WO2000069393A1

WO2000069393A1 - Fluoride releasing orthodontic adhesive

Info

Publication number: WO2000069393A1
Application number: PCT/US1999/021693
Authority: WO
Inventors: Joan V. Brennan; Sharon M. Rozzi; Mynde G. Reiman
Original assignee: 3M Innovative Properties Company
Priority date: 1999-05-13
Filing date: 1999-09-20
Publication date: 2000-11-23
Also published as: AU6050799A

Abstract

A one part orthodontic adhesive for adhering an orthodontic appliance to a tooth surface is provided. The adhesive is moisture tolerant and comprises a hydrophilic monomer, a polymerizable acidic monomer, oligomer or polymer, a pyrrolidone containing monomer, oligomer, or polymer, a photopolymerization initiator, a filler, and a fluoride source. The orthodontic adhesive is substantially free of added water and has a Water Uptake Value of greater than about 0.5%. The concentrations of the components are present in amounts such that the orthodontic adhesive has a Consistency Value between 32-62.

Description

FLUORIDE RELEASING ORTHODONTIC ADHESIVE

Field of the Invention

This invention relates to orthodontic adhesives. More specifically, this invention relates to one-part orthodontic adhesives for use in bonding orthodontic articles such as bands and brackets to teeth.

Background

The typical orthodontic formulation used for banding belongs to the class of material called a glass ionomer and is comprised of two parts, either powder/liquid or paste/paste. Glass ionomers are known to provide sustained fluoride release, although release of fluoride typically occurs to a much larger extent within the first 24 hours, declining rapidly with time. However, the industry standard is to provide fluoride release because numerous clinical studies have detailed the decreased incidence of white spots in patients where dental or orthodontic adhesives containing fluoride were used as compared to those which did not. To date, it is still not known quantitatively how much fluoride release is required and over what length of time it is needed to provide a caries inhibitory effect. Although high fluoride release is the main attraction of these materials, their two-part nature dictates the need for prior mixing. Typical mixing is conducted on a mix pad prior to distributing the cement around the inner part of the band. This mix step is difficult as it can be hard to obtain the desired ratio of Part A to Part B and from one mix to the next, consistency can vary quite a bit.

Attempts have been made to eliminate the mixing step by providing a one- part cement, such as that available under the tradename ULTRA BAND LOK

(Reliance; Chicago, IL), which is a one part, fluid cement. See also U.S. Patent No. 5,846,075. It can be used for banding or for bonding of brackets. ULTRA BAND LOK, however, it is instructed to be used only on dry teeth and does not possess the exceptional flow characteristics and consistency of the material described herein of the present invention. Other similar products are commercially available through Dentsply (York, Pennsylvania) under the tradenames DYRACT AP and DYRACTFLOW. DYRACT AP is a compomer product with an extremely thick consistency, developed for the dental restorative area. Due to its consistency, DYRACT AP is difficult to work with if used as an orthodontic band cement. DYRACTFLOW is a one part, flowable, syringeable product. Still other cement compositions such as the glass ionomer cements available under the tradenames MULTI-CURE (3M Co., St. Paul, MN), FUJI ORTHO LC (GC

America, City & State) are available for orthodontic cementing. However, it is known in the industry that such cements are difficult to deband at the end of treatment — at times, a great deal of force is needed to remove the bands. Furthermore, removal of these cements remaining on the tooth at the end of treatment can be difficult to remove and detect.

Summary of the Invention

A one-part fluoride-releasing orthodontic adhesive is provided. This adhesive comprises components a) hydrophilic monomer, oligomer or polymer, b) polymerizable acidic monomer, oligomer or polymer, c) pyrrolidone containing monomer, oligomer, or polymer, d) photopolymerization initiator, e) filler, and f) fluoride source. The orthodontic adhesive is substantially free of added water, and has a Water Uptake Value of greater than about 0.5%. The components a-f are present in the adhesive in amounts such that the orthodontic adhesive has a Consistency Value between 32-62.

Detailed Description of the Invention

The adhesive of the present invention is a one-part, light curable adhesive that releases fluoride. Due to its exceptional flow properties, it can be easily dispensed from a syringe or other extruding mechanism onto an orthodontic appliance or other substrate without having to mix and spatulate.

The orthodontic adhesive uses compomer chemistry technology, where the properties of the material lie between that of a standard composite and a glass ionomer. Compomers are typically used in the dental industry as restorative materials. It has been discovered that with careful selection of components and concentrations, a compomer-based adhesive proves particularly useful for orthodontia and surprisingly possesses desirable flow and adhesion characteristics. Using typical resin modified glass ionomer technology, which is the basis of light cure glass ionomers, the components necessary to release fluoride cannot usually co-exist in the same composition without causing the typical acid-base setting reaction to occur. Surprisingly, it has been found that the compomer chemistry used in the present invention allows polymerizable components (e.g., acidic monomers) to exist together with fluoride-containing fillers in a stable, one part formulation. This chemistry provides a reasonable shelf life of at least one year at room temperature.

A major advantage this invention has over conventional orthodontic cements is that it offers the orthodontic practitioner a substantial time savings in the form of a simplified adhesive technique; i.e. a one part system that requires no prior mixing and can be delivered directly to an orthodontic appliance, such as a band or bracket via a syringe in controlled quanities. In particular, a disposable tip can deliver adhesive to bands to avoid cross-contamination such as what is disclosed in application number 54863USA2A, filed on even date, entitled

"Method and Apparatus for Applying a Bonding Agent to an Orthodontic Band," which has a common assignee as the present invention. For bonding brackets in a dry environment, the adhesive works well even without the use of an initial coating of primer. A further advantage the orthodontic adhesive of the present invention provides is its adhesive strength. It has been clinically found that the adhesive of the present invention has a low incidence of band retention failure, yet is easy to remove. Particularly, substantially less force is required to deband the adhesive of the present invention as compared to commercially available resin-modified glass ionomer band cements.

In the orthodontic field, easy and complete removal of adhesive from a debanded tooth is desireable. The adhesive of the present invention possesses the ability to be nearly entirely removed when the tooth has been debanded. Specifically, studies have shown that the present adhesive is easily and almost completely removed after a microetched band has been taken off a tooth. Thus this orthodontic adhesive provides a distinct advantage of easy clean-up to the practitioner at the time of band removal. Clean-up could also be further enhanced by increasing the visibility of the adhesive by incorporating a stable pigment, if desired.

Further benefits of the adhesive of the present invention include moisture tolerance, exceptional flow characteristics, minimal run-on, and good wetting of enamel and stainless steel surfaces. The moisture tolerance stems from the hydrophilic nature of the resin components in the adhesive. Thus, the adhesive is compatible with a moist environment and poses minimal risk of adhesive failure between the orthodontic appliance and the tooth. This is unlike conventional one- part light cure band cements which tend to be useful only in dry conditions. The exceptional flow characteristics of the adhesive provide well-controlled delivery and a creamy-like consistency. In combination with a well-designed dispenser, the adhesive of the present invention shows minimal to no syringe run- on. "Run-on," as used herein, is the phenomenon whereby material continues to flow or extrude from a syringe or other dispenser after pressure has been taken off the syringe's plunger.

Optionally, adhesion promoters may be added to the composition of the present invention. These promoters provide higher band retention for micro-etched bands. The adhesive with adhesion promoters proves particularly useful when plain bands are used, which generally display poorer adhesion between band and adhesive than between adhesive and microetched bands. Adhesion promoters that have great affinity towards stainless steel are particularly preferred, as it is often desirable during debanding or bracket removal for the adhesive to stay with the orthodontic appliance rather than the tooth.

One key feature in the orthodontic adhesive is that it is solventless and substantially free of added water. For purposes of the present invention, the term

"substantially free of added water" means that the composition does not contain water that is intentionally added as a non-complexed or coordinated entity. It is understood that many materials, such as metals or glasses, contain water that is taken up from the atmosphere or is present as a coordination complex in its normal state. Water taken up by hygroscopic materials or present as a hydrate is permissibly present in the compositions described herein. Any water that is present in the composition, regardless of source, should not be present in amounts such that the water will have a deleterious effect on the long-term properties of the composition. For example, water should not be present in an amount that would facilitate reaction of the acid -reactive filler with the acidic component so that lumpiness or graininess of the material develops during commercially required storage time

Another key property of the orthodontic adhesive of the present invention is its ability to uptake water and therefore be moisture tolerant. The present adhesive has a Water Uptake Value of greater than about 0.5%, preferably greater than about 0.7%. It has been surprisingly found that the adhesive retains its strength even when used in moisture contaminated conditions. In orthodontic bracket bonding procedures, for example, it is not necessary to dry the substrate, as long as a coating of moisture tolerant primer is applied to the tooth, prior to bonding the an orthodontic appliance. Teeth primed with moisture tolerant primers can in fact be recontaminated as in situations where bonding has been delayed or where a patient secretes excessive crevicular fluid. In these cases, it has been found that the adhesives of the present invention have the ability to absorb moisture from this recontamination situation where conventional adhesives do not. A decreased incidence of bracket bond failures is expected using these new adhesives as compared to conventional ones. Additionally, in orthodontic banding procedures, complete drying of the tooth is not required pior to banding.

This adhesive also possesses the ability to provide rechargeable fluoride release. That is, the fluoride material can be recharges through the use of, for example, toothpaste containing fluoride, fluoridated water or fluoridated mouthwash. Preferably, the hydrophilic monomer, oligomer or polymer has a molecular weight of between about 100 to 5000, and more preferably, has a molecular weight between about 300 and 1000. Mixtures of both higher and lower molecular weight polymerizable materials are also contemplated as providing special benefits in handling properties and the physical properties of the ultimate cured material. In a preferred aspect of the present invention, at least some of the hydrophilic monomer material is relatively lower in viscosity than other ingredients of the composition so that it serves as a viscosity lowering function in the overall uncured material. Preferably, at least some of the hydrophilic material is a monomer that has a viscosity of less than about 2 Pa-s, more preferably less than about 0.5 Pa-s, and most preferably less than about 0.3 Pa-s. Blends of materials exhibiting such viscosity characteristics are desirable as well. Preferred hydrophilic materials include 2-hydroxyethyl acrylate, 2- hydroxyethyl methacrylate ("HEMA"), hydroxypropyl acrylate, hydroxypropyl methacrylate, glycerol di- acrylate, glycerol di-methacrylate, polyethylene glycol mono methacrylate, polypropylene glycol mono methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, glycidyl acrylate, glycidyl methacrylate and the like. Other preferred hydrophilic monomers include glycerol mono- and diacrylate, glycerol mono- and di- methacrylate, ethyleneglycol diacrylate, ethyleneglycol dimethacrylate, polyethyleneglycol diacrylate (where the number of repeating ethylene oxide units vary from 2 to 30), polyethyleneglycol dimethacrylate [where the number of repeating ethylene oxide units vary from 2 to 30, especially triethylene glycol dimethacrylate ("TEGDMA")].

Other examples of hydrophilic components include monomers or polymers such as pyrrolidone, a moiety containing hydroxy groups and polyether groups, a moiety containing a sulfonate group, a moiety containing a sulfmate group, N- oxysuccinimide, N-vinylacetamide and acrylamide. More specific examples of preferred hydrophilic components are non-ionic polymers or copolymers, e.g. polyalkylene oxides (polyoxymethylene, polyethyleneoxide, polypropylene oxide) polyethers (polyvinylmethyl ether), polyethyleneimine copolymers, polyacrylamides and polymethacrylamides, polyvinylalcohol, saponified polyvinylacetate, polyvinylpyrrolidone, polyvinyloxazolidone, polymers containing N-oxysuccinimdo groups, ionic or ionizable polymers and copolymers containing polyacrylic acid, polymethacrylic acid in unionized, partially neutralized or fully neutralized form, polyethyleneimine and its salts, polyethylene sulfonic acid and polyaryl sulfonic acids in unionized, partially neutralized or fully neutralized form, polyphosphoric and polyphosphonic acids in unionized, partially neutralized or fully neutralized form.

Generally, any compound having a polar group may provide a hydrophilic aspect to a composition. Preferred hydrophilic compounds may be prepared by reaction of vinylic monomers such as acrylates, methacrylates, crotonates, itaconates and the like that contain polar groups that are acidic, basic or provided as a salt. These groups can also be ionic or neutral.

Examples of polar or polarizable groups include neutral groups such as hydroxy, thio, substituted and unsubstituted amido, cyclic ethers (such as oxanes, oxetanes, furans and pyrans), basic groups (such as phosphines and amines, including primary, secondary, tertiary amines), acidic groups (such as oxy acids, and thiooxyacids of C, S, P, B) and ionic groups (such as quarternary ammonium, carboxylate salt, sulfonic acid salt and the like) and the precursors and protected forms of these groups. More specific examples of such groups follow.

The hydrophilic component may, for example, be derived from mono- or multifunctional hydroxy group containing molecules represented by the general formula:

CH₂=CR²-CO-L-R³-(OH)_d

where R²=H, methyl, ethyl, cyano, carboxy or carboxyalkyl, L=O, NH, d=l-5 and R³ is a hydrocarbyl radical of valence d+1 containing from 1-12 carbon atoms. The preferred monomers in this class are hydroxyethyl (mefh)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, glycerol mono(meth)acrylate, tris(hydroxymethyl)ethane monoacrylate, pentaerythritol mono(meth)acrylate, N- hydroxymethyl (meth)acrylamide, hydroxyethyl (mefh)acrylamide and hydroxypropyl (meth)acrylamide.

The hydrophilic component may alternatively be derived from mono- or multifunctional amino group containing molecules of the general formula:

CH₂=CR²-CO-L-R³-(NR⁴R⁵)_d

where R², L, R³, and d are as defined above and R⁴ and R⁵ are H or alkyl groups of 1-12 carbon atoms or together they constitute a carbocyclic or heterocyclic group.

Preferred monomers of this class are aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, N- isopropylaminopropyl (meth)acrylamide and 4-methyl-l-acryloyl-piperazine.

The hydrophilic component may also be derived from alkoxy substituted (meth)acrylates or (meth)acrylamides such as methoxyethyl (meth)acrylate, 2(2- ethoxyethoxy)ethyl (meth)acrylate, polyethylene glycol mono(meth) acrylate or polypropylene glycol mono(meth)acrylate.

Hydrophilic components may be derived from substituted or unsubstituted ammonium monomers of the general formula:

CH₂=CR²-CO-L-R³-(NR R⁵R⁶)_dQ-

where R², R³, R⁴, R⁵, L and d are as defined above, and where R⁶ is H or alkyl of 1- 12 carbon atoms and Q- is an organic or inorganic anion. Preferred examples of such monomers are 2-N,N,N-trimethylammonium ethyl (meth)acrylate, 2-N,N,N- triethylammonium ethyl (meth)acrylate, 3-N,N,N-trimethylammonium propyl

(meth)acrylate, N(2-N',N',N'-trimethylammonium) ethyl (meth)acrylamide, N- (dimethyl hydroxyethyl ammonium) propyl (meth)acrylamide etc. where the counterion may be fluoride, chloride, bromide, acetate, propionate, laurate, palmitate, stearate etc. The monomer can also be N,N-dimethyl diallyl ammonium salt of an organic or inorganic counterion.

Ammonium group containing polymers can also be prepared by using as the hydrophilic component any of the amino group containing monomer described above, and acidifying the resultant polymers with organic or inorganic acid to a pH where the pendant amino groups are substantially protonated. Totally substituted ammonium group containing polymers may be prepared by alkylating the above described amino polymers with alkylating groups, the method being commonly known in the art as the Menschutkin reaction.

The hydrophilic component of the invention can also be derived from sulfonic acid group containing monomers, such as vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methyl propane sulfonic acid, allyloxybenzene sulfonic acid, and the like. Alternatively, the hydrophilic component may be derived from phosphorous acid or boron acid group-containing monomers. These monomers may be used in the protonated acid form as monomers.

The acidic component of the compositions of the present invention is provided by compounds that are monomers, oligomers or polymers of molecular weight less than about 10,000 and containing at least one acidic group. The acidic group is preferably selected from oxyacids or thio-oxy acids of C and P. More preferably, the acidic component is a compound that is an acid of C or P. If desired, a precursor to the acid such as an acid anhydride, e.g., 4-Methacryloxyethyl Trimellitate Anhydride (4-META), or ester can be used in place of the acid itself, e.g., to generate the desired acid in situ. Suitable acids include, carboxylic acids, sulfonic acids, and phenols, with carboxylic acids, alkylsulfonic acids, arylsulfonic acids, and phosphonic acids being preferred.

Suitable organic acids include acetic acid, α-chloropropionic acid, 2- acrylamido-2-methylpropane sulfonic acid, acrylic acid, benzenesulfonic acid, benzoic acid, bromoacetic acid, 10-camphorquinone-sulfonic acid, 10- camphorsulfonic acid, chloroacetic acid, citraconic acid, citric acid, dibromoacetic acid, dichloroacetic acid, di-Hema ester of 1,2,4,5 benzenetetracarboxylic acid, 2,4- dinitrophenol, formic acid, fumaric acid, 2-hydroxy-4-methoxybenzophenone-5- sulfonic acid, maleic acid, methacrylic acid, 2-naphthalene sulfonic acid, nitric acid, oxalic acid, p-nitrophenol, phenol, phosphoric acid, phosphorous acid esters (such as

2,2'-bis(a-methacryloxy-b-hydroxypropoxyphenyl) propane diphosphonate (Bis- GMN diphosphonate), dibutyl phosphite, di-2-ethyl-hexyl phosphate, di-2-ethyl- hexyl phosphite, hydroxyethyl methacrylate monophosphate, glyceryl dimethacrylate phosphate, glyceryl-2-phosphate, glycerylphosphoric acid, methacryloxyethyl phosphate, pentaerythritol triacrylate monophosphate, pentaerythritol trimethacrylate monophosphate, dipentaerythritol pentaacrylate monophosphate, and dipentaerythritol pentamethacrylate monophosphate), pivalic acid, propionic acid, sulfuric acid, toluene sulfonic acid, tribromoacetic acid, trichloroacetic acid, trifluoroacetic acid, trifluoromethanesulfonic acid, and trihydroxybenzoic acid. Mixtures of such acids can be used if desired. Preferred acids are capable of complexing with a reactive glass. Especially preferable acid groups are carboxylic acids, sulfonic acids, phoshoric acids, phosphonic acids, and boric acids, the salts of the foregoing acids or precursors of the foregoing acids that are easily converted to these acids in conditions encountered during a dental restorative procedure. Examples of such compounds are acryloyl or methacryloyl substituted carboxylic acids, phosphoric acid esters of hydroxyethyl methacrylate, hydroxy propyl methacrylate and glycerol dimethacrylate, and acrylates and methacrylates of pentaerythritol dimethacrylate and dipentaerythritol penta-acrylate.

Examples of such preferred compounds include the aliphatic carboxy compounds, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, aconitic acid, glutaconic acid, mesaconic, citraconic acid, citric acid, tiglicinic acid, 2-chloroacrylic acid, 3-chloroacrylic acid, 2- bromoacrylic acid, 1 -methacryloyl malonic acid, 1 -acryloyl malic acid, N- methacryloyl and N-acryloyl derivatives of amino acids, and acids such as tartaric acid, citric acid, malic acid that have been further functionalized with an ethyl enic functionality. For example, citric acid may be ethylenically functionalized by substituting with an acryloyl or methacryloyl functionality. A preferred example of this is "CDMA," which is the reaction product of citric acid and isocyanato ethyl methacrylate. These polymerizable groups may be attached directly to the acid containing compound, or may be optionally attached through a linking group. Preferred linking groups include substituted or unsubstituted alkyl, alkoxyalkyl, aryl, aryloxyalkyl, alkoxyaryl, aralkyl or alkaryl groups. Particularly preferred linking groups comprise an ester functionality and most particularly preferred linking groups comprise an amide functionality.

Other preferred compounds are the aromatic carboxy compounds, such as benzoic acid, and acryloyl or methacryloyl derivatives of salicyclic acid, trimellitic acid, phthalic acid,and the like.

The polymerizable acidic component may be derived from mono- or multifunctional carboxyl group containing molecules represented by the general formula: CH₂=CR²G-(COOH)_d

where R²=H, methyl, ethyl, cyano, carboxy or carboxymethyl, d=l-5 and G is a bond or a hydrocarbyl radical linking group containing from 1-12 carbon atoms of valence d+1 and optionally substituted with and/or interrupted with a substituted or unsubstituted heteroatom (such as O, S, N and P). Optionally, this unit may be provided in its salt form. The preferred monomers in this class are acrylic acid, methacrylic acid, itaconic acid and N-acryloyl glycine.

Particularly preferred pyrrolidone containing compounds are poly(N-vinylpyrrolidone) polymers ("p-NVP"). Copolymers of vinylpyrrolidone and other monomers or grafted poly(N-vinylpyrrolidone) with other groups also are preferred. For example, poly(l-vinylpyrrolidone-co-styrene), poly(l- vinylpyrrolidone-co-vinyl acetate), are preferred.

Preferred pyrrolidone containing polymers have a molecular weight between about 100 and 500,000; more preferably, between about 5,000 and

100,000.

The photoinitator should be capable of promoting free radical crosslinking of the ethyl enically unsaturated moiety on exposure to light of a suitable wavelength and intensity. It also preferably is sufficiently shelf stable and free of undesirable coloration to permit its storage and use under typical dental conditions.

Visible light photoinitiators are preferred. The photoinitiator frequently can be used alone, but typically it is used in combination with a suitable donor compound or a suitable accelerator (for example, amines, peroxides, phosphorus compounds, ketones and alpha-diketone compounds). Preferred visible light-induced initiators include camphorquinone (which typically is combined with a suitable hydrogen donor such as an amine), diaryliodonium simple or metal complex salts, chromophore-substituted halomefhyl-s-triazines and halomethyl oxadiazoles. Particularly preferred visible light-induced photoinitiators include combinations of an alpha-diketone, e.g., camphorquinone, and a diaryliodonium salt, e.g., diphenyliodonium chloride, bromide, iodide or hexafluorophosphate, with or without additional hydrogen donors (such as sodium benzene sulfinate, amines and amine alcohols). Preferred ultraviolet light-induced polymerization initiators include ketones such as benzyl and benzoin, and acyloins and acyloin ethers. Preferred commercially available ultraviolet light-induced polymerization initiators include 2,2-dimethoxy-2-phenylacetophenone ("LRGACURE 651") and benzoin methyl ether (2-methoxy-2-phenylacetophenone), both from Ciba-Geigy Corp.

The photoinitiator should be present in an amount sufficient to provide the desired rate of photopolymerization. This amount will be dependent in part on the light source, the thickness of the layer to be exposed to radiant energy, and the extinction coefficient of the photoinitiator. Typically, the photoinitiator components will be present at a total weight of about 0.001 to about 5%, more preferably from about 0.01 to about 1%, based on the total weight of the composition.

Reactive or non-reactive fillers may be included in compositions of the present invention. These fillers may or may not have the property of releasing fluoride.

Reactive fillers include those that are commonly used with ionomers to form ionomer cements. Examples of suitable reactive fillers include metal oxides such as zinc oxide and magnesium oxide, and ion-leachable glasses, e.g., as described in U.S. Patent Nos. 3,655,605; 3,814,717; 4,143,018; 4,209,434; 4,360,605 and 4,376,835. Such reactive fillers may be incorporated to modify the handling characteristics or to affect the setting properties of the ultimate compostion.

The reactive filler is preferably a finely divided reactive filler. The filler should be sufficiently finely divided so that it can be conveniently mixed with the other ingredients and used in the mouth. Preferred average particle diameters for the filler are about 0.2 to about 15 micrometers, more preferably about 1 to 10 micrometers, as measured using, for example, a sedimentation analyzer.

The fillers used in composition of the present invention are preferably acid- reactive. Suitable acid-reactive fillers include metal oxides, metal salts and glasses. Preferred metal oxides include barium oxide, calcium oxide, magnesium oxide and zinc oxide. Preferred metal salts include salts of multivalent cations, for example aluminum acetate, aluminum chloride, calcium chloride, magnesium chloride, zinc chloride, aluminum nitrate, barium nitrate, calcium nitrate, magnesium nitrate, strontium nitrate and calcium fluoroborate. Preferred glasses include borate glasses, phosphate glasses and fluoroaluminosilicate glasses.

Most preferred of the acid reactive fillers are those that release fluoride. Fluoride releasing glasses, in addition to providing good handling and final composition properties as discussed above, provide the benefit of long-term release of fluoride in use, for example in the oral cavity. Fluoroaluminosilicate glasses are particularly preferred. Suitable acid reactive fillers are also available from a variety of commercial sources familiar to those skilled in the art. Mixtures of fillers can be used if desired.

If desired, the acid reactive filler can be subjected to a surface treatment. Suitable surface treatments include acid washing, treatment with phosphates, treatment with chelating agents such as tartaric acid, treatment with a silane or silanol coupling agent. Particularly preferred acid reactive fillers are silanol treated fluoroaluminosilicate glass fillers, as described in U.S. Patent No. 5,332,429.

Non-acid reactive fillers may be selected from one or more of any material suitable for incorporation in compositions used for medical applications, such as fillers currently used in dental restorative compositions and the like. The filler is finely divided and preferably has a maximum particle diameter less than about 10 micrometers and an average particle diameter less than about 1.0 micrometers.

More preferably, the filler has a maximum particle diameter less than about 1.0 micrometers and an average particle size of diameter less than about 0.1 micrometer. The filler can have a unimodal or polymodal (e.g., bimodal) particle size distribution. The filler can be an inorganic material. It can also be a crosslinked organic material that is insoluble in the polymerizable resin, and is optionally filled with inorganic filler. The filler should in any event be non-toxic and suitable for use in the mouth. The filler can be radiopaque, radiolucent or non- radiopaque.

Examples of suitable non-acid reactive inorganic fillers are naturally- occurring or synthetic materials such as quartz, nitrides (e.g., silicon nitride), glasses derived from, for example Ce, Sb, Sn, Zr, Sr, Ba and Al, colloidal silica, feldspar, borosilicate glass, kaolin, talc, titania, and zinc glass; low Mohs hardness fillers such as those described in U.S. Patent No. 4,695,251; and submicron silica particles (e.g., pyrogenic silicas such as the "Aerosil" Series "OX 50", "130", "150" and "200" silicas sold by Degussa and "Cab-O-Sil M5" silica sold by Cabot Corp.). Examples of suitable non-reactive organic filler particles include filled or unfilled pulverized polycarbonates, polyepoxides, and the like. Preferred non-acid reactive filler particles are quartz, submicron silica, and non-vitreous microparticles of the type described in U.S. Patent No. 4,503,169. Mixtures of these non-acid reactive fillers are also contemplated, as well as combination fillers made from organic and inorganic materials. Preferably the surface of the filler particles is treated with a coupling agent in order to enhance the bond between the filler and the polymerizable resin. The use of suitable coupling agents include gamma- methacryloxypropyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, and the like. The fluoride-releasing material of the present invention may be naturally occuring or synthetic fluoride minerals, fluoride glass such as fluoroaluminosilicate glass, simple and complex inorganic fluoride salts, simple and complex organic fluoride salts or combinations thereof. Optionally these fluoride sources can be treated with surface treatment agents. In certain instances, the Fluoride source and the filler can be one and the same.

Examples of the fluoride-releasing material are fluoroaluminosilicate glasses described in U.S. Patent No. 4,3814,717, which may be optionally treated as described in U.S. Patent No. 5,332,429.

The fluoride releasing material may optionally be a metal complex described by the formula

M(G)_g(F)_n or M(G)_g(ZF_m)_n

where M represents an element capable of forming a cationic species and having a valency 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 a fluoride atom g, m and n are at least 1.

Examples of preferred M elements are the metals of groups IIA, ILIA, IV A, and transition and inner transition metal elements of the periodic table. Specific examples include Ca⁺², Mg⁺², Sr⁺², Zn⁺², At³, Zr⁺\ Sn"², Yb⁺³, Y⁺³, SN⁴. Most preferably, M is Zn⁺².

The G group, as noted above, is an organic chelating moiety. This chelating moiety may or may not contain a polymerizable group. Although not absolutely essential, in some instances it may be advantageous for the chelating moiety to contain a polymerizable functionality that matches the reactivity of the polymerizable matrix into which it is incorporated.

A wide range of chelating moieties may be used in the present invention. Chelates in which the metal ion is bound in a ring structure of 4-8 members are preferred, with the 5-7 membered ring chelates being particularly preferred. The chelates useful in the present invention are multidentate, and are preferably bi-, tri- or quadra-dentate. Chelates containing hydroxyl or carboxy groups or both are more particularly preferred. Examples of such chelating agents are tartaric acid, citric acid, ethylenediamine tetraacetic acid, salicylic acid, hydroxybenzoic acids, hydroxytartaric acids, nitrilotriacetic acid, salicylic acid, melletic acids, and polyglycols. Chelates containing one or more acid groups derived from phosphorus, boron or sulfur can also be used, with the proviso that the molecular weight of the chelating agent is less than about 1000. Examples of especially suitable metal chelates include complexes of β-diketones and β-ketoesters.

The polymerizable metal-fluoride chelates preferably contain one or more polymerizable groups that match the reactivity of the polymerizable matrix into which it is incorporated. In addition to the chelating functionalities outlined above, these complexes can contain ethylenically unsaturated groups, epoxy groups, ethyleneimine groups and the like.

Preferred G groups include the polyphosphates, such as sodium tripolyphosphate and hexametaphosphoric acid; aminocarboxylic acids, such as ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotriacetic acid, Ν-dihydroxyethylglycine and ethylenebis(hydroxyphenylglycine); 1,3-diketones, such as acetylacetone, trifluoroacetylacetone and thenoyltrifluoroacetone; hydroxycarboxylic acids, such as malic acid, tartaric acid, citric acid, gluconic acid, and 5-sulfosalicylic acid; polyamines, such as ethylenediamine, triethylenetetramine and triaminotriethylamine; aminoalcohols, such as triethanolamine and N- hydroxyethylethylenediamme; aromatic heterocychc bases, such as dipyridyl and o-phenanthroline; phenols, such as salicyladehyde, disulfopyrocatechol and chromotropic acid; aminophenols, such as oxine, 8-hydroxyquinoline and oxinesulfonic acid; oximes, such as dimethylglyoxime and salicyladoxime hydroxamic acid and its derivative; Schiff bases, such as disalicyladehyde 1,2- propylenedimine; tetrapyrroles, such as tetraphenylporphin and phthalocyanine; sulfur compounds, such as toluenedithiol(Dithiol), dimercaptopropanol, thioglycolic acid, potassium ethylxanthate, sodium diethyldithiocarbamate, dithizone, diethyl dithiophosphoric acid and thiourea; synthetic macrocyclic compounds, such as dibenzo[18]crown-6(5), (CH₃)₆[14]4,l l-dieneN₄ (6) and (2.2.2-cryptate) (7); polymeric compounds such as polyethylenimine, polymetharyloylacetone, and poly(p-vinylbenzyliminodiacetic acid); and phosphonic acids, such as nitrilotrimethylenephosphonic acid, ethylenediaminetetra(methylenephosphonic acid) and hydroxyethylidenediphosphonic acid. Particularly preferred G groups are compounds of the following formulas:

Fluoride is associated with the complexed metal as either a counterion or as a ligand. Thus, the designation (YF) above indicates that the fluoride is associated with the Y group as a complex, which in turn is associated with the metal as a counterion or as a ligand.

Compositions of the present invention may optionally comprise at least two sources of fluoride. In an example of such a system, the first source may be the fluoride-containing metal complex as described above. The second source may be a fluoride-releasing fluoroaluminosilicate glass. With the use of both materials, excellent fluoride release may be provided both in the initial period and over the long-term use of the composition.

The orthodontic adhesive of the present invention may preferably comprise components a-f in the following concentrations: a) hydrophilic monomer, oligomer, or polymer present in an amount no less than about 1% and no greater than about 90% by weight, b) the polymerizable acidic monomer, oligomer or polymer present in an amount no less than about 1 % and no greater than about 90% by weight, c) the pyrrolidone containing monomer, oligomer, or polymer present in an amount of amount no less than about 0.01% and no greater than about 5% by weight, d) the photopolymerization initiator present in an amount no less than about 0.001%) and no greater than about 5%, e) the filler and f) fluoride source in combination are present in no less than about 10% and no greater than about 90% by weight. More preferably the adhesive comprises a) hydrophilic monomer, oligomer, or polymer present in an amount no less than about 10% and no greater than about 20% by weight, b) the polymerizable acidic monomer, oligomer or polymer present in an amount no less than about 5% and no greater than about 10% by weight, c) the pyrrolidone containing monomer, oligomer, or polymer present in an amount of less than about 2% by weight, d) the photopolymerization initiator present in an amount no less than about 0.01% and no greater than about 2%, e) the filler and f) fluoride source in combination are present in no less than about 70% and no greater than about 75% by weight.

The adhesive of the present invention may additionally comprise materials that are not hydrophilic, provided that the overall composition has a Water Uptake value greater than about 0.5%. Preferred materials are the esters of acrylic or methacrylic acid. Examples of these compounds are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, the diglycidyl methacrylate of bis-phenol A ("Bis-GMA"), neopentyl glycol diacrylate, neopentylglycol dimethacrylate, trimethylolpropane triacrylate, trimethylol propane trimethacrylate, mono-, di-, tri-, and tetra- acrylates and methacrylates of pentaerythritol and dipentaerythritol, 1 ,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1 ,4-butanedioldiacrylate, 1 , 4-butanediol dimethacrylate, 1 ,6- hexane diol diacrylate, 1,6-hexanediol dimethacrylate di-2-methacryloyloxethyl hexam ethylene dicarbamate, di-2-methacryloyloxyethyl trimethylhexanethylene dicarbamate, di-2-methacryloyl oxyethyl dimethylbenzene dicarbamate, methylene-bis-2-methacryloxyethyl-4-cyclohexyl carbamate, di-2- methacryloxyethyl-dimethylcyclohexane dicarbamate, mefhylene-bis-2- methacryloxyethyl-4-cyclohexyl carbamate, di-1 -methyl-2-methacryloxyethyl- trimethyl-hexamethylene dicarbamate, di-l-methyl-2-methacryloxyethyl- dimethylbenzene dicarbamate, di-l-methyl-2-methacryloxyethyl- dimethylcyclohexane dicarbamate, methylene-bis- 1 -methyl -2-methacryloxyethyl- 4-cyclohexyl carbamate, di-1 -chloromethyl-2-methacryloxyethyl-hexamethylene dicarbamate, di- 1 -chloromethyl-2-methacryloxyethyl-trimethylhexamethylene dicarbamate, di-1 -chloromethyl-2-methacryloxyethyl-dimethylbenzene dicarbamate, di- 1 -chloromethyl-2-methacryloxyethyl-dimethylcyclohexane dicarbamate, methyl ene-bis-2-methacryloxy ethyl -4-cyclohexyl carbamate, di-1- methyl-2-methacryloxyethyl-hexamethylene dicarbamate, di- 1 -methyl-2- methacryloxyethyl-trimethylhexamethylene dicarbamate, di-l-methyl-2- methacryloxyethyl-dimethylbenzene dicarbamate, di-l-methyl-2- methacryloxyethyl-dimethylcyclohexane dicarbamate, methylene-bis- 1 -methyl-2- methacryloxyethyl-4- cyclohexyl carbamate, di-b l-chloromethyl-2- methacryloxyethyl-hexamethylene dicarbamate, di-l-chloromethyl-2- methacryloxyethyl-trimethylhexamethylene dicarbamate, di- 1 -chloromethyl-2- methacryloxyethyl-dimethylbenzene dicarbamate, di- 1 -chloromethyl-2- methacryloxyethyl-dimethylcyclohexane dicarbamate, methylene-bis- 1 - chloromethyl-2-methacryloxyethyl-4-cyclohexyl carbamate, 2,2'-bis(4- methacryloxyphenyl)propane, 2,2'bis(4-acryloxyphenyl)propane, 2,2'-bis[4(2- hydroxy-3 -methacryloxy-phenyl)]propane, 2,2 ' -bis [4(2-hydroxy-3 -acryloxy- phenyl)propane, 2,2'-bis(4-methacryloxyethoxyphenyl)propane, 2,2'-bis(4- acryloxyethoxyphenyl)propane, 2,2'-bis(4-methacryloxypropoxyphenyl)propane, 2,2'-bis(4-acryloxypropoxyphenyl)propane, 2,2'-bis(4- methacryloxydiethoxyphenyl)propane, 2 ,2 ' -bis(4- acryloxydiethoxyphenyl)propane, 2,2'-bis[3(4-phenoxy)-2-hydroxypropane-l- methacrylate]propane, 2,2'-bis[3(4-phenoxy)-2-hydroxypropane-l- acrylatejpropane, and the like. Other preferred components can be substituted acryl amides and methacrylamides. Examples are acrylamide, methylene bis-acrylamide, methylene bis-methacrylamide, diacetone/acrylamide diacetone methacylamide, N-alkyl acrylamides and N-alkyl methacrylamides where alkyl is a lower hydrocarbyl unit of 1-6 carbon atoms. Other suitable examples of polymerizable components are isopropenyl oxazoline, vinyl azalactone, vinyl pyrrolidone, styrene, divinylbenzene, urethane acrylates or methacrylates, epoxy acrylates or methacrylates and polyol acrylates or methacrylates.

If desired, the compositions of the invention can contain adjuvants such as cosolvents, pigments, inhibitors, accelerators, viscosity modifiers, surfactants, rheology modifiers, colorants, medicaments, adhesion promoters and other ingredients that will be apparent to those skilled in the art. Optionally, the compositions may contain stabilizers.

Cosolvents useful in the present invention include, but are not limited to, low molecular weight organic solvents. The word "cosolvent", as used herein refers to a material that aids in the dissolution of materials in the composition, in order to form a homogeneous composition. Examples of suitable cosolvents include ethanol, propanol, and glycerol. Adhesion promoters can be added to enhance adhesion to an orthodontic appliance. Adhesion promoters or coupling agents may be inorganic or organic, and may be present in concentrations of less than about 5 percent by weight, preferably between about 0.1 to 1% by weight. Selection of an appropriate combined adhesion and coupling agent provides significant benefits: in addition to the benefit of improved adhesion between the adhesive and the substrate, the use of an adhesion promoter and/or coupling agent can also lower the viscosity of the adhesive, promote dispersion of fillers in adhesives and improve mechanical properties of the adhesive. Examples of inorganic adhesion promoters include any number of suitable titanates, zirconates, aluminates or combinations thereof may be used to promote adhesion. Titanates are preferred and can be described as monoalkoxy, neoalkoxy, cycloheteroatom, chelate, coordinate, or quaternary type. More preferred titanates are those with the more polar moieties such as the amino titanates available through Kenrich Petrochemicals (Bayonne, NJ) under the tradenames LICA 97

(Titanium IV 2.2(bis 2-propenolatomethyl) butanolato, tris (3-amino) phenylato) and LICA 44 (Titanium IV 2.2(bis 2-propenolatomethyl) butanolato, tris (2-ethylenediamino) ethylato), and the pyrophosphato titanate, LICA 38 (Titanium IV 2.2(bis 2-propenolatomethyl) butanolato, tris (dioctyl) pyrophosphato-0). These tend to be the most beneficial for adhesion to polar substrates such as metals, ceramics, and acrylics. For stainless steel application, zirconium adhesion promoters such as N238, KRTTS and KR55 may be used. Preferably, these adhesion promoters are present as less than 5% of the total composition, and more preferably are less than 1% of the composition. Organic adhesion promoters include acid-functionalized compounds such as those already listed for the polymerizable acidic monomer, oligomer or polymer. Monomers, oligomers, or polymers containing multi-acid functionality are preferred as the carboxylic acid functionality is known to adhere well to stainless steel. A preferred organic adhesion promoter is the copolymer of acrylic acid and itaconic acid. Another preferred adhesion promoter is 4-META. Additional organic adhesion promoters such as trifunctional acrylate esters available through Sartomer under the tradenames SR9012 and CD9052 are also useful, as they are specifically designed for promoting adhesion to stainless steel. Alternatively, an organofunctional silane may be utilized as coupling agent to enhance adhesion. Suitable siliane coupling agents and other coupling agents are described in U.S. Patent No. 5,454,716. Methods of use of the present adhesive include procedures whereby an adhesive is applied to a surface of a substrate or an orthodontic appliance such as a bracket or band, and subsequently applying the adhesive-coated substrate to a tooth. For proper adhesion, the orthodontic appliance or substrate must be placed on or around the tooth surface such that the adhesive is in intimate contact with the tooth surface.

A preferred method of using the present one-part orthodontic adhesive comprises the steps of etching and drying the tooth, applying the one-part orthodontic adhesive on the bracket; and adhering the adhesive-coated bracket to the tooth. If necessary, a coating of primer may be applied to the tooth prior to adhering the adhesive-coated bracket to the tooth. When a primer is used, the drying step may or may not be required, depending upon the type of primer applied.

The present invention will be further understood in view of the following examples which are merely illustrative and not meant to limit the scope of the invention. Unless otherwise indicated, all parts and percentages are by weight and all molecular weights are weight average molecular weights

PREPARATORY EXAMPLE 1 Treated Fluoroaluminosilicate Glass ("S/T FAS") The ingredients set out below in TABLE 1 were mixed, melted in an arc furnace at about 1350-1450°C, poured from the furnace in a thin stream and quenched using chilled rollers to provide an amorphous single-phase fluoroaluminosilicate glass. TABLE 1

The glass was ball-milled to provide pulverized frits with an average surface area of 3 m²/gm measured using the Brunauer, Emmet and Teller (BET) method.

The glass was silane treated using the following procedure. Deionized water (36.5 parts) was mixed together with 0.3 parts of glacial acetic acid and 2.43 parts of gamma-methacryloxypropyl trimethoxysilane ("A-174", Witco, Inc.). The mixture was stirred for approximately one hour to effect hydrolysis of the silane. The glass (60.8 parts) was then charged to the aqueous silane mixture and slurried for approximately 30 minutes at ambient temperature. The slurry was poured into a plastic-lined tray and dried for 10 hours at 80°C. The silane treated dried powder was sieved through a 74 micron screen.

PREPARATORY EXAMPLE 2

Treated OX-50 (fumed silica) ("S/T OX-50") A silanol solution was prepared by mixing together deionized water (7.2 parts), methanol (33.1 parts), glacial acetic acid (10.2 parts), and A-174 (49.7 parts). The mixture was stirred for approximately one hour at ambient temperature. Fumed silica ("Aerosil OX-50", Degussa, Inc., 207 parts) was charged to a solids blender, and the blender was rotated. The prepared silanol solution was pumped to and sprayed into the solids blender. The treated OX-50 was then removed from the solids blender, and placed in a tray to be oven dried. The OX-50 was dried at 67°C for approximately 4 hours, and then at 100°C for approximately one hour. The silane treated dried powder was sieved through a 74 micron screen.

PREPARATORY EXAMPLE 3 Preparation of preferred polymerizable acidic component - "CDMA"

Citric acid (400g) was dissolved in 2 L of tetrahydrofuran ("THF") in a reaction vessel fitted with a mechanical stirrer, condenser, addition funnel and air inlet tube. To the resultant homogenous solution was added 0.52g butylated hydroxytoluene ("BHT"), 0.5g of triphenylantimony ("TPS") and 0.98g dibutyltin dilaurate ("DBTDL"). Dry air was introduced into the reaction mixture through the inlet tube. 2-Isocyanatoethyl methacrylate ("IEM"; 161.5g; 1.04 moles) was added dropwise through the addition funnel so as to maintain the reaction temperature at about 40°C. The reaction was followed by infrared spectroscopy ("LR"). After all the IEM had been added and the IR spectrum no longer showed the presence of isocyanate group, the solvent was removed under vacuum from the reaction mixture and the resultant viscous liquid was dried. Nuclear magnetic resonance spectroscopy ("NMR") confirmed the presence of added methacrylate functionalities and the retention of carboxy groups.

PREPARATORY EXAMPLE 4

Preparation of filler for Comparative Example #2

A silanol solution was prepared by mixing together 34.7 parts of deionized water, 0.1 parts of trifluoroacetic acid, and 1.78 parts of A-174. This mixture was stirred for one hour at approximately 30°C. To this silanol solution was added 62.43 parts of quartz (average particle size = 2.7 microns) and 1 part of Aerosil

OX-50. This slurry was mixed for 90 minutes. The slurry was poured into a plastic-lined tray and dried at 60°C for 18 hours. The treated dried powder was sieved through a 74 micron screen. COMPARATIVE EXAMPLE 1 Resin Cement - Compomer Restorative

Activated Resin Compounding

Glycerol dimethacrylate (GDMA) (220 parts) was mixed with 1 part butylated hydroxy toluene (BHT), 2.5 parts camphorquinone (CPQ), 5 parts of Tinuvin P, and 10 parts of EDMAB. This mixture was stirred for 90 minutes. To this mixture was added 32 parts of polyvinyl pyrrolidone "pNVP" (Plastone K-29/31 form International Specialty Products, Wayne, NJ), and stirring continued for approximately 4 hours. To this mixture was added 265 parts of CDMA of Preparatory Example 3 and 265 parts of GDMA, and stirring continued for two hours. The activated resin was screened through a 100-micron mesh nylon screen.

Paste Compounding

The activated resin (16.3 parts) was combined with 1.89 parts of the treated OX-50 of Preparatory Example 2 and 81.8 parts of the treated FAS glass filler of Preparatory Example 1) using the compounding procedure described in Example 1.

Composition Table

Consistency Value = 27

COMPARATIVE EXAMPLE 2 Hydrophobic Resin Adhesive

Activated Resin Compounding

BisGMA (600 parts) was mixed with 400 parts of Diacryl 101 (AXZO Chemical Co.) at about 60°C for approximately one hour. To this mixture was added one part of BHT and stirring continued for about 45 minutes. To this mixture was added 2.5 parts of CPQ, 10 parts of EDMAB, and 6 parts of diphenyliodonium hexafluorophosphate (DPIHFP), and stirring continued for about 90 minutes. Paste Compounding

The activated resin (24.8 parts) was combined with 75.2 parts of the treated filler of Preparatory Example 4) using the compounding procedure described in Example 1, below.

Composition Table

Consistency Value = 38

EXAMPLE 1

The example orthodontic adhesives of Table 2 were prepared using the following procedure. All the resin components (a) through (e) as listed below were mixed together to form the "activated resin". This activated resin was then compounded into the final paste. Paste compounding was achieved by conducting several mix cycles in which the full quantity of filler, i.e. silane treated fluoroaluminate glass from Preparatory Example 1 ("S/T FAS") and silane treated silica from Preparatory Example 2 ("S/T OX-50"), was divided into a few (may vary) smaller filler charges which were added in stepwise fashion to the activated resin. After all of the filler was added, the paste was mixed to a uniform dispersion, and then the paste was tested for Consistency Value. Blue pigment (FD&C Blue No. 2 Aluminum Lake), commercially available from Warner- Jenkinson Co. (St. Louis, MO) was added to the formulation to provide color and visual enhancement.

Resin components: a) hydrophilic mononomer: 1,3-glycerol dimethacrylate ("GDMA"), b) polymerizable acidic monomer, oligomer or polymer: dimethacrylate derived from citric acid ("CDMA" Preparatory Example 3) c) pyrrolidone containing monomer, oligomer, or polymer:: poly n-vinyl pyrrolidone ("pNVP," "Plastone K-29/31 ," International Specialty Products, Wayne, NJ) d) photoinitiator system: Camphroquione ("CPQ") and Ethyl 4- Dimethylamino Benzoate ("EDMAB") and Diphenyl Iodonium Hexafluorophosphate (DPIHFP) e) adjuvants: UV inhibitor (Tinuvin-P) and BHT.

Table 2

Water Uptake Test

Water uptake was measured by forming each composition into cylinders 4 mm in diameter and 4 mm thick using an open-ended teflon mold. To keep the uncured material in place, the opposite side from that being charged was set against polyethylene terephthalate ("PET") film which was placed on white paper prior to curing. Once uncured material was added to the mold, the top was then covered with PET film and light cured for 30 seconds using an Ortholux XT™ Visible Light Curing Unit from 3M Unitek. Intimate contact between PET covered sample and the light guide was ensured. The PET films were then removed and the cylinder of cured material was removed from the mold. Within one hour, each cured cylinder was weighed and placed in a glass vial to which was added 8 mL of deionized water. Each sample was maintained at 40°C for a period of five days.

At the specified time, the sample was removed from the vial, the superficial water was removed using a facial tissue or cotton and the sample was immediately weighed. The weight was recorded and water uptake for 2 samples of each composition was measured and the average reported in % increased water weight (defined as Water Uptake Value).

Table 3: Water Uptake Values

COMPARATIVE EXAMPLES (40°C, 5 days); 30 sec cure, 4mm thick cylinders

Product % Water Uptake (40°C. 5 days) Fluoride Releasing Orthodontic Adhesive 0.70

Sample F from Table 2

Fluoride Releasing Orthodontic Adhesive 0.86

Sample G from Table 2

Comparative Example 1 0.40

Resin Cement - Compomer Restorative

Comparative Example Reliance Ultra Band Lok 1.0

0.90 (w/60 sec. cure)

Comparative Example 2 0.08

Hydrophobic Resin Adhesive Consistency Value

The Consistency Value was conducted at room temperature, approximately 25°C, using the following procedure: A cylindrical sample of paste (1 cm in diameter, 0.7 cm in height, approximately 1.04 g in weight) was placed on a square glass plate, 4" X 4". A glass plate, 4" X 4", was then placed on top of the paste sample to be tested. The combined mass of a two pound compression weight plus the top glass plate on top of the sample is 1027 +/- 10 g. The diameter of the circle resulting from flattening or compressing the cylinder with this total weight was measured after two minutes.

The circular diameter of the flattened cylinder of paste was measured in units of 1/32" and recorded as the "Consistency Value."

Debanding Test To test the strength of orthodontic adhesives on human enamel, the following procedure was followed:

Human molars were potted into dental acrylic. The tooth root was placed into the acrylic while the tooth crown was standing up and out of the acrylic. The teeth were pumiced, rinced and allowed to air dry. Trial band fitting was performed to determine the correct band for each tooth. The bands had previously had lingual hook/seating lugs welded to the mesial and distal sides of the bands to allow for attachment of the test fixture. Orthodontic adhesive was syringed around the gingival edge inside the micro-etched band resulting in a ribbon of adhesive coating the bottom third to half of the interior of the band. The band was placed over the dry tooth and seated using finger pressure or a band seater as required to fully seat the band. In the cases where moist samples were tested, the band having adhesive applied onto it was placed over a moist tooth, moistened with deionized water. Excess adhesive that had extruded out around the top of the band was wiped away with a lab tissue. The adhesive was cured with a 30 second exposure to the Ortholux XT curing unit (3M Unitek). The light was shown perpendicular to the crown of the tooth. Banded and cured teeth were stored in 37°C water before testing. Storage was a minimum of 24 hours.

To test the band strength, an Instron machine was used (Instron; Los Alamitos, CA). The teeth were mounted into a jig that held the acrylic mounts on either side. Ligature wire loops (0.014") were looped under each lingual hook and slack taken up manually.

Testing was computer controlled by TEST WORKS™ software (Sintech; Spring Valley, CA). Pull rate was 0.02"/minute. The force (in pounds) required to remove the band from the tooth was recorded as the debanding force.

Human Molar Debanding Study: Dry & Moist Samples COMPARATIVE TESTING

Debanding Force is in lbs., using Victory Series Microetched Bands, 482-

120. Thirty second cure or manufacturer's recommended time. The banded teeth were stored for a minimum of 24 hrs at 37°C prior to debanding with an Instron

4204 (Instron; Los Alamitos, CA)

Table 4

Debanding Force

Sample Dry (std. dev.) Moist (std. dev.)

Fluoride-Releasing Orthodontic Adhesive 37.2 (17.6) 38.3 (19.0)

Reliance Ultra Band Lok 37.2 (14.8) 43.2 (18.2)

Table 4: Debanding Study: Dry Samples

COMPARATIVE TESTING

The Debanding Force was measured using Victory Series Microetched Bands, 482- 120, with the bonding material being cured for either 30 seconds or the time recommended by the manufacturer. Dry human molars were used. Banded teeth were stored for a minimum of 24 hrs at 37°C prior to debanding with Instron. Product Manufacturer Debanding Force in lbs (std. dev.)

Exp. Band Adhesive 3M Unitek 29.1 (13.1)

Ultra Band Lok Reliance 3.8 (13.5)

Dyractflow Dentsply 19.1 (8.7)

3M Multi-Cure Glass Ionomer 3M Co. 48.9 (14.4)

Fuji Ortho LC (Glass Ionomer) GC America 40.8 (11.2)

In side-by-side comparisons, the Ultra Band Lok material showed excessive run-on after the product was delivered.

Claims

What is Claimed:

1. A one part orthodontic adhesive for adhering an orthodontic appliance to a tooth surface comprising components a) hydrophilic monomer, oligomer, or polymer b) polymerizable acidic monomer, oligomer or polymer, c) pyrrolidone containing monomer, oligomer, or polymer, d) photopolymerization initiator, e) filler, and f) fluoride source, wherein said orthodontic adhesive is substantially free of added water and has a Water Uptake Value of greater than about 0.5% and components a-f are present in amounts such that the orthodontic adhesive has a Consistency Value between 32-

62.

2. An orthodontic adhesive according to claim 1 wherein said orthodontic appliance is a band and said adhesive has a Consistency Value of 32-42.

3. An orthodontic adhesive according to claim 1 wherein said orthodontic appliance is a bracket and said adhesive has a Consistency Value of 52-62.

4. An orthodontic adhesive according to claim 1, wherein the hydrophilic monomer, oligomer or polymer is present in an amount no less than about 10% and no greater than about 20% by weight, the polymerizable acidic monomer, oligomer or polymer is present in an amount no less than about 5% and no greater than about 10%) by weight, the pyrrolidone containing monomer, oligomer, or polymer is present in an amount of less than about 2% by weight, the photopolymerization initiator is present in an amount no less than about 0.01 % and no greater than about

2%>, the filler and fluoride source in combination are present in no less than about 70%) and no greater than about 75% by weight.

5. An orthodontic adhesive according to claim 1 wherein the hydrophilic monomer, oligomer or polymer is selected from the group consisting of 2- hydroxyethyl acrylate, 2 -hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glycerol, glycerol mono-acrylate, glycerol diacrylate, glycerol mono-methacrylate, glycerol di-methacrylate, polyethylene glycol mono methacrylate, polypropylene glycol mono methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, glycidyl acrylate, glycidyl methacrylate, ethyleneglycol diacrylate, ethyleneglycol dimethacrylate, polyethyleneglycol diacrylate, and triethyleneglycol dimethacrylate.

6. An orthodontic adhesive according to claim 1 wherein the polymerizable acidic component is selected from monomers, oligomers or polymers containing at least one acidic group selected from oxyacids or thio-oxy acids of C and P.

7. An orthodontic adhesive according to claim 1, wherein said polymerizable acidic monomer, oligomer or polymer is a compound that is an acid of C or P.

8. An orthodontic adhesive according to claim 1, wherein said polymerizable acidic component is selected from the group consisting of acryloyl or methacryloyl substituted carboxylic acids, phosphoric acid esters of hydroxyethyl methacrylate, hydroxy propyl methacrylate and glycerol dimethacrylate, and acrylates and methacrylates of pentaerythritol dimethacrylate and dipentaerythritol penta- acrylate.

9. An orthodontic adhesive according to claim 1, wherein the pyrrolidone containing monomer, oligomer or polymer component has a molecular weight between about 100 and 500,000.

10. An orthodontic adhesive according to claim 1, wherein the pyrrolidone containing oligomer or polymer component has a molecular weight between about

5,000 and 100,000.

11. An orthodontic adhesive according to claim 1 , wherein said filler or fluoride source is a fluoride-releasing fluoroaluminosilicate glass.

12. An orthodontic adhesive according to claim 1, wherein the filler is a reactive filler.

13. An orthodontic adhesive according to claim 1 , wherein the filler is a non- reactive filler.

14. An orthodontic adhesive according to claim 1 wherein the hydrophilic monomer comprises glycerol di-methacrylate, the polymerizable acidic monomer, oligomer or polymer is CDMA, the pyrrolidone containing monomer, oligomer, or polymer is poly n-vinyl pyrrolidone, the fluoride-releasing material filler is silane treated fluoroaluminosilicate glass, and the filler is silane treated silica.

15. An orthodontic adhesive according to claim 1, further comprising an adhesion promoter for enhancing adhesion to an orthodontic appliance.

16. An orthodontic adhesive according to claim 15 wherein the adhesion promoter is selected from the group consisting of amino titanates, and pyrophosphato titanates.

17. A method of adhering a substrate to a tooth, comprising the steps of:

(a) applying the one-part adhesive of claim 1 to at least one surface of a substrate;

(b) placing the substrate on or around a tooth surface so that the adhesive is in intimate contact with the tooth surface; and

(c) light curing the adhesive.

18. The method of claim 17, wherein the substrate is an orthodontic bracket.

19. The method of claim 17, wherein the substrate is an orthodontic band.

20. A method of bonding an orthodontic bracket to a tooth, comprising the steps of:

(a) etching the tooth; (b) drying the tooth;

(c) applying the one-part orthodontic adhesive of claim 1 on the bracket; and

(d) adhering the adhesive-coated bracket to the tooth.

21. A method of bonding an orthodontic bracket to a tooth, comprising the steps of:

(a) etching the tooth;

(b) applying a primer to the tooth;

(c) applying the one-part orthodontic adhesive of claim 1 on the bracket; and

(d) adhering the adhesive-coated bracket to the tooth.

22. An orthodontic article comprising an adhesively effective amount of the orthodontic adhesive according to claim 1 , wherein the adhesive is disposed on at least one surface of the article.