Abstract:
An apparatus for whitening teeth comprises a mouth tray comprising a horseshoe-shaped trough sized to accommodate a dental ridge. A planar projection extends from the outer side of the trough so that its far end is external of the mouth. A light box containing a plurality of LEDs couples with the external end of the projection and illuminates the projection end. The mouth tray and projection are formed of a light-transmissive material to irradiate a peroxide gel in the trough to whiten the user&#39;s teeth.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority of U.S. Provisional Patent Application 61/444,304 filed Feb. 18, 2011, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to methods and apparatus for whitening surfaces of teeth employing an intra-oral mouth tray having a trough shaped to accommodate a toothed ridge, formed of light-conductive materials which may be filled with whitening gels and an extra-oral light source based on laser diodes which mates with the trough to apply the radiation from the LEDs to the material in the trough. 
       BACKGROUND OF THE INVENTION 
       [0003]    The aesthetic value of whitened visible tooth surfaces has led to the development of a number of techniques for whitening ranging from the application of plastic veneers to the visible surfaces of the teeth to whitening toothpastes. 
         [0004]    Many of these techniques employ bleaching involving the application of gels to the visible teeth surfaces. The gels break down either over time or at an accelerated rate by the application of radiant energy to produce byproducts operative to oxidize the discolored tooth surfaces and produce whitening. The bleaching compounds typically employ forms of peroxide and are often applied using trough-like mouth trays which may be filled with the gel-like peroxide compounds so that all of the visible surfaces of a patient&#39;s teeth are whitened at the same time. 
         [0005]    Radiation may be directed at the gel covered teeth surfaces to accelerate the decomposition of the gels. A variety of systems have been proposed for applying radiant energy to the gels within an oral tray such as the systems shown in U.S. Pat. No. 7,645,137 and U.S. Pat. No. 8,029,278. These systems generally provide intra-oral light sources, either within or on the outer side of the trays containing the gels. The power sources for these lights may be either battery power or power applied from a source outside the mouth which is connected into the mouth. 
         [0006]    The application of electric power for the illumination sources within the mouth is problematic. The user of the device is required to bite the tray and there exists a danger of applying the electrical potentials used to power the lights into the patient&#39;s mouth. The illumination sources are also fragile and the oral pressures applied during the use of the device may break them. Moreover, while the devices are often used in dentists&#39; offices, it would be desirable to provide a system simple and safe enough to be adaptable for home use so that it could be employed by consumers to periodically perform the whitening process and thereby maintain a highly aesthetic look over extended periods of time. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is broadly directed to such a system. A preferred embodiment of the system of the present invention, which will subsequently be described in detail, broadly consists of a horseshoe shaped, trough-like mouth tray formed of a material that is transparent or translucent to radiation of a wavelength capable of accelerating the whitening process. The trough is adapted to be filled with any conventional tooth whitening gel, preferably of the peroxide type. The tray has a base section which extends forwardly of the trough, so that the trough may be filled with gel, inserted into a user&#39;s mouth so that the user&#39;s teeth are disposed within the trough with the user&#39;s lips closed about the top and the bottom of the forwardly extending base section. The forward end of the base section terminates in a male dovetail shape. 
         [0008]    The entire tray, trough, base, and dovetail are preferably formed of a relatively soft medical grade silicone or plastic material that is transparent to and internally transmissive of light of an appropriate wavelength. In the case of the preferred embodiment, this light is produced by blue LEDs having a 450-500 nm dominant wavelength. 
         [0009]    The male dovetail, which extends upwardly at the forward end of the trough base, is adapted to be inserted within a complementary female dovetail formed at one end of a generally rectangular light source. The light source preferably contains a series of blue LEDs arranged at regular intervals adapted to illuminate the forward edge of the male dovetail. The LEDs are powered by a 1.5 volt rechargeable battery which feeds a voltage multiplier current supported on a printed circuit board within the light source. A switch on the light source controls the powering of the LEDs and when illuminated the LEDs transmit light through the male dovetail section of the trough extension into the base and upwardly through the trough walls so that all sides of the teeth are irradiated by the light. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Other objects, advantages, and applications of the present invention will be made apparent by the following detailed description of a preferred embodiment of the invention. The description makes reference to the accompanying drawings in which: 
           [0011]      FIG. 1  is a semi schematic view of a user&#39;s mouth while employing the preferred embodiment of the invention, shown in cross section; 
           [0012]      FIG. 2  is a perspective view from the rear top of a preferred embodiment of the invention with the two sections, the trough-like mouthpiece and the light box, engaged with one another; 
           [0013]      FIG. 3  is a similar perspective view with the two sections separated from one another; 
           [0014]      FIG. 4  is a view similar to  FIG. 3  in which the components of the light box are shown in exploded view; and 
           [0015]      FIG. 5  is an enlarged longitudinal cross section through the preferred embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    Referring to the drawings, the preferred embodiment of the device of the present invention generally comprises two components, a tray with a general U-shaped mouth trough, generally indicated at  10 , and a light box, generally indicated at  12 . The two units may be joined together as illustrated in  FIG. 2  or separated from one another as illustrated in  FIG. 3 . The light box  12  preferably employs a series of five blue LEDs  14 , best seen in  FIG. 4 , and accordingly the plastic used for the trough  10  is particularly transparent to light in the 450-500 nm wavelength generated by blue lasers  14 . 
         [0017]    The mouth tray  10  generally comprises a horseshoe configuration with an upper trough section  16  and a lower trough section  18  which are configured to accommodate the upper and lower dental ridges of a user as generally illustrated at  28  in  FIG. 1 . The upper and lower trough sections  16  and  18  have a common planar base  20 . At the forward side of the trough, in the same plane as the base  20 , a forward projection  22  terminates at its far end with a male connecting section  24  comprising a section, convex in cross section, and curved in a convex manner in the plane of the base  20 . The projecting section  22  and the male coupling section  24  are separated by a vertically projecting curved section  26  which extends above and below the plane of the base  20  and the connecting section  22 . In the preferred embodiment of the invention the plastic used for the mouth tray  10  and projection  22  is a urethane, substantially transparent to the wavelength of the LEDs, such as BASF Elastollan 1170A. 
         [0018]    As is best seen in  FIG. 1 , the tray  10 , in use, is disposed within the user&#39;s mouth with the user&#39;s upper and lower teeth  30  and  32  extending into the upper and lower trough sections  16  and  18  respectively, with the ends of the teeth abutting the top and the bottom surfaces of the base  20 . Previous to insertion of the trough within the user&#39;s mouth the troughs will be partially filled with a material, usually in gel form, which will break down to produce hydrogen peroxide which acts to oxidize and whiten inter-prismatic extrinsic staining formed on the tooth enamel. 
         [0019]    Although any of a wide range of gels which are commercially available may be used with the invention, a preferred gel is carbamide peroxide, also termed urea hydrogen peroxide, blended with percarbamide, an oxidizing agent. The molecular formula for this gel is CH 6 N 2 O 3  or CH 4 N 2 O.H 2 O 2 . It is a white crystalline solid that releases oxygen in contact with water. This peroxide oxidizing agent is preferably used in combinations below about 30% carbamide peroxide (10% hydrogen peroxide equivalent) and at least 10% carbamide peroxide. The most preferred formula is 22% carbamide peroxide (7% hydrogen peroxide equivalent). 
         [0020]    While the preferred embodiment contains the complementary troughs  16  and  18 , so as to operate upon both the upper and lower dental ridges, in alternative embodiments of the invention only a single trough could be employed so as to make it useful for either the upper or lower dental ridges, but not both simultaneously. The gel contained within the dental trough decomposes at an accelerated rate when subjected to light from the LEDs  14 , or alternative light sources, to substantially reduce the time required for a brightening session. 
         [0021]    In use, as illustrated in  FIG. 1 , the user&#39;s teeth  30  are disposed within the trough or troughs which have been previously filled with gel so that they coat the user&#39;s teeth. Alternatively, the gel could be applied to the teeth before they are put into the troughs, which would also contain some gel, to ensure full coverage of the teeth. The user&#39;s lips are positioned over the projection  22  between the inner wall of the section  26  and the outer wall of the troughs. 
         [0022]    The mouth tray  10  may be assembled with the light box  12  either before the trough section is inserted in the user&#39;s mouth or afterward. The light box  12  mates with the section  24  of the mouth tray by means of a curved groove  30  that is open at one end  32  and closed at the other end by a side wall  34  of the light box. The groove  30  is curved in a complementary manner to the mouth tray extending section  24  so that one end of the trough may be inserted through the opening  32  and will snugly engage the convex projection  24  along their entire lengths of contact. 
         [0023]    When the upper light cover section  38  is joined to the lower section, as illustrated in the figures, the front end of the channel  32  is fully closed off, but the rear wall of the channel has a cutaway section  40  that connects to the interior of the closed light box and allows light from the LEDs  14  to project along the length of the male connecting section  24 . By virtue of the light-conducting ability of the plastic used in the trough  10 , this conducts light into the trough walls and thus into the gel coating the user&#39;s teeth. The curvature of the connecting section  24  evenly distributes the light from the LEDs into the trough and the convex shape of the section  24  acts much like a lens to distribute the light. 
         [0024]    This arrangement of putting the light source externally of a mouth and simply transmitting light into the mouth obviates the need to bring electric current into the mouth which is problematic. 
         [0025]    The LEDs  14  are supported on and project from a printed circuit board  42  which is supported in slots  44  formed in both sections of the light box cover. The printed circuit board supports a 1.5 volt rechargeable battery  46  on the side opposite the LEDs  14 . Circuitry on the PC board  42  includes a voltage multiplier which raises the voltage applied to the LEDs to approximately 4.5 volts, and conductors for recharging the battery from the exterior of the light box. 
         [0026]    The energization of the LEDs from the PC board is controlled by a switch  48  supported on the PC board, which may be actuated by a pushbutton  50  supported in the top section  38  of the light box. The pushbutton  50  is pivoted at one of its ends and when depressed actuates the switch  40 . 
         [0027]    The devices of the present invention are thus simple in construction and easy to use without the need to accommodate electrical circuitry within the user&#39;s mouth. 
         [0028]    Having thus described our invention,