Patent Application
20090298007
This invention relates to trays for making dental impressions of the teeth. The impression tray holds a temporarily viscous material which is pressed against the teeth. Within a short period of time the material becomes sufficiently firm to hold an impression of the teeth when the tray with the impression material is removed from the mouth. The dental laboratory uses the impression to make models of the teeth of the patient. Usually the impression trays consist of a base and of at least two side walls which together surround the area from which the impression is to be taken. The impression material is placed in the tray and the material in the tray is then placed firmly against the teeth and/or jaw for imposition of the impression.
It is sometimes desirable to have an impression of both upper and lower teeth taken at one time. This makes it possible to more clearly register the relationship of the teeth as they come together during biting. A triple tray is used to simultaneously register the upper and lower bite. Most triple trays currently on the market are molded as a single piece from thermoplastic compound. In some instances, this plastic may be distorted during the taking of the impression by the bite pressure. Any distortion of impression material will result in an ill-fitting prosthesis.
Impressions are often taken when preparing an implant after dental implants have healed into the underlying bone structures of the mandible or maxilla and the soft gum tissue has healed. A full set of upper and lower impressions (negative casts) of the mouth are made using individual full or partial arch upper and lower trays. Positive casts of these impressions are mounted upon a mechanical articulator that mimics the motion of the jaws. A separate bite registration cast is also made. The positive casts can then be manipulated to accurately replicate the structures in the mouth. These positive casts are tested against the bite registration cast.
U.S. Pat. No. 6,913,461 to Gittleman teaches a double bite tray for taking impressions of teeth on one side of the jaw. The tray has a mesh separating the impression material which encounters the upper teeth and the impression material which will take the impression of the teeth of the lower jaw. The impression tray is equipped with several hinges which are rendered inflexible by a light-cured compound. The impression trays of Gittleman take impressions of only a part of the jaw (right or left). (While trays of the instant invention can, indeed, be made for use in taking impressions of part of the teeth, it is sometimes most useful to have double impressions of the full teeth on each jaw.) The trays of Gittleman also require complex hinge means which can be rendered inflexible by use of a light cured compound when the hinge is exposed to a light of appropriate frequency.
U.S. Pat. No. 7,021,929 to DiMarino, et al., teaches an impression tray which will take a double impression of a full bite. The impression tray of DiMarino has an inner wall and an outer wall, each of which has projections into the space into which the impression material is placed to keep the impression material from slipping and moving. The tray presents two problems. First, it is sometimes difficult to extract the solidified impression material from the tray. Furthermore, the projections are such that they can distort the impression because of pressure in the area where the teeth impact the impression material.
Several patents disclose impression trays for obtaining an impression of either the upper or lower jaw, but not an impression of both at one time. U.S. Pat. No. 6,468,078 to Guillaume, et al.; U.S. Pat. No. 6,786,722 to Craig, et al.; U.S. Pat. No. 6,447,292 to Champagne, et al. and U.S. Pat. No. 6,247,925 to Schreinemakers all teach impression trays for taking impression of the upper and/or lower jaw separately.
The dental impression trays of the invention have a peripheral buccal supporting wall, a second wall which is parallel to the peripheral supporting wall with connecting means between the first supporting wall and the second wall. A partition is attached to the second wall to create a superior receptive cavity or compartment and an inferior receptive cavity or compartment in the impression tray. The impression tray has a handle attached to the peripheral supporting wall. In a preferred embodiment, the handle has, as a part thereof, a rib which adds stability to the tray. The webbing that transversely separates the space within the wall into an superior compartment or upper cavity holds impression material which will contact the upper teeth and/or jaw and the inferior compartment or lower cavity which is designed to hold impression material which will contact the lower teeth and/or jaw. There is a second crescent shaped wall (preferably a double wall) extending into the upper and lower compartments at a position distal from the handle which functions as a second retaining wall in both the upper and lower cavity and inhibits transfer of impression material from going down the throat of the patient.
The making of dental impressions presents several problems for the dental practitioner. If the impression of the upper and lower teeth/jaw are taken separately, the impression may not give optimal information regarding bite. The trays of the invention have a first buccal supporting wall, a second wall which is parallel to the first supporting wall with interspersed connecting means between the first supporting wall and the second well. There are open spaces between the connecting means connecting the peripheral wall with the second wall running parallel to the first wall. There is stretches across the second wall a partition, usually a mesh, which divides the space horizontally to create a superior receptive cavity or compartment and an inferior receptive cavity or compartment in the impression tray. The partition may be made of any material which will be sufficiently strong to hold the impression material. Preferred are synthetic fabrics such as polyester or nylon. While the partition may be woven or non-woven, it is preferred that the material be a mesh which will hold the impression material more firmly so that it does not slip and slide freely.
The trays of the invention make it possible to make an accurate, simultaneous impression of both the upper and lower teeth in the alignment usual when biting. Both the upper or superior compartment and the lower or inferior compartment of the tray are filled with impression material. The tray is placed in the mouth so that the impression material in the superior or upper cavity or compartment contacts the upper teeth and/or jaw, and the impression material in the inferior or lower cavity or compartment contacts the lower teeth or jaw. The mesh partition is then oriented between the mating occlusal surfaces of the teeth. In this manner, a set of aligned upper and lower impressions registering an accurate bite registration is made.
Impression materials usually used in dentistry can be used. For example, elastomeric impression materials such as polyvinylsiloxane or polyether, are appropriate because of their dimensionally stability and, before hardening, their flexibility which allows removal of the impression material from the teeth when the material has attained sufficient structural integrity to retain its shape. If an impression from a single area of the teeth/jaw is to be made, a half-arch triple tray can be used. The trays may be made of any plastic that is sufficiently firm to provide support and avoid distortion of the final product. Hard rubber would also be acceptable.
“Buccal Wall” is the wall that touches the buccal lining of the cheek when then the impression is being taken.
“Superior compartment or cavity” is the cavity into which impression material will be placed that will be in contact with the upper teeth or jaw when making the impression. (“Teeth or jaw” is used in this description since it is essential that an impression show where teeth are missing, including those instances where all or most teeth are missing.)
“Inferior compartment or cavity” is the cavity into which impression material will be placed that will contact the lower teeth or jaw when making the impression.
“Slots” applies to grooves in the side of a wall. They do not extend through the wall. They are undercut to provide extra means for the impression fluid to flow between the superior cavity and the inferior cavity.
“Slats” applies to the narrow projections that are between the grooves.
“Slits” applies to openings in the wall through which excess impression material can escape when under pressure from biting.
Referring to the figures,
