DENTAL COMPOSITIONS

Abstract: A two part composition for sealing and/or filling root canals. One or more elastomeric (meth)acrylate oligomers are mixed with one or more diluent comonomers, one or more radiopaque fillers and one or more polymerization initiator systems. One or more antimicrobial agents may also be included in the composition. The components are mixed, undergo a setting reaction and are subsequently cured. In use, the composition is easily removed from the tooth structure if rework is needed, yet provides a tight and effective seal in the root canal. The composition also has a desirable flowable consistency and exhibits good adhesiveness with a tooth substrate.

Description: DENTAL COMPOSITIONS Field of the Invention The mvention is directed to dental compositions, particularly for filling and sealing a toot canal Background of the Invention When treating an mfected root canal, the infected dentin is removed and the pulp and canal are then cleaned and dismfected The disinfected canal is shaped and filled with a filling material that is cemented with a sealer The desirable properties for a root canal filling material include ease of removal from the canal if rework is needed, ease of manipulation with ample working time, dimensional stability (minimal shπnkage oi change of form after insertion), ability to seal the canal laterally and apically (conforming and adapting to the various shapes and contours of individual canals), lack of irritation to peπapical tissues, inertness and insolubility in tissue fluids A desirable loot canal filling material also provides bactenostatic properties and is radiopaque Gutta percha is currently the root canal filling material of choice because, with careful manipulation, gutta percha can fulfill many of the above requirements Gutta percha is available in cone shapes with different sizes Its composition is gutta percha (a natural rubber) as a thermoplastic resm matrix, zinc oxide as a filler, one or more barium- or strontium-containing compounds as a filler and radiopacifier, waxes or resms, pigments and plasticizers The most common sealing material is a zmc oxide-eugenol type in a powder and liquid configuration The powder is composed of zmc oxide and other additives such as a radiopacifier and colloidal silica, and the liquid is composed of eugenol and other resinous material and additives such as a plasticizei When the powder and liquid are rmxed m the presence of moisture, zmc oxide and eugenol undergo a setting reaction and the pasty material slowly becomes a solid The sealer is used to fill any gaps between the gutta percha cones as well as m the lateral canal branches The gutta percha filler needs to be softened by heat and then condensed into the canal, forcing the sealer to have an intimate contact with the canal wall and to fill the lateral canal blanches The above method of filling and sealing the canal is however rathei complicated Separate sealmg and filling materials are used The gutta percha cone needs to be softened bv heat in ordei to compact it inside the canal, and has a rather limited working time once the heat source is removed Also there aie some othei drawbacks associated with both materials The zmc oxide-eugenol mixture is brittle, fragile, not very coherent and can easily disintegrate under a small stress The zinc oxide-eugenol sealer is quite soluble m oral fluids, slowly dissolvmg away and leavmg gaps between the filling material and the canal wall Bacteria or other microorganisms can multiply in such gaps, causmg infection and inflammation inside the canal and surrounding tissues The gutta percha filling materials are quite hard and difficult to remove whenever rework is needed, removal often requnes the application of a toxic organic solvent to soften the material The gutta percha filling materials are also quite brittle and prone to breakage durmg insertion into root canals due to their intricate shape Therefore, there is a need to improve existing canal filling and oi sealing matenals Summary of the Invention The mvention is directed to a dental composition that may be used as a loot canal sealing matei lal a root canal filling material, or a root canal filling and sealing matenal in one The composition ma\ be a tv\ o pan system of a powder/liquid or a paste/paste The inventive composition provides a tight and effective seal in the loot canal, yet is easily removed from the tooth structure if rework is needed The composition also has a desirable flowable consistency and exhibits good adhesiveness with a tooth substiate without the need for using a sealei The composition has at least one elastomeric acrylate (acrylate, as used herein, means eithei acrylate or methacrylate and may be abbreviated as (meth)acrylate) ohgomer, at least one diluent comonomer that has at least one ethylemcally unsaturated group, at least one fillei and at least one polvmeπzation initiator s\ stem The elastomeric (meth)acrylate ohgomer mav be a ui ethane (meth)acι ldte ohgomti ui a polyalkyleneglycol (meth)acrylate ohgomer The concentration of the elastomei ic ( meth)acι v late olmomei be 0.5-50% by weight The filler may be inorganic metal, salt, inorganic oxide, silicate, alurmnosihcate aluminoborosihcate, fluoroalummosihcate, colloidal silica, precipitated silica, polymeric solid, or mixtuies of the above The polymerization initiator system may be a redox initiator system The composition may optionally contain one or more antimicrobial agents The antimiciobial agent may be, for example, benzalkomum chloride, lodoform, eugenol. zmc oxide, tnclosan, butyl parahydroxybenzoate or mixtures of the above The inventive compositions may also contain calcium hvdi oxide one or more adhesion promoters, a plasticizer, and a wetting agent oi surfactant The invention also includes a method of sealing and oi filling a loot canal by piepai ing the inventive composition and providing the prepared composition to fill and oi seal a ot canal These and other embodiments of the inventive composition w ill be apparent in light of the following detailed description and examples Detailed Description A two part composition for use in filling and sealing root canals is disclosed One or more elastomeπc acrylate (acrylate, as used herein, means either acrylate or methacrylate and may be abbreviated as (mefh)acrylate) oligomers are mixed with one or more diluent comonomers, one or more radiopaque filleis and one or more polymerization or curing initiator systems In one embodiment, one or more antimicrobial agents may be included in the composition The elastomeric (meth)acrylate ohgomer provides soft or elastomeπc materials upon setting. The diluent comonomer controls the viscosity and optimizes the physical properties of the composition The radiopaque filler facilitates detection of gaps or voids The optional antimicrobial agent connols infection In use, the components are mixed and undergo a setting reaction The set components are subsequently cured The composition, upon curing, has a low modulus and is theietoie flexible w hich facilitates easy removal from the tooth structure should dental rework be needed The composition exhibits only a small amount of shrinkage upon curing and may even slightly expand upon water absorption This produces a tight and - 4 - effective seal m the root canal The composition also has a desirable flowable consistency at ambient temperatuie hence it is not necessary to heat the composition when using it to fill a root canal Conventional gutta peicha in contrast, is a thermoplastic material and must be heated to make it flowable The composition exhibits good adhesiveness with a tooth substrate without the need for using a sealei This is in contiast to conventional gutta percha which is not adhesive and therefore requires use of a sealer pπoi to application Thus, the composition is an endodontic matenal that can function as a sealing and oi a filling material, and thereby eliminate the need for separate filling and sealing materials The invention is also directed to a root canal sealing and/or filling material that, when hardened remams soft and flexible so that it can be easily removed from the canal if rework becomes necessaiy This is achieved by utilizing a special (meth)acrylate ohgomer that is flexible upon hardenmg The composition, when applied, does not require the application of heat to compact it inside the canal The composition is antibacterial in some embodiments, is ladiopaque, exhibits minimal volumetric shrinkage during curmg, is dimensionally stable in oral fluids and has limited solubility in oral fluids It has good adhesive properties and adapts well to canal walls and irregularities The root canal sealmg and/or filling compositions of the invention comprise one oi moi t elastomeric (meth)acrylate oligomers that have a low elastic modulus and that remain soft and flexible upon cuimg through free radical polymerization "Acrylate" as used herein is a monomer, ohgomer or prepolymer that contains one or more acrylate or methacrylate functional groups and may be abbieviated as (meth)acrylate ' Elastomei IC as used herein means that the (meth)acrylate ohgomer, after polymerization, has a rather low elastic modulus and is quite elastic and flexible Preferred elastomeric (meth)acrylate oligomers are urethane (meth)acrylate oligomers and a polyalkyleneglycol (meth)acrylate ohgomer The urethane (meth)acrylate ohgomer may be ( 1 ) the reaction product between one or more polyols (polyether polyols, polyester polyols, or polyether/polyester polyols), one or more organic dnsocyanates and one or more monohydπc (meth)acrylate (aciylate monomei w ith one ι eactι\ e hvdi oxv l gi oup) and oi ( 2 ι ihc reaction product between one oi more polyols (polyethei polyols polyestei polvols oi polyethei polvestei polvols i one or more organic dnsocyanates, and one or more isocyanatoalkyi (meth)acrvlates (aci ylate monomei w ith on reactive isocyanate group) The polyalkyleneglycol (meth)acrylate ohgomer is an acrylate ester of a polyalkylene glycol The root canal sealmg and/or filling compositions may also include other ingredients such as an (meth) acrylate comonomer, a curmg initiator, an antibacterial agent, a radiopaque filler, an adhesion promoter and a plasticizer Compositions contaming the disclosed (mefh)acrylate ohgomer would yield a soft and elastic polymeric material upon curing This invention discloses a novel endodontic sealing matenal that can be used as a sealing matenal and/or filling material This new endodontic obtuiation matenal offers the follow ing desnable chai actenstics It has a low elastic modulus after setting and remains elastic and flexible so it can be easiK ed if i ew oi k is necessary, offering easy manipulation with ample working time and an easy root canal proceduie It has good adhesive properties allowing it to adhere well to tooth structures and minimize gap formation Upon setting, it exhibits minimal shrinkage and therefore can create excellent contacts with loot canal walls minimizing gap formation It has excellent dimensional stability and minimal solubility m water Therefore, it can maintain a good seal and contact with tooth structures, ensuring long lasting sealing, and it has the ability to adapt to intricate canal geometries It exhibits excellent antibacterial properties m some embodiments and pi events miciooiganism gio th and infection It exhibits good radiopacity for easy detection of gaps and voids The endodontic sealmg and/or filling material utilizes (mefh)acrylate monomers/ohgomeis which undergo free-radical polymerization using a polymerization l tiatoi svstem such as l edox mitiatoi s\ stem I lie composition of this endodontic filling/sealing material comprises the follow ing components (a) one oi moi e elastomeπc (meth)acrylate oligomers, such as an elastomeπc urethane (meth)acrylate ohgomei oi an elastomei ic polyalkyleneglycol (meth)acrylate ohgomer, (b) one or more (meth)acrylate comonomers, (c) one oi moie fillei and (d) a polymerization initiator system Component (a), the elastomeπc (meth)acrylate ohgomer, exhibits a low elastic modulus and remams flexible upon curing As a root canal sealing and/or filling material, this elastic and flexible propeity allow s the cured material to be removed with little difficulty if rework is needed at a later time Also, the uncured paste is quite fluid and can be easily condensed into the canal and contoim to the canal geomenies without the need to heat, as in the case with conventional gutta percha cones When the mventive composition is used as a sealei one or more pie-manufactuied cone( s ) can be used to fill the canal The cone can be manufactured of gutta percha, 01 can be manufactuied from a cuied foim of the mventive composition The latter embodiment is prefeπed because the filling material and sealei have the same ingredients, resulting in a homogeneous entity rendering good adhesion between the sealer and filling material To insert the cone, a sealer is first delivered into a canal The pre-manufactuied cone is then inserted and excess sealei that overflows the canal is subsequently removed before the sealei is cuied Alternatively the pie-manufactui ed cone(s) is coated with the mventive composition and is inserted into the canal In one embodiment, the first prefeπed elastomeric (meth)acιylate ohgomei is a uiethane (meth)acrylate ohgomer There are two types of urethane (meth)acιvlate ohgomeis which ma\ be used The i st type of elastomeric urethane (meth)acrylate ohgomer (see Sttucture I below) is a leaction product bet een one oi more polyols (selected from polyether polyols, polyester polyols, oi polyether/polyester polyols), one or more orgamc dnsocyanates, and one or more monohydric (mefh)acrylates (acrylate monomers with one leactive hvdroxyl group) Examples of monohydπc (meth)acrylate include, but are not limited to, 2-hydroxyethyl acrylate, 2- hydroxyethyl mefhacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxy-2'-ethoxyethyl acrylate, 2-hydroxy-2'-ethoxyethyl methacrylate and mixtures thereof The second type of elastomeric urethane (meth)acrylate ohgomer (see Structure II below) is a reaction product between one or more polyols (selected from polyether polyols, polyester polyols, or polyether/polyester polyols), one or more organic dnsocyanates, and one or more lsocyanatoalkyl (meth)acιylates (acrylate monomers with one reactive isocyanate group) - 1 ■ STRUCTURE I ( Urethane Acrylate Oiigomer Type 1 ) H 2 C = -C = CH 2 AND STRUCTURE II ( Urethane Acrylate Oiigomer Type 2 ) H 2 C = CH 2 Where x= 0-30; R', R" =H or CH 3 ; R' and R" may be the same or different; R., R 2 = — C n H 2n -, n=1 — 14; R 1 and R 2 is an aliphatic group and may be the same or different; R 3 , R 4 and R 5 are the bivalent radicals of an organic dusocyanate compound and may be the same or different; R 1 , R = — (G— O) — G , y = 0— 0; R 1 , R 2 may be the same or different; R 3 , R 4 , R 5 may be the same or different, and is selected from the following structures: -(G-0) p -, -(G-O)p-f- Where p, q= 1-40; m= 1-30; and G in R 1 , R 2 , R 3 , R 4 and R 5 is selected from the following structures: CH 7 C 2 H 5 I J - (CH 2 ) n - -CHCH 2 - -CHCH 2 -, n = 1-12 The prefeπed R„ R : group above is either -CH 2 CH , -CH 2 CH : CH or -CH,CH,CH 2 CH : - Examples of useful bivalent radicals of an organic dusocyanate compound (1 e R,. R 4 , and R, above) include, but are not lumted to, 1 ,4-tetramethy lene dusocyanate, 1,5-pentamethylene dusocyanate 1,6-hexamethylene dusocyanate; 1,7-heptamethylene dusocyanate, 1,8-octamethylene diisocvanate, 1,9-nonamethylene dusocyanate 1,10-decamethylene dusocyanate, 2,4,4-tπmethyl- 1,6-hexamethylene dusocyanate, 2,2,4-tπmethyl-l,6- hexamethylene dusocyanate, 2,2,4-tπmethyl- 1 ,5-pentamethylene dusocyanate, toluene dusocyanate, dιphenylmethane-4,4'-dusocyanate; isophorone dusocyanate, dιcyclohexylmethane-4,4'dnsocyanate, 1,4-cyclohexyl dusocyanate, and 1,3-cyclohexyl dusocyanate The prefeπed dnsocyanates are 1,6-hexamethylene dusocyanate 2,4,4-tπmethyl- 1,6-hexamethylene dusocyanate. 2,2,4-tπmethvl- l 6-hexamethvlene diisocvanate toluene dusocyanate, dιphenylmethane-4,4'-dnsocyanate and isophorone dusocyanate The elastomeric urethane (meth)acrylate oligomers w ith an average moleculai eight of 500 to 50,000 are prefeπed The more prefeπed average molecular weight is 1 000 to 10 000 The mosi pi c ten cd e i ι_c molecular weight is 1,500 to 5,000 The urethane (meth)acrvlate ohgomer can ha\ e one or moie acrvlate oi methacrylate functional groups There are several commercially available elastomeric urethane (meth)acrylate oligomers that may be used m the cuπent invention Examples of those ohgomei s include Ebeci v senes l esins (e.g. Ebecryl® 270, 230, 810, USB Radcure Corporation, Smyrna, GA) and CN series lesins (e g CN964 CN966 CN970, Sartomer Co , Exton, PA) In another embodiment, the elastomeric (meth)acrylate ohgomer is a polyalkyleneglycol acrvlate ohgomer. The polyalkyleneglycol (meth)acrylate can contam one or more acrylate or methacrylate groups The elastomeπc polyalkyleneglycol (meth)acrylate has the following structure STRUCTURE III (Polyalkyleneglycol acrylate oiigomer) o II H 2 C = C -C -0 -(G- 0) χ -(G'- 0) y - M R' Where x = 0 —100; y = 0 —100, and x + y = 6 — 100 R' = H or CH 3 ; G and G' are selected from the following structures: CH 3 C 2 H 5 - (CH 2 ) m - , -CHCH 2 - -CHCH 2 - where m = 1 — 1 2, is selected from following structures: O II H C n H 2n . -i (al yl groupl , - C -C = CH 2 I R" where n = 1 — 8 ; R" = H or CH- Smtable polyalkyleneglycol (meth)acrylate oligomers useful for the present invention include, but are not limited to, polyethyleneglycol mono- or dι-(meth)acιylate polypropylenegl col mono- oi di ( meth )acι \ late polyisopropyleneglycol mono- or dι-(meth)acrylate, and polytetramethyleneglycol mono 01 dι-(meth)acι vlate The prefeπed molecular weight for the polyalkyleneglycol (meth)acrylate ohgomer is in the range of 400-5 000 the more prefeπed molecular weight is in the range of 500-3,000 and the most prefeπed molecular weight is m the range of 600-2,500 The above elastomeric urethane (meth) acrylate ohgomer or polyalkyleneglycol (meth)acrylate ohgomer can be used alone or can be used as a mixture of several different oligomers They are usually quite viscous and often require the mcorporation of other low viscosity diluent comonomers to reduce the viscosity This makes it easy to formulate the resm with other mgredients and makes the paste easy to manipulate Other comonomers can also be used to increase the polymeπzation rate of the elastomeric (mefh)acrylate ohgomei that usuallv has a slow cure response The comonomer has at least one ethylemcally unsaturated group and can copolymeπze w ith the elastomeric (meth)acrylate ohgomer Examples of ethylemcally unsaturated groups include vinyl acrylate and methacrylate groups Prefeπed ethylemcally unsatuiated gioups aie aci ylate and methaα \ late gioups Lxample s oi comonomers mclude, but are not limited to, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate hydroxybutyl (meth)acrylate, glycerol dι(meth)acrylate, glycerol mono(meth)acrylate, methyl (meth)acrylate ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate lauryl (meth)acrylate, decyl (meth)acrylate, tπdecyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2'-ethoxy-2-ethoxyethyl (meth)acrylate, ethyleneglycol dι(meth)acrylate, diethyleneglycol dι(meth)acrylate, triethyleneglycol dι(meth)acrylate, tetraethyleneglycol dι(meth)acrylate, polyethyleneglycol (PEG) mono- or di- (meth)acrylate with the molecular weight of PEG ranging from 160 to 400, polypropyleneglycol (PPG) mono- or di- (meth)acιylate with the molecular weight of PPG rangmg from 50 to 400, polyisopropyleneglycol mono- or di- (meth)acrylate with the molecular weight of polyisopropyleneglycol ranging from 50 to 400, polytetramethyleneglycol mono- or di- (meth)acrylate with the molecular weight of polytetramethyleneglycol ranging from 60 to 400 hexanediol dι(meth)acrylate, tπmethylolpropane tπ(meth)acrylate, UDMA (reaction product of 2-hydroxyethyl methacrylate with 2,4,4-tπmethylhexane dusocyanate), ethoxylated bisphenol A dι(meth)acrylate, teUahydrofurfuryl (meth)acrylate, or mixtures thereof The prefeπed concentration of the elastomeπc (meth)acrylate ohgomei is about 0 5- 50" o by weight, the more prefeπed concentration is about 1-40% by weight, and the most pi efeπ ed concenti ation is about 2 30% by weight An inorganic filler is used to piovide enhancement to the mechanical and i heologicai pi ope I t ie o i the composition, to mcrease radiopacity for easy detection of gaps oi v oids and to I educe polvmenzation shi lnka e Examples of fillers mclude inorganic metal, salt, oxide, silicate, alummosihcate, aluminoborosihcate fluoroalurmnosihcate, colloidal silica, precipitated silica, polymeπc solid, and mixtuies theieoi The pieten ed morgamc fillers for increased x-ray contrast include metal, silicate, alummosihcate. salt and oxide containing elements of high atomic number such as strontium, bismuth, tungsten, barium, ytterbium, yttrium, etc , with examples mcludmg barium sulfate, silver, strontium fluoride, barium fluoride, ytterbium fluoride, yttrium fluonde. baπum tungstate, zinc oxide, bιsmuth(III) oxide, bismuth subcarbonate (BιO)-,CO,, baπumalummosihcate, bariumalurmnoborosilicate, strontmm-alurmnosihcate, baπumalummofluorosihcate, strontiumalummofluorosilicate zincaluminosihcate, etc. Fumed silica, colloidal silica, or precipitated silica can also be incorpoiated to impiove the dispersion of the filler, as well as the rheological and handling properties of the matenal The curing or hardenmg of the resm is through free-radical polymerization of the ethv lenicalh unsaturated group, e.g., the (mefh)acrylate group. A redox initiator system that comprises at least one leducing agent and at least one oxidizing agent may be used Among prefeπed reducing agents are a tertiary amine. an organic compound contammg the -SO,M group (where M is H or alkali metal ion), and ascorbic acid and its derivatives The most prefeπed reducing agent is either N,N-dιhydroxyethyl p-toluidine, N,N-dιmethyl p-toluidine, N,N- drmethylarmnophenylethyl alcohol, N,N-dιmethylammophenylacetιc acid, benzenesulfimc acid, toluenesulfimc acid, sodium benzenesulfinate, potassium benzenesulfinate, sodium toluenesulfinate or potassium toluenesulfinate The prefeπed oxidizing agent is an organic peroxide. The most prefeπed peroxide is either benzoyl peroxide, hydrogen peroxide, di-t-butyl peroxide or t-butyl hydrogen peroxide The concentration of the mitiators should be in the range of about 0.01-3.0% by weight with a prefeπed concentration range of about 0 05-2 0% In one embodiment the composition is a two-part liquid/powder or paste/paste system with each part contammg a component of the redox initiator system (either reducing agents or oxidizing agents) When the two parts are mixed, the (meth)acrylate resms of the mixed paste start to polymerize and the paste starts to harden The working time and the set time can be adjusted by varying the concentration of the initiators and the stabilizers The prefeπed stabilizers include 4-methoxyphenol and 2,6-dι-(t-butyl)-4-methylphenol When the configuration is a powder/liquid combmation, the liquid mixture is formed by mixing all the (meth)acrylate resms (including monomers, oligomers and prepolymers) and all the additives (initiator, stabilizer, antibacterial agent, plasticizer. wettmg agent) that are soluble m the (meth)acrylate resin mixture The powder mixture is formed by blending all the fillers with the initiator (either the reducing or the oxidizing agent) together along with any solid additives The paste mixture is formed by mixing the liquid mixture with powders In some embodiments of the present mvention, the composition can also include one or more adhesion promoters to improve adhesion to the tooth structure Prefeπed adhesion promoters include organic compounds contammg at least one of the following hydrophihc groups, either a hydroxyl group or an acidic group selected from -COOH; OR Where R is an alkyl group. The most prefeπed adhesion promoter also contains at least one ethylemcally unsaturated group so that it can copolymeπze with other monomers or oligomers Examples of adhesion promoters include but aie not limited to, glycerm, polyethyleneglycol, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate glycerol dι(meth)acrylate, glycerol mono(meth)acrylate, glyceroldι(meth)acrylate phosphate, (meth)acryloyloxydecvl phosphate, 4-(meth)acryloxyethyl tπmelhtic anhydride, (meth)acryloxyethyl maleate, phthahc acid monoethyl(meth)acrylate, a reaction product of pyromelhtic dianhydπde with hydroxyethyl (meth)acrylate, a reaction product of pyromelhtic dianhydπde with glyceroldι(mefh)acrylate, or mixtures thereof In another embodiment, the composition also includes a plasticizer to further increase flexibility Examples of plasticizers include, but are not limited to, dibutylphthalate dibutoxyethoxyethyl adipate dibutoxyethoxylethyl formal, etc In yet another embodiment, the composition contains one or moie antimicrobial agents Examples of antimicrobial agents include, but are not limited to, benzalkomum chloπde lodotoim eugenol zinc oxide tπclosan, butyl parahydroxybenzoate and mixtures thereof Calcium hydroxide has a pharmaceutical effect and is said to promote the growth of secondary dentm When incorporated in the cuπent compositions, similar effects aie expected In other embodiments, the compositions of the present invention may also contain a wettmg agent or surfactant to improve the wettmg or dispersion of the morgamc filler m the resm Consistency measurement The viscosity of the paste is roughly characterized by a consistency measurement One ( 1 00) gram of paste is placed onto a 2" x 3" glass slide A second 2" x 3" glass slide and an additional mass with a total weight of 120 ± 2 g was gently placed over the paste After exactly 10 minutes, the weight was removed and the minoi and major diameter of the slumped paste was immediately measured in centimeters The consistency alue is the a\ eι s_c of he two diameters A paste of higher viscosity would usually yield a smaller consistency value Elastic modulus measurement The flexural modulus of the inventive composition was measuied as well as the flexuial modulus of conventional gutta percha and a restorative composite resm (Pi odιgv l : Ken orpoiation) I he elastic modulus was measured from the slope of the initial linear region on the sttess-stiain cuive dunng the flexui al tcstin I k xtu i l testmg is a three-point bendmg setup using specimens with a rectangular bar geometry The base paste contains the reducmg agent, e g , a tertiary amine, of the redox initiator system and the catalyst paste contains the oxidizing agent, e g , an organic peroxide, of the redox initiator system Five specimens were prepared for each pan of base/catalyst sealer formulas A split mold made of stainless steel with an inside dimension of 3 mm x 3 mm x 30 mm was used for fabncatmg the specimens A Mylar sheet was placed on a 2" x 3" glass slide and then the assembled split mold was placed on the Mylar sheet Equal amounts of base and catalyst pastes wei e mixed w ith a spatula for about 30 sec The mixed paste was slightly overfilled into the mold and another Mylar sheet was placed on the top Another 2" x 3" glass slide was placed on top of the Mylar sheet and some pressure was applied to remove excess paste from the mold The paste was allowed to set and haiden foi about one houi in the mold The specimen was then carefully removed from the mold and any excess matenal oi flashes from the specimen w ei e also removed The specimen was placed m a container filled with water and stored in a 37°C oven tor 24 h before testing Testing was performed on an Instroh Testing Machine (Model 4467, Instion Corp ) A three point bending apparatus with a support span of 2 mm was used Testmg was conducted with a crosshead speed of 5 mm/mm The force and displacement were digitally collected by a computer loaded with an Instron IX software package The modulus was calculated automatically by the software Shore "A" Hardness measurement Equal amounts of base and catalyst pastes were mixed The mixed paste was filled into a 10 0 mm x 2 0 mm (diameter x height) stainless steel mold resting on a 1 " x 3" glass slide The mold was overfilled an 18 mm x 18 mm cover glass slip was placed on the top and the assembly was pressurized with a 1 " x 3" glass slide to remove excess paste The paste was allowed to set and harden for about one h and then the specimens were removed from the mold A Shore "A" Durameter (Shoie Instrument Co ) w as used to measuie haidness In all the following examples for making a paste, a homogeneous unfilled resm mixture was made first by mixing all resms with mitiators and additives The resin mixture was then further blended togethei with appropnate fillers including colloidal silicas The invention will be further appreciated in light of the following examples In the examples the following matenals were used A- 174 γ -methacryloyloxypropy ltrunethoxysilane BaAlBSi filler barmmalummoborosilicate filler that has a mean particle size of 1 0 μm and the following composition (mole%) Sι0 2 (67), BaO (16 4), B 2 0, ( 10), A1 2 0 3 (6 6) BAC benzalkomum chlonde BHT 2,6-dι-(tert-butyl)-4-methylphenol Bis-GMA 2,2-bιs[4-(2-hydroxy-3-methacryloylpropoxy)-phenyl]-propane BPB butyl para-hydroxybenzoate BPO benzoyl peroxide CN966 a urethane diacrylate ohgomer based on polyester polyol (Sartomer Co ) Ebecryl® 270 urethane acrylate ohgomer (UCB Radcure Inc ) EBPADMA ethoxylated bisphenol A dimethacrylate EOEOEA 2-(2-ethoxyethoxy)ethyl acrylate DHEPT N,N-dιhydroxyethyl-p-toluιdιne GPDM glycerylphosphate dimethacrylate HEMA 2-hydroxyethyl methacrylate MEMA methacryloyloxyethyl maleate OX-50 fumed silica or colloidal silica (Degussa) PEG-600 DMA poly(ethyleneglycol) dimethacrylate (average molecular weight of PEG is 600) R-972 surface treated fumed silica or colloidal silica (Degussa) SR604 polypropyleneglycol monomethacrylate with a molecular weight of 405 (Sartomer Co ) TEGDMA triethyleneglycol dimethacrylate TS-530 surface treated fumed silica or colloidal silica (Cabot Corp EXAMPLE 1 A) Base Resin mixture composition B) Catalyst Resin mixture composition C) Base and Catalyst Paste composition (in parts by weight) 'Both BaAlBSi filler and OX-50 fumed silica were surface treated with γ-mefhacryloyloxypropyltπmethoxysilane The Base Paste had a consistency value of 4 5 cm and the Catalyst Paste had a consistency \ alue ot 4 0 cm The Mixed Base and Catalyst Paste had a working time of 24 mm and set time of 43 mm The set material had a Shore A hardness of 82, a flexural modulus of 8 ± 1 MPa and a flexural stiength of 1 4 ± 0 2 MPa In comparison, conventional gutta percha had a flexural modulus of 470 ± 20 MPa and the Prodigy™ composite resm had a flexural modulus of 10,300 ± 800 MPa Indeed, the mventive composition desirably has a much lower flexural modulus m comparison to gutta percha or Prodigy™ composite resm EXAMPLE 2 A) Base Resin mixture composition B) Catalyst Resin mixture composition C) Base and Catalyst Pastes compositions (in parts by weight) 'Both BaAlBSi filler and OX-50 fumed silica were surface treated with γ-methacryloyloxypropyltπmethoxysilane The Base Paste had a consistency value of 4.6 cm and the Catalyst Paste had a consistency value of 5.8 cm. The mixed Base and Catalyst Paste had a working time of 21 mm and set time of 30 mm The set material had a Shore A hardness of 87, a flexural modulus of 45 ± 11 MPa and a flexural strength of 7.2 ± 0.8 MPa. In compaπson, conventional gutta percha had a flexural modulus of 470 ± 20 MPa, and the Prodigy™ composite resm had a flexural modulus of 10,300 ± 800 MPa Indeed, the inventive composition desirably has a much lowei flexuial modulus m comparison to gutta percha or Prodigy™ composite resm COMPARATIVE EXAMPLE This example is for comparison only, not m accordance w ith the cuπent invention A) Base Resin mixture composition B) Catalyst Resin mixture composition C) Base and Catalyst Paste compositions (in parts by weight) 'Both BaAlBSi filler and OX-50 fumed silica were surface treated with γ-methacryloyloxypropyltπmethoxysilane The Base Paste had a consistency value of 6 1 cm and the Catalyst Paste had a consistency value of 5.6 cm. The mixed Base and Catalyst Paste had a workmg tune of 19 mm and set time of 25 mm The set material had a Shore A hardness of 98, a flexural modulus of 3900 ± 500 MPa and a flexural strength of 104 7 ± 5 2 MPa S ce these pastes were formulated without any elastomeric (meth) acrylate oligomers, the cured material was rather hard, which is reflected by both its much higher flexural modulus and much higher Shore A hardness value when compared with the set materials m Examples 1 and 2 Therefore, the material in this comparative example was not suitable as a root canal sealmg and/or filling material because it would be extremely difficult to remove the set material from the root canal if rework was needed. The above Examples are for illustration only and in no way limit the scope of the cuπent invention It should be understood that the embodiments of the present invention shown and described m the specification are only prefeπed embodiments of the mventor who is skilled in the art and are not limiting m any way. Therefore, various changes, modifications or alterations to these embodiments may be made or resorted to without departing from the spirit of the mvention and the scope of the following claims. What is claimed is:

Claims: 1 A method for sealmg and filling a root canal of a tooth comprising providing to said canal a cone and a sealer, said sealer compπsmg a) at least one elastomeric (meth)acrylate ohgomer selected from the group consisting of an elastc ^eπc urethane (meth)acrylate ohgomer and an elastomeric polyalkyleneglycol (meth)acrylate ohgomer b) at least one diluent comonomer having at least one ethylemcally unsaturated group c) at least one filler, and d) a polymerization initiator system, and inserting said cone mto said canal 2 The method of claim 1 wherem said cone is selected from the gioup consisting of gutta pei cha and a polymerized form of the sealer 3 The method of claim 1 wherem said cone is a polvmeπzed toi m ol the sealei t pi v idt enhance d adhesion between the cone and the sealer 4 The method of claim 1 wherem said sealer is delivered into said canal and said cone is thereaftei inserted to said canal 5 The method of claim 1 wherem said cone is coated with said sealer and is thereafter inserted into said canal 6 A method for simultaneously sealing and filling a root canal comprising providing a composition to simultaneously seal and fill said root canal that is flowable at ambient temperature 7 The method of claim 6 wherem said composition comprises l) at least one elastomeric (meth)acrylate ohgomer selected from the group consisting of an elastomeric urethane (meth)acrylate ohgomer and an elastomeric polyalkyleneglycol (meth)acrylate ohgomer, n) at least one diluent comonomer having at least one ethylemcally unsatuiated group, in) at least one filler, and IV) a polymerization initiator system 8. A method of sealmg and/or filling a root canal comprising preparing a composition comprising a) at least one elastomeric (meth)acrylate ohgomer selected ti om the gi oup consisting ot ,\v elastomeπc urethane (meth)acrylate ohgomer and an elastomeπc polyalkyleneglvcol ( meth )acry late ohgomei b) at least one diluent comonomer having at least one ethylemcally unsatuiated gioup c) at least one filler, and d) a polymerization initiator system, and curing said composition to form a composition having minimal water solubility 9. The method of claim 7 wherem said composition provides radiopacity 10. A method for simultaneously sealmg and filling a root canal comprising providing a composition to simultaneously seal and fill said root canal and that is capable of adhering to a tooth structuie 11. A material for simultaneously filling and sealmg a root canal comprising a composition having a low elastic modulus after setting. 12. The method of claim 6 wherein said composition is delivered fiom a synnge 13. A material for filling a root canal that adheres to a sealer and a gutta percha provided to said canal 14. A material for simultaneously filling and sealing a root canal that has increased resistance to chemical breakdown 15. An endodontic sealmg and/or filling material comprising a) at least one elastomeric (mefh)acrylate ohgomer selected from the group consisting of an elastomeπc urethane (meth) acrylate ohgomer and an elastomeric polyalkyleneglycol (meth)acrylate ohgomer, b) at least one diluent comonomer havmg at least one ethylemcally unsaturated group, c) at least one filler, and d) a polymerization initiator system 16 The sealmg and/or filling matenal of claim 15 wherem the elastomeric urethane (meth)acrylate ohgomer is selected from the group consistmg of STRUCTURE I ( Urethane Acrylate Oiigomer Type 1 H2C = CH 2 AND STRUCTURE II ( Urethane Acrylate Oiigomer Type 2 ) H 2 C = CH 2 Where x= 0— 30; R', R" =H or CH 3 ; R' and R" may be the same or different; R R 2 =-C n H 2n — , n= 1 — 14; _ j and R 2 is an aliphatic group and may be the same or different, R , R 4 and Rg are the bivalent radicals of an organic dusocyanate compound and may be the same or different; R 1 , R 2 = — (G— O) — G , γ = 0— 40; R 1 , R 2 may be the same or different; R 3 , R 4 , R 5 may be the same or different, and is selected from the following structures: -(G-0) p -, Where p, q= 1-40; m= 1—30: and G in R 1 , R 2 , R 3 , R 4 and R 5 is selected from the following structures: CH-: ?2 H 5 - (CH 2 ) n -, -CHCH 2 - , -CHCH 2 -, n = 1-12 17. The sealmg and or fillmg material of claim 16 where R,, R 2 is selected from the group consisting of -CH 2 CH,-, -CH 2 CH 2 CH 2 -, and -CH 2 CH 2 CH 2 CH,-. 18. The sealing and/or fillmg material of claim 16 where R 3 , R 4 and R, are the bivalent radicals of an organic diisocyanate compound selected from the group consisting of 1 ,4-tetramethylene dusocyanate. 1.5- pentamethylene dusocyanate; 1,6-hexamethylene dusocyanate, 1,7-heptamethylenedusocyanate, 1 ,8-octamethylene diisocyanate; 1,9-nonamethylene dusocyanate; 1,10-decamethylene dusocyanate; 2,4,4-tπmethyl- 1 ,6-hexamethylene diisocyanate; 2,2,4-tπmethyl- 1,6-hexamethylene dusocyanate, 2,2,4-tπmethyl-1.5-pentamethvlene diisocv anate toluene diisocyanate; dιphenylmethane-4,4'-dnsocyanate. isophorone dusocyanate. dιc\ clohexylmethane-4 4'- diisocyanate; 1,4-cyclohexyl diisocyanate and 1,3-cyclohexyl dusocyanate 19. The sealing and/or filling material of claim 16 wheie R„ R 4 and R, aie the biv alent l adicals of an organic dusocyanate compound selected from the group consisting of 1,6-hexamethylene dusocyanate, 2.4,4- trimethyl- 1,6-hexamethylene diisocyanate; 2, 2,4-trιmethyl- 1,6-hexamethylene dusocyanate; toluene dusocyanate, diphenylmethane-4,4'-diιsocyanate and isophorone diisocyanate. 20. The sealmg and/or fillmg matenal of claim 16 where G is selected from the group consisting of - CH 2 CH 2 -, -CH 2 CH 2 CH 2 -, -CH(CH 3 )CH 2 -, and -CH 2 CH 2 CH 2 CH 2 -. 21. The sealing and/or filling material of claim 16 wherem R 1 and R 2 are selected from the group consisting of -CH,CH 2 -; -CH 2 CH 2 CH 2 -; -CH(CH 3 )CH 2 -; -CH 2 CH 2 CH 2 CH,-; -CH 2 CH 2 OCH 2 CH 2 - and - CH(CH 3 )CH 2 OCH(CH 3 )CH 2 - . 22. The sealing and/or fillmg material of claim 15 wherem the elastomeiic urethane ( meth )acι vlate ohgomer has an average molecular weight of 500-50,000 23. The sealmg and/or filling material of claim 15 wherem the elastomeric urethane (meth)acrylate oiigomer has an average molecular weight of 1 ,000-10,000. 24. The sealing and/or filling material of claim 15 wherein the elastomeπc polyalkv leneghcol (meth)acrylate oiigomer has the followmg structure STRUCTURE III (Polyalkyleneglycol acrylate oiigomer) o II H C = C-C-0-(G-0) > ■ (G'-Oly-M R" Where x = 0—100; y = 0 — 100, and x + y= 6-100 R'= H or CH 3 ; G and G' are selected from the following structures: CH 3 C 2 H 5 - (CH 2 ) m - , -CHCH 2 - -CHCH 2 - where m = 1 —12; M is selected from following structures: 0 II C n H 2n+ 1 (alkyl group), -C-C = CH 2 R" where n = 1 —8; R" = H or CH 3 . 25 The sealing and/or filling material of claim 15 wherem the elastomeric polyalkyleneglycol (meth)acrylate ohgomer is selected from the group consisting of polyethyleneglycol mono-(meth)acιylate polyethyleneglycol dι-(meth)acrylate, polyisopropyleneglycol mono-(meth)acrylate, polyisopropvleneglycol di (meth)acrylate, polytetramethyleneglycol mono-(meth)acιvlate polvtetiamethvleneglycol dι-(meth )acι \ late 26 The sealing and/or fillmg material of claim 15 wherem the elastomeiic polyalkyleneglycol (meth)acrylate ohgomer has an average molecular weight of 400-5,000 27 The sealing and/or filling material of claim 15 wherem the elastomeric polyalkyleneglycol (meth) acrylate ohgomer has an average molecular weight of 600-3,000 28 The sealing and/or fillmg material of claim 15 wherem the ethylemcally unsaturated group is selected from the group consisting of a vmyl group and a (meth)acrylate gioup 29 The sealmg and/or filling material of claim 15 wherem the concentration of the elastomeric (meth)acrylate ohgomer is 0 5-50% by weight 30 The sealing and/or fillmg material of claim 15 wheiein the concentration of the elastomei ιc (meth)acrylate ohgomer is 2-30% by weight 31 The sealmg and or fillmg material of claim 15 wherem the filler is selected from the group consistmg of inorganic metal, salt, inorganic oxide, silicate, alummosihcate aluminoboiosihcatt fluoroaluminosihcate, colloidal silica, precipitated silica, polymeric solid and mixtures thereof 32 The sealing and/or filling material of claim 15 wherem the filler contains elements selected fiom the group consisting of barium, zinc, silver, strontium, bismuth tungsten, ytterbium yttπum and mixtuies theieof 33 The sealmg and/or fillmg material of claim 15 wherein the filler is selected from the gioup consistmg of silver, barium sulfate, strontium fluoride, barium fluoride, ytterbium fluoride, yttrium fluoride, barium tungstate, zmc oxide, bιsmuth(III) oxide, bismuth subcaibonate (BιO),CO, baπumaluminosihcate banumalummoborosilicate, sttontiumaluminosilicate barmmaluminofluorosihcate stiontiumalummofluoiosilicatc zincaluminosihcate and mixtures thereof 34 The sealing and/or fillmg material of claim 15 wheie the polymeπzation mitiatoi system is a ι initiator system 35. The sealmg and/or fillmg material of claim 34 wherein the redox initiator system comprises at least one reducmg agent and at least one oxidizing agent. 36. The sealmg and/or filling matenal of claim 35 wherein the reducing agent is selected from the group consisting of a tertiary amme. an organic compound containing the -SO,M gioup heie M=H oi alkali metal ion, ascorbic acid, ascorbic acid derivatives and mixtures thereof 37 The sealing and/or filling material of claim 35 wherein the reducing agent is selected from the group consisting of N,N-dιhydroxyethyl p-toluidine, N,N-dιmethyl p-toluidine \ N-dimethylaminophenvlethv l alcohol, N,N-dιmethylammophenylacetιc acid, benzenesulfimc acid, toluenesulfinic acid, sodium benzenesulfinate potassium benzenesulfinate, sodium toluenesulfinate and potassium toluenesulfinate 38. The sealing and/or fillmg material of claim 35 wherein the oxidizing agent is an organic peroxide 39. The sealmg and/or fillmg material of claim 38 wherein the organic peroxide is selected from the group consistmg of benzoyl peroxide, hydrogen peroxide, di- t-butyl peroxide and t-butyl hydrogen peroxide 40. The sealmg and/or fillmg matenal of claim 15 wherein the composition further comprises an antimicrobial agent. 41. The sealing and/or filling material of claim 40 wherein the antimicrobial agent is selected from the group consistmg of benzalkonium chloride, lodoform, eugenol, zinc oxide, tπclosan, butyl parahydroxybenzoate and mixtures thereof. 42. The sealing and/or filling material of claim 15 wherem the composition further comprises calcium hydroxide. 43. The sealing and or fillmg matenal of claim 15 wherein the composition further comprises one or more adhesion promoters that contam at least one hydrophilic group selected from the group consisting of a hydroxyl group and an acidic group, wherein said acid group is selected from the group consisting of -COOH; OR Where R is an alkyl group. 44. The sealing and/or fillmg material of claim 43 wherem the adhesion promoter comprises at least one ethylemcally unsaturated group 45 The sealing and/or filling material of claim 43 wherem the adhesion promoter is selected fiom the group consisting of hydroxyethyl (meth)acrylate, glycerol dι(meth)acιylate, glyceiol mono(meth)acιylate, glyceryldι(meth)acrylate phosphate, (meth)acryloyloxydecyl phosphate, 4-(meth)acryloxyethyl dimellitic anhydnde and mixtures thereof 46 The sealing and/or fillmg material of claim 15 wherem the composition furthei comprises a plasticizer 47 The sealing and/or filling material of claim 46 wherem the plasticizei is selected fi om the gi oup consistmg of dibutylphthalate, dibutoxyethoxyethyl adipate, dibutoxyethoxylethyl fomial and mixtures theieof 48 The sealing and/or filling composition of claim 15 where the composition fuither comprises at least one wettmg agent or surfactant 49 The sealmg and/or fillmg matenal of claim 15 wherein the composition is a two-part system selected from the group consistmg of a powder/liquid two-part system and a paste/paste two-part system 50. The sealmg and/or fillmg material of claim 15 wherem the polymerization initiator system is a two- part redox system with one part contammg a reducmg agent and the other part contammg an oxidizing agent 51. The sealmg and/or fillmg material of claim 15 wherein the composition is selected from the group consisting of a root canal sealmg matenal, a root canal fillmg material, and a root canal filling and sealing matenal one 52. A method of sealing and/or filling a root canal comprising preparing the composition of claim 1 and providmg said composition to said root canal

Inventors: QIAN XUEJUN, QIAN, XUEJUN
Applicants: KERR CORP, KERR CORPORATION
Application year: 2000
Main classification: A61K6
IPC codes: A61K6