Dentistry – Prosthodontics – Holding or positioning denture in mouth
Reexamination Certificate
1998-12-31
2001-07-31
Lewis, Ralph A. (Department: 3732)
Dentistry
Prosthodontics
Holding or positioning denture in mouth
Reexamination Certificate
active
06267596
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to removable dental appliances and, in particular, to dental appliances applicable to prosthetic, restorative periodontal and orthodontic dentistry.
BACKGROUND OF THE INVENTION
The loss of natural teeth may warrant the use of a partial denture or dental appliance. Some of the factors that influence the decision as to whether a partial denture is required include shrinkage of the gums, reduction or removal of the alveolar process or foundation that partially supports the dental appliance, and loss of molars which reduces the number of abutments available for anchoring and supporting the appliance. Another difficulty is that the few remaining teeth may be mobile.
One form of partial denture is known as a clasp type partial. The partial includes hook like portions that are formed of metal or plastic and extend around individual abutment teeth to support the dental appliance in the mouth. When one or more of the abutment teeth is lost, the dentist may recommend an alternative dental appliance such as that disclosed in U.S. Pat. No. 3,271,858. The dental appliance of the 3,271,858 patent addresses the difficulties involved with developing and using partial dentures with a design that includes a metal lingual section adapted to engage abutment teeth, a first metal frame section extending from one end of the lingual section for supporting replacement teeth and a second metal frame section extending from the other end of the lingual section for supporting replacement teeth. A metal labial bar extends between the first and second frame sections. Plastic replacement tissue material extends around the replacement teeth that are carried by the first and second frame sections. A metal hinge member is disposed at one side of the labial bar and a metal latch member is disposed at the other side of the labial bar. The labial bar is connected to the hinge so as to be swingably movable relative to the abutment teeth. The labial bar includes a hook type catch that engages the latch member to enable the abutment teeth to be firmly clasped between the lingual section and the labial bar.
A disadvantage of the dental appliance of the 3,271,858 patent is that the labial bar, the hinge member and the latch member are formed of metal. Therefore, clasp type partials cannot easily be restored so as to utilize this design. In addition, although a plastic replacement tissue portion may be carried by the metal labial bar, the labial bar is bulky in the patient's mouth, may cause discomfort and is unsightly.
SUMMARY OF THE INVENTION
In general, the dental appliance of the present invention comprises a lingual section adapted to engage at least one abutment tooth, a first tissue replacement portion extending from one end portion of the lingual section, a second tissue replacement portion extending from another end portion of the lingual section, a gate adapted to engage the at least one abutment tooth at a buccal or labial position and a hinge partially formed by an end portion of the gate, wherein the end portion of the gate is comprised of cured tissue replacement (e.g., plastic) material.
More specifically, the dental appliance may also include a latch disposed at another end portion of the gate. The entire gate including a hinge portion and a latch portion is preferably comprised of nonmetallic, cured material (e.g., plastic) and free of metal reinforcement. The hinge may be comprised of a mechanical interlocking of the gate end portion and the first tissue replacement portion, and pivotally connects the first tissue replacement portion and gate together. Alternatively, the hinge may be a living hinge formed by continuous material between the first tissue replacement portion and the gate. The second tissue replacement portion comprises a recess for receiving a latch portion of the gate. The first and second tissue replacement portions are preferably comprised of plastic such as acrylic, or a polyamide, for example. The gate is comprised of a suitable plastic material such as one of the above plastic materials, preferably a material other than acrylic. In the case of a restoration of a dental appliance, portions of the hinge and the recess may be comprised of secondary acrylic material bonded to acrylic material that comprises the first and second tissue replacement portions. Dental appliances may also be restored using the lost wax process.
The appliance may comprise first and second metal frame sections disposed in the first and second tissue replacement portions, respectively, the first and second frame sections being adapted to support replacement teeth. In one aspect, the lingual section is comprised of metal and is integrally formed with the first and second frame sections. In another aspect, the first and second plastic tissue replacement portions are configured and arranged to support replacement teeth without a metal framework. In the case of restoring clasp-type partial dentures, the first and second tissue replacement portions are comprised of acrylic tissue replacement portions from a clasp-type partial denture.
A preferred embodiment is directed to a dental appliance comprising: a lingual section adapted to engage at least one abutment tooth; a first plastic tissue replacement portion extending from one end portion of the lingual section; a second plastic tissue replacement portion extending from another end portion of the lingual section; a gate adapted to engage the at least one abutment tooth at a buccal or labial position; a hinge comprised of a mechanical interlocking between an end portion of the gate and a portion of the first tissue replacement portion that enables the gate to be swingably movable relative to the abutment teeth, the end portion of the gate being comprised of a curable tissue replacement material; and a latch disposed at another end portion of the gate.
A method of making a dental appliance according to the invention, especially a new appliance, comprises the steps of positioning a replacement tooth-supporting member in investment mold material contained by a vessel. The member includes tissue replacement portions comprised of wax. A hinge form is positioned in the investment mold material. A latch form is positioned in the investment mold material. Wax portions are removed to expose regions that are intended to receive replacement tissue material. Replacement tissue material is applied to the exposed regions. The material is hardened to form a first tissue replacement portion extending from one end portion of a lingual section of the member adapted to engage at least one abutment tooth. A hinge is formed in the first tissue replacement portion. A latch is formed in the second tissue replacement portion.
In the case in which the buccal or labial tissue replacement portion is not present when the plastic tissue replacement portions are injected, the method comprises positioning a wax tissue replacement portion in investment material in the vessel in a buccal or labial opening between the first tissue replacement portion and the second tissue replacement portion, the wax tissue replacement portion including the hinge form and the latch form. The wax material of the wax tissue replacement portion is removed thereby exposing a region intended to receive tissue replacement material. Curable tissue replacement material is applied to the exposed region left by removal of the wax tissue replacement portion. The material is hardened to form a tissue replacement gate including a hinge portion that forms at least a portion of the hinge and a latch portion that forms at least a portion of the latch. The gate is movable such that the at least one abutment tooth can be enclosed by the lingual section and the gate.
Another aspect of the method uses the hinge recess-forming member and the latch recess-forming member as part of a nonmetallic cured buccal or labial tissue replacement gate. In this case, the tissue replacement portions are formed of wax and either alone or using a framework, support the replacement teeth. The
Lewis Ralph A.
Watts Hoffman Fisher & Heinke Co., L.P.A.
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