Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
  • C08J3/241—Preventing premature crosslinking by physical separation of components, e.g. encapsulation
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
  • A61K6/884—Preparations for artificial teeth, for filling teeth or for capping teeth comprising natural or synthetic resins
  • A61K6/887—Compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
  • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
  • C08F20/10—Esters
  • C08F20/12—Esters of monohydric alcohols or phenols
  • C08F20/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms

Definitions

• the contents of the two package components are essentially the same with the exception that one package component contains together with the resin binder and filler, an accelerator for the resin binder and the other package component contains a catalyst for the resin binder.
• an accelerator for the resin binder In preparing a fill ing a portion of the contents of one package compo nent is mixed with a portion of the content of the other package component.
• one of the package components may be prepared in different tints.
• any packaging systems diluent monomer which had been previously prepared for fillings of this type should be such as to reduce the by the dentist and a portion of the reactive monomer chance of error on the dentists part with respect to the containing activator from package component (3).
• BIS-GMA admixed with from the different containers to obtain the proper ratio other active monomers referred to by Bowen as reacof monomers and the proper ratio of binder to inortive diluents.
• the binder resin system is activated ganic filler and to completely blend the mixture. All of through the inclusion of both an activator and a catathis had to be done immediately prior to placing the lyst. In marketing such systems it has heretofore been filling in the cavity. The blending must be done rapidly the practice to prepare a paste of the BIS-GMA monootherwise the binder would polymerize to too hard a mer and the finely divided filler, as a paste is much mass prior to the dentist being able to place the easier for the dentist to handle when making the final blended filling in the tooth and work it into the cavity.
• Blending must also be uniform otherwise the filling will present.
• Portions of the other active monomers have vary in consistency depending on the ratio of binder to heretofore been packaged separately from the BIS- filler found in the final filling.
• This packable care must be exercised in measuring out the aging has been thought necessary in order to obtain the proper quantities from the respective package compoextended life required for any such prepackaged sysnents. All of these factors place a substantial strain on tern. Asaresult, although stable prepackaged materials the dentist preparing the filling with the result that for making fillings of the type described in Bowen Pat.
• dental fillings so prepared may vary substantially with No. 3,066,112 have been made commercially availthe best results not being obtained. Also, substantial able, stability has been obtained by careful separation waste is encountered as it is extremely difficult to meaof many of the component parts to avoid prepolymerisure accurately the small quantities needed to fill one zation with the result that the package made available or two teeth with the result that substantially more to the dentist contained four separate package compofilling material is blended than is actually needed. nents. It has been discovered that in dental restorativesys- Of these package components, package component terns such as that of Bowen Pat. No.
• 3,066,l 12 where (1) contained a paste comprising a mixture of BIS- an inorganic filler is present in amounts substantially GMA and inorganic filler, package component (2) greater than the binder resin and an activator and catalyst are employed that the monomers comprising the binder resin can all be premixed with the finely divided inorganic filler and be kept in this premixed state for many months even in the presence of a catalyst or an activator without undue deterioration of the binder system occurring.
• Direct filling mterials of the type utilizing a binder system composed of unreacted monomers, an inorganic filler, and an activator andcataylst, particularly of the type where one of the reactive monomers is a his phenol A containing monomer are packaged in a two component package wherein each of the package components contains a mixture of the unpolymerized resin binder and the inorganic filler in substantially the proportions in which they will be present in the final cured filling and one of the package components contains, together with the premixed nonpolymerized binder and filler, an accelerator for the binder system while the other package component contains together with the premixed nonpolymerized binder and inorganic filler a catalyst for the binder system.
• the dental filling can be readily prepared by taking approximately equal portions of each of the two components of the package and blending together.
• the packaging system is ideally suited for providing the dentist with several base shades which he then can blend to obtain the particular shade which he may desire for the filling.
• One of the package components, where tinting is desired, is made up in several of the basic shades.
• the dentist then blends various proportions of the basic shades together to get the shade desired and then blends this mix, which is still unreactive, with a substantially equal portion of the other package components which contain the missing catalyst or activator depending on which was used in preparing the various basic shade mixes.
• Bowen suggests than an active monomer be added as a diluent to control the viscosity of his bis phenol A backbone monomer.
• One of the advantages of using a monomer system of this type is the large amount of finely divided inorganic filler with which the same can be blended in making a filling. Inorganic filler can be blended in with the binder resin in amounts as high as 78 percent by weight of the dental filling material. Substantial difficulty has, however, been encountered in the packaging of the necessary ingredients for making fillings of this general type, that is, a difficulty in prepackaging in such manner that the work and responsibility on the part of the dentist for handling and obtaining accurate blend is substantially reduced.
• the ratio of finely divided inorganic filler to resin binder is such that the filler is present in amounts of at least 65 percent by weight of the total mix that the unpolymerized components of the binder resin will remain unpolymerized for extended periods of time.
• such premixed inorganic filler and unpolymerized resin binder can have blended therewith either the activator for the system or the catalyst for the system and still remain in an unpolymerized state for many months.
• the binder when a portion of the premixed resin and inorganic filler containing the activator is blended with a portion of the premixed binder and inorganic filler containing a catalyst for the system, the binder then polymerizes and cross-links to give a strong, useful filling.
• the packaging system of the present invention may be used for the prepackaging of any cement formed of an inorganic filler and binder therefor where the inorganic filler is present in amounts at least equal to the weight of the unpolymerized binder, the same is particularly suitable for the prepackaging of cement systems suitable for filling teeth utilizing as the primary binder monomer or one of the primary binder monomers a bis phenol A backbone monomer with terminal acrylic groups.
• the dental filling materials described in Bowen Pat. No. 3,066,1 12 are good examples of filling materials of this type, the same will be used in more specifically describing the practice of the present invention.
• the dental filling system of Bowen Pat. No. 3,066,112 comprises in essence a finely divided inorganic filler bonded together by a cross-linked resin binder.
• the ingredients in unpolymerized system which when blended together on polymerization give the aforementioned filling are the binder system, an activator for the binder system, a catalyst for the binder system, and a finely divided inorganic filler.
• BlS-GMA THE BINDER SYSTEM H HCH g l H I this particular monomer is hereinafter referred to as BlS-GMA.
• the BIS-GMA may be the only bis phenol A backbone containing monomer in the system or the system may be modified through the inclusion of other bis phenol A backbone monomers.
• a bis phenol A backbone monomer is the primary monomer in the binder system.
• BIS-GMA the his phenol A backbone monomer of Bowen
• the viscosity of the his phenol A backbone monomer is adjusted to a medium viscosity syrup by addition of reactive diluent monomers such as methyl methacrylate and the glycol dimethacrylate such as ethylene glycol dimethacrylate through tetraethylene glycol dimethacrylate with the preferred reactive diluent monomer being triethylene glycol dimethacrylate.
• the bis phenol A backbone monomer will generally comprise about 80 percent or more of the binder system with the active diluent monomer or monomers making up the rest of the interpolymerizable monomers present.
• an activator is used for the binder system.
• Suitable activators are, for example, N,N-dimethyl-para-toluidine and para-toluenesulfinic acid. However, the activator is not limited to these particular ones, but other amine activators may be used.
• a suitable catalyst is employed, such as benzoyl peroxide. Other activators are described, for example, in US. Pat. No. 2,558,139. The activator reacts with the peroxide catalyst to produce free radicals. The amount of activator will depend on the particular activator used and the working time needed prior to the commencement of hardening after the binder and finely divided filler have been mixed ands catalyzed.
• the activator will generally be present in amounts of about 0.1 to 2 percent by weight of the reactive monomers in the binder system. Where a catalyst such as benzoyl peroxide is used it would generally be present in amounts of about 1 to 2 percent by weight of the binder system.
• the activator and catalyst are not considered as a part of the binder system as the term is used herein, as the same are used to catalyze and control the rate of polymerization of the monomers which interact to give the final cured binder in the dental filling.
• the filler may be any finely divided solid which when dispersed through the binder system will give improved structural strength when the binder system is polymer- H H Him 0 H I H r t -Q 3 H I I H 0 HgH 1-1 0 ized into a cured resin.
• the best fillers are finely divided inorganic materials such as fused silica, aluminum oxide, crystalline quartz, small glass beads and the like.
• the finely divided filler has a particle size generally in the range of about 2 to with the preferred size being within the range of about 5 to 75 microns. The best results are obtained where the inorganic filler is treated with a keying agent to improve the bond between the organic polymer binder and the surface of the finely divided filler particles.
• Keying agents which have been found highly suitable are the ethylenically unsaturated organosilane finishing or keying agents where the filler is fused silica, glass, aluminum oxide, or crystalline quartz and the binder system is of the type described.
• the finely divided filler may be treated with the keying agent, for example, in the manner described .in US. Pat. No. 3,066,! 12 wherein an aqueous solution of tris( 2-methoxy ethoxy) vinyl silane is catalyzed with sodium hydroxide to give a pH of 9.3 to 9.8, and the filler treated with this solution, for example, one-half percent of the silane being used per weight of fused quartz.
• a slurry so formed is dried at about C. and cooled.
• the binder system is then blended with the inert filler into a paste comprising from about 65 to 75 percent by weight filler with the remainder being the binder system.
• the binder system is the blend of active monomers which later polymerize to give the cured organic polymer forming the binder in the filling.
• the inert filler is present in amounts of at least 70 percent.
• the paste comprising the binder system and the finely divided filler is divided into substantially equal portions and to one portion is added an accelerator for the binder system while to the other portion is added a catalyst for the binder system.
• the catalyst and accelerator areadded after the paste of binder system and finely divided filler has been prepared, one could add the catalyst and the accelerator during the blending of the finely divided filler and binder system the same being proportioned prior to blending rather than afterwards.
• the binder system inert filler paste containing the activator will hereinafter be called package component A and the blend of binder system and finely divided filler containing the catalyst will be referred to as package component B.
• package component A and package component B are both found to be quite stable over many months storage under normal room conditions. This is quite surprising when it is considered that if the catalyst is added to the binder system, polymerization of the binder system will be found to occur after a few days. Also, the binder system itself even without the addition of the catalyst where it contains a mixture of active monomers is found to be unstable and tend to polymerize, particularly where such active monomer diluents as methyl methacrylate are present. Thus, it is quite surprising that the binder system-inorganic filler paste withthe catalyst present is stable and may still be used after 7 many months.
• Package component A and package component B may be placed in any type of container formed of a material that is inert to the system.
• the container may be a tube formed of such materials as chemically inert plastics such as polyethylene, polypropylene, tinlined metal and the like or small dishes formed of such materials, as well as glass containers and the like. It is generally preferred to include in the paste small amounts of ultraviolet light absorbers and inhibitors to further assure stability of the system.
• a suitable inhibitor for example, is butylated hydroxy-toluene which may be added in amounts of .01 to .03 percent by weight based on the total binder system filler paste and ultraviolet absorbers such, for example, as Z-hydroxy- 4-methoxy-benzophenone in amounts of .2 to .3 percent based on the weight of the binder system finely divided filler paste. Also, in packaging the pastes of package component A and package component B in glass or other light-permeable containers, it is generally desirable to have the same tinted to exclude ultraviolet light.
• the filler is aluminum oxide having a particle size of to 50 microns
• 1 to 4 percent by weight of submicron floculated silica are added.
• no evidence of this separation or settling is found to occur in smaller masses, 20 to 30 grams, of either package component A or package component B even after storage as much as 3 months at room temperature.
• larger masses such, for example, as more than 50 grams of fused alumina in the particular mass some settling, as previously indicated, has been found to occur.
• the submicron silica may be mixed with the resin binder before the same is mixed with the fused alumina or other finely divided filler.
• the binder is colorless and as most of the preferred filler materials are white, it may be desirable to include some pigment. However, unless the dentist is himself able to blend to the particular shade in which he is interested, pigmented filling mixes are not too desirable. It has heretofore been proposed to use various blends of inert filler to optically match the tooth structure so as to permit some of the underlying color of the tooth to pass through. This may by achieved by selecting the proper blend of glass beads and quartz to give the proper light index to the set filling material.
• the present package system blends itself ideally to where pigmented fillings are desired as either package component A or package component B can be put up in several separate containers each having a different base color shade thus, as base color shades, one may use brown, gray, yellow, universal and unpigmented.
• the dentist then in preparing the filling would take small proportions of different ones of the base colored package components A and blend the same to obtain the desired shade which he was seeking. There would be no pressure on the dentist with respect to the binder setting while he was selecting and doing his blending as all of the material blended would be package component A.
• the basic color shades could be prepared in package component B rather than A.
• a binder system is prepared by blending together 95 parts BlS-GMA and 17 parts triethylene glycol dimethacrylate. Fourteen parts by weight of submicron silica are blended in with the binder system. The binder system so prepared containing the submicron silica is then divided into two equal parts. One part is then blended with fused alumina having a particle size range of 10-15 microns in the proportion of 25 parts by weight binder to parts by weight of fused alumina. Two parts by weight of benzoyl peroxide are added to the mix and blended therein.
• binder system containing the submicron silica is divided into five parts.
• Organic dyes are then added to give one part of brown tint, one a gray, one a yellow, one a universal tint and the other is left unpigmented.
• an activator N,N-dimethyl-p-toluidine is added to the binder mix prior to dividing into the five parts as above described.
• the activator is added in an amount of 2 parts activator to 98 parts by weight total monomer present.
• Each of the pigmented and unpigmented portions of the monomer mix are then blended with the fused alumina in the proportion of 25 parts by weight monomer to 75 parts by weight fused alumina.
• the mix prepared with the catalyst benzoyl peroxide is referred to as package component B and the mixes prepared with the activator are referred to as package component A.
• the color blending is first done by using small amounts of differ ent colors from the package components A.
• a small amount of brown paste from a package component A brown
• a small amount of paste from package component A gray
• paste from a package component A neutral
• the mix so obtained having the desired shade is then blended with an approximately equal proportion of material taken from package component B.
• the two pastes are mixed by spatula on a mixing slab.
• the mix so obtained is placed in a preprepared cavity of a tooth where it hardens in approximately 2 minutes from the time that the material from package components A is blended with the material from package component B.
• package component A and package component B are found to still be active and exhibit no separation after several months storage under ordinary room conditions.
• a method of filling a tooth comprising the steps of:
• a second quantity of paste-like material consisting essentially of: substantially the same premixed unpolymerized resin binder system which is in said first quantity of material; a finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said second quantity of paste-like material; and an activator for said catalyst to cause the aforesaid generation of free radicals in sufficient quantities to produce relatively rapid polymerization of said binder system; 7 extracting from each of said quantities of material approximately equal amounts of the same sufficient to effect the desired tooth restoration;
• a method of producing a hard dental filling comprising the steps of:
• a. taking a quantity of paste-like material consisting essentially of: pre-mixed unpolymerized resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said materal; and free radical generating catalyst for said system in which the free radicals when generated in sufficient quantities will produce relatively rapid polymerization of said system;
• a storable and activatable paste-like material for use in producing a hard dental filling material consisting essentially of: an intimate mix of resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said material; and a free radical generating catalyst which when activated will generate free radicals in sufficient quantity to produce relatively rapid polymerization of said system and which material will remain substantially unpolymerized and ready to be activated for a period of months.
• a storable and activatable paste-like material for use in producing a hard dental filling material consisting essentially of: an intimate mix of resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups; finely-divided, organosilane keying agent-treated, inorganic filler selected from the group consisting of fused silica, aluminum oxide, crystalline quartz and glass beads, said filler constituting at least 65 percent by weight of said material; and a free radical generating catalyst which when activated will generate free radicals in sufficient quantity to produce relatively rapid polymerization of said system and which material will remain substantially unpolymerized and ready to be activated for a period of months.
• a storable and activatable paste-like material for use in producing a hard dental filling material consisting essentially of: an intimate mix of resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups; finelydivided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said material, in which a small portion of said filler is replaced by an amount of hydrophobic submicron silica sufficient to substantially eliminate separation between said binder system and filler; and a free radical generating catalyst which when activated will generate free radicals in sufficient quantity to produce relatively rapid polymerization of said system and which material will remain substantially unpolymerized and ready to be activated for a period of months.
• a storable and activatable paste-like material for use in producing a hard dental filling material consisting essentially of: an intimate mix of resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups and which resin binder system includes at least 85 percent by weight of bis phenol A backbone monomer; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said material; and a free radical generating catalyst which when activated will generate free radicals in sufficient quantity to produce relatively rapid polymerization of said system and which material will remain substantially unpolymerized and ready to be activated for a period of months. 7.
• a manufacturespecifically for a dentist to use in producing hard dental fillings in a substantially uniform manner said manufacture being composed of two paste-like materials disposed in separate containers and from each of which containers a dentist may extract necessary amounts of materials to produce a dental filling to be made, the material in one of said containers consisting essentially of: premixed unpolymerized resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said paste-like material; and free radical generating catalyst for said system in which the free radicals when generated in sufficient quantities will produce relatively rapid polymerization of said system; the material in the other of said containers consisting essentially of: substantially the same premixed unpolymerized resin binder system as in said first container; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight
• a manufacture specifically for a dentist to use in producinng hard dental fillings in a substantially uniform manner said manufacture being composed of two paste-like materials disposed in separate containers and from each of which containers a dentist may extract necessary amounts of material to produce a dental filling to be made, the material in one of said containers consisting essentially of: premixed unpolymerized resin binder system containing active polyfunctional monomer havinga central portion which contains at least one aromatic ring and at least two acrylic end groups; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said paste-like material; and free radical generating catalyst for said system in which the free radicals when generated in sufficient quantities will produce relatively rapid polymerization of said system; the material in the other of said containers consisting essentially of substantially the same premixed unpolymerized resin binder system as in said first container; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent
• a manufacture specifically for a dentist to use in producing hard dental fillings in a substantially uniform manner said manufacture being composed of two paste-like materials disposed in separate containers and from each of which containers a dentist may extract necessary amounts of material to produce a dental filling to be made, the mateial in one of said containers consisting essentially of: premixed unpolymerized resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups; finely-divided, organosilane keying agent-treated, inorganic filler selected from the group consisting of fused silica, aluminum oxide, crystalline quartz and glass beads, said filler constituting at least 65 percent by weight of said paste-like material; and free radical generating catalyst for said system in which the free radicals when generated in sufficient quantities will produce relatively rapid polymerization of said system; the material in the other of said containers consisting essentially of: substantially the same premixed unpolymerized resin binder system a.
• finely-divided, organosilane keying agent-treated, inorganic filler selected from the group consisting of filsed silica, aluminum oxide, crystalline quartz and glass beads, said filler constituting at least-65 percent by weight of the material in said other container; and activator reactive with the catalyst in the material of said one container to cause generation of free radicals in sufficient quantity to produce relatively rapid polymerization of said system; the mixture of material extracted from each of said containers causing polymerization of said binder system to be initiated and hardening of the mixture to occur in a known and substantially uniform time to produce a hard dental filling after being placed in a tooth; and the quantity of material containing the activator being colored so that said mixture will substantially match the color of the tooth in which it is to be placed.
• a manufacture specifically for a dentist to use in producing hard dental fillings in a substantially uniform manner said manufacture being composed of two paste-like materials disposed in separate containers and from each of which containers a dentist may extract necessary amounts of materials to produce a dental filling to be made, the material in one of said containers consisting essentially of: premixed unpolymerized resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said paste-like material, in which a small portion of said filler is replaced by an amount of hydrophobic submicron silica sufficient to substantially eliminate separation between said binder system and said filler; and free radical generating catalyst for said system in which the free radicals when generated in sufficient quantities will produce relatively rapid polymerization of said system; the material in the other of said containers consisting essentially of: substantially the same premixed unpolymerized resin
• a manufacture specifically for a dentist to use in producing hard dental fillings in a substantially uniform manner said manufacture being composed of two 14 paste-like materials disposed in separate containers and from each of which containers a dentist may extract necessary amounts of material to produce a dental filling to be made, the material in one of said containers consisting essentially of: premixed unpolymerized resin binder system containing active polyfunctional monomer having a central portion which contains at least one aromatic ring and at least two acrylic end groups and in which said resin binder system includes at least percent by weight of his phenol A backbone monomer; finely-divided, organosilane keying agent-treated, inorganic filler constituting at least 65 percent by weight of said paste-like material; and free radical generating catalyst for said system in which the free radicals when generated in sufficient quantities will produce relatively rapid polymerization of said system; the material in the other of said containers consisting essentially of: substantially the same premixed unpolymerized resin binder system as in said first container; finely-divided,
• binder system itself even without the addition of the catalyst where it contains a mixture of active monomers is found 6 be unstable and tend to polymerize, particularly where such active monomer diluents I as methyl methacrylate are present.
• active monomer diluents I as methyl methacrylate are present.

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• Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Organic Chemistry (AREA)
• Polymers & Plastics (AREA)
• Medicinal Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Veterinary Medicine (AREA)
• Public Health (AREA)
• Analytical Chemistry (AREA)
• General Health & Medical Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• Epidemiology (AREA)
• Plastic & Reconstructive Surgery (AREA)
• Dental Preparations (AREA)

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Cited By (114)

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Citations (4)

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  • 1969-06-12 DK DK316269AA patent/DK125822B/da not_active IP Right Cessation
  • 1969-06-12 DE DE19691929831 patent/DE1929831A1/de active Pending
  • 1969-06-13 CH CH910969A patent/CH529558A/de not_active IP Right Cessation
  • 1969-06-13 FR FR6919711A patent/FR2010905A1/fr active Pending
  • 1969-06-13 AT AT564969A patent/AT287922B/de not_active IP Right Cessation
  • 1969-06-13 ZA ZA694207A patent/ZA694207B/xx unknown
  • 1969-06-13 IE IE814/69A patent/IE33163B1/xx unknown
  • 1969-06-13 BR BR209765/69A patent/BR6909765D0/pt unknown
  • 1969-06-13 ES ES368341A patent/ES368341A1/es not_active Expired
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  • 1969-06-13 NO NO2451/69A patent/NO131532C/no unknown
  • 1969-06-13 GB GB30149/69A patent/GB1268115A/en not_active Expired
  • 1969-06-13 SE SE6908456A patent/SE374265B/xx unknown
  • 1969-06-13 NL NLAANVRAGE6909087,A patent/NL167090C/xx not_active IP Right Cessation
  • 1969-06-13 FI FI691764A patent/FI50385C/fi active
• 1970
  • 1970-10-15 US US081156A patent/US3926906A/en not_active Expired - Lifetime
• 1973
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• 1975
  • 1975-08-08 CA CA233,150A patent/CA1018294B/xx not_active Expired

Patent Citations (4)

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