Abstract:
A dental handpiece for applying dental material to polish a tooth. The handpiece includes a conduit and a plunger for dispensing dental material adjacent a polishing member. The plunger and the polishing member can be controlled by a drive member, which may move in both a forward and reverse direction.

Description:
RELATED APPLICATION 
   This application claims the benefit of co-pending provisional patent application Serial No. 60/411,297, filed 17 Sep. 2002. 

   BACKGROUND OF THE INVENTION 
   The present invention relates generally to a dental handpiece, and more specifically to a dental handpiece adapted to apply dental material to a patient&#39;s tooth or teeth and having removable sections. 
   Dental handpieces for dispensing dental material are well known in the art. For example Charlton (U.S. Pat. No. 6,083,000) and Lewis (U.S. Pat. No. 3,389,3468) are designed to distribute dental material in a controlled fashion. Generally, a predetermined amount of dental material is stored in a reservoir within the handpiece and a longitudinally moving plunger pushes a plug into the reservoir, dispensing the dental material in a controlled fashion. The dental material may be loaded directly within the reservoir or contained within a capsule that is placed within the reservoir. 
   Although dental handpieces and disposable capsules have become a convenient way to dispense a controlled amount of dental material into a patient&#39;s mouth, the handpieces do not necessarily provide the most sterile environment. Though capsules of dental material can be measured for a single patient use, there still may be residue dental material in the handpiece itself after use. Especially when a corkscrew style plunger is used, the handpiece may not be sufficiently cleaned or sterilized between consecutive patients. The dental material is not easily washed out of the devices, and one cannot be certain that the material has been completely removed. 
   For the foregoing reasons, there is a need for a device that will allow a dentist, hygienist, or a dental assistant to dispense a controlled amount of dental material into a patient&#39;s mouth in a manner that is efficient and hygienic. 
   SUMMARY OF THE INVENTION 
   The present invention alleviates the above problem by disclosing a dental handpiece that is easily kept clean and sterile. The handpiece is designed generally to dispense prophy paste or similar material in a safe, sanitary manner. 
   The handpiece comprises a detachable shield that fits securely onto the body of the handpiece. The shield contains a conduit passing through the shield. At one end the conduit is in fluid communication with a reservoir of dental material, and the opposing end of the conduit is in fluid communication with the area where the dental material will be dispensed. Once the shield has been used, it may be removed and discarded, or autoclaved if preferred. The disposable shield helps ensure that residual dental material will not pass from one application to the next. 
   Along with the shield, the reservoir for the dental material contributes to the sanitary nature of the invention. The reservoir is adapted to receive a cartridge of dental material having opposing ends. One end of the capsule is in fluid communication with a conduit located in the shield, while the opposite end is in communication with a plunger. The plunger pushes the dental material through the reservoir so that the dental material may enter the conduit located in the shield. Because of the design of the reservoir, plunger, and the cartridge, the dental material has minimal contact with the walls of the reservoir, and the cartridge may be discarded after being used, thereby contributing to the overall sanitary features of the handpiece. Likewise, the design prevents dental material from coming in contact with any of the mechanical parts of the handpiece. 
   The plunger pushes the dental material through the conduit in the shield, allowing the material to exit at an area where a tooth is to be polished by a rotating polishing device, such as a prophy cup. 
   The plunger can be operated manually, but is preferably driven by a drive mechanism located within the body of the handpiece. The plunger has a semi-helical design, which meshes with a gear or cog connected to the drive mechanism. The drive mechanism also drives the polishing device or other attachment located on the end of the handpiece. A reversible direction trigger controls the drive mechanism, allowing easy control of the handpiece. The drive mechanism is enclosed within the body of the handpiece and does not come into contact with the dental material. 
   The overall design allows for an efficient dental handpiece with improved sanitary operating conditions. Dental material will generally be completely removed after each application, and the mechanical features of the device will not come into contact with the dental material. 
   These and other advantages will become more evident in the following description. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of an embodiment of the current invention. 
       FIG. 2  is a perspective view of an embodiment of the current invention. 
       FIG. 3  is a cutaway view of the invention shown in  FIG. 2 . 
       FIG. 4  shows a cutaway view of the present invention in use by a person. 
       FIG. 5  shows a cutaway view of the present invention after a user has finished applying a dental material. 
   

   DETAILED DESCRIPTION 
   Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention that may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     FIG. 1  shows an exploded view of a handpiece  9  in accordance with the present invention. The handpiece  9  has a body  10  that allows a user to engage the handpiece  9 . A removable shield  12  fits securely onto a front portion  11  of the body  10 . A reservoir  14  sits on a back portion  13  of the body  10 . The reservoir  14  and the body may be formed from one piece of material or separate pieces. The reservoir  14  is in communication with a plunger  16  having a helical underside  18 . The reservoir  14  will also contain a through cartridge  20  containing a dental material or prophy paste  21 . The cartridge  20  has a first end  22  and a second end  24 . The first end  22  can be sealed, while the second end  24  is generally open. The second end  24  may contain a removable cover (not shown) for when the cartridge  20  is not in use. A trigger device  26  is connected to the body  10  and can control the action of a polishing member  28 . An adaptor  30  allows the handpiece  9  to be powered from a power source, preferable an air source, but any suitable power source will be allowed (not shown). 
     FIG. 2  shows a perspective view of the handpiece  9  of the present invention. The shield  12  fittingly sits on the front end  11  of the body  10  and protects the body  10  from undue splatter when the polishing member  28  is in use. The cartridge  20  fits securely between the reservoir  14  and the shield  12 , with a portion of the cartridge  20  secured inside of the reservoir  14 . Generally, the cartridge  20  will be secured in the handpiece  9  before the shield  12  is secured on the handpiece  9 . The opposing ends  22  and  24  are in fluid communication with the shield  12  and the reservoir  14 , respectively. This communication can be seen clearer in  FIG. 3 . 
     FIG. 3  is a sectional view of the handpiece  9 . The shield  12  has a through conduit  32  having a proximal end  34  and a distal end  36 . The distal end  36  is located near the polishing member  28  and allows an exit for the dental material  21 . The proximal end  34  is in fluid communication with the first end  22  of the cartridge  20 . The proximal end  34  is sharpened so that it can pierce and penetrate the closed first end  22  of the cartridge  20 . This ensures that the dental material  21  will only be delivered into the conduit  32  of the shield, rather into or onto the handpiece  9 . As a safety measure, the proximal end  34  preferably does not extend past the end of the shield  12 . 
   Still referring to  FIG. 3 , the second end  24  of the cartridge  20  is secured within the reservoir  14 . The cartridge  20  is shown protruding out of the reservoir  14 , but it is possible that the reservoir  14  would encompass most or the entire cartridge  20 . The second end  24  is arranged so that it will be able to receive the plunger  16 . The helical underside  18  of the plunger  16  is in contact with a threaded cog  44 . The helical underside  18  meshes with the cog  44 , and as the cog  44  turns, the plunger  16  is moved forward to engage the dental material  21  within the cartridge  20 . If the plunger  16  is to be withdrawn, the cog  44  is rotated in the opposite direction and the plunger  16  moves backward. While the design of the plunger  16  allows it to move backward and forward without rotating, it is also conceivable that the plunger  16  may be designed to rotate. 
   Essentially a drive mechanism  38  drives the cog  44 . The drive mechanism  38  consists of a main drive shaft  40 , a motor  41 , a main drive gear  42 , a secondary drive shaft  46 , and a secondary drive gear  47 . The drive mechanism  38  receives power through the adaptor  30 , which can be joined to any suitable power source. Ideally, the device is driven with air as a power source, but any suitable power source is allowable. 
   The motor  41  turns the main drive gear  42 . The teeth of the main drive gear  42  mesh with the teeth of the secondary drive gear  47 . The main drive gear  42  will turn, thereby rotating the secondary drive gear  47 , causing the secondary drive shaft  46  to rotate, as well. The secondary drive shaft  46  turns the cog  44 , thereby moving the plunger  16 , as stated above. 
   The main drive shaft  40  is connected to the polishing means  28 . As the motor  41  turns the main drive gear  42 , the main drive shaft  40  is also turned, thereby spinning the polishing means  28 . In a preferred embodiment, the polishing means  28  is a prophy cup. The handpiece  9  is designed so that the polishing means  28  and the plunger  16  are rotated or moved concurrently, thereby allowing the user to manipulate a single control to polish a patient&#39;s tooth. 
   Referring to  FIGS. 4 ,  5 , and  6 , the handpiece  9  is shown engaged by a finger  48 . The finger  48  makes contact with the trigger  26 . The trigger is connected to and controls the motor  41 , thereby controlling the drive mechanism  38 . The trigger  26  allows for both a forward and reverse direction of the drive mechanism  38 . As shown in  FIG. 4 , the drive mechanism  38  is activated by pulling the trigger  26  backwards toward the back portion  13  of the handpiece  9 , allowing the plunger  16  to move forward and into the reservoir  14 , contacting the cartridge  20  of dental material  21 . The dental material  21  passes through the conduit  32  and exits at the distal end  36  of the conduit  32 . The dental material  21  can then be deposited on a tooth  50  (see  FIG. 6 ), which will be polished by the polishing means  28 . If one wishes to stop the flow of dental material  21 , one simply removes their finger from the trigger  26 . 
   When the polishing is finished, the trigger  26  can be moved in the opposite direction towards the front portion  11  of the handpiece  9 , as shown in  FIG. 5 , thereby causing the plunger  16  to withdraw from the reservoir  14  and the cartridge  20 . The empty cartridge  20  may then be removed from the handpiece  9  and discarded. It is also possible that the plunger  16  may be designed so that one could manually disengage the helical side  18  of the plunger  16  from the cog  44  and be removed from the reservoir  14  manually. The cartridge  20  and the shield  12  are then discarded, or autoclaved if desired. The result is a polished tooth  50  and a handpiece  9  without residual dental material  21  built up on the handpiece  9 . 
   While the drive mechanism  38  is described to control both the polishing means  28  and the plunger  16 , it is foreseeable that they could be operated by separate controls. Also, if desired, the plunger  16  could be operated manually rather than by a motor, and the movement of the plunger  16  could also control the polishing means  28  without use of a motor. 
   The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.