Patent Application
20060068357
This invention relates to improvements in dental impression trays, and more particularly to improvements in metal dental impression trays.
Dental impression trays are often used by dentists, orthodontists, and others engaged in various fields of dentistry to make an impression of selected areas of a patient's teeth and gums. For example, the dentist may desire to have an impression of an area of a patient's dentition (often including not just one tooth but also adjacent teeth and opposing teeth) where one or more teeth are missing or damaged, so that a suitable prosthesis may be made from a model taken from the impression as a guide. Commonly a dentist will take an impression of a tooth that has been damaged via an accident or deterioration through natural aging. The impression is an accurate replica of the tooth or teeth. Once completed, the impression is subsequently sent to a dental laboratory where it is “poured up” in dental stone, creating a positive model of the dentist's impression. This model is then used to fabricate a replacement prosthesis (such as a new crown bridge or denture) and is sent back to the dentist for insertion into the patient's mouth. The models may also serve as a permanent record of a patient's teeth before and after treatment, and sometimes at selected intervals during treatment.
To prepare an impression, curable elastomeric dental impression material is placed in an impression tray and the tray is positioned in the patient's mouth so that the impression material fills and surrounds the selected area to be restored. Once the impression material has cured, a finished impression along with the tray is removed from the mouth as one unit. A dental model of the patient's tooth structure and gingival tissue can be made from the finished impression.
A variety of dental impression trays are available to hold dental impression material as impressions are made. Some dental impression trays have an overall, generally “U”-shaped configuration in plan view that matches the overall, generally “U”-shaped configuration of the patient's upper or lower dental arch. These are referred to as full arch trays. Other impression trays have an overall, generally “J”-shaped configuration in plan view for making an impression of one quadrant of the patient's oral cavity (i.e., the right or left half of either the patient's upper dental arch or lower dental arch). These are known as quadrant or quad arch trays. Quadrant arch tray designs allow impressions to be made of both the upper and lower mouth simultaneously and are known as dual arch trays. Typically, a central area of the dental impression tray has a mesh or other generally flat material which serves as a support for holding dental impression material. The dental impression material can comprise one of several elastomeric dental impression materials including, for example, reversible hydrocolloids, irreversible hydrocolloids, polysulfides, polyethers, and condensation silicones, especially polyvinyl siloxanes.
Dental impression trays are commercially available in a variety of materials, including stainless steel or aluminum. Other, less rigid impression trays are made of a plastic material such as polyethylene or polypropylene, or made of polystyrene foam. Plastic dental impression trays have problems associated with their relative flexibility. More specifically, plastic trays may partially distort when a patient bites down with the tray/dental impression material in the mouth. When the patient opens his mouth and the plastic tray is removed, the plastic often rebounds, and this rebound can cause distortions in the impression, which in turn produces distortions in the model and ultimately the prosthesis. Even slight rebounding can produce prostheses that simply do not fit, or are at best uncomfortable or unacceptable to the patient. For this reason it is generally preferable to use metal trays. Although known metal trays work well, it would be desirable to have an improved metal, memory-free, sideless dental impression tray to avoid rebounding. Rebounding is caused by horizontal stress from a mesh pulling on the side walls of the tray and axial roll caused by the viscous impression material flexing or bending an arm of the tray.
In accordance with a first aspect, a dental impression tray is disclosed comprising a frame having left and right side walls and a distal bar. The distal bar has a distal end and structural arcs on either side of the distal end which connect the distal bar to the corresponding left and right side walls, and a mesh is attached to the frame at the side walls and at the distal end, and the mesh cooperates with the frame to define openings formed between the mesh and the structural arcs. In accordance with another aspect the distal end is tapered to help reduce impingement of teeth and gums at the retro molar pad.
From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology of dental impression trays. Particularly significant in this regard is the potential the invention affords for providing a dental impression tray which is easier for both a patient and a doctor to use. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.
It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the dental impression tray disclosed here, including, for example, the specific dimensions of the frame and tray will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to enhance visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity of illustration. All references to direction and position, unless otherwise indicated, refer to the orientation illustrated in the drawings.
It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the dental impression tray disclosed here. The following detailed discussion of various alternative and preferred features and embodiments will illustrate the general principles of the invention with reference to a dental impression tray particularly suitable for use as a dual arch tray, where dental impression can be taken of a section of upper teeth and a corresponding section of lower teeth simultaneously. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure.
Referring now to the drawings,
A mesh 16 is pinched to the frame 12 at three gaps: left side gap 28, right side gap 29, and distal end gap 24 so as to cover most of a central area 99. Silicone or other suitable dental impression materials may be applied to both sides of the mesh 16 so that dental impressions can be made on both a top row and a bottom row of teeth. Openings 36 are located between the mesh 16 and the structural arcs 20 near the corresponding generally right angle bends 94 in the metal frame 12.
In accordance with a highly advantageous feature, the frame 12 is formed from a unitary piece of solid aluminum wire, for example 3/16 of an inch in thickness. The wire is cut to length, for example, 8 inches, and in additional to bending the wire into the shape of the frame, the gaps 28, 29, 24 are cut into the wire.
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Owing to the strength of the muscles in the jaw and the irregular shape of the teeth and surrounding tissue, it has been found that slight changes in design of dental impression trays can have important effects both in terms of accuracy of the dental impression prosthesis and as well as comfort to the patient. In accordance with another highly advantageous feature, the mesh is attached at the distal end 21 as well as the left and right side walls. This advantageously helps secure the mesh to the frame, while maintaining structural arcs that do not contain gaps helps maintain overall tray rigidity, increasing the accuracy of the dental impression generated using these trays. As it is not desirable to keep the mesh too taut, preferably the force used to stamp the gaps is such that there is still some give in the mesh. This allows the mesh to adapt more accurately to the shape of the teeth and bite during the closing of the patient's mouth without placing horizontal forces on either side wall of the tray.
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The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to use the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
