CA1157892A - Zinc-containing glass composition - Google Patents
Zinc-containing glass compositionInfo
- Publication number
- CA1157892A CA1157892A CA000385221A CA385221A CA1157892A CA 1157892 A CA1157892 A CA 1157892A CA 000385221 A CA000385221 A CA 000385221A CA 385221 A CA385221 A CA 385221A CA 1157892 A CA1157892 A CA 1157892A
- Authority
- CA
- Canada
- Prior art keywords
- composition
- glass
- oxide
- paste
- accordance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C12/00—Powdered glass; Bead compositions
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/15—Compositions characterised by their physical properties
- A61K6/17—Particle size
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/70—Preparations for dentistry comprising inorganic additives
- A61K6/71—Fillers
- A61K6/77—Glass
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/70—Preparations for dentistry comprising inorganic additives
- A61K6/78—Pigments
-
- 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
- A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
- A61K6/807—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising magnesium oxide
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/11—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen
- C03C3/112—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen containing fluorine
- C03C3/115—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen containing fluorine containing boron
- C03C3/118—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen containing fluorine containing boron containing aluminium
Abstract
Abstract This invention is a novel glass composition and a dental filling composition for making dental restore-tions. More particularly, the invention provides a radio-paque dental filling material. Specifically, the dental filling material contains a zinc-containing glass as the component imparting opacity to X-rays.
Description
184,916 CA~I/DPE
I
Descri ~tion Zinc-Containing G1ass Composition Technical Field This invention relates to zinc-containing glass compositions and to dental filling compositions containing such ylass composition in the form o~ -finely divided ~iller.
Background Art A variety of substances has been used over the years to repair damaged teeth. The best known currently include silver amalgams, which are frequently first encountered at an early age as a filling for small cavities, even in deciduous teeth. Gold alloys are a particularly valuable filling material, used frequently when a tooth has been considerably damaged, such as after several cavitjes have occurred and a lot of tooth must be restored. Fre-quently, for example, several smaller extending cavities, e.g. in the occlusal surface, will be combined and a restoration made with a single gold inlay or onlay. The gold alloys have gained an excellent reputation for strength, reliability and long life in service. However, both the gold alloys, and the other metals, such as the stainless steels, which have been technically successful in dental reconstructions and crowns, do not impart a natural tooth appearance.
Gold and other metallic-looking restorations are used for molars and teeth which are not immediately open to view when the wearer opens his mouth or smiles. For anterior teeth, however, current practice is to use 3G materials closer in appearance to natural teeth. These are known colloqu~ally as porcelain or plastic fillings.
They are composite rnaterials characterized by containing usually predominantly inorganic materials, normally finely divided powders, inert to the oral environment, bound together with polymeric material. The inorganic materials are frequen-tly ~inely-ground fused oxides, particular1y glasses, or crystalline quartz, while the polymer moiety ls commonly a polyacrylate. These compo-site systems are available~ for example, as pastes whichare polymerized in situ, after having been activated, e.g.
by add;ng a catalyst to initiate a polymerization reaction, just before being placed in the prepared tooth.
Fillings and restorations of thls kind can be made to look much like natural teeth. In particular, the color of the restoration can be adjusted to a shade quite close to that of a patient's natural teeth by tinting wlth pigments. In addition, the translucency or pearlescence of the natural tooth can also be approximated through adjustment of the relative refractive indices of the materials used in the restoration. When color and re-fractive indices are well matched, it is possible to obtain a restoration that is barely perceptible to the glance.
However, the attainment of good color and overall appearance is very difficult to achieve in practice. This is particularly true when one desires also to optimize other features of a good restoration, particularly radiopacity.
It is highly desirable for a filling or other re-storation to be radiopaque, for it is by X-ray examination that a dent~st determines whether or not d filling remains sound. From radiographs a dentist determines the condi-tion of a filling, e.g. whether it has cracked, or whether decay is occurring at the intertace between the tooth and the filling. Fillings and restorations which are made of metal are readily observable in X-rays. Fillings of the porcelain/plastic art are not observable by X-rays unless they have radiopaque materials therein.
Currently, dental filling materials are rendered radiopaque by incorporating barium into the inorganic powder moiety of the filling material. The most effective radiopaque agents are elements of high atomic number (i.e. the "heavy elements" of the periodic table); it is unfortunate, however, that most of these elements are either radioactive or toxic, such as thorium or lead.
earium is toxic also, but in certain medical uses it is present in a for~ 50 highly insoluble that the body is unable to metabolize enough of it to beco~ne intoxicated.
In dental applications barium glasses have been used as components of dental restorations, on the hypothesis that barium ions within the structure of a glassy matrix will not be available to oral fluids (saliva, bevPrages, etc.) and will not, therefore, pose a problem of toxicity.
Examples of the use of barium glass in dental restorations can be found in U.S. Patents 3,801,344; 3,808,170; 3,826,778;
3,911~581; 3,959,212, 3,975,203 and 4,032,504. Unfor-tunately, in practice, the barium glasses are not as stable as had originally been hoped, and they have not, therefore, found favor in the art on account of the risk they pose of poisoning the patient (see, e.g. U.S. Patent 3,971,754). A further problem encountered with the barium glasses is that of matching refractive indices to that of the other components of the restoration. For example, it would be desirable to use components with refractive indices in the ranse of about 1.5 to 1.6 (so as to closely match the refractive index of commonly used organic binders) but most bar;um glasses with refract;ve indices in this range are unsuitable for dental use according to U.S. Patent 4,032,504 It is difficult, therefore, to prepare restorations containing barium glass which present an unobtrusive appearance when used for anterior surface repair. An additional problem of the barium glasses is their alkalinity. Typical1y, barium glasses show alkalin~ty values of pH 9 or greater, whereas a pH of 7 is preferred. Highly alkaline fillers appear to degrade the siloxane coating resulting from etching of the prepared tooth cavity and also cause rapid decomposition of any peroxide catalyst present in the dental restorative composition during storage.
Recent efforts in the field of dental restoration materials have resulted in the use of fillers other than barium-containing compounds as an X-ray detectable com-ponent. For example, U.S. Patent 3,971,754 describes the use of certain oxides or carbonates, particularly those of lanthanllm, s-trontium, tantalum and, less use~
~ully, hafnium. These sal-ts are mixed with glass-making componen-ts at the time the glass is made, ~ielding a lanthanum, strontium, tantalum or ha~nium glass ~hich possesses a measure o-f radiopdcity. U.S. Patents 3,973,972 and 4,017,454 describe glass ceramics which possess both a low coefficient of thermal expansion (an advantage in dental f;llings) and a useful degree of radiopacity, by virtue o~ a high content of rare earth elements, particularly lanthanum. The rare earth elements absorb ~ rays in the wavelength range of 0.2 -0.3A, a range commonly available from dental X-ray machines. However, the cost and problems with availabi-lity of these rare earth fillers make them ~enerally unsuitable for commercial use.
In another approach to preparing radiopaque composites for dental use, organic halide (e.g. an alkyl iodide) has been incorporated into plastic materials (e.g. acrylate polymers), from which molded articles are made (e.g. U.S. Patent 3,715,331). However, the articles molded from such compositions lack the strength of restorations made from glass or ceramic materials.
U.S. Patent 4,250,277 describes a glass composition used for crosslinking polycarboxylic acid cement, wherein the glass contains zino oxide and a large amount of boric oxide, in addition to other ingred;ents. This glass, however, is too water soluble to be useful in dental restorative compositions and prosthetic devices.
U.S. Patent 4,215,033 dPscribes a composite dental material containing a glass which in one embodiment is described as single phase. ~lowever, this patent does not appear to recognize that a single phase glass containing zinc oxide can be made radiopaque. Also, the single phase glass composition described in this patent is very difficult to make. Furthermore, such glass does not contain any aluminum fluoride.
-S-Disclosure of Invention _____ In accordance with the present in~/ention there is provided a novel glass and a dental -~illing cornposition co~nprising a polymerizable resin binder and a finely divided inorganic glass fi'ller which is X-ray opaque and single phase, wherein said X-ray opaque inorganic glass fi'ller consists essentially of, in percent by weight:
Zinc oxide 20 to 35%
Silica 45 ~o 65%
Boric oxide 3 to 15%
Aluminum oxide 0 to 10%
Aluminum fluorideAt least 2 Alkali metal oxide 0 to 3%
or alkaline earth meta'l oxlde wherein the combined weight of aluminum oxide and aluminum fluoride is at least about 10%, and wherein said glass exhibits an "X-ray absorption characteristic" of at least 1/16 inch (0.16 cm) Best Mode for Carr~in~_O t the Invention It has been discovered that glasses containing high levels of zinc can be prepared which possess physical characteristics (e.g. refractive index, pH, coefficient of expansion) making them especially suitable for use in dentalrestorative compositions. Moreover, these glasses have been found to be radiopaque and to be capable of being made into dental composites which have greater radiopacity than those made with harium, the best known radiopacifying agent used heretofore. This is quite surprising, considering barium has an atomic number of 56, iodine an atomic number of 53, the s~
lanthanides having atomic numbers of 57 to 71, and zinc having an ~tomic number o-f only 30. Moreover, it has been found possible to make the n~w zinc glasses with refractive indices in the desired range -For dental restorative compositions. In addition, the new glasses can be prepared at a pH close to 7. This ls a highly desirable feature ln regard to the preparation of high quality dental composltes. In particular, when the glass is near neutral in p~l (i.e. ~.5 to 8), the stabi-lity of the dental composite is significantly enhanced.Improved color stability, and reliable setting charac-teristics after the activated ~mposite is emplaced in the tooth being repaired. The new glasses are signi-ficantly better than the barium ~lasses of the prior art in this regard.
It is believed that the problems encountered with the barium glasses are contributed to by the relatlve alkalinity of these materials. ~arium is an alkaline earth element in the periodic system, and, therefore, more electropositive than zinc, which is a transition element. The higher p~s characteristic of the barium glasses cause decomposition of the peroxide catalysts normally used in these formulations and thus greatly reduce storage stability. A significant advantage of the new glasses, which is an improvement over any known heretofore, is that they contain an element, namely, zinc, that has been in regular dental use for many yea,s.
Zinc oxide-containing ointments have long been used in medicine as safe and mild antibacterial agents and zinc oxide has long been used as a component in dental cements or adhesives. These latter agents are used for cementing prostheses, onlays, bridges, crowns, and the like, to the teeth. In this use they have proved safe and effective over many years. In other words, zinc compounds have a long history of being safe to use in the oral cavity, and are thus vastly preferable to use compared with those of un~nown safety or known toxicity, such as compounds of barium.
The new single phase glasses used in this inYentior have the following composition in percent by weight:
Zinc oxide (ZnO~ 20 to 35~
Silica (SiO2) 45 to 65%
Boric oxide(Bz03) 3 to 15%
Aluminum oxide(A1203) 0 to 10%
Aluminum fluoride(AlF3) At least 2%
Alkali meta'l oxide O to 3 or alkaline earth metal oxide wherein the combined weight of aluminum oxide and aluminum fluoride is at least about 10%, and wherein the glass exhibits an "X^ray absorption characteristic"
15 of at least 1/16 inch (0.16 cm). The alkali metal oxide or alkaline earth metal oxide may be, for example, sodium oxide, potassium oxide, lithium Gxide, calcium oxide, magnesium oxide, or the like, or combinations thereof, so long as the combined weight of such oxides does not exceed about 3% of the glass, thus maintaining the pH
of the glass in the desired range o~ about 6 5 to 8 Of course, as will be recognized by those skilled in the art, various other ingredients may also be present in minor amounts so long as the resulting glass exhibits the desired X-ray opacity and the desired pH. However~ it is highly preferred to avoid the inclusion of toxic metals such as lead, cadmium~ mercury, arsenic, etc.
A preferred embodiment of the new glass for use in dental restoratiYes intended for anterior appli-cations has the following composition:
Zinc oxide 25 to 28%
Silica 46 to 48%
Boric oxide 6 to 9%
Aluminum oxide 1 to 3%
Aluminum fluor~de17 to 19%
-B-wherein the combined weight of aluminum oxide and alllminum fluoride is not greater than about 20%, and wherein the glass exhibits an X-ray absorption characteristic of at least 3/32 inch (0.24 cm).
The compositions given above are ~ritten ir, terms of the salts (e.g. oxides and fluorides) whlch are used in preparing the Melt from which the glass is obtained upon cooling. This is a common practice in the glass-making art. There is, of course, no oxide, fluoride, or other simple salt in the resultant glass. Glasses used in this invention all possess a useful degree of radiopacity.
The refractive index oF the glasâ may be varied, depending upon the particular amount of each ingredient present. It is preferred that the refractive index of the glass Filler be substantially the same as that of the binder resin when the glass is used in a dental filling composition, i.e. within about 0.05, when the composition is used in anterior applications. When the binder resin comprises the well known BIS-GMA, the refractive index for the glass filler is preferably 1.556 ~ 0.05.
Matching of the refractiYe indices of the glass filler and the binder resin is less important when the composi-tion is intended for posterior dental applications.
When BIS-GMA resin is diluted with another acrylic resin (e.gO triethyleneglycol dimethacrylate) to facilitate higher filler loadings to make a composition having particular use for posterior filling applications, the resultant resin mixture may have a refractive index of 1.545, for example. Conse~uently, for such an application it may be preferred to use a glass composi-tion having a refractive index of 1.545 if close matching of the resin and filler is desired. When it is desired to preparP a dental filling composition which is light curable it is important to obtain a close match of the refractive indices of the polymerizable resin and the ~ ~racO~ a~k ylass Filler so that complete and rapid cure of the resin will be achieved ~/hen jt is exposed to the activating light Of course, when the cornposition is intended for use elsewhere in the body (i.e. where esthetics are not a factor) and where the composition is not 1ight curable, there is no need to attempt matching the refractive index of the glass to the refractive index of the binder resin.
Radiopacity, which reflects the materia1s's ability to attenuate X-rays, is conveniently measured by com-paring the X-ray film image density values of a disc of the cured composite of a standard thickness, e.3. 0.040 inch (0.1 cm), with corresponding values of a known standard.
Film image density measurements are made with a suitable densitometer, such as a Macbeth Transmission Densito-meter, Model TD 504, with visible light filter (manu-factured by Macbeth Div. of Kollmorgan Corp., ~lewburgh, N.Y.) A convenient standard is a stepped aluminurn wedge, for e~a~ple, a ten step wedge having a thickness of 1/32 inch (0.08 cm) at the thinnest step increasing to 5/16 inch (0.8 cm) at the thickest step. One empirically determines the X-ray film image density values corresponding to steps on the wedge, which indicate degrees of X-ray beam attenuation which provide, in actual practice, proper differentia-tion between a composite restoration and the surrounding tooth structure. A proper level of radiopacity wil1 permit one skilled in the art to differentiate between the restoration and primary and recurrent caries in the tooth structure, and will also ~/isualize defects in the restoration itself. By way of illustration, using a wedge, the glasses of this invention when tested in this manner give values ofl/16 inch (0.16 cm) at 26% ZnO; 3/32 - l/8 inch (0.24 - 0.32 cm) at 26.5 - 28% ZnO, Typical barium glasses of the prior art, tested under identical conditions give values ofl/16 - 3/32 inch (0.16 - 0.24 cm). The typical "plastic" or "porcelain" filling materials (containing quartz or borosilicate filler) common in contemporary dental practive give va1ues of zero. A silver amalgam gives a values of~ 5/16 inch (0.~ cm). It will be understood, of course, that these values are completely empirical. Using different wedges and experimental apparatus, the actual numbers one gets may be djfferent. For the purposes of this invention, useful glasses exhibit an X-ray absorption characteristic of at least 1/16 inch (0.16 cm).
Inso~ar as the preparation o~ the zinc glass is concerned, standard techn~ques well-known in the glass-making art are used. See, for example, The Handbook ofGlass Manufacture, Fay and Tooley, Volume I (1974).
After the mel-t has cooled, the glass is cornmlnuted to a size that passes through a 325-mesh standard sieve (~
microns). For grinding the glass into smaller sizes a ball mill is used, and grinding aids such as ammonium carbonate or alcohols may be present in an amount of approximately 0.5% based on the weight of the glass.
When making dental composite restorative, the glass powder is then prepared for incorporating into an organic binder matrix by treating the surface with a silane com-pound. This is a well-known technique for rendering re-latively polar materials, such as siliceous po~ders, more compatible with relatively non-polar materials, such as organic polymers.
The zinc glass is then mixed into a dental paste.
The paste may be formed of any of the polymerizable resin systems useful in dentistry. Especially useful resin systems comprise free-radically pol~merizable materials such as the polyfunGtional acrylate systems.
Particularly useful in the system is BIS-GMA, a well-known material which is the reaction product of bisphenol-A and glycidyl methacrylate, widely used in dentistry.
Other commonly used resin binders include polyurethanes, methyl methacrylate, and isobutyl methacrylate.
3~ The zinc glass may be used alone or it may be blended with other suitable materials, such as inert glass powders, ~hen mixed into the binder - depending, for example, on the degree o~ radiopacity desired in the final composite. Along with the glass, other ma-ter;als may also be mixed into the paste, such as pigments for making the restoration match the pat;ent's natural tooth color, and reagents like hydroquinone monomèthyl ether, as an inhibitor of premature poly-merization of the binder. Immediately before use, and after the dentist has preparecl the tooth for receiving the restoration, the paste is activated by mixing into it the appropriate amount of catalyst, such as benzoyl peroxide. For example, the dental restorative composi-tion may be in the form of two pastes (one paste con-taining filler, resin binder and catalyst while the other contains filler, resin binder and accelerator), or a liquid resin and powdered filler system, or a paste-liquid resin, or any other desired form. The mixed composition is promptly emplaced in the tooth, harden-ing in the manner characteristic of the resin binder and catalyst system being used. For example, using the well-known BIS-GMA/benzoyl peroxide system, the composite becomes grossly rigid in about 5 minutes and may be finely ground and polished, to give the finished restora-tion, in about 10 minutes. At any time after emplace-ment, but more particularly after significant time has elapsed, such as many months or years afterwards, the condition of the restoration and the adjacent tooth structures can be determined by diagnostic dental X-rays.
Curable com,oositions which contain the no~el glass and which are useful in other applications (e.g. medical and dental prosthPses, pit and fissure sealants, hard tissue cements) may be prepared in similar fashion using polymerizable resin binders.
The invention is further illustrated by means of the following representative examples wherein the term "parts" rPfers to parts by weight unless otherwise indicated.
1 ~
Example 1 Silica (47 gms), zinc oxide (26 gms)j boric oxide (8 gms), aluminum oxide (1 grr.) and aluminum fluoride (18 gms) are thoroughly mixed, as fine powders, in a silica-lined crucible. The mixture is heated in a muffle furnace at 1450F, (788C.) until the powder has become a trans-parent melt.
The molten glass is then removed from the crucible through a small hole in the crucible wall, by tilting the crucible and allowing a thin stream of glass to flow through, giving a filament of glass of aboutl/32 inch (0.08 cm) diameter. This filament is quenched rapidly in cold water, to give a completely clear glass (as opposed to being opalescent). Mere air cooling of the glass is not sufficiently rapid to prevent phase separation.
The clear glass is then ground, e.g. in a ball mill, to a mean particle size range of 0.5 - 15 ~m.
~e~
Gamma-methacryloxy-propyltrimethoxy silane (2 gms) is mixed with glacial acetic acid (0.033 gms) and water (44.4 gms) in a plastic beaker. Glass powder (100 gms for example, from Example 1) is added to the mixture, and the system is stirred for 1.5 hours at room tempera-ture. The glass slurry i5 dried by warming it at 140F.
(60 C.) for 24 hours, followed by heating it in an oven for 2.5 hours at 240F. (115 C.~.
Example_3 Two pastes, A and Bj are prepared, having the following compositions:
30 Ingredient Paste A P_ste_B
BIS-GMA resin 14.48 gm 14.67 gm Triethylene glycol dimethacrylates 4.67 4.63 Silane-treated filler 80.0 80.0 (from Example 2) 35 Benzoyl peroxide - - - - .21 Dihydroxyethyl p-toluidine .46 .b Ingredient Paste A Paste B
"Tinuvir, P"~ a UV absorber .16 Phenylsalicylate glycidyl .14 .16 methacrylate adduct, a UV
absorber Butylated hydroxytoluene - - - - .16 Bisphenol A - - - - .14 Pigments-titanium dioxide and .17 .17 iron oxides - yellow raw sienna, burnt umber), ottalume TOTAL 100.00 gm 100.00 gm The pastes are prepared as follows:
For each paste, A and B, two preliminary mixes are made. The glass ~from Example 2) and the pigments are mixed thoroughly to give an evenly colored powder. This mix is the same for each paste. The resins, accelerator3 UV absorbers and inhibitor are mixed to give the mix for paste A. The resins, catalyst, UV absorber, and inhibitor are mixed to give the mix for paste 8. After the two mixes, glass and resin based respectively~ have been prepared, the procedure for preparing each paste, A and B, is the same.
Each resin mix is added to a vessel and then the respective glass mix is added. The two mixes are first roughly blended together, such as by shaking, and are then thoroughly mixed preferably by prolonged mechanical mixing.
The resultant homogeneous pastes, A and B, are the precursors to the dental restorations made from the materials of this invention. Pastes A and B are kept separate until immediately before the appropriate repair is made in a tooth which has been prepared to receive it.
They are then mixed together thoroughly and promptly emplaced in the manner well-known in dental art.
tra cl~ k -14~
xam~le 4 Using the procedure of Example 3, two pastes, A and B, are prepared having the following comyositions:
Ingredient Paste A Paste B
. .
Dlacetyl BIS-GMA resin* 19.20 gm 19.57 gm Silane treated filler 80.0 80.0 (from Example 2) Benzoyl peroxide ~ .24 Dihydroxyethyl p-toluidine .47 "Tinuvin P" - a UV absorber .16 - - - -Butylated hydroxytoluene - - - - .02 Pigments - titanium dioxide and ,17 .17 iron oxides (yellow, raw sienna, burnt umber), ottalume TOTAL lOO.OO gm lOO.OO gm * CH3 Iq CH3 Iq CH3
I
Descri ~tion Zinc-Containing G1ass Composition Technical Field This invention relates to zinc-containing glass compositions and to dental filling compositions containing such ylass composition in the form o~ -finely divided ~iller.
Background Art A variety of substances has been used over the years to repair damaged teeth. The best known currently include silver amalgams, which are frequently first encountered at an early age as a filling for small cavities, even in deciduous teeth. Gold alloys are a particularly valuable filling material, used frequently when a tooth has been considerably damaged, such as after several cavitjes have occurred and a lot of tooth must be restored. Fre-quently, for example, several smaller extending cavities, e.g. in the occlusal surface, will be combined and a restoration made with a single gold inlay or onlay. The gold alloys have gained an excellent reputation for strength, reliability and long life in service. However, both the gold alloys, and the other metals, such as the stainless steels, which have been technically successful in dental reconstructions and crowns, do not impart a natural tooth appearance.
Gold and other metallic-looking restorations are used for molars and teeth which are not immediately open to view when the wearer opens his mouth or smiles. For anterior teeth, however, current practice is to use 3G materials closer in appearance to natural teeth. These are known colloqu~ally as porcelain or plastic fillings.
They are composite rnaterials characterized by containing usually predominantly inorganic materials, normally finely divided powders, inert to the oral environment, bound together with polymeric material. The inorganic materials are frequen-tly ~inely-ground fused oxides, particular1y glasses, or crystalline quartz, while the polymer moiety ls commonly a polyacrylate. These compo-site systems are available~ for example, as pastes whichare polymerized in situ, after having been activated, e.g.
by add;ng a catalyst to initiate a polymerization reaction, just before being placed in the prepared tooth.
Fillings and restorations of thls kind can be made to look much like natural teeth. In particular, the color of the restoration can be adjusted to a shade quite close to that of a patient's natural teeth by tinting wlth pigments. In addition, the translucency or pearlescence of the natural tooth can also be approximated through adjustment of the relative refractive indices of the materials used in the restoration. When color and re-fractive indices are well matched, it is possible to obtain a restoration that is barely perceptible to the glance.
However, the attainment of good color and overall appearance is very difficult to achieve in practice. This is particularly true when one desires also to optimize other features of a good restoration, particularly radiopacity.
It is highly desirable for a filling or other re-storation to be radiopaque, for it is by X-ray examination that a dent~st determines whether or not d filling remains sound. From radiographs a dentist determines the condi-tion of a filling, e.g. whether it has cracked, or whether decay is occurring at the intertace between the tooth and the filling. Fillings and restorations which are made of metal are readily observable in X-rays. Fillings of the porcelain/plastic art are not observable by X-rays unless they have radiopaque materials therein.
Currently, dental filling materials are rendered radiopaque by incorporating barium into the inorganic powder moiety of the filling material. The most effective radiopaque agents are elements of high atomic number (i.e. the "heavy elements" of the periodic table); it is unfortunate, however, that most of these elements are either radioactive or toxic, such as thorium or lead.
earium is toxic also, but in certain medical uses it is present in a for~ 50 highly insoluble that the body is unable to metabolize enough of it to beco~ne intoxicated.
In dental applications barium glasses have been used as components of dental restorations, on the hypothesis that barium ions within the structure of a glassy matrix will not be available to oral fluids (saliva, bevPrages, etc.) and will not, therefore, pose a problem of toxicity.
Examples of the use of barium glass in dental restorations can be found in U.S. Patents 3,801,344; 3,808,170; 3,826,778;
3,911~581; 3,959,212, 3,975,203 and 4,032,504. Unfor-tunately, in practice, the barium glasses are not as stable as had originally been hoped, and they have not, therefore, found favor in the art on account of the risk they pose of poisoning the patient (see, e.g. U.S. Patent 3,971,754). A further problem encountered with the barium glasses is that of matching refractive indices to that of the other components of the restoration. For example, it would be desirable to use components with refractive indices in the ranse of about 1.5 to 1.6 (so as to closely match the refractive index of commonly used organic binders) but most bar;um glasses with refract;ve indices in this range are unsuitable for dental use according to U.S. Patent 4,032,504 It is difficult, therefore, to prepare restorations containing barium glass which present an unobtrusive appearance when used for anterior surface repair. An additional problem of the barium glasses is their alkalinity. Typical1y, barium glasses show alkalin~ty values of pH 9 or greater, whereas a pH of 7 is preferred. Highly alkaline fillers appear to degrade the siloxane coating resulting from etching of the prepared tooth cavity and also cause rapid decomposition of any peroxide catalyst present in the dental restorative composition during storage.
Recent efforts in the field of dental restoration materials have resulted in the use of fillers other than barium-containing compounds as an X-ray detectable com-ponent. For example, U.S. Patent 3,971,754 describes the use of certain oxides or carbonates, particularly those of lanthanllm, s-trontium, tantalum and, less use~
~ully, hafnium. These sal-ts are mixed with glass-making componen-ts at the time the glass is made, ~ielding a lanthanum, strontium, tantalum or ha~nium glass ~hich possesses a measure o-f radiopdcity. U.S. Patents 3,973,972 and 4,017,454 describe glass ceramics which possess both a low coefficient of thermal expansion (an advantage in dental f;llings) and a useful degree of radiopacity, by virtue o~ a high content of rare earth elements, particularly lanthanum. The rare earth elements absorb ~ rays in the wavelength range of 0.2 -0.3A, a range commonly available from dental X-ray machines. However, the cost and problems with availabi-lity of these rare earth fillers make them ~enerally unsuitable for commercial use.
In another approach to preparing radiopaque composites for dental use, organic halide (e.g. an alkyl iodide) has been incorporated into plastic materials (e.g. acrylate polymers), from which molded articles are made (e.g. U.S. Patent 3,715,331). However, the articles molded from such compositions lack the strength of restorations made from glass or ceramic materials.
U.S. Patent 4,250,277 describes a glass composition used for crosslinking polycarboxylic acid cement, wherein the glass contains zino oxide and a large amount of boric oxide, in addition to other ingred;ents. This glass, however, is too water soluble to be useful in dental restorative compositions and prosthetic devices.
U.S. Patent 4,215,033 dPscribes a composite dental material containing a glass which in one embodiment is described as single phase. ~lowever, this patent does not appear to recognize that a single phase glass containing zinc oxide can be made radiopaque. Also, the single phase glass composition described in this patent is very difficult to make. Furthermore, such glass does not contain any aluminum fluoride.
-S-Disclosure of Invention _____ In accordance with the present in~/ention there is provided a novel glass and a dental -~illing cornposition co~nprising a polymerizable resin binder and a finely divided inorganic glass fi'ller which is X-ray opaque and single phase, wherein said X-ray opaque inorganic glass fi'ller consists essentially of, in percent by weight:
Zinc oxide 20 to 35%
Silica 45 ~o 65%
Boric oxide 3 to 15%
Aluminum oxide 0 to 10%
Aluminum fluorideAt least 2 Alkali metal oxide 0 to 3%
or alkaline earth meta'l oxlde wherein the combined weight of aluminum oxide and aluminum fluoride is at least about 10%, and wherein said glass exhibits an "X-ray absorption characteristic" of at least 1/16 inch (0.16 cm) Best Mode for Carr~in~_O t the Invention It has been discovered that glasses containing high levels of zinc can be prepared which possess physical characteristics (e.g. refractive index, pH, coefficient of expansion) making them especially suitable for use in dentalrestorative compositions. Moreover, these glasses have been found to be radiopaque and to be capable of being made into dental composites which have greater radiopacity than those made with harium, the best known radiopacifying agent used heretofore. This is quite surprising, considering barium has an atomic number of 56, iodine an atomic number of 53, the s~
lanthanides having atomic numbers of 57 to 71, and zinc having an ~tomic number o-f only 30. Moreover, it has been found possible to make the n~w zinc glasses with refractive indices in the desired range -For dental restorative compositions. In addition, the new glasses can be prepared at a pH close to 7. This ls a highly desirable feature ln regard to the preparation of high quality dental composltes. In particular, when the glass is near neutral in p~l (i.e. ~.5 to 8), the stabi-lity of the dental composite is significantly enhanced.Improved color stability, and reliable setting charac-teristics after the activated ~mposite is emplaced in the tooth being repaired. The new glasses are signi-ficantly better than the barium ~lasses of the prior art in this regard.
It is believed that the problems encountered with the barium glasses are contributed to by the relatlve alkalinity of these materials. ~arium is an alkaline earth element in the periodic system, and, therefore, more electropositive than zinc, which is a transition element. The higher p~s characteristic of the barium glasses cause decomposition of the peroxide catalysts normally used in these formulations and thus greatly reduce storage stability. A significant advantage of the new glasses, which is an improvement over any known heretofore, is that they contain an element, namely, zinc, that has been in regular dental use for many yea,s.
Zinc oxide-containing ointments have long been used in medicine as safe and mild antibacterial agents and zinc oxide has long been used as a component in dental cements or adhesives. These latter agents are used for cementing prostheses, onlays, bridges, crowns, and the like, to the teeth. In this use they have proved safe and effective over many years. In other words, zinc compounds have a long history of being safe to use in the oral cavity, and are thus vastly preferable to use compared with those of un~nown safety or known toxicity, such as compounds of barium.
The new single phase glasses used in this inYentior have the following composition in percent by weight:
Zinc oxide (ZnO~ 20 to 35~
Silica (SiO2) 45 to 65%
Boric oxide(Bz03) 3 to 15%
Aluminum oxide(A1203) 0 to 10%
Aluminum fluoride(AlF3) At least 2%
Alkali meta'l oxide O to 3 or alkaline earth metal oxide wherein the combined weight of aluminum oxide and aluminum fluoride is at least about 10%, and wherein the glass exhibits an "X^ray absorption characteristic"
15 of at least 1/16 inch (0.16 cm). The alkali metal oxide or alkaline earth metal oxide may be, for example, sodium oxide, potassium oxide, lithium Gxide, calcium oxide, magnesium oxide, or the like, or combinations thereof, so long as the combined weight of such oxides does not exceed about 3% of the glass, thus maintaining the pH
of the glass in the desired range o~ about 6 5 to 8 Of course, as will be recognized by those skilled in the art, various other ingredients may also be present in minor amounts so long as the resulting glass exhibits the desired X-ray opacity and the desired pH. However~ it is highly preferred to avoid the inclusion of toxic metals such as lead, cadmium~ mercury, arsenic, etc.
A preferred embodiment of the new glass for use in dental restoratiYes intended for anterior appli-cations has the following composition:
Zinc oxide 25 to 28%
Silica 46 to 48%
Boric oxide 6 to 9%
Aluminum oxide 1 to 3%
Aluminum fluor~de17 to 19%
-B-wherein the combined weight of aluminum oxide and alllminum fluoride is not greater than about 20%, and wherein the glass exhibits an X-ray absorption characteristic of at least 3/32 inch (0.24 cm).
The compositions given above are ~ritten ir, terms of the salts (e.g. oxides and fluorides) whlch are used in preparing the Melt from which the glass is obtained upon cooling. This is a common practice in the glass-making art. There is, of course, no oxide, fluoride, or other simple salt in the resultant glass. Glasses used in this invention all possess a useful degree of radiopacity.
The refractive index oF the glasâ may be varied, depending upon the particular amount of each ingredient present. It is preferred that the refractive index of the glass Filler be substantially the same as that of the binder resin when the glass is used in a dental filling composition, i.e. within about 0.05, when the composition is used in anterior applications. When the binder resin comprises the well known BIS-GMA, the refractive index for the glass filler is preferably 1.556 ~ 0.05.
Matching of the refractiYe indices of the glass filler and the binder resin is less important when the composi-tion is intended for posterior dental applications.
When BIS-GMA resin is diluted with another acrylic resin (e.gO triethyleneglycol dimethacrylate) to facilitate higher filler loadings to make a composition having particular use for posterior filling applications, the resultant resin mixture may have a refractive index of 1.545, for example. Conse~uently, for such an application it may be preferred to use a glass composi-tion having a refractive index of 1.545 if close matching of the resin and filler is desired. When it is desired to preparP a dental filling composition which is light curable it is important to obtain a close match of the refractive indices of the polymerizable resin and the ~ ~racO~ a~k ylass Filler so that complete and rapid cure of the resin will be achieved ~/hen jt is exposed to the activating light Of course, when the cornposition is intended for use elsewhere in the body (i.e. where esthetics are not a factor) and where the composition is not 1ight curable, there is no need to attempt matching the refractive index of the glass to the refractive index of the binder resin.
Radiopacity, which reflects the materia1s's ability to attenuate X-rays, is conveniently measured by com-paring the X-ray film image density values of a disc of the cured composite of a standard thickness, e.3. 0.040 inch (0.1 cm), with corresponding values of a known standard.
Film image density measurements are made with a suitable densitometer, such as a Macbeth Transmission Densito-meter, Model TD 504, with visible light filter (manu-factured by Macbeth Div. of Kollmorgan Corp., ~lewburgh, N.Y.) A convenient standard is a stepped aluminurn wedge, for e~a~ple, a ten step wedge having a thickness of 1/32 inch (0.08 cm) at the thinnest step increasing to 5/16 inch (0.8 cm) at the thickest step. One empirically determines the X-ray film image density values corresponding to steps on the wedge, which indicate degrees of X-ray beam attenuation which provide, in actual practice, proper differentia-tion between a composite restoration and the surrounding tooth structure. A proper level of radiopacity wil1 permit one skilled in the art to differentiate between the restoration and primary and recurrent caries in the tooth structure, and will also ~/isualize defects in the restoration itself. By way of illustration, using a wedge, the glasses of this invention when tested in this manner give values ofl/16 inch (0.16 cm) at 26% ZnO; 3/32 - l/8 inch (0.24 - 0.32 cm) at 26.5 - 28% ZnO, Typical barium glasses of the prior art, tested under identical conditions give values ofl/16 - 3/32 inch (0.16 - 0.24 cm). The typical "plastic" or "porcelain" filling materials (containing quartz or borosilicate filler) common in contemporary dental practive give va1ues of zero. A silver amalgam gives a values of~ 5/16 inch (0.~ cm). It will be understood, of course, that these values are completely empirical. Using different wedges and experimental apparatus, the actual numbers one gets may be djfferent. For the purposes of this invention, useful glasses exhibit an X-ray absorption characteristic of at least 1/16 inch (0.16 cm).
Inso~ar as the preparation o~ the zinc glass is concerned, standard techn~ques well-known in the glass-making art are used. See, for example, The Handbook ofGlass Manufacture, Fay and Tooley, Volume I (1974).
After the mel-t has cooled, the glass is cornmlnuted to a size that passes through a 325-mesh standard sieve (~
microns). For grinding the glass into smaller sizes a ball mill is used, and grinding aids such as ammonium carbonate or alcohols may be present in an amount of approximately 0.5% based on the weight of the glass.
When making dental composite restorative, the glass powder is then prepared for incorporating into an organic binder matrix by treating the surface with a silane com-pound. This is a well-known technique for rendering re-latively polar materials, such as siliceous po~ders, more compatible with relatively non-polar materials, such as organic polymers.
The zinc glass is then mixed into a dental paste.
The paste may be formed of any of the polymerizable resin systems useful in dentistry. Especially useful resin systems comprise free-radically pol~merizable materials such as the polyfunGtional acrylate systems.
Particularly useful in the system is BIS-GMA, a well-known material which is the reaction product of bisphenol-A and glycidyl methacrylate, widely used in dentistry.
Other commonly used resin binders include polyurethanes, methyl methacrylate, and isobutyl methacrylate.
3~ The zinc glass may be used alone or it may be blended with other suitable materials, such as inert glass powders, ~hen mixed into the binder - depending, for example, on the degree o~ radiopacity desired in the final composite. Along with the glass, other ma-ter;als may also be mixed into the paste, such as pigments for making the restoration match the pat;ent's natural tooth color, and reagents like hydroquinone monomèthyl ether, as an inhibitor of premature poly-merization of the binder. Immediately before use, and after the dentist has preparecl the tooth for receiving the restoration, the paste is activated by mixing into it the appropriate amount of catalyst, such as benzoyl peroxide. For example, the dental restorative composi-tion may be in the form of two pastes (one paste con-taining filler, resin binder and catalyst while the other contains filler, resin binder and accelerator), or a liquid resin and powdered filler system, or a paste-liquid resin, or any other desired form. The mixed composition is promptly emplaced in the tooth, harden-ing in the manner characteristic of the resin binder and catalyst system being used. For example, using the well-known BIS-GMA/benzoyl peroxide system, the composite becomes grossly rigid in about 5 minutes and may be finely ground and polished, to give the finished restora-tion, in about 10 minutes. At any time after emplace-ment, but more particularly after significant time has elapsed, such as many months or years afterwards, the condition of the restoration and the adjacent tooth structures can be determined by diagnostic dental X-rays.
Curable com,oositions which contain the no~el glass and which are useful in other applications (e.g. medical and dental prosthPses, pit and fissure sealants, hard tissue cements) may be prepared in similar fashion using polymerizable resin binders.
The invention is further illustrated by means of the following representative examples wherein the term "parts" rPfers to parts by weight unless otherwise indicated.
1 ~
Example 1 Silica (47 gms), zinc oxide (26 gms)j boric oxide (8 gms), aluminum oxide (1 grr.) and aluminum fluoride (18 gms) are thoroughly mixed, as fine powders, in a silica-lined crucible. The mixture is heated in a muffle furnace at 1450F, (788C.) until the powder has become a trans-parent melt.
The molten glass is then removed from the crucible through a small hole in the crucible wall, by tilting the crucible and allowing a thin stream of glass to flow through, giving a filament of glass of aboutl/32 inch (0.08 cm) diameter. This filament is quenched rapidly in cold water, to give a completely clear glass (as opposed to being opalescent). Mere air cooling of the glass is not sufficiently rapid to prevent phase separation.
The clear glass is then ground, e.g. in a ball mill, to a mean particle size range of 0.5 - 15 ~m.
~e~
Gamma-methacryloxy-propyltrimethoxy silane (2 gms) is mixed with glacial acetic acid (0.033 gms) and water (44.4 gms) in a plastic beaker. Glass powder (100 gms for example, from Example 1) is added to the mixture, and the system is stirred for 1.5 hours at room tempera-ture. The glass slurry i5 dried by warming it at 140F.
(60 C.) for 24 hours, followed by heating it in an oven for 2.5 hours at 240F. (115 C.~.
Example_3 Two pastes, A and Bj are prepared, having the following compositions:
30 Ingredient Paste A P_ste_B
BIS-GMA resin 14.48 gm 14.67 gm Triethylene glycol dimethacrylates 4.67 4.63 Silane-treated filler 80.0 80.0 (from Example 2) 35 Benzoyl peroxide - - - - .21 Dihydroxyethyl p-toluidine .46 .b Ingredient Paste A Paste B
"Tinuvir, P"~ a UV absorber .16 Phenylsalicylate glycidyl .14 .16 methacrylate adduct, a UV
absorber Butylated hydroxytoluene - - - - .16 Bisphenol A - - - - .14 Pigments-titanium dioxide and .17 .17 iron oxides - yellow raw sienna, burnt umber), ottalume TOTAL 100.00 gm 100.00 gm The pastes are prepared as follows:
For each paste, A and B, two preliminary mixes are made. The glass ~from Example 2) and the pigments are mixed thoroughly to give an evenly colored powder. This mix is the same for each paste. The resins, accelerator3 UV absorbers and inhibitor are mixed to give the mix for paste A. The resins, catalyst, UV absorber, and inhibitor are mixed to give the mix for paste 8. After the two mixes, glass and resin based respectively~ have been prepared, the procedure for preparing each paste, A and B, is the same.
Each resin mix is added to a vessel and then the respective glass mix is added. The two mixes are first roughly blended together, such as by shaking, and are then thoroughly mixed preferably by prolonged mechanical mixing.
The resultant homogeneous pastes, A and B, are the precursors to the dental restorations made from the materials of this invention. Pastes A and B are kept separate until immediately before the appropriate repair is made in a tooth which has been prepared to receive it.
They are then mixed together thoroughly and promptly emplaced in the manner well-known in dental art.
tra cl~ k -14~
xam~le 4 Using the procedure of Example 3, two pastes, A and B, are prepared having the following comyositions:
Ingredient Paste A Paste B
. .
Dlacetyl BIS-GMA resin* 19.20 gm 19.57 gm Silane treated filler 80.0 80.0 (from Example 2) Benzoyl peroxide ~ .24 Dihydroxyethyl p-toluidine .47 "Tinuvin P" - a UV absorber .16 - - - -Butylated hydroxytoluene - - - - .02 Pigments - titanium dioxide and ,17 .17 iron oxides (yellow, raw sienna, burnt umber), ottalume TOTAL lOO.OO gm lOO.OO gm * CH3 Iq CH3 Iq CH3
2 CH2C~ 2- ~ C-~ O-CH2CHCH20-C - C 3 CH
C-O C=O
The two pastes, when mixed together, form a very useful dental restorative composition.
Example 5 The glass filler of Example l was ball milled to a mean particle size of 4.5 microns and silane treated according to the method described in Example 2. A light-curable paste was prepared having the followin3 compo-sitions.
Ingredient Parts BIS-GMA resin 5.655 Triethylene glycol dimethacrylate 5.655 Triphenyl antimony .002 N,N-diethylaminoethyl methacrylate ,47 dl - camphoroquinone .048 Silane treated filler + 1.58~ by 88.0 weight "Aerosil R-972"
x~
Ingredient Parts Pigments - titanium dioxide, iron .17 oxides (yellow, raw sienna, burnt umber) and ottalume The paste is prepared as follows:
The mill~d and treated filler (from Example 2), Aerosil R-972 (colloidal silica, commercially available from DeGussa Corporation, average particle diameter of 16 millimicrons, surface area of llO square meters/
gram) and the pigments are blended to give an evenly co10red powder. The resins, inhibitor, accelerator and photoinitiator are mixed in a dark area in a ~essel excluding light. The filler blend is then added to the mixing vessel containing the resin mix. The ~iller, resins and other components are then thoroughly mixed by prolonged mechanical mixing, with the entire opera-tion carried out in the absence of light.
A commercially available "KULZER TRANSLUX" irra-diation device with a light guiding rod is used to cure the paste. Test samples are prepared by packing the paste into an open-ended Teflon mold with a cylindrical cavity. The loaded mold is then placed between 2 pieces of clear polyester film (each 25 microns thick). Test samples of prescribed thickness are then irradiated for a period of exposure necessary to polymerize or cure the resin in the paste. Barcol hardness measurements are made on the top and bottom of the test sample to determine the extent of polymerization. The following Barcol hardnesses are determined on cured test samples using two different sample thicknesses.
Hardness l Min Post Cure l Hr. Post Cure 2 mm sample thickness 81 - top side 91 - top side - 20 sec- exposure 64 - bottom side 82 - bottom side
C-O C=O
The two pastes, when mixed together, form a very useful dental restorative composition.
Example 5 The glass filler of Example l was ball milled to a mean particle size of 4.5 microns and silane treated according to the method described in Example 2. A light-curable paste was prepared having the followin3 compo-sitions.
Ingredient Parts BIS-GMA resin 5.655 Triethylene glycol dimethacrylate 5.655 Triphenyl antimony .002 N,N-diethylaminoethyl methacrylate ,47 dl - camphoroquinone .048 Silane treated filler + 1.58~ by 88.0 weight "Aerosil R-972"
x~
Ingredient Parts Pigments - titanium dioxide, iron .17 oxides (yellow, raw sienna, burnt umber) and ottalume The paste is prepared as follows:
The mill~d and treated filler (from Example 2), Aerosil R-972 (colloidal silica, commercially available from DeGussa Corporation, average particle diameter of 16 millimicrons, surface area of llO square meters/
gram) and the pigments are blended to give an evenly co10red powder. The resins, inhibitor, accelerator and photoinitiator are mixed in a dark area in a ~essel excluding light. The filler blend is then added to the mixing vessel containing the resin mix. The ~iller, resins and other components are then thoroughly mixed by prolonged mechanical mixing, with the entire opera-tion carried out in the absence of light.
A commercially available "KULZER TRANSLUX" irra-diation device with a light guiding rod is used to cure the paste. Test samples are prepared by packing the paste into an open-ended Teflon mold with a cylindrical cavity. The loaded mold is then placed between 2 pieces of clear polyester film (each 25 microns thick). Test samples of prescribed thickness are then irradiated for a period of exposure necessary to polymerize or cure the resin in the paste. Barcol hardness measurements are made on the top and bottom of the test sample to determine the extent of polymerization. The following Barcol hardnesses are determined on cured test samples using two different sample thicknesses.
Hardness l Min Post Cure l Hr. Post Cure 2 mm sample thickness 81 - top side 91 - top side - 20 sec- exposure 64 - bottom side 82 - bottom side
3 mm sample thickness 83 - top side 86 - top side - 20 sec. exposure 56 - bottom side 74 _ bottom side cle r~ a r1c Barcol hardness values in excess of 80 are considered outstanding. Standard, commercially available dental restorative composites typically haYe Barcol hardness values o-f 70 - 75 after 24 hours cure.
The filler loading levels of 88~ attained with the zinc glass must also be considered to be extraordinary.
Conventional radiopaque barium glass permits maximum filler loadings of 78 - 80% when using similar particle slze distributions.
Example 6 The glass filler of Example 1 was ball milled to a mean particle size of 1,8 microns and silane treated according to the method described in Example 2. A
light-curable paste having the following composition was prepared using the procedure of Example 5:
In~redient Parts BIS-GMA resin 7.09 Triethylene glycol dimethacrylate 7.09 Triphenyl antimony .003 N,N-diethylaminoethyl methacrylate .59 dl - camphoroquinone .059 Silane treated filler + 10% by weight 85.0 "OX-50" (colloidal silica com-mercially available from De&ussa Corporation, average particle diameter of 40 millimicrons, surface area of 50 square meters/gram) Pigments - titanium dioxide, iron .168 oxides (yellow, raw sienna, burnt umber) and ottalume TOTAL 100.00 Barcol hardnesses were determined on 2 mm thick test samples of composition cured at two different exposure times:
Hard_ess 1 Min. Post Cure 1 Hr. Post Cure 20 sec. exposure 83 - top side 2~ - bottom side 30 sec. exposure 83 - top side 84 - top side 54 - bottom side 75 - bottom side _xample _ The glass filler of Example 1 was ball milled to a mean particle size of 4.5 - 5.0 microns. Radiopaque impression pastes, containing the ingredients listed below, were prepared by mixing the ingredients in a con-ventional Ross brand mixer:
Ingredient Paste A Paste B
Low molecular weight vinyl 2000 grarns 1800 grams siloxane polymer (2300 cps) Filler of Example 1 1700 grams 1700 grams (not silane treated) Chloroplatinic acid 4.2 grams - - -(catalyst) Hydrogen polysiloxane - - - 70 grams The concentration of the filler may be varied, as desired, to produce compositions having various viscosities.
Compositions contain;ng 30 - 40% filler are of low viscosity, while composition 5 containing 80 - 90~ filler have a putty consistency.
The filler loading levels of 88~ attained with the zinc glass must also be considered to be extraordinary.
Conventional radiopaque barium glass permits maximum filler loadings of 78 - 80% when using similar particle slze distributions.
Example 6 The glass filler of Example 1 was ball milled to a mean particle size of 1,8 microns and silane treated according to the method described in Example 2. A
light-curable paste having the following composition was prepared using the procedure of Example 5:
In~redient Parts BIS-GMA resin 7.09 Triethylene glycol dimethacrylate 7.09 Triphenyl antimony .003 N,N-diethylaminoethyl methacrylate .59 dl - camphoroquinone .059 Silane treated filler + 10% by weight 85.0 "OX-50" (colloidal silica com-mercially available from De&ussa Corporation, average particle diameter of 40 millimicrons, surface area of 50 square meters/gram) Pigments - titanium dioxide, iron .168 oxides (yellow, raw sienna, burnt umber) and ottalume TOTAL 100.00 Barcol hardnesses were determined on 2 mm thick test samples of composition cured at two different exposure times:
Hard_ess 1 Min. Post Cure 1 Hr. Post Cure 20 sec. exposure 83 - top side 2~ - bottom side 30 sec. exposure 83 - top side 84 - top side 54 - bottom side 75 - bottom side _xample _ The glass filler of Example 1 was ball milled to a mean particle size of 4.5 - 5.0 microns. Radiopaque impression pastes, containing the ingredients listed below, were prepared by mixing the ingredients in a con-ventional Ross brand mixer:
Ingredient Paste A Paste B
Low molecular weight vinyl 2000 grarns 1800 grams siloxane polymer (2300 cps) Filler of Example 1 1700 grams 1700 grams (not silane treated) Chloroplatinic acid 4.2 grams - - -(catalyst) Hydrogen polysiloxane - - - 70 grams The concentration of the filler may be varied, as desired, to produce compositions having various viscosities.
Compositions contain;ng 30 - 40% filler are of low viscosity, while composition 5 containing 80 - 90~ filler have a putty consistency.
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A single phase glass composition consisting essentially of, in percent by weight:
Zinc oxide 20 to 35%
Silica 45 -to 65%
Boric oxide 3 to 15%
Aluminum oxide 0 to 10%
Aluminum fluoride At least 2%
Alkali metal oxide or 0 to 5%
alkaline earth metal oxide wherein the combined weight of aluminum oxide and aluminum fluoride is a-t least about 10% and wherein said glass exhibits an "X-ray absorption characteristic"
of at least l/16 inch (0.16 cm).
Zinc oxide 20 to 35%
Silica 45 -to 65%
Boric oxide 3 to 15%
Aluminum oxide 0 to 10%
Aluminum fluoride At least 2%
Alkali metal oxide or 0 to 5%
alkaline earth metal oxide wherein the combined weight of aluminum oxide and aluminum fluoride is a-t least about 10% and wherein said glass exhibits an "X-ray absorption characteristic"
of at least l/16 inch (0.16 cm).
2. A dental filling composition comprising a polymerizable resin binder and a finely divided inorganic glass filler which is X-ray opaque and single phase, wherein said glass filler has the composition of claim l.
3. A composition in accordance with claim 2, wherein said binder com-prises a free-radically polymerizable resin.
4. A composition in accordance with claim 3, wherein said polymerizable resin binder comprises BIS-GMA.
5. A composition in accordance with claim 2, wherein the index of refrac-tion of said glass filler and said resin are substantially the same.
6. A composition in accordance with claim 2, wherein said composition is in the form of two pastes, the first said paste comprising polymerizable resin binder, inorganic glass filler, and a catalyst.
and the second said paste comprising polymerizable resin binder, inorganic glass filler, and an accelerator.
and the second said paste comprising polymerizable resin binder, inorganic glass filler, and an accelerator.
7. A composition in accordance with claim 6, wherein said filler represents at least about 70% by weight of each said paste.
8. A composition in accordance with claim 6, wherein said binder in each said paste comprises BIS-GMA.
9. A composition in accordance with claim 4, wherein said glass filler consists essentially of, in percent by weight:
Zinc oxide 25 to 28%
Silica 46 to 48%
Boric oxide 6 to 9%
Aluminum oxide 1 to 3%
Aluminum fluoride 17 to 19%
wherein the combined weight of aluminum oxide and aluminum fluoride is not greater than about 20%.
Zinc oxide 25 to 28%
Silica 46 to 48%
Boric oxide 6 to 9%
Aluminum oxide 1 to 3%
Aluminum fluoride 17 to 19%
wherein the combined weight of aluminum oxide and aluminum fluoride is not greater than about 20%.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US18491680A | 1980-09-08 | 1980-09-08 | |
| US184,916 | 1994-01-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1157892A true CA1157892A (en) | 1983-11-29 |
Family
ID=22678845
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000385221A Expired CA1157892A (en) | 1980-09-08 | 1981-09-04 | Zinc-containing glass composition |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0059194A4 (en) |
| JP (1) | JPS57501376A (en) |
| AU (1) | AU550056B2 (en) |
| CA (1) | CA1157892A (en) |
| IT (1) | IT1142743B (en) |
| WO (1) | WO1982000827A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4503169A (en) * | 1984-04-19 | 1985-03-05 | Minnesota Mining And Manufacturing Company | Radiopaque, low visual opacity dental composites containing non-vitreous microparticles |
| GB2264711A (en) * | 1992-03-06 | 1993-09-08 | British Tech Group | Glass-polyalkenoate cements |
| PL3218317T3 (en) | 2014-11-13 | 2019-03-29 | Gerresheimer Glas Gmbh | Glass forming machine particle filter, a plunger unit, a blow head, a blow head support and a glass forming machine adapted to or comprising said filter |
| FR3116823B1 (en) * | 2020-11-30 | 2023-03-24 | Commissariat Energie Atomique | Thermal insulation coating based on a PREceramic Polymer to improve the performance of heat engines |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3826778A (en) * | 1970-02-17 | 1974-07-30 | Owens Illinois Inc | Tooth filling and facing compositions comprising a radiopaque glass and method of making the same |
| US3911581A (en) * | 1970-02-17 | 1975-10-14 | Owens Illinois Inc | Tooth filling and facing composition comprising a radiopaque glass and method of using the same |
| US3715331A (en) * | 1970-05-01 | 1973-02-06 | Coe Labor | Monomer soluble x-ray opaque methacrylate particles |
| US3882080A (en) * | 1971-01-15 | 1975-05-06 | Espe Pharm Praep | Self-hardening compound, particularly for dental-medical application |
| US4028325A (en) * | 1972-08-09 | 1977-06-07 | King Alan G | Composite dental material and method of preparing same |
| GB1450157A (en) * | 1973-03-06 | 1976-09-22 | Colgate Palmolive Co | Dental powder cement and filling material |
| US4017454A (en) * | 1973-09-21 | 1977-04-12 | Jenaer Glaswerk Schott & Gen. | Glass ceramic as filler in polymerizable dental filling compositions |
| AT339523B (en) * | 1973-09-21 | 1977-10-25 | Jenaer Glaswerk Schott & Gen | CERAMIC GLASS FOR FULL DENTALS |
| US3971754A (en) * | 1973-12-10 | 1976-07-27 | Pennwalt Corporation | X-ray opaque, enamel-matching dental filling composition |
| US4050947A (en) * | 1976-03-17 | 1977-09-27 | Bullseye Glass Co. | Process for opalizing glass |
| US4215033A (en) * | 1978-09-08 | 1980-07-29 | American Dental Association Health Foundation | Composite dental material |
| US4250277A (en) * | 1980-01-07 | 1981-02-10 | International Standard Electric Corporation | Glass composition for water setting ion-polymer cements |
-
1981
- 1981-08-18 WO PCT/US1981/001104 patent/WO1982000827A1/en not_active Application Discontinuation
- 1981-08-18 AU AU75348/81A patent/AU550056B2/en not_active Ceased
- 1981-08-18 JP JP56502852A patent/JPS57501376A/ja active Pending
- 1981-08-18 EP EP19810902360 patent/EP0059194A4/en not_active Ceased
- 1981-09-04 CA CA000385221A patent/CA1157892A/en not_active Expired
- 1981-09-07 IT IT49244/81A patent/IT1142743B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| IT1142743B (en) | 1986-10-15 |
| IT8149244A0 (en) | 1981-09-07 |
| AU7534881A (en) | 1982-04-05 |
| EP0059194A1 (en) | 1982-09-08 |
| AU550056B2 (en) | 1986-02-27 |
| JPS57501376A (en) | 1982-08-05 |
| WO1982000827A1 (en) | 1982-03-18 |
| EP0059194A4 (en) | 1984-03-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| USRE32073E (en) | Dental filling composition utilizing zinc-containing inorganic filler | |
| US4358549A (en) | Dental filling composition utilizing zinc-containing inorganic filler | |
| CA1340760C (en) | Radiopaque fluoride releasing vlc dental composites and the use of specific fillers therein | |
| US4350532A (en) | Glass composition and articles | |
| US3971754A (en) | X-ray opaque, enamel-matching dental filling composition | |
| CA1283239C (en) | Radiopaque dental material | |
| US4814362A (en) | Glasses and poly(carboxylic acid) cement compositions containing them | |
| EP1137387B1 (en) | Opalescent fillers for dental restorative composites | |
| EP0620804B1 (en) | Fluoride ion-leachable glasses and dental cement compositions containing them | |
| US4500657A (en) | Dental restorative compositions having improved mechanical properties and hydrolytic stability | |
| JPH08225423A (en) | Glass for dentistry containing no barium and exhibiting good x-ray absorption | |
| JP3490720B2 (en) | Processable material and its use as a filling material for periodontal sulcus | |
| JP5805045B2 (en) | Barium-free radiopaque glass and use thereof | |
| EP0102199B1 (en) | Dental restorative compositions having improved mechanical properties and hydrolytic stability | |
| USRE32299E (en) | Glass composition and articles | |
| CA1157892A (en) | Zinc-containing glass composition | |
| DE19858126A1 (en) | Glass powder for use in dental ionomer cements | |
| US20210032154A1 (en) | Glass composition and glass powder, in particular for the use in the dental field | |
| GB2064550A (en) | Radio-opaque dental restorative compositions | |
| KR20190093512A (en) | Radiopaque glass and use thereof | |
| JPH07206470A (en) | Glass transmitting no x-ray and slowly releasing fluoride ion and dental material containing the same | |
| RO122832B1 (en) | Radio-opaque composition for dental restoration and process for preparing the same | |
| IE49125B1 (en) | Radio-opaque dental compositions |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |