Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1995-06-05
2002-11-19
Page, Thurman K. (Department: 1615)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S118000, C522S103000, C522S104000, C522S096000, C522S090000, C522S088000, C522S048000, C522S083000, C522S908000, C428S522000
Reexamination Certificate
active
06482871
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method for adhering to hard tissue. This invention also relates to adhesive compositions for use on hard tissue.
BACKGROUND ART
In recent years there has been intense interest in the dental field in adhesives that bond to hard tissues such as dentin. Forces generated by the polymerization contraction of dental restorative materials suggest that a minimum adhesion strength for bonding restorative materials to hard surfaces in in vivo clinical procedures would be desirable. For example, M. Jensen,
Polymerization Shrinkage and Microleakage International Symposium on Posterior Composite Resin Dental Restorative Materials,
243-44 (1985) reports a contraction force of 7.3 MPa. for conventional composite materials. In many instances the minimum adhesive strength has not been achieved, resulting in direct communication between dentin and the oral cavity via gaps between the dental restorative material and the cavity walls. This may be responsible, in part, for patient complaints of sensitivity and for pulpal irritation and inflammation. See, Tao,
The relationship between dentin bond strengths and dentin permeability Dental Materials,
Vol. 5, 133-39 (1989).
Recently a novel priming method was developed in the laboratory of the assignee of this invention and is sold commercially as ScotchBond 2™ Light Cure Dental Adhesive with Scotchprep™ Dentin Primer (commercially available from 3M). This priming method has achieved average shear strengths in vitro in excess of 20 MPa. U.S. Pat. No. 4,719,149 (Aasen et al.) describes that invention as an acid and a water-soluble film former useful for priming hard tissue (e.g., dentin). The acid has a pKa less than or equal to that of phenol. The calcium salt(s) of the acid are soluble in the film former. The film former is exemplified as comprising various difunctional and monofunctional monomers and optional cosolvents with 2-hydroxyethylmethacrylate and water being preferred.
Kusumoto et al., U.S. Pat. No. 4,535,102 discloses an adhesive coating material for a hard tissue comprising (1) a polymer having an acid value of 30 to 700 and including in recurring units a hydrophobic group and two carboxyl groups or one carboxylic anhydride group bonded to the polymer, and (2) a polymerizable vinyl compound or a mixture of said polymerizable vinyl compound and an organic titanate compound.
Engelbrecht et al., U.S. Pat. No. 4,806,381 discloses oligomeric or prepolymeric organic compounds that contain both polymerizable unsaturated groups and acid radicals, their salts or their reactive-derivative radicals. The compounds adhere to biological substrates such as tooth tissue.
Beech et al., U.S. Pat. No. 4,732,943 discloses an adhesive comprising (a) a condensate of &egr;-caprolactone with one or more acrylic monomers containing hydroxy groups and (b) a polymer containing binding groups capable of binding to the dentin.
One major limitation in the prior art has been the difficulty of adhering to hard tissue which is not dry. This necessitates maintaining a dry tooth surface during the priming procedure which is in practice difficult to ensure. For instance, the oral cavity is inherently humid and the hard tissue is susceptible to fluid perfusion from the pulp chamber. The susceptibility of the tooth surface to this fluid perfusion is believed to be a function of the proximity of the prepared surface to the pulp chamber. Near the pulp, the tubules are very close together and the water content of this deep dentin is very high. See, Pashley,
Dentin: A Dynamic Substrate Scanning Microscopy,
Vol. 3, No. 1, 161-76 (1989).
Additionally, dental materials adhere poorly to sclerotic dentin and cervical enamel. Sclerotic dentin is characterized as hypermineralized dentin (i.e., the dentinal tubular contents are mineralized) and has a coloration that can range from transparent to intense yellow or yellow-brown.
SUMMARY OF THE INVENTION
The invention provides a pretreatment (a primer) that is applied directly to the hard tissue. The invention has particular utility for adhering to or coating sclerotic dentin and cervical enamel or for adhering to or coating hard tissue in a high humidity environment. The primer enables formation of extremely strong bonds to dentin (including sclerotic dentin), exhibiting shear strengths as high as 30 MPa., when tested in shear using the procedure described herein. Tests to date indicate that an extremely durable adhesive bond with little or no detectable microleakage can be obtained. The primers of the invention can, if desired, be water-based, thus substantially reducing the need to apply them in a dry field. The primers of the invention work very well in high humidity environments or when bonding to sclerotic dentin.
The present invention provides, in one aspect, a method for adhering to or coating hard tissue,,comprising the steps of:
(a) applying to the hard tissue adhesively effective amounts of an acid and a water-dispersible film former comprising a polymer and
(b) hardening said film former.
For purposes of this invention “hardening” is defined as the formation of a covalently or ionically crosslinked polymer as opposed to merely drying a previously prepared polymer of its carrier solvent or merely cooling a previously melted thermoplastic polymer.
The present invention also provides novel primer compositions for use in such method, comprising a mixture of an acid and a film former comprising a polymer prior to the hardening step, said mixture being in the form of a film atop said hard tissue.
DETAILED DESCRIPTION
In the practice of the present invention, the hard tissues which can be adhered to or coated include human and animal tissues such as teeth (including the component parts which are enamel, dentin, and cementum), bone, fingernails, and hoofs. The invention has particular utility for adhering to or coating dentin, sclerotic dentin, enamel, and cervical enamel.
The acid and film former can be applied to hard tissue concurrently or sequentially. If they are applied sequentially, then if desired the acid can be rinsed from the hard tissue (e.g., using a water rinse) before application of the film former, or the film former can be applied to the acid without an intermediate rinsing step. For brevity, formulations comprising the film former will sometimes be referred to as the “primer,” regardless of whether the concurrent or sequential application method is employed. Thus, when the acid and film former are applied to the hard tissue concurrently, then the acid and film former will sometimes be referred to collectively as the “primer”. When the acid and film former are applied to the hard tissue sequentially, then the acid, if in a solvent, will sometimes be referred to as an “etchant” and the film former will sometimes be referred to as the “primer.”
In one method of the invention, the primer is permitted to stand on the hard tissue for a desired period of time, readily volatile cosolvents are removed therefrom (e.g., by air-drying) to modify the surface of the hard tissue and leave a residual film on the surface of the hard tissue (and in the case of dentin to form a “hybrid layer” with the hard tissue), the residual film is overcoated with a layer of additional film former (the additional film former can be water-soluble or water-insoluble but should preferably form a homogeneous solution when combined with the residual film), then the additional film former and residual film are hardened and optionally overcoated with a composite, restorative, glass ionomer cement, sealant or other hardenable coating (hereafter such composites, restoratives, glass ionomer cements, sealants, and other hardenable coatings will be referred to collectively as “restoratives”). As used herein, “surface modified hard tissue” refers to hard tissue that has been exposed to the primers of the invention. As used herein, “hybrid layer” refers to the layer of resin-reinforced dentin that consists of collagen and perhaps hydroxyapatite that is infiltrated and surrounded by the monomers, oligomers and polym
Aasen Steven M.
Fundingsland Jon W.
Mitra Sumita B.
Oxman Joel D.
Ubel, III F. Andrew
3M Innovative Properties Company
Fubara Blessing
Page Thurman K.
Skolnick Steven E.
LandOfFree
Method for adhering to hard tissue does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for adhering to hard tissue, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for adhering to hard tissue will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2936750