Dentistry – Method or material for testing – treating – restoring – or... – Endodontic
Reexamination Certificate
2003-05-20
2004-11-02
Shaver, Kevin (Department: 3732)
Dentistry
Method or material for testing, treating, restoring, or...
Endodontic
Reexamination Certificate
active
06811400
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The invention is in the field of compositions and methods for sealing a root canal during an endodontic procedure. More particularly, the invention involves compositions having enhanced adhesion to hydrophilic dental tissues found within root canals which assists their ability to effectively seal and protect a newly cleaned root canal. Such compositions are preferably radiopaque and are cured more rapidly compared to existing endodontic sealing compositions, thus allowing for quicker placement of a final filling or crown to complete the root canal procedure.
2. The Relevant Technology
Following an endodontic root canal procedure, in which the root canal is cleaned using special root canal tools and irrigation devices, it is important to fill and seal the evacuated root canal in order to preserve the dead tooth from further decay that might compromise the integrity of the tooth and cause infection. In a typical procedure, one or more soft, resilient, needle-like inserts known as “gutta percha” points are inserted in each root canal branch in order at least partially seal and fill the root canal.
The term “gutta percha” refers to a rubbery material derived from natural rubber, typically blended with zinc oxide. This particular rubbery material is preferred because it is compressible, flexible and relatively soft so that it can be used to fill voids within the exposed root canal. The gutta percha points are typically impregnated with other materials such as radiopaque solids, zinc oxide, for its medicinal properties, and other passive or active ingredients as desired. It is impossible, however, to completely seal a root canal from all ingress of fluids, which may be laden with bacteria, using gutta percha alone. Conventional techniques require multiple gutta percha cones per canal and laborious “later condensation” techniques. For some, it requires a heating the gutta percha in an attempt to make it flow into the lateral canals. However, this technique, coupled with the properties of gutta percha, make it hard to achieve fine adaptation to canal walls and flow into the dentinal tubules.
The filling and sealing of the root canal can be further enhanced by inserting flowable materials, such as antiseptic pastes and/or sealing resins along with the gutta percha points. Due to the high viscosity of typical antiseptic pastes, such as zinc oxide/eugenol, or sealing resins, which tend to be epoxy-based, such materials are first applied to the gutta percha and then inserted into the root canal along with each gutta percha point. Alternatively, they may be inserted using a lentalo applicator. In this manner, it is hoped that the remaining spaces between the gutta percha points and the root canal can be filled with the antiseptic paste or resin. In addition, it is hoped that the epoxy-based resin will help to seal the root canal.
One of the drawbacks of using conventional pastes or resins is that such materials tend to be hydrophobic. This renders such materials somewhat incompatible with dental tissues within the root canal, which are highly mineralized, somewhat moist and therefore extremely hydrophilic. The hydrophilic nature of the root canal environment inhibits wetting and adhesion of the root canal by hydrophobic materials. As a result, conventional antiseptic pastes and epoxy-based resins actually form a poor seal between the gutta percha points and the walls of the root canal, thus potentially providing access for microbes and infection.
A further problem of conventional antiseptic pastes and epoxy-based endodontic sealing resins are their inability to adequately penetrate into, wet and seal the lateral canals which extend laterally from the root canal into the root of the tooth. Occasionally, the inability to seal the lateral fissures using conventional pastes and/or epoxy-based resins creates one more place where microbes may establish a beach head and be capable of festering over time.
In addition to the inability of the antiseptic pastes or epoxy-based resins to adequately adhere to and seal the root canals and lateral fissures, another problem relates to the inability to evacuate all air bubbles or pockets from the root canal during placement of the gutta percha points and associated pastes or resins. As the gutta percha point coated with pastes or resins is packed into the root canal, or as sealers are worked in with a lentalo applicator, upper portions of the gutta percha or sealer can seal against the root canal wall, thus trapping air between the coronal portion and the root canal apex. Failure to remove such air pockets creates an area where subsequent infection can fester. Although gutta percha is highly radiopaque, even if the dentist can observe whether or not the root canal spaces have been adequately filled, the task of removing the packed materials and repeating the procedure is time consuming, expensive, and uncomfortable for the patient. Moreover, many sealer pastes are only moderately radiopaque and include silver powder, which makes the root canal too dark.
Lateral condensation using gutta percha is typically not sufficient to force the highly viscous pastes, gutta percha, or resins into the lateral canals. Merely pushing against the top portion of the gutta percha does not exert very much force on the flowable pastes or resins, since pressurized fluids can escape around the space between the gutta percha, lateral condensation instrument, and the root canal rather than being forced into the lateral canals or other areas occupied by air bubbles or pockets.
Finally, in the case where nonpolymerizable pastes, such as zinc oxide/eugenol are used, the chemistries of such materials can interfere with the ability of subsequently placed prosthetic filling materials to chemically bond or adhere to the tooth.
In short, it would be an improvement of the art of endodontic procedures to provide compositions and methods which improved the ability of an endodontic sealing material to penetrate, wet, adhere and seal to the dental tissues surrounding or defining the root canals.
It would be an additional improvement in the art to provide compositions and methods that provided for a more thorough evacuation of air bubbles or air pockets within the root canal, as well as including lateral spaces or canals connected to or in communication with the main root canal branches.
It would also be an improvement in the art to provide compositions and methods which yielded a filled root canal in which the sealing material did not interfere with the ability of a subsequently placed composite resin material to bond or adhere to the tooth.
It would be a further advancement in the art if such compositions and methods provided for the ability to allow for variable curing times such as faster or slower curing, to account for variations in difficulty and success that may be experienced by a dental practitioner.
It would yet be an improvement in the art if such compositions could also be light cured so as to reduce the time a patient must wait until the root canal sealing material was sufficiently cured to permit subsequent filling of the remainder of the tooth with a composite filling material.
Such compositions and methods for more effectively filling and sealing a root canal and providing a bonding surface are disclosed and claimed herein.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention encompasses adhesive resins for use in filling and/or sealing a root canal during an endodontic procedure, as well as procedures for filling and sealing a root canal. The adhesive sealing and filling resins according to the present invention include a component that is compatible with a hydrophilic environment and that allows the resin to wet, penetrate and adhere to the dental tissue surrounding the root canal. In addition, such resins are better able to penetrate into and seal the lateral canals that often extend from the main root canal branches. In order to assist such sealing, improved methods for applying a pressure to the sealing and fi
Fischer Dan E.
Jensen Steven D.
Bumgarner Melba
Shaver Kevin
Ultradent Products Inc.
Workman Nydegger
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