Abstract:
A reusable dental impression tray having a reusable rigid tray holder with opposing sidewalls spaced apart substantially a first distance, a connector at a distal end of the tray holder couples the sidewalls together, the sidewalls and connector define an inward facing surface, a channel formed in and extends along the inward facing surface, and a disposable mesh bite tray having a generally U-shaped frame having an open end and a closed end, the U-shaped frame is made of a flexible material wherein the U-shaped frame has a static shape having a width at the closed end substantially the first distance and a width at the open end which is greater than the first distance, wherein with the U-shaped frame received in the channel, the open and of the U-shaped frame is held with the open end having a compressed width substantially the same as the first distance.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority to New Zealand Application No. 588307, filed Sep. 29, 2010, and New Zealand Application No. 592695, filed May 6, 2011, the entire contents of which both are hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a dental impression tray, and in particular, a reusable dental impression tray for taking an impression of the posterior teeth. 
     BACKGROUND OF THE INVENTION 
     The prior art includes dental impression trays designed for taking an impression of all or some of the lower or upper teeth. Such trays are often a single piece device made of all metal or other material which is autoclavable. The prior art also includes dental instruments for taking posterior impressions. Such dental impression trays may be extremely rigid and reusable. Dental impression trays are anatomically shaped to fit over the patient&#39;s teeth. An impression material is then secured in the tray, often with an adhesive, before being placed inside the patient&#39;s mouth where they bite down on the impression material until it sets. The tray, with set impression material, is then removed from the patient&#39;s mouth and is used as a mould to form a model of the patient&#39;s dentition. 
     U.S. Pat. No. 3,468,029 discloses a dental impression frame and disposable tray. The frame is split and hinged at one end so the frame may clamp down on a gauge material, firmly, on all but one side, such as the lingual, wherein the gauge material is secured but to allow slippage as the gauge material is pulled while being clamped between the teeth. U.S. Pat. No. 5,820,372 discloses a dental impression tray. The tray includes a frame and handle member and removable impression tray. 
     In order to make accurate and quality impressions, moulds and dental prostheses, the stability of the bite tray is critical. Current bite trays lack this stability due to their construction material and/or design. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a rigid dental impression tray that overcomes the problems of the prior art dental impression trays and produces an accurate, undistorted impression. 
     It is a further object of the present invention to include a secure method of attaching the impression material to the dental impression tray. 
     It is still a further object of the present invention to offer a dental impression tray that fits almost any mouth shape. 
     It is yet a further object of the present invention to provide a dental impression tray which does not require the use of an adhesive. 
     It is still yet a further object of the present invention to provide a cost effective dental impression tray. 
     The present invention therefore provides a reusable dental impression tray having a reusable rigid tray holder with opposing sidewalls spaced apart substantially a first distance, the opposing sidewalls extend longitudinally in a curved manner, a connector located at a distal end of the tray holder couples the sidewalls together, the sidewalls and connector define an inward facing surface, a channel formed in and extends along the inward facing surface, and a handle located at a mesial end of the tray holder, and a disposable mesh bite tray having a generally U-shaped frame having an open end and a closed end, the U-shaped frame is made of a flexible material wherein the U-shaped frame has a generally static shape having a width at the closed end substantially similar to the first distance and a width at the open end which is greater than the first distance, and wherein with the U-shaped frame received in the channel, the open end of the U-shaped frame is held in a compressed state with the open end having a compressed width substantially the same as the first distance. 
     The present invention further provides a corresponding kit, as well as a corresponding disposable mesh bite tray. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a reusable dental impression tray in accordance with one embodiment of the present invention, including the reusable tray holder and the disposable biting tray; 
         FIG. 2  is a back side view of the reusable dental impression tray of  FIG. 1  in accordance with the present invention; 
         FIG. 3  is a top view of the reusable dental impression tray of  FIG. 1  in accordance with the present invention; 
         FIG. 4  is a top view of the disposable biting tray of  FIG. 1  in accordance with the present invention; 
         FIG. 5  is a perspective view the disposable biting tray of  FIG. 1  in accordance with the present invention; 
         FIG. 6  is a top view of a reusable tray holder in accordance with a second embodiment of the present invention; 
         FIG. 7  is an end view of the reusable tray holder of  FIG. 6  in accordance with the present invention; 
         FIG. 8  is a back side view of the reusable tray holder of  FIG. 6  in accordance with the present invention; 
         FIG. 9  is a perspective view of the span between the opposing sidewalls of the reusable tray holder of  FIG. 6  in accordance with the present invention; 
         FIG. 10  is an end view of the span between the opposing sidewalls of the reusable tray holder of  FIG. 6  in accordance with the present invention; 
         FIG. 11  is a perspective front view of the reusable tray holder of  FIG. 6  in accordance with the present invention; 
         FIG. 12  is a side-by-side top view of the reusable tray holder and disposable mesh insert tray of  FIG. 6  in accordance with the present invention; 
         FIG. 13  is a front perspective view of the reusable tray holder in accordance with a third embodiment of the present invention; and 
         FIG. 14  is a front perspective view of the reusable tray holder in accordance with the third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a reusable dental impression tray  10  in accordance with one embodiment of the present invention. The reusable dental impression tray  10  includes a reusable tray holder  12  and a disposable bite tray  14 . The reusable tray holder  12  includes a pair of opposing sidewalls or fins  16  connected via a curved arm or connector  18 . The reusable tray holder  12  further includes a stem  20  upon which a handle  22  is secured thereto. Alternatively, the reusable tray holder  12  may be a one-piece component, including the handle. The handle includes a smooth surface. The smooth surface facilitates writing or attaching tracking details. In addition, the handle or some other part of the reusable tray holder  12  may be color coded to represent difference sizes of the reusable tray holder  12 . The slim design fits comfortably in the patient&#39;s mouth. The opposing sidewalls are anatomically designed to support impression material evenly. The solid walls of the opposing sidewalls impose a hydraulic pressure on the impression material. 
     The curved connector  18  is reinforced to prevent the dental impression tray  10  from twisting. The curved connector  18  may be approximately 2 mm to 3 mm high and 3-6 mm wide. In one embodiment, the connector  18  is approximately 4 mm wide. 
       FIG. 2  shows a back side view of the reusable dental impression tray  10 . It can be seen that the disposable bite tray  14  includes a frame  24  and a mesh  26 . It is apparent from  FIG. 2  that the mesh is not taut. Rather, the mesh  26  forms a wave or ripple.  FIG. 2  also shows that the lingual or palatal sidewall  30  includes a distal end  32  having a curved and blunt profile. The lingual sidewall  30  further includes a mesial end  34  having a curved and more pointed profile. It will be noted that the lingual sidewall  30  tapers from a wide distal end  32  to the narrower mesial end  34 . The lingual sidewall  30  is designed to control the tongue so as to prevent distorted impressions. In addition, the mesial end  34  of the lingual sidewall  30  provides the smaller or pointed profile in part for shallow palates. 
       FIGS. 1 and 2  also show that the buccal sidewall  38  includes a mesial end  40  having a curved and blunt profile. The buccal sidewall  38  further includes a distal end  42  having a curved and more pointed profile. It will be noted that the buccal sidewall  38  tapers from a wide mesial end  40  to a narrower distal end  42 . The frame  24  may be color coded to represent difference sizes of the disposable bite tray  14 , in the same manner as the handle. 
       FIG. 3  shows a top view of the reusable dental impression tray  10 . The opposing sidewalls  16  are readily apparent to be arched so as to conform with the posterior teeth. The disposable bite tray  14  is shown extending between the opposing sidewalls  16  within a groove or channel  50 .  FIG. 4  shows the disposable bite tray  14  having the molded springy frame  24  and the mesh  26 .  FIG. 5  is a perspective view of the disposable bite tray  14 . The molded springy frame  24  includes a buccal portion  52 , a lingual portion  54 , a connector portion  56 , and an open end  58 .  FIG. 4  shows that the distance between the buccal portion  52  and lingual portion  54  is wider at the open end  58  in comparison to the connector portion  56 . This is the static state or position of the disposable bite tray  14 , with the buccal portion  52  and lingual portion  54  diverging from the connector portion  56 . 
       FIG. 6  shows a top view of a reusable tray holder  112  in accordance with a second embodiment. The reusable tray holder  112  includes opposing sidewalls or fins  116  connected via a connector  118 . A handle  122  is coupled to the reusable tray holder  112  via a stem  120 . The opposing sidewalls  116  include a pair of ledges  160 .  FIG. 7  shows a back side view of the reusable tray holder  112  wherein the ledges  160  are seen on the lingual sidewall  130  and the buccal sidewall  138 .  FIG. 8  shows a back side view of the reusable tray holder  112 , wherein the buccal sidewall  138  includes a mesial end  140  having a curved and blunt profile. The buccal sidewall  138  further includes a distal end  142  having a curved and more pointed profile. It will be noted that the buccal sidewall  138  tapers from a wide mesial end  140  to a narrower distal end  142 . The narrower distal end  142  of the buccal sidewall  138  prevents impingment on tissues. In contrast, the wider or taller mesial end  140  of the buccal wall  138  supports the canine teeth. 
     As can be seen from  FIGS. 8 and 11 , the lingual or palatal sidewall  130  includes a distal end  132  having a curved and blunt profile. The lingual sidewall  130  further includes a mesial end  134  having a curved and more pointed profile. It will be noted that the lingual sidewall  130  tapers from a wide distal end  132  to a narrower mesial end  134 . 
       FIGS. 9-11  show the reusable holder  112  of the second embodiment, wherein a groove or channel  150  extends along the middle of the inwardly facing surface  170  of the opposing sidewalls  116  and connector  118 . 
       FIG. 12  shows the side-by-side comparison of the reusable tray holder  112  and the disposable bite tray  114 . It can be seen that the connector portion  156  substantially conforms to the dimensions of the groove or channel  150  at the connector  118 . However, the open end  158  as defined by at the buccal portion  152  and lingual portion  154  is wider than the holder open end defined at the mesial end  134  and mesial end  140 . It will be appreciated that with the disposable bite tray  114  is inserted into the channel  150  towards the connector  118 , the buccal portion  152  and lingual portion  154  and urged together with increasing tension as the open end  158  approaches the channel  150 . With the disposable bite tray  114  fully inserted into the reusable tray holder  112 , buccal portion  152  and lingual portion  154  maintain a constant outward tension so as to create a compression fit within the channel  150  and remain securely in place throughout the impression and mold process steps. The dimensions of the channel and frame may be selected to additionally provide an interference fit, for greater securement. 
       FIGS. 3 ,  7  and  10 , in particular, show the flared nature of the opposing sidewalls. The flared opposing sidewalls self-lock impression material against displacement forces.  FIGS. 1 ,  3 ,  7  and  10 , in particular, show how the curved intersection of the connector and sidewalls define a back seal  90  which prevents distal overflow of the impression material. The self-locking nature of the reusable tray holder means that an adhesive is not required, but is optional. 
       FIG. 13  shows a front perspective view of the reusable tray holder  212  in accordance with a third embodiment of the invention. Instead of ledges  160 , the top and bottom of the opposing sidewalls or fins  216  are provided with slots  280 . The slots  280  may extend horizontally, as shown, or at any other angle. For example, the slots may extend parallel to one another but angularly with respect to the channel. Still further, the slots may diverge from one another, in a distal direction. It will be understood that other orientations of the slots are possible as well. The slots  280  allow the impression material to flow through the slots  280 . Once the impression material sets, the impression material is held firmly in place. 
     The reusable tray holder may be made of a rigid material such as stainless steel or titanium.  FIG. 13  is an example of a one-piece reusable tray holder. A color coded label or indicia is provided on the handle to identify the size of the reusable tray holder. 
     In practice, the appropriate sized reusable rigid tray holder is selected based on the color code and the particular patient. A corresponding disposable bite tray is similarly selected based on the same color code. The disposable bite tray is fitted to the reusable tray holder and is then loaded with the impression material which adheres to the tray holder and bite tray without the use of an adhesive. The reusable dental impression tray with impression material is placed inside the patient&#39;s mouth and the patient bites down on the soft impression material until the material sets. The tray and impression material is then removed from the patient&#39;s mouth and sent to the dental laboratory. Dental stone is poured into the impression to form a model of the patient&#39;s tooth dentition. Due to the rigidity of the tray holder, multiple impressions can then be cast without the impression material deforming. Once all casting is complete, the disposable bite tray is removed from the reusable rigid tray holder, along with the impression material. The reusable rigid tray holder can then be cleaned and sterilized, and a new disposable bite tray may be inserted, ready for use. 
     While the present invention has been described in connection with a specific application, this application is exemplary in nature and is not intended to be limiting on the possible applications of this invention. It will be understood that modifications and variations may be effected without departing from the spirit and scope of the present invention. It will be appreciated that the present disclosure is intended as an exemplification of the invention and is not intended to limit the invention to the specific embodiments illustrated and described. The disclosure is intended to cover, by the appended claims, all such modifications as fall within the scope of the claims.