Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2002-03-13
2004-06-29
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S024000, C522S047000, C522S074000, C522S081000, C522S083000, C522S104000, C522S107000, C522S120000, C522S113000, C522S129000, C522S130000, C522S150000, C522S153000, C522S178000, C522S182000, C523S113000, C523S115000, C523S116000, C523S118000, C433S226000, C433S217100, C433S219000, C433S228100
Reexamination Certificate
active
06756417
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The invention is in the field of dental restoration compositions and methods, more particularly in the field of compositions and methods for bonding an amalgam restorative to a dental substrate. The bonding compositions are cured in steps to promote enhanced adhesion of the amalgam to the dental substrate.
2. The Relevant Technology
In the field of dental restorations, a variety of materials have been used to fill and restore cavities and other defects in a person's teeth. These include metals, such as gold, silver, platinum, alloy, and amalgams, curable polymers such as polyalkyl methacrylates, polycarbonates, cured products of polyfunctional vinyl monomers, composite resins comprising fillers and the aforementioned polymers, and ceramics such as porcelain. Because such materials do not readily adhere to dental tissues, the tooth, and in particular the pulp, should be sealed or capped in order for the tooth to remain vital and avoid being infected with bacteria.
Polymeric restoration materials such as composites, as opposed to metal-based restoration materials such as amalgam, are fairly compatible with bonding agents and adhesives. This quality allows composites and other polymeric restoration materials to be directly bonded to the teeth, thereby allowing such materials to be firmly and sealingly attached to the patient's tooth, regardless of the shape of the hollow or dental preparation formed in the tooth. This allows the dental practitioner to remove only so much of the decayed or damaged tooth as will prevent further damage or decay to the tooth once the dental preparation has been sealed and filled using a combination of the composite restoration material and bonding agent. In addition, composite restoratives can be formulated to match the color of the patient's teeth, thus resulting in a more cosmetically pleasing tooth restoration compared to amalgam or other metal restoratives, which typically assume the color of the metal or metals that make up the restorative.
Amalgams and other metal restoratives are generally incapable of forming a strong bond with dental substrates, even when used in combination with conventional adhesive bonding agents. Restoration techniques that involve the use of amalgam or other metal restoratives typically require the removal of much larger quantities of the dental substrate, as compared to composite restorative techniques, in order to provide for mechanical overhangs of dental tissue that mechanically retain the cured or hardened metal restoration material within the dental preparation. Thus, in contrast to restoring a tooth using a polymer-based restoration materials, the practitioner must not only remove the decayed or damaged portion of the tooth but also so much of the surrounding healthy and undamaged tooth as will result in a dental preparation of the proper shape for mechanically retaining the hardened or cured metal restoration material. In general, dental preparations suitable for receiving amalgam or other metal restoratives advantageously widen toward the interior of the tooth. In this way, the hardened or cured metal restorative is mechanically held in place by overhanging or converging dental tissues. Because there is no significant bond between the amalgam and the tooth, microleakage at the margins can occur.
Even though amalgams and other metal restoration materials are typically stronger and more durable than polymeric restoration materials, the use of amalgam and other metals generally results in a weaker, less durable restored tooth compared to a tooth restored using a composite restorative. Increased tooth weakness results from the necessity of removing substantially more of the tooth than simply the decayed portion and from the inability of the amalgam or other metal to strongly bond to the tooth. Preparing the tooth to receive the amalgam or other metal restorative results in a prepared tooth that is at once smaller in size and which contains a much larger weakening discontinuity or void therethrough compared to a tooth prepared to receive a polymeric restorative. In addition, the lack of any significant bond between the remaining dental tissue and the amalgam or other metal restorative results in much lower total composite strength of the finished tooth compared to a restored tooth in which the restorative and tooth form a strong composite bond.
In view of the advantages of composite restorative materials and techniques described herein, the use composites is rapidly increasing, at least in the United States, while the use of amalgams or other metal restoratives is generally declining. Nevertheless, there is still significant demand for amalgam restoratives. Many dentists have used amalgam restoratives for decades and are very skilled in the techniques used to prepare teeth to receive such restoratives. Dentistry, like other professions, is a skilled profession in which practitioners often opt to continue using procedures that they are comfortable with. Similarly, many patients who have had amalgam fillings all their lives are conservative and resistant to change simply because composites are new and possibly “high tech”. As the common adage goes, “if it ain't broke, don't fix it.”
Moreover, amalgam restoratives have certain advantages over composite restoratives, not the least of which is cost. Another is ease of use. Amalgam restoratives typically comprise a mixture of relatively inexpensive metals (e.g., mercury, silver, copper and tin) that, when mixed together, are initially pliable and packable but which quickly cure or harden into a durable tooth filling as the metals react and become compounded. Examples of commonly-used amalgam restorative materials include TYTIN, which is manufactured and sold by Kerr Corporation, located in Orange, Calif., and VALIANT PH.D., which is distributed in the United States by Vivadent/Ivoclar North America, located in Amherst, N.Y. In contrast, composite restoratives typically include polymerizable resins, fillers, adhesives, and curing agents which, in the aggregate, are many times more expensive than amalgam restoratives. Whereas the cost differential may not matter to the wealthy or vain who will pay anything for stronger and/or more cosmetically appealing teeth, it does matter to many, particularly individuals on limited budgets and in less affluent countries.
Another problem with composite restoratives is that they are subject to greater variability in quality and strength compared to amalgam restoratives. Their use also requires more technical skill. When polymers cure they tend to shrink, and polymerization shrinkage is a problem that is generally dealt with by technique rather than by formulation. Technique is a learned trait, and a dentist with poor technique can improperly bond the composite to the patient's tooth. A composite restorative that is not adequately bonded to the tooth, i.e., that is partially detached, can provide ingress of bacteria into the dentine or pulp. Such restorations should be repaired by removing and replacing the improperly bonded composite material. Worse, improper placement of a shrinkable composite within a fragile tooth can cause it to crack or fracture, thus requiring major dental repair such as a crown.
In view of the foregoing, the choice between whether to use composite restoratives, on the one hand, or amalgam restoratives, on the other, to repair a decayed or damaged tooth comes down to weighing the respective advantages and disadvantages of each and then determining which are most important to the dental practitioner and/or the patient. When properly placed, the use of composite restoratives generally result in a much better composite bond with the tooth and a more cosmetically pleasing look. On the other hand, amalgam restoratives provide greater simplicity of use and much lower cost. For this reason, restorations involving a child's “baby” (or milk) teeth are performed using amalgam, since such restorations are, by definition, only temporar
Allred Peter M.
Fischer Dan E.
Jessop Neil T.
McClendon Sanza L.
Seidleck James J.
Ultradent Products Inc.
Workman Nydegger
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