoride glass and an acidic liquid. Glass ionomers and resin-modified glass ionomers generally have high fluoride release and recharge capabilities, but they have low strength and poor esthetic qualities. Composite resins have been widely used in restorative dentistry because they have high strength, good wear resistance, and excellent esthetics, but they release relatively small amounts of fluoride, and have low fluoride-recharge capabilities. There is an unfilled need for dental composite resins with high strength, good wear resistance, high fluoride release rates, and high fluoride recharge capability.
Currently, fluoride released from resin-based dental restorative materials comes from four main sources: (1) a soluble free salt, such as NaF, KF, or SnF
2
added to the material; (2) fluoride-releasing glass fillers such as fluoroaluminosilicate glass or sparingly soluble inorganic salts such as YbF
3
; (3) polymer molecules containing an anion-exchangeable fluoride moiety such as —N(CH
3
)
2
HF; (4) or organic fluoride sources such as those from alkylonium tetrafluoroborate.
U.S. Pat. No. 6,391,286 discloses fluoride releasing materials for use in dental compositions, having the formula M(G)
g
(F)
n
or M(G)
g
(ZF
m
)
n
, where M is an element capable of forming a cationic species and having a valence of 2 or more; G is an organic chelating moiety capable of complexing with the element M; Z is hydrogen, boron, nitrogen, phosphorus, sulfur, antimony, or arsenic; F is fluoride; and g, m, and n are at least 1.
U.S. Pat. No. 4,871,786 discloses dental compositions employing one or more substantially soluble organic compounds that serve as fluoride sources by incorporating tetrafluoroborate. Preferred non-polymerizable fluoride sources were said to be compounds of the formula: R
n
—M
+
BF
4
−
where M is I, N, P, or S; n is 2, 3, or 4, depending on the identity of M; and R is one of several specified types of substituted or unsubstituted hydrocarbon chains. Preferred polymerizable fluoride sources were said to be compounds of the formula: R
(n−1)
—M
+
(L) BF
4
−
where the other symbols were as previous stated, and L is an organic ligand comprising a moiety capable of polymerization via a cationic, condensation, or free radical mechanism.
Published international patent application WO 00/69394 discloses what were said to be stable one-part dental materials comprising a compound having only one acid functionality and at least one polymerizable functionality on each compound. The material does not contain storage-deleterious quantities of polyacid compounds. The material also contains a fluoride source containing polyvalent metal ions, and a photopolymerization initiator.
A Yuchi et al., “Complexes of Hard Metal Ions with Amine-N-Polycarboxylates as Fluoride Receptors,”
Bull. Chem. Soc. Jpn.
, vol. 69, pp. 3173-3177 (1996) discloses studies of equilibria in the reaction of hard metal complexes (M
m+
: Al
3+
, Zr
4+
, Hf
4+
, Th
4+
; H
n
L: amine-N-polycarboxylic acid) with fluoride. The zirconium (IV) complex of N-methyliminodiacetic acid was reported to be an excellent fluoride receptor.
M. Chikuma et al., “Selective Sorption of Fluoride Ions by Anion-Exchange Resin Modified with Alizarin Fluorine Blue-Praseodymium (III) Complex,”
Reactive Polymers
, vol. 13, pp. 131-138 (1990) disclosed a resin for the selective sorption of fluoride ion, prepared from an anion exchange resin, Amberlite IRA 400, and a praseodymium (III) complex of alizarin fluorine blue.
H. Rawls et al., “Esthetic Materials with Active Agent Control Release Capabilities and Their Future Roles,” pp. 130-135 in
Symposium on Esthetic Restorative Materials,
1991 (American Dental Association 1993) provides a review of dual-purpose dental restorative materials: those that can serve the needs of esthetic dentistry and that can also serve as sustained-release sources of therapeutic agents, such as fluoride. See also H. Rawls, “Preventive Dental Materials: Sustained Delivery of Fluoride and Other Therapeutic Agents,”
Advances in Dental Research
, vol. 5, pp. 50-55 (December 1991).
A. Peutzfeldt, “Resin Composites in Dentistry: The Monomer Systems,”
Eur. J. Oral Sci.
, vol. 105, pp. 97-116 (1997) provides a general review of dental resin monomers and composites, including some that release fluoride.
E. Glasspoole et al., “A Fluoride-Releasing Composite for Dental Applications,”
Dental Materials
, vol.17, pp. 127-133 (2001) discloses the incorporation of an organic fluoride material, tetrabutylammonium tetrafluoroborate, into a hydrophilic monomer system made of 2,2-bis[4-(2-hydroxy-3-methacroyloxypropoxy)phenyl]-propane and 2-hydroxyethyl methacrylate. Resulting fluoride release rates were reported to exceed those of several glass ionomer materials that were also tested.
B. Zimmeran et al., “Prevention of in vitro Secondary Caries with an Experimental Fluoride-Exchanging Restorative Resin,”
J. Dental Res.
, vol.63, pp. 689-692 (1984) reported clinical observations in which experimental composite resins that released fluoride by ion exchange were seen to reduce the incidence of caries in immediately adjacent areas, as compared to the rates of caries observed when non-fluoride-containing materials were used.
We have discovered novel fluoride-releasing compositions that may be incorporated into dental composite restorative materials or other dental materials, to produce materials with high fluoride release rates and high fluoride recharge capability. Such resins may be used, for example, in dental restorative materials to help reduce the level of dental caries in patients, particularly the level of caries occurring on the margins of the restorative materials.
The novel chelating and fluoride-releasing monomers may be described by the following general formulas, where the first formula below depicts a chelating monomer, and the second depicts the monomer chelated to a metal atom, which in turn is coordinated to one or more fluoride ions:
where R
1
is a substituted or unsubstituted aliphatic or aromatic group having 2 to 24 carbon atoms, and having at least one polymerizable group, the polymerizable group being preferably, but not necessarily, located in a terminal position; R
2
is a substituted or unsubstituted aliphatic or aromatic group having 2 to 50 carbon atoms; M is a metal atom having a valence of +2 or higher; R
3
and R
4
are unidentate or multidentate ligands that can form a coordination bond or ionic bond with M; R
3
and R
4
can be the same or different, but at least one them is a multidentate (at least a bidentate) ligand; i, j, l, and n are positive integers; F is a fluoride atom; Z is a counter-ion to maintain the neutrality of the monomer; and m is an integer from 0 to 4.
One advantage of having two coordinating ligands, R
3
and R
4
, is that the combination forms a mo
Burgess John O.
Ding Xingzhe
Ling Long
Xu Xiaoming
Board of Supervisors of Louisiana State University and Agricultu
Nazario-Gonzalez Porfirio
Runnels John H.
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