Abstract:
A powdering attachment for applying powder to tooth surfaces is disclosed. Such an attachment is useful in operations such as preparations of a tooth before the use of dental equipment in the CEREC® family of products. The powdering attachment may be connected to a dry air syringe that is adapted to allow for the removable connection of dental accessories such as the powdering attachment. When connected to the dry air syringe, the control valve mechanism on the dry air syringe controls the air flow into the powdering attachment. An air tip assembly is given as an illustration of another dental accessory that may be attached to the modified dry air syringe.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The disclosed device and method for use are in the field of dental tools. 
     2. Description of Prior Art 
     Restorative dental work includes a computer-aided method of making a replica tooth from a ceramic block through the use of a computer controlled milling machine. The replica tooth is made based on the tooth to be restored. This tooth is in the patient&#39;s mouth. The tooth is prepared by removal of silver fillings and any decayed material. The next step is to capture the shape of the tooth. In order to capture the digital image of the tooth by an imaging device, the tooth is made to contrast with the rest of the patient&#39;s mouth by coating the surfaces of the tooth with a suitable powder. This step is known as “powdering” the tooth. The imaging device is used to collect an image of the powdered tooth. 
     One such method uses a powder comprised of titanium dioxide and talc. The imaging system is a handheld infrared camera. Such a system is manufactured by Siemens Dental Products Division and distributed in the United States by Patterson Dental Supply, Inc. of St. Paul, Minn. under the name CEREC® 3. 
     Although the CEREC® 1, CEREC® 2 and now CEREC® 3 systems have been used for over a decade, the powdering devices are not well liked by the dentists that powder teeth. The powdering device is important because powdering is the first step towards successful completion of this restorative dental work. Problems with the application of the powder interfere with the attainment of suitable results in the imaging and digitizing steps. More specifically, the CEREC® 3 computer converts the light and dark areas of the image of the tooth into values representative of the height and depth of the surface of the tooth. This imaging process requires the application of a uniform coat of powder so that the entire target surface is covered. Too much powder is a problem as is too thin a coat. Thus, it is important to have a process that applies a uniform coat of powder to the target area. 
     One prior art device for this critical “powdering” step involved a pair of containers. One container held pressurized butane gas. The second container held the reflective powder. The device operated by releasing butane from the first container into the second container. The butane then carried reflective powder out of the second container and through a flexible tube towards the tooth to be coated. Such an applicator was distributed by Vita Zahnfabrik H. Rauter Graph and Co. KG of Bad Sackingen, Germany. Alternative suppliers of the butane propellant devices are Ivoclar™ (sold as ProCad powder) and Vita™ brand powder. Typically, these powdering techniques call for using a brush to apply imaging liquid to all the surfaces visible in the imaging step. The surfaces are blown dry after the imaging liquid is applied. Next the powder is sprayed on in a steady stream from a nozzle held about one or two centimeters from the tooth surface. 
     An alternative device is described in U.S. Pat. Nos. 5,944,521 and 6,099,306 for a Tooth Powdering Applicator issued to David Lawler. The Lawler device replaces the attached container of pressurized butane with a connection to a pressurized fluid. The outlet tube is rigid and curved. The Lawler device was designed to allow a dentist to use a single hand to hold the device and simultaneously rotate the outlet tube without use of the second hand of the dentist. The stated advantage was that the outlet tube can be rotated to allow the discharge stream from the powdering device to be aimed at various tooth surfaces without tilting the powder reservoir. Tilting the powder reservoir in the powdering device was thought to increase the risk of clumping the powder. Some embodiments of the Lawler device would include a valve on the powder container to allow the dentist to control the flow of fluid and powder with the hand holding the powdering device. Often a second foot controlled valve would be used in combination with the valve on the powder container. A device based on the Lawler patent is sold under the name PowderMeister™ by Powder Meister, Inc. of Bloomington, Ind. 
     Problems with Prior Art Solutions 
     The PowderMeister™ device requires an adjustment process each time it is used. The process includes closing the valve on the container using a thumbscrew so that no air can go into the powder container. Next, the foot control for the pressurized air is fully depressed. With the foot control remaining depressed, the thumbscrew is used to slowly open the valve on the container until the powder begins to flow. It is suggested that the initial spraying of powder within the mouth be directed to a tooth adjacent to the tooth to be powdered for imaging. This allows the clumps of powder to be discharged somewhere other than on the target tooth. Some clumps are attributed to storing the PowderMeister™ on its side or upside down so that excess powder enters the powdering tube. Water in the pressurized source of air poses a problem with the PowderMeister™ as the water will cause the powder to clump. 
     A second problem area with the PowderMeister™ device is the thumbscrew controlled air valve on the container. The amount of powder applied to the tooth is very sensitive to the position of the thumbscrew. That is, very little movement of the thumbscrew is needed to effect a change in the powder flow. Some dentists find that thumbscrews turn too freely. One corrective trick is to apply Super Glue™ to the threads of the thumbscrew air regulator to keep the thumbscrew from rotating too easily. 
     It is an object of this invention to provide a powdering device that is adapted to work with a valve that can be operated with one hand to apply a precise amount of airflow into the powder container. 
     It is an object of this invention to provide a powdering device that is easy to store in an upright position so that powder clumps do not form from non-upright storage. 
     It is an object of this invention to eliminate powder clumping caused by moisture in the pressurized air supply. 
     It is an object of this invention to allow the precision controlled dry air supply to be used in dental steps other than powdering to allow the dentist the option of purchasing less equipment. 
     It is an object of this invention to allow for quick changes between an air delivery function and the function of providing a dry air supply to the powdering device. 
     It is an object of this invention to provide these advantages while providing a device that is ergonomic such that is provides both accurate placement of powder while being comfortable to use. 
     These and other advantages of the present invention are apparent from the drawings and the detailed description that follows. 
     BRIEF SUMMARY OF DISCLOSURE 
     The improved powdering device disclosed herein is a powdering attachment designed to be used in conjunction with an existing piece of dental equipment known as a dry air syringe. The combination of the powdering attachment and the air syringe forms a powdering device. The dry air syringe is an ergonomic device with integral moisture filter designed for one-handed operation by the dentist. A precision valve on the top of the device allows the dentist to control the airflow by pressing with the thumb of the hand holding the air syringe. The powdering attachment is added to the outlet tube of the air syringe. No valve is needed on the powdering attachment. Nothing needs to be set. A foot-operated valve is not needed to turn the airflow on and off. The outlet tube on the powdering attachment rotates against resistance to allow alteration of the placement of the powder through use of the dentist&#39;s other hand. The powdering attachment is designed to allow quick removal of the outlet tube so that the outlet tube can be removed for sterilization after each patient. 
     The powdering attachment is designed to be easily removed from air syringe. Once disconnected from the air syringe, the powdering attachment is easy to store as it does not have an airline attached to it. When not used for powdering, the air syringe can be used for other operations such as porcelain bonding or any other bonding with dry air. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded cross section of the tooth powdering device comprising the tooth powdering applicator and the dry air syringe. 
     FIG. 2 shows additional details on the rigid outlet tube  128  and ball plunger assembly  152 . 
     FIG. 3 shows how the rigid inlet tube  124  may be created from an air syringe air tip  226 . 
     FIG. 4 shows details on the components of the air tip assembly  300 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art of which the invention relates. 
     Tooth Powdering Applicator 
     Referring now more particularly to the drawings there is shown a tooth powdering applicator  100  including a powder holding container  108  for holding the reflective powder to be applied to the tooth to form a reflective coating thereon. The container has an air inlet  112  and a powder outlet  116  provided in the manifold block  174 . A rigid inlet tube  124  has one end connected to air inlet  112  and the opposite end connected to a dry air syringe body  200  supplying filtered air. As used within this specification and the claims that follow, the term dry air is used in the context of dental devices. Thus the air does not need to be absolutely dry, simply dry enough to serve as “dry air”. 
     Container  108  is hollow for holding a reflective powder. By way of illustration one such reflective powder is a mix of a titanium oxide and talc powder (CEREC® 2 POWDER by VIDENT available from Patterson Dental Supply, of St. Paul, Minn.). The manifold block  174  is attached to the threaded removable container cover  120  by the securing screw  160 . Threaded removable container cover  120  is removed when the tooth powdering applicator  100  is to be filled with reflective powder. 
     Dry Air Syringe 
     The dry air syringe body  200  is operated by button  202  to provide input to the control valve mechanism  204  to deliver precise amounts of filtered air into powder holding container  108  exiting bottom end of down tube  164  through bottom end tip  168 . The dry air exiting through the bottom end tip  168  to agitate and transport tooth powdering powder out of the powder holding container through outlet channel  118 . 
     The dry air syringe body  200  such as found in a bonding dry air syringe from American Dental Accessories, Inc. of Minneapolis, Minn. provides dry pressurized air. The body with its pistol type grip is ergonomically designed for comfortable use. The delivery of dry air helps prevent moisture contamination of the imaging powder. Optionally the dry air syringe body can be fitted with a quick disconnect (not shown) to allow the line connecting the dry air syringe to the air supply line to be quickly connected or disconnected. 
     The dry air syringe body is also an extremely useful tool when used with the optional air tip assemblies (described below). The quick disconnect feature with thumbscrew  148  allows for immediate conversion from a powdering device to a dry air bonding syringe useful in numerous dental procedures. The dry air syringe body can be conveniently located and stored in many places in and around a dental unit due to its standardized size and holding devices. This is an advantage when compared to other devices which have no suitable holders or holding fixtures. The present invention is not limited to use with a particular bonding dry air syringe. The present invention can be easily adapted by those of skill in the art to connect to other dry air syringes. 
     While the internal operation of the dry air syringe is not part of the present invention, for those not familiar with the operation of a dry air syringe, FIG. 1 shows additional detail. Air is provided to the air syringe body  200  through tubing connected to air supply outlet  220 . The air enters the dry air syringe body  200  and passes through a moisture filter  218  such as cotton within a filter case  224  within the core of the handpiece handle  216 . The dry air exits the moisture filter  218  and passes through the control valve mechanism  204  of the valve operated by push button  202 . The traditional use of a dry air syringe body  200  would be with an air tip  226  (shown in FIG.  3 ). This air tip  226  would be attached to the threaded air outlet  222  of the dry air syringe body by tip holding nut  210 , plastic tip cone  212 , O-ring adapter nut  214 , syringe tip adaptor nut  206 , and O-ring  208 . 
     When used in connection with the tooth powdering applicator  100 , air tip  226  is replaced with rigid inlet tube  124 . Optionally, rigid inlet tube  124  may be made by modifying an air tip  226 . The comparison between air tip  226  and rigid inlet tube  124  is best seen in FIG.  3 . As described below, the substitution of rigid inlet tube  124  for air tip  226  allows the dry air syringe body  200  to be used with a variety of dental accessories. The modified dry air syringe may be used with other dental accessories not discussed within this application which need a controlled source for dry air. 
     Air Tip Assembly 
     While it would be possible to have one dry air syringe for providing dry air to the tooth powdering applicator and one for use in providing dry air to the mouth, it is advantageous to use one dry air syringe for both uses. Accordingly it is advantageous to be able to quickly shift from one function of the air syringe to the other. Disassembling elements  210 ,  212 ,  214 , from threaded air outlet  222  in order to switch back and forth from air tip  226  and rigid inlet tube  124  would take too long as a dentist using a powdering device often needs to switch from powdering to blowing with air to powdering again in a span of twenty or thirty seconds. Thus, it is advantageous to use air tip assembly  300  shown in FIG.  4 . 
     The dry air syringe may be used without the powdering device to deliver air precisely to areas that are difficult to reach, by attaching the air tip assembly  300 . The tooth powdering applicator is quickly removed by turning inlet tube thumbscrew  148  (or an alternative hand manipulated fastening mechanism) to remove the rigid inlet tube  124  from the inlet to the tooth powdering applicator  100 . The air tip assembly  300  slips over the end of rigid inlet tube  124  and stays on with a friction fit. The air tip assembly  300  can be made by adapting an ACCESS® Tip  304  sold be CENTRIX of Shelton, Connecticut as part number 290016 18ga, as part of its line if ACCESS® delivery syringes. The intended use of the ACCESS® Tip  304  is to deliver a silicon type impression material. The ACCESS® Tip  304  is combined with tubing shown as element  308  which can be cut to size from tubing stock from American Dental Accessories, Inc. The dry air syringe body  200  with rigid tube  124  and the air tip assembly  300  is very useful in dental bonding procedures where moisture free dry air is crucial. 
     Outlet Tube Assembly 
     As shown in FIG.  1  and FIG. 2, outlet tube  128  is attached to the manifold block  174  by the interaction of a plunger ball  156  of the ball plunger assembly  152  fitting into a detent  144  allowing for easy removal for sterilization purposes. Such a plunger is well known to those of skill in the art and typically has a threaded shank with a spring loaded steel ball within a hollow core of the plunger. A preferred material for the ball plunger assembly  152  is stainless steel. A preferred material for the outlet tube  128  is a medical grade stainless steel, such as a  316  stainless steel. The outlet tube  128  is easily rotated while holding the powder container  108  upright and rotating the outlet tube  128  with the other hand. The preferred methods for connecting the rigid outlet tube  128  allow for endless rotation of the rigid outlet tube  128 . In a preferred embodiment, the rigid outlet tube  128  is adapted to make it easier to grip. In one highly preferred embodiment, the rigid outlet tube  128  is placed inside of a silicon rubber sleeve  136  which is held in place by a locking ferrule  140 . The snap fit of the rigid outlet tube  128  is an advantage for quick changing of the outlet tube and for removal for sterilization. 
     The outlet tube assembly is comprised of a rigid outlet tube  128 . Rigid outlet tube  128  has a proximal end  146  connected to powder outlet  116  and a distal end  132  through which the powder is sprayed on the tooth. In a most preferred embodiment, the distal end  132  is arranged at an approximately 50-degree angle with respect to the to provide convenient access to all areas of the mouth. Note, that the invention is not limited to an approximately 50 degree angle as other angles between approximately 40 degrees and 90 degrees would work. The range of 45 to 75 degrees is thought to work better than 40 to 90 degrees with the most preferred angle at approximately 50 degrees. Note that as the outlet tube assembly is preferably set for quick connection/disconnection, an alternative embodiment would use two or more outlet tube assemblies with one assembly have a more severe angle than the other. 
     The tooth powdering applicator  100  can be easily removed (as described above) so that it can be stored upright. Storage of the tooth powdering applicator is simple in that there is no flexible tubing to be wrapped up or stored. 
     Loading and Use 
     The tooth powdering applicator  100  is loaded by first removing the removable container cover  120 . Next, reflective powder (not shown) is added to the powder holding container  108 . The height of the reflective powder should be below bottom end tip  168 . Typically the reflective powder is added until it fills approximately one third of the powder holding container  108 . 
     After filling the device with powder and attaching to compressed air line, it is aimed at a tooth that has been coated with suitable wetting agent causing the powder to stick as it is sprayed on the tooth. Care is taken to uniformly coat the tooth with a layer of reflective powder. The powder coats most uniformly when sprayed at a right angle to the surface you are coating. The delivery nozzle can be rotated to make it easier to spray the reflective powder on the various faces of the tooth. 
     Cleaning is accomplished by disassembling and blowing out with compressed air. The unit is disassembled. The air tip assembly  300  is placed on the dry air syringe. The dry air syringe and air tip is used to blow out each orifice in the disassembled unit. Generally the unit will not need to be rinsed with water unless the unit was contaminated by moisture. In that rare case, the unit can be washed and then completely dried before the next use. 
     Examples of preferred materials for the present invention include 8-36×{fraction (11/32)} stainless steel ball plunger; 6-32×⅜ stainless steel SHC screw; 6-32×14 stainless steel SHC screw; knurled knobs; medical grade stainless steel tubing; medical grade silicone tubing; {fraction (1/16)} inch tubing (brass); ⅛ inch tubing (brass); ½ inch aluminum bar (6061); and a medicine bottle. 
     Those skilled in the art will recognize that the methods and apparatus of the present invention has many applications and that the present invention is not limited to the specific examples given to promote understanding of the present invention. Moreover, the scope of the present invention covers the range of variations, modifications, and substitutes for the system components described herein, as would be known to those of skill in the art. 
     The legal limitations of the scope of the claimed invention are set forth in the claims that follow and extend to cover their legal equivalents. Those unfamiliar with the legal tests for equivalency should consult a person registered to practice before the patent authority which granted this patent such as the United States Patent and Trademark Office or its counterpart.