Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-11-23
2002-05-14
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S547000, C524S556000, C524S801000, C524S807000, C524S832000, C526S227000, C526S278000
Reexamination Certificate
active
06387982
ABSTRACT:
The invention relates to dental adhesive primers. In particular, the invention provides a self-etching dental adhesive primer composition and polymerizable surfactants. The primer composition is used in a method of coating a water insoluble polymerizable monomer mixture on a tooth or bone substance. The primer composition is useful as an adhesive or adhesion promoter to affix dental filling materials or bone cements to tooth material. Other uses include forming a protective film on the tooth or bone, or for fixing bone cements in position. The composition essentially comprises an emulsion of water immiscible polymerizable monomers, oligomers and adhesion promoters in water. By using an emulsion of the polymerizable substances in water the need for volatile organic solvents is avoided and biocompatability is enhanced. A further advantage is that independent of the resin phase, the pH of the aqueous phase can be adjusted to provide a self-etching action on the tooth and bone substance, thus enhancing adhesion of the layer to the tooth or bone without requiring a separate etching step. The composition preferably further comprises initiators, accelerators, and inhibitors as often used in unsaturated polymerizable mixtures. Further, the composition preferably comprises surfactants and colloidal silica particles to aid in the formulation of an emulsion and to help keep this stable. Optionally, fluoride releasing agents, bactericidal substances or medicinally beneficial materials may also be included in either aqueous or the resin phase of the composition. The emulsion will typically contain droplets with diameters of less than 30 microns of the polymerizable monomers, oligomers and adhesion promoters. More preferably most of the droplets have a diameter less than 10 microns. Preferably a portion of the droplets will have a diameter less than 1 micron. On applying the composition to the tooth or bone substance the film may first be left for a few seconds to allow an etching action to occur. The water may then be gently blown away, whereby the droplets of polymerizable monomers, oligomers and adhesion promoters coalesce to form a continuous film. No washing of the treated surface is required.
The present invention provides surfactants containing polymerizable monomers for use in compositions. The surfactants are able to polymerize into the matrix to become part of the polymer, and are thereby immobilised. Applications for surfactants containing polymerizable monomers are wide and varied, and include for instance paints and coatings, inks, and glues, particularly those where the coating, ink, or glue is cured by exposure to light. In particular, the surfactants of the present invention are useful in dental restorative materials.
BACKGROUND OF THE INVENTION
Prior art water-soluble hydrophilic materials form very weak spongy polymers, and have undesirable physical characteristics in the cured film layer. The polymerizable resin mixtures and composites used for the repair and replacement of tooth substance, or for the fixation of prosthesis into bone do not adhere of themselves to the tooth or bone substance, and some means is needed to keep them in place. This has long been a problem, and various methods have been developed to overcome it. Initially the attachment method was purely mechanical, and in dental practice large volumes of tooth had to be drilled away to provide sufficient anchorage to keep the filling material in place. U.S. Pat. No. 4,514,342 discloses adhesion promoters such as PENTA. U.S. Pat. No. 5,645,429 discloses primer and adhesive combined into one formulation. Although this has excellent adhesion to dentin, adhesion to unetched enamel is lower than when the enamel is first etched. Therefore when the highest adhesion to both dentin and enamel is required the enamel still needs to be etched, and the steps needed to produce an adhering tooth filling material are first etching, next applying the combined primer/adhesive, and finally applying the filling material. Although this is a considerable improvement over two component adhesives, it still requires considerable time and skill on the part of the dentist. After the tooth material has been etched, for instance, it has to be totally protected from contamination with body fluids. If contamination does occur, then the etching procedure has to be repeated. It would therefore be a further advantage if the etching procedure could be combined with the application of the adhesive, since this would not only save the dentists time, but would also eliminate one of the steps in which contamination of the prepared surface is possible. This would in consequence lead to a further improvement in the quality and reliability of the completed restoration of the tooth. These problems of prior art dental primer/adhesive are overcome by the composition, method and product of the present invention.
Surfactants are used in a wide range of purposes, often to help liquids to spread out over a surface, or to help otherwise incompatible components to mix and remain as a homogenous formulation. Often, a surfactant has to do both simultaneously. A common example is washing-up liquid, which enables water to spread out on a greasy surface, and also helps to keep the loosened globules of fat suspended in the water. There are many types of surfactant, but all consist basically of a hydrophobic part and a hydrophilic part. Both the hydrophobic and hydrophilic parts can comprise either a long chain, or a compact “head”. In addition, the hydrophilic part can be either ionic or non-ionic. There are many possible ways of combining these different hydrophobic and hydrophilic parts, leading to a wide range of possible surfactants. Another common use of surfactants is in cosmetic creams and medicaments, where they are used to keep for instance paraffin oil or other water insoluble materials suspended in an aqueous base. This type of formulation is also known as an oil in water emulsion. By suitable choice of surfactant it is also possible to keep droplets of water suspended and stable in a non water miscible oil, and this is known as a water in oil emulsion. Surfactants are also often used in paints, glues, and other surface coatings, and sometimes two or more surfactants are used together to provide optimum surface wetting properties as well as optimum emulsion stability. With a paint, or other coating that is intended to dry, it is usually desirable that when the coating is dry, the surfactant is de-activated or immobilised in some way. In the case of coatings, leaching of the surfactant or its migration towards the air—coating interface can produce discoloration, whereas migration and concentration at the hard surface to which the paint or coating is attached can cause the coating to come loose from the surface to which it is adhering. In essence a surfactant is a material which contains both a non polar hydrophobic end and a polar hydrophilic end, and which is able to form an interface between two surfaces of differing polarity. The word “surfaces” is used broadly when applied to surfactants, and can mean either two solid surfaces, two liquid surfaces, or one solid and one liquid surface. However, not all materials which have both polar and non-polar ends are effective surfactants. The non polar end, for instance has to be large enough to keep it firmly attached to a non polar solid surface, or to keep it directed towards or within the surface of a non polar liquid surface. Likewise, the polar end has to be large enough to keep it within the polar environment. The ratio of the polarity of the hydrophilic end to the non polarity of the hydrophobic end also has to be correct and ideally should be optimised for each application. Because it is often hard to find one single surfactant with the ideal properties, mixtures of two or more surfactants are often used in practical formulations. The polar—nonpolar properties of the surfactants are approximately additive, and by choice of a suitable ratio of suitable surfactants a wide range of applications can be cove
Bieber James B.
Dentsply DeTrey G.m.b.H.
Lovercheck Dale R.
Szekely Peter
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