Abstract:
A device for sharpening one or more cutting edges of a dental curette has a base support with a frame articulated thereon, and at least one sharpening guide. The frame supports a grinding wheel rotationally driven by a motor and a sharpening guide support intended to receive the sharpening guide(s). The guide includes at least one indicator in the form of a line marked on the guide, whose angle with the horizontal being between 10° and 50° but preferably equal to 10°, 20° or 30° and corresponding to the type of dental curette to be sharpened. The sharpening guide(s) can move with respect to the support, and the support and/or the guide include(s) indexing and positioning elements determining indexing positions of the guide on the support, each indexing position corresponding to a different indicator. A method of sharpening one or more cutting edges, and a sharpening guide are described.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device and a method for sharpening dental curettes. 
     Sharpening dental tools is problematic in that it must be able to be performed regularly by the operator or his assistants and must be precise and uniform. 
     2. Description of the Related Art 
     Manual sharpening devices for dental curettes are known, such as the Kramer sharpener or the device described in document CH 683 505, and motorised devices are known, such as the “Hawe PerioStar 3000” (trademark) from Kerr Hawe, the “LM Rondo Plus” from LM Dental Oy, or the “Sidekick” (trademark) from Hu-Friedy. 
     It often takes longer and is more complex to uniformly and precisely sharpen a cutting edge of a dental curette using manual devices. These devices require a great amount of dexterity and precision on the part of the operator in the placement and movements imparted to the curette. The motorised devices are easier to use but still require precise positioning of the curette with respect to the sharpening stone. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to a device and method for sharpening dental curettes which are simple, less costly, easy to implement by the operator or his assistants and which permit precise and simple positioning of a dental curette to be sharpened in order to achieve precise and uniform sharpening of the cutting edge(s) of said curette. The present invention also relates to a sharpening guide for implementing the sharpening method using said device. 
     The device and the method for sharpening dental curettes in accordance with the invention are characterised by the features listed in claim  1  and claim  16  respectively. The sharpening guide for implementing said sharpening method is for its part characterised by the features listed in claim  19 . 
     In particular, in one preferred embodiment of the invention, the device comprises a magnifying lens in line with the grinding wheel providing a magnification of the sharpening area and thus permitting precise and easy positioning of a dental curette to be sharpened by the operator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings schematically illustrate, by way of a non-limiting example, several embodiments of the device for sharpening dental curettes in accordance with the invention for the implementation of the method for sharpening such curettes in accordance with the invention. 
         FIG. 1  is a side view of a first embodiment of the device in accordance with the invention. 
         FIGS. 2 and 3  are front and rear views respectively of a sharpening guide of the sharpening device illustrated in  FIG. 1 . 
         FIG. 4  is a side view of a second embodiment of the device in accordance with the invention. 
         FIGS. 5 and 6  are front and rear views respectively of a sharpening guide of the sharpening device illustrated in  FIG. 4 . 
         FIG. 7  is a view of the device illustrated in  FIG. 1  during use thereof by a practitioner for sharpening a dental curette. 
         FIG. 8  illustrates a dental curette. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the device in accordance with the invention will now be described with reference to  FIGS. 1 to 3 . The sharpening device  1  for dental curettes in accordance with the invention, shown in a first embodiment in  FIG. 1 , has a base plate  2  on which there is articulated a frame  3  and at least one sharpening guide  4 . 
     Preferably, the inclination of the frame  3  with respect to the base plate  2  is adjustable using a first adjustment screw  5  for example. 
     The frame  2  supports a magnifying lens  6 , a sharpening guide support  7  as well as a motorised grinder  8 . 
     The magnifying lens  6  is fixed to the free end  3   a  of the frame  3 . The axis of the magnifying lens  6  and the axis of the guide support  7  are preferably perpendicular to the axis of the frame  3 . Second adjustment screws  10   a ,  10   b  enable the height of the guide support  7  and of the magnifying lens  6  respectively to be adjusted with respect to the frame  3 . 
     The grinder  8  as illustrated in  FIG. 1  comprises an electrical connecting cable  11 , a trigger  12  and a mandrel  13  intended to receive a grinding wheel  14 . Preferably, the grinding wheel  14  has a cylindrical flat form and the active surface of the grinding wheel  14  is parallel to the axis of the frame  3 . 
     Preferably, the mandrel  13  and the grinding wheel  14  are designed such that the grinding wheel  14  is press-fitted to the mandrel  13  and can be removed from said mandrel  13  using neither an unscrewing process nor another tool. It is thus easier to change the grinding wheel and it is very easy to simply turn over the grinding wheel  14  when one surface thereof is worn for example. 
     The grinding wheel  14  could be of a different size, shape or abrasive grain and the grinder  8  could further comprise a speed regulator or even be battery-operated. 
     The grinder  8  is placed on the frame  3  between the magnifying lens  6  and the guide support  7  and the axis of the grinding wheel  14  is preferably perpendicular to the axis of the frame  3 . Preferably, and as illustrated in  FIG. 1 , the grinder  8  is fixedly attached to the frame  3  by locking screws  15  and a secondary frame  16 . 
     The sharpening device  1  in accordance with the invention is intended to be placed on a table or any other working surface. For ease of use, the base plate  2  preferably comprises feet  17 . Said feet  17  could be height-adjustable. For safe and suitable gripping of the device, the feet preferably comprise anti-slip pads  18 . This device could comprise any other suitable fixing means such as a clamp for example. 
     The sharpening guide support  7  is formed in this first embodiment by a rod  19  whose height can be adjusted with respect to the frame  3 . The rod  19  supports a rotating guide disk  4  fixed to said rod  19  using a screw  20  for example. The guide disk  4  is freely rotatable with respect to the rod  19 . Indexing means are provided to determine the different usage positions of the guide disk during rotation thereof. Preferably, these indexing means comprise a protrusion (not shown) provided on the rod  19  and co-operating with at least one but preferably six recesses  21  in the rear face  4   b  of the guide disk as shown in  FIGS. 2 and 3 . 
     The guide disk is divided into at least one but preferably six sectors on its front face  4   a  shown in  FIG. 2 . Each indexing position of the guide disk is determined by a recess  21  and corresponds to a sector. The recesses  21  and the sectors are designed such that the correct position for each sector with respect to the grinding wheel  14  is ensured when snap-fitting the protrusion of the guide support  7  into the recess  21  corresponding to said sector. 
     Each of the sectors of the guide disk  4  comprises an indicator formed preferably of four markings:
         the first marking  22  is the letter R or L and indicates that said sector is intended to be used as a guide for a right-handed or left-handed operator respectively.   the second marking  23  contains the name of the type of curette to which the sector corresponds. There are three types of dental curettes: universal curettes, scalers (sickles) and Gracey-type curettes.   the third marking  24  designates the respective angles 10°, 20° and 30° corresponding to the different types of curette: 10° corresponding to the universal curettes, 20° to the scalers (sickles) and 30° to the Gracey-type curettes.   the fourth marking  25  is an indicating line, the angle of which with the horizontal corresponding to the angle of the third marking (the angles and orientations of the markings are defined for each sector in its indexing position). It is this line which will be used as a guide for the operator during sharpening. As illustrated in  FIG. 2 , the inclination of the indicating line also depends upon the laterality of the guide, i.e., upon the first marking  22 : if said sector is intended to be used as a guide for a right-handed operator, the indicating line rises from left to right from the point of view of the operator. If said sector is intended to be used as a guide for a left-handed operator, the indicating line then falls from left to right from the point of view of the operator.       

     Thus, a single guide disk  4  allows three different types of curette to be sharpened, whatever the laterality of the operator. 
     As a variation, the device could comprise two guide disks  4 , one for right-handed operators and one for left-handed operators. Each disk would then be divided into three sectors, one for each type of curette, each sector having an indicator formed of the second  23 , third  24  and fourth  25  markings described above. The rear face of such disks then comprises three recesses  21 , each corresponding to a sector and allowing the disk to be positioned by means of a snap-fitting arrangement with the protrusion of the guide support  7 . 
     Preferably, and as illustrated in  FIG. 1 , the sharpening device in accordance with the invention further comprises an eyepiece  26  stored in a storage mount  27  provided for this purpose on the base plate  2 . The eyepiece  26  enables the result of the sharpening operation to be verified after it is completed. 
     Preferably, the device in accordance with the invention further comprises an illumination system  29  allowing the grinding wheel  14  and the sharpening area of the dental curette to be sharpened to be illuminated. In the embodiments described in the Figures, the illumination system  29  comprises a hinged arm  30  fixed to the frame  3  between the magnifying lens  6  and the grinder  8  using a fixing screw  31  and preferably having a light-emitting diode (LED) lamp  32 . The hinged arm  30  can be pivoted with respect to the frame in order to position the illumination system in a suitable manner depending upon whether the operator is right-handed or left-handed. 
     Preferably, the device in accordance with the invention further comprises a stabilising support  33  fixed to the secondary frame  16 , the lateral and height position of which on said frame being adjustable using a third adjustment screw  34  for example. Said stabilising support  33  is designed to provide a support platform for the hand of the operator when sharpening a dental curette. The hand of the operator is thus stabilised and possible shaking is minimised, ensuring an even greater degree of precision when sharpening the dental curette. 
     A second embodiment of a device for sharpening dental curettes in accordance with the invention will now be described with reference to  FIGS. 4 to 6 . In this embodiment, the guide disk  4  is replaced by at least one but preferably six sharpening guides  40 . The sharpening guides  40  are in the form of a rectangular plate. The rear face  40   b  of each of the sharpening guides  40 , which is shown in  FIG. 6 , has a recess  41  whose position varies depending upon the guides. The role and said position of the recess  41  will be explained hereinafter. The front face  40   a  of each of the guides, which is shown in  FIG. 5 , has markings which will also be explained hereinafter. 
     In this embodiment, the base plate  2  has second storage mounts  43  which are each intended to receive a sharpening guide  40  in a vertical position. The presence of said storage mounts  43  thus facilitates the storage of the sharpening guides  40  as well as their accessibility for the operator. 
     The storage mounts  43  could be replaced by any other storage system, whether fixed to the base plate  2  or not. Thus, the sharpening device could comprise a housing used to store the sharpening guides  40 . 
     The frame  3  supports, as in the first embodiment, a magnifying lens  6 , a sharpening guide support  7  as well as a motorised grinder  8 . 
     In this embodiment, the sharpening guide support  7  has the shape of a rest  44  comprising a leg  45  and a tray  46  provided with a shoulder  47  intended to receive a sharpening guide  40 . The tray  46  has a protrusion  48  intended to co-operate with the recess  41  in each of the sharpening guides  40 . The correct positioning of a sharpening guide  40  on the tray  46  is ensured when snap-fitting the protrusion  48  into the recess  41  in said guide and by the shoulder  47  preventing the guide from pivoting. Of course, the sharpening guides  40  could conversely comprise a protrusion on their rear face which then co-operates with a recess in the tray of the rest. 
     The protrusion  48 , the recess  41  and the shoulder  47  of the rest  44  thus form positioning means for the sharpening guides  40  on the rest  44 . In general, these positioning means could be formed by any other suitable element and the rest  44  does not have to comprise a shoulder  47 . 
     There are four markings on the front face  40   a  of each sharpening guide  40  shown in  FIG. 5 , these markings being similar to those shown on each sector of the guide disk  4  described in the first embodiment of the invention:
         the first marking  22  is the letter R or L and indicates that the guide is intended to be used by a right-handed or left-handed operator respectively.   the second marking  23  contains the name of the type of curette to which the guide corresponds.   the third marking  24  designates the respective angles 10°, 20° and 30° corresponding to the different types of curette: 10° corresponding to the universal curettes, 20° to the scalers (sickles) and 30° to the Gracey-type curettes.   the fourth marking  25  is an indicating line, the angle of which with the horizontal corresponding to the angle of the third marking  24 . It is this line which will be used as a guide for the operator during sharpening. As illustrated in  FIG. 5 , the inclination of the indicating line also depends upon the laterality of the guide, i.e., upon the first marking: if the guide is intended for a right-handed user, the indicating line rises from left to right from the point of view of the operator. If the guide is intended for a left-handed user, the indicating line falls from left to right from the point of view of the operator.       

     The position of the recess  41  on the rear face  40   b  of each sharpening guide  40  also depends upon the type of dental curette to which the guide corresponds as well as the laterality of said guide. 
     The other components of the device in accordance with the second embodiment, such as the magnifying lens  6 , the illumination system  29 , the stabilising support  33  and the grinder  8  are similar to those described in the first embodiment in every respect. 
     The method of sharpening dental curettes in accordance with the invention implemented using a device for sharpening dental curettes in accordance with the first embodiment will now be described with reference to  FIG. 7  and has the following steps:
         1. The operator adjusts the inclination of the frame  3  with respect to the base plate  2 , the height of the guide support  7  and of the magnifying lens  6  as well as the position of the illumination system  29  and of the stabilising support  33  in accordance with his height, his laterality, the height of the chair and/or the table on which the device is placed.   2. The operator selects a sector of the guide disk  4  corresponding to the type of dental curette  50  to be sharpened, illustrated in  FIG. 8 , and to the laterality of the operator and causes the guide disk  4  to pivot until said sector is suitably positioned. Said sector is correctly positioned when the protrusion of the guide support  7  co-operates with the recess  21  of the rear face  4   b  of the disk  4  corresponding to the selected sector.   3. The curette to be sharpened is manually held by the operator who applies the edge  51  to be sharpened onto the grinding wheel  14  whilst aligning the last straight part x of the curette  50  on the line  25  marked on the sharpening guide.   4. The grinder  8  is started using the trigger  12 . Whilst keeping the straight part x of the curette  50  aligned with the line  25  of the guide and the edge  51  to be sharpened supported against the grinding wheel  14 , the operator simultaneously imparts a rotational movement to the handle of the curette  50  on an axis coinciding with said handle to follow the curve of the edge  51  to be sharpened. This operation is greatly facilitated owing to the magnification provided by the magnifying lens  6  thus permitting extremely precise positioning and sharpening.   5. The operator monitors the result of the sharpening using the eyepiece  26  placed on the base plate  2  of the device.       

     The method of sharpening dental curettes in accordance with the invention implemented using a device for sharpening dental curettes in accordance with the second embodiment is similar to the above-described method except that step  2  is replaced by the following step:
         2′: The operator places a sharpening guide  40  corresponding to the type of dental curette  50  to be sharpened, illustrated in  FIG. 8 , and to the laterality of the operator onto the rest  44 . The sharpening guide  40  is correctly positioned when the protrusion  48  of the tray  46  of the rest  44  co-operates with the recess  41  in the rear face  40   b  of the guide  40 .       

     By providing a suitable mode of operation, this device may also be used to sharpen excavators, small operating scissors or other instruments which require sharpening. 
     The magnifying lens  6  enables the operator to easily and precisely position the dental curette to be sharpened with respect to the corresponding guide. The magnifying lens preferably has a diameter of 100 mm and thus also acts as a protective screen between the grinding wheel and the operator. 
     The described device is simple and is characterised by extremely safe usage, an extremely quick positioning of the tool, an extremely fine cutting surface state, precise sharpening and a working position which is comfortable and suitable for everyone.