Abstract:
A grinding disk has a pilot region or ring that does not include abrasive material. The pilot region aids in positioning the disk between teeth or in other orientations. The disk may be used in conjunction with a guard. For example, the guard may include grip enhancements such as finger plates or cups. Guards can accommodate contra-angles. Guards made of transparent plastic improve work area visibility for a dentist or user. Some guards are made of plastic and are disposable. Embodiments of the guard may include a lubrication port for introducing a lubricant to the disk. The port may include an orifice in a wall of the guard. The port may also include a tube, for guiding the placement of a lubricating hypodermic needle and/or a hose barb for communication with a lubrication source via tubing. A disk stop in the guard can position the disk for receiving lubricant.

Description:
CROSS REFERENCE 
       [0001]    This application is related to seven other applications by the same inventor, each titled GRINDER GUARD, filed contemporaneously herewith. All of these applications are included herein by reference. 
       BACKGROUND 
       [0002]    Embodiments disclosed herein are related to the art of dentistry. More particularly, embodiments are related to guards for dental grinding tools or other working elements. Moreover, some embodiments are related to disposable guards for dental working elements. However, some embodiments may be sterilized and reused. 
         [0003]    In the practice of dentistry, it is sometimes necessary to clean, polish, drill and/or grind the teeth of a patient. Various tools and components are available that aid in performing these procedures. For example, U.S. Pat. No. 583,735 to C. W. Dodge describes a dental polishing disk. U.S. Pat. No. 503,258 to R. G. Stanbrough discloses a dental disk and carrier. 
         [0004]    U.S. Pat. Nos. 689,596 to Platt; 1,535,187 to Terry; and 2,448,758 to Angell disclose dental hand pieces which receive and drive grinding, polishing or drilling elements. 
         [0005]    U.S. Pat. Nos. 925,379 to Reed, et al.; 1,042,039 to Schlund; 1,534,817 to Thiedemann, et al.; 1,548,180 to Brown, et al.; 1,621,190 to Brown; 1,678,096 to Andresen; 1,999,488 to Swisher, et al.; 2,504,233 to Staunt; 2,568,315 to Björklund; 2,591,772 to Björklund; 2,879,595 to Uhler, et al.; 2,928,174 to White; 2,945,299 to Fritz; 3,014,278 to Aymar, et al.; 3,509,629 to Kidokoro, et al.; 3,521,358 to Berman; 3,629,944 to Avakoff, et al., and 5,915,966 to Miller describe dental hand pieces or driving mechanisms that include contra-angles or tool receiving and driving heads that are disposed at an angle to a longitudinal axis of the dental hand piece. 
         [0006]    U.S. Pat. Nos. 159,048 to Starr; 399,350 to Sisson; 525,278 to Peck; 635,244 to Gholson; 696,155 to Williams; 763,918 to Magoon; 787,981 to Green; 823,167 to Green; 973,894 to Toomey; 994,829 to Fell; 1,004,118 to Waters; 1,021,065 to Neil, Jr.; 1,067,571 to Abbott; 1,101,947 to Morgan; 1,117,660 to Gilmore; 1,152,122 to Samphere; 1,285,273 to Luzzi; 1,390,354 to Fried; 1,841,915 to Reiter; 2,307,677 to Hawkinson; 2,731,722 to Wilen; illustrate guards, shields, holders and the like for protecting the patient and dentist from abrasive or cutting edges of spinning polishing, grinding and drilling elements. 
         [0007]    U.S. Pat. No. 1,943,668 to Hartman discloses a guide attachment for a contra-angle. 
         [0008]    All of these references are incorporated herein by reference for all that they disclose. 
         [0009]    Attachments, such as the guards, shields, holders and guides described in the references mentioned above, must be sterilized before they can be used in a procedure on a patient. For example, the guards, shields, holders or attachments are processed through an autoclave. This requires that the attachments be made of material that can survive the autoclaving process. For example, such attachments are often made of stainless steel. Stainless steel attachments are relatively expensive. Additionally, the cleaning and sterilization process is time consuming and prone to error. 
         [0010]    Therefore, there has been a desire for inexpensive and/or disposable shields, guards or attachments for dental instruments. Additionally, there has been a desire for guards, shields or attachments that are compatible with or can be used in conjunction with contra-angles or dental hand pieces including contra-angles or contra-angle attachments. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of an illustrative guard for a dental working element. 
           [0012]      FIG. 2  is a perspective view of an illustrative guard including finger plates. 
           [0013]      FIG. 3  is a perspective view of an illustrative guard including finger cups. 
           [0014]      FIG. 4  and  FIG. 5  are schematic views of illustrative guards adapted for use with contra-angles. 
           [0015]      FIG. 7  is a perspective view of an illustrative guard including an illustrative lubrication port and an illustrative disk stop protrusion. 
           [0016]      FIG. 6 ,  FIG. 8  and  FIG. 9  are schematic views of illustrative guards installed or being installed on dental drive elements or hand tools. 
           [0017]      FIG. 10  is a perspective view of a grinding disk that includes a safety or pilot region. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Referring to  FIG. 1 , an attachment or guard  100  for an associated dental working element (e.g.,  104 ) includes a shaft portion  108  and a guard portion  112 . The shaft portion  108  can include a mating end  116  and a guard end  120 . The mating end  116  can include an attachment mechanism. For instance, the attachment mechanism is adapted to attach to a dental drive element or hand tool. The guard end  120  carries the guard portion  112 . The guard portion  112  includes a plate portion  124  and a wall portion  128  extending above a surface  132  of the plate portion  124  and is disposed adjacent to a peripheral edge (e.g.,  136 ) of at least a portion of the plate portion  124 . The plate portion includes a plate passage  140  for receiving a working element drive shaft (e.g.,  144 ) or mandrel. The shaft  108  may include a shaft passage (e.g.,  148 ). If the shaft  108  includes a shaft passage (e.g.,  148 ), the shaft passage and the plate passage are axially aligned for cooperatively receiving the associated drive shaft (e.g.,  144 ) of the associated working element  104 . 
         [0019]    For example, the working element  104  can be a grinding disk such as a diamond coated grinding disk for grinding and shaping teeth of a dental patient. Alternatively, the working element may be a drill bit or a polishing wheel or disk. 
         [0020]    The guard portion  112  is shaped to guard or protect the fingers and hands of a dentist using the working element and to protect portions of the mouth of the patient that are not intended to be acted on by the working element (e.g.,  104 ). For example, the guard portion  112  is shaped to protect the lips, cheeks, tongue and other mouth portions from the spinning working element (e.g.,  104 ) while still allowing the working element (e.g.,  104 ) to be applied to the intended portion of the mouth (e.g., a particular tooth). 
         [0021]    In the illustrated embodiment of  FIG. 1 , the working element  104  is a grinding disk. The plate portion  124  is generally disk shaped and has a diameter that is a bit larger than a diameter of the grinding disk. 
         [0022]    The wall  128  extends around a portion of the perimeter  136  of the generally disk-shaped plate portion  124  and is spaced away from a peripheral edge of the associated disk  104  when the disk is installed in the guard  100 . The wall  128  has a height that is higher than a thickness of the disk  104 . When the disk  104  is installed in the guard  100 , the disk  104  is below a top edge  152  of the wall  128 . Therefore, the fingers of the dentist and the tongue, cheeks and lips of the patient are prevented from approaching portions of an edge  156  of the disk  104  guarded by the wall  128 . 
         [0023]    While the wall  128  has a generally circular cross section and the plate  124  is generally circular, there is at least one gap or access point  160  provided in both the wall  128  and plate  124 . For instance, the gap  160  provides an exposure for a portion of the working element or disk  104 . The exposed portion of the working element  104  can be applied to the target portion of the patient&#39;s mouth. For example, the portion of the disk  104  exposed by the gap  160  can be applied to a tooth or between two teeth in order to grind, shape a tooth or enlarge or create a space between two teeth. 
         [0024]    Additional voids may be provided in the guard portion  112 . For example, debris exit apertures  164  may be included in the plate portion  124 , as an aid to preventing the buildup of bone, tooth structure and fluid behind or around the working element  104 . Additionally, or alternatively, apertures or slits may be provided in the wall  128  for similar purposes. Preferably, the voids are sized large enough to prevent clogging, while at the same time being small enough to prevent contact between the fingers of the dentist, or the tongue or cheeks of the patient, and the working element  104 . 
         [0025]    As indicated above, the shaft  108  may include a shaft passage  148  for receiving the drive shaft  144  or mandrel of the working element  104 . Alternatively, as will be discussed in greater detail below, the shaft may simply serve as a connecting or linking element between the guard portion  112  and the attachment mechanism (not shown). 
         [0026]    The attachment mechanism (not shown) may be any known or later developed attachment mechanism. For example, the illustrated cylindrical shaft  108  may include threads for threading onto a driving head of a dental drive element or hand tool. Other embodiments may include a bayonet or snap-on mechanism. The shaft may include grip enhancing means such as a knurled portion  168  to help prevent slippage during guard attachment. 
         [0027]    The guard portion  112  may also include group enhancing means. For example, an outer surface  172  of the wall  128  may include knurled portions  176  or rubber or rubber-like pads or pad (not shown). For instance, the dentist may hold the guard portion  112  between two fingers in order to guide and steady the work element  104 , guard  100  and a drive element assembly during a dental procedure. Grip enhancing means such as the knurled portion  176  of the wall  128 , or rubber pads, reduce the risk of the guard  100  slipping from the grasp of the dentist. 
         [0028]    Other guard portion grip enhancing elements may be included. For example, referring to  FIG. 2 , a guard  200  includes a guard portion  212  having a wall portion  228  having an outer surface  272  that carries first and second finger plates  276 . The first and second finger plates  276  are carried approximately tangentially on spaced portions of the outer surface  272 . For example, the first and second finger plates  276  may be carried on opposite portions of the outer surface  272  of the wall portion  228 . Alternatively, the first and second finger plates  276  are located at other convenient locations for aiding the dentist in grasping the guard  200 . 
         [0029]    Referring to  FIG. 3 , a third illustrative guard  300  is similar to the second illustrative guard  200 . However, instead of carrying finger plates  276 , a guard portion  312  includes a wall portion  328  having an outer surface  372  that carries first and second finger cups  376 . For example, the finger cups  376  are plates curved to approximate the contours of a thumb and forefinger of a dentist. Alternatively, the finger cups  376  may be in the form of more complete pockets approximating tip portions of fingers of a glove. As described with reference to the second illustrative guard  200  and the finger plates  276  associated therewith, the finger cups  376  may be carried on spaced portions of the outer surface  376  of the wall portion  328 . For instance, the finger cups  376  may be carried on opposite portions of the outer surface  376  of the wall portion  328 . Alternatively, the finger cups  376  may be located at some other location that is convenient and/or enhances the grip of the dentist on the guard  300  during a dental procedure. Finger plates and cups may include additional grip enhancements, such as knurls or rubber-like pads. 
         [0030]    Referring to  FIG. 4 , a fourth illustrative guard  400  protects a patient and/or dentist from unnecessary exposure to abrasive or cutting portions of a working element (e.g.,  404 ) and is adapted for use with a contra-angle. The fourth illustrative guard  400  includes a shaft portion  408  and a guard portion  412 . The shaft portion  408  includes a mating end  416  and a guard end  420 . The guard portion may be similar to any of the guard portions  112 ,  212 ,  312  described above. For example, the guard portion  412  includes a plate portion  424  and a wall portion  428 . The wall portion  428  extends away from a surface  432  of the plate portion. The wall portion  428  is disposed adjacent to a peripheral edge (not shown) of at least a portion of the plate portion  424 . The guard portion  412  includes a passage  440  for receiving an associated working element drive shaft or mandrel  444  of the associated working element (e.g.,  404 ). The shaft  408  may also include a passage  448 . If the shaft  408  includes a shaft passage  448 , the guard passage  440  and the shaft passage  448  are axially aligned with each other for cooperatively receiving the drive shaft or mandrel  444  of the working element  404 . 
         [0031]    The fourth illustrative guard  400  includes an attachment mechanism  452  adapted to attach to a dental drive element or hand tool that includes a contra-angle. For instance, the attachment mechanism  452  is of such size, shape and material that it acts as a grasp, grip or snap-on mechanism for securing the guard  400  to the contra-angle of the dental drive mechanism or hand tool. For example, the attachment mechanism  452  includes a shaft wall  456  and a distal wall  460  and a linking arm or wall  464  therebetween. For instance, the linking arm or wall  464  and/or junctions  472 , between the linking arm or wall  464  and one or both of the shaft wall  456  and the distal wall  460  may be resilient thereby allowing temporary displacement of the distal wall  460  and/or linking arm or wall  464  during a guard  400  attachment procedure. For instance, portions of the attachment mechanism  454  are deflected as the distal wall  460  is urged over wide or larger portions of the contra-angle and then return to a natural grasping or gripping position when the guard  400  is in a fully installed position with respect to the contra-angle. Alternatively, and/or additionally, the deflection may be temporary during an installation process and be relieved or partially relieved when the guard is fully installed and captured by mating contours of the attachment mechanism  452  and the contra-angle (see  FIG. 7 ). Optionally, portions of the attachment mechanism  452  may include such depressions and protrusions (not shown) or contours as are required or desired to provide a custom fit to a particular model or type of contra-angle. 
         [0032]    The shaft wall  456  abuts and may be contiguous with the mating end  416  of the shaft  408 . The shaft wall  456  includes a passage  468  for receiving the drive shaft or mandrel  444  of the working element  404  and passing through to the contra-angle of the dental drive element or hand tool. If the shaft  408  includes a shaft passage  448 , then the shaft wall passage  468  is axially aligned with the shaft passage  448 . 
         [0033]    Referring to  FIG. 5 , a fifth illustrative guard  500  for a working element  504  includes a shaft portion  508  and a guard portion  512 . The guard portion  512  may be similar to any of the guard portions  112 ,  212 ,  312 ,  412  described above. The shaft portion  508  may be considered to include a mating end  516  and a guard end  520 . However, the mating end and the guard end may be close together or even coincide. For instance, in some embodiments, a back surface  580  of a plate portion of the guard portion  512  may be intended to abut a portion of an associated dental drive element or hand tool when the guard (e.g.,  500 ) is installed thereon. Therefore, the back surface  580  of the plate portion might be considered part of an attachment mechanism. Alternatively, the back surface  580  may be spaced from the dental drive element by a portion of the shaft portion  508 . 
         [0034]    As indicated above, in the fifth illustrative guard, an attachment mechanism  582  may include the rear surface  580  of the guard portion  512  or plate portion. Additionally, or alternatively, the attachment mechanism  582  may include side walls  584  (see also  FIG. 8 ), a distal wall  586  and a linking arm or wall  588 . The linking arm or wall  588  and/or junctions  590  between the linking arm or wall  588  and the side walls  584  and/or distal wall  586  may be resilient. In a manner similar to that described with reference to the fourth illustrative guard  400  and the attachment mechanism  452  thereof, the walls  584 ,  586  junctions  590  and/or the linking arm  588  of the attachment mechanism  582  of the fifth illustrative guard  500  may flex or be deflected about portions of a contra-angle. The flexure and resiliency of the attachment mechanism  582  portions  584 ,  586 ,  588  and/or  590  may provide a gripping force to secure the fifth illustrative guard  500  to the contra-angle. Alternatively, and/or additionally, the deflection may be temporary during an installation process and be relieved or partially relieved when the guard is fully installed and captured by mating contours of the attachment mechanism  582  and the contra-angle (see  FIG. 8 ). 
         [0035]    Referring to  FIG. 6 , some guards (e.g.,  100 ,  200 ,  300 ) may attach, and include attachment mechanisms for attaching, to straight drive heads of dental drive elements or hand tools. The attachment mechanisms may include threads, bayonet mounts, snap-on mechanisms, and/or friction fits. Some guards may simply be held in place because they are captured by the working element (e.g.,  104 ,  204 ,  304 ) when the drive shaft or mandrel (e.g.,  144 ) is captured in a chuck or other working tool capture mechanism of the drive head (e.g.,  610 ) of the dental hand tool or drive element. 
         [0036]    Referring to  FIG. 7 , a sixth illustrative guard  700  can include any of the elements or features of the previously described guards (e.g.,  100 ,  200 ,  300 ,  400 ,  500 ). For example, as illustrated, the sixth illustrative guard  700  includes a first gap or access point  760  and finger plates or cups  776  that are similar to those described in reference to, for example,  FIGS. 1-3 . Additionally, the sixth guard  700  includes a second gap or access point  780  at a second location in a guard wall  782  and guard plate  784 . For example, the second gap  780  may be located opposite or displaced 180 degrees from the first gap  760 . Alternatively, the second gap  780  may be positioned at other positions relative to the first gap  760 . The second gap  780  may provide added flexibility for holding and positioning the dental tool while performing a dental procedure, thereby increasing the likelihood that a comfortable working position and/or tool orientation may be found. Additionally, the second access point or gap  780  may allow a dentist to shape an upper tooth after first working on a lower tooth without repositioning and/or reorienting the dental tool during the dental procedure. 
         [0037]    The sixth guard  700  also includes a lubrication well or port  790  and a disk stop protrusion, guide or shelf  794  adjacent thereto. 
         [0038]    For instance, the lubrication port or well  790  is configured to receive a needle of a dental hypodermic. The hypodermic may be filled with a dental lubricant such as, for example, a fluoride gel, water or other natural lubricant. For example, the lubricant port takes the form of an orifice or tube through a portion of the wall portion (e.g.,  782 ) of a guard (e.g.,  700 ). For instance, the needle of the hypodermic is received through the lubrication port so that lubricant can be applied to a surface, such as a top surface of an outer edge of a work element, such as a grinding disk. Alternatively, the lubrication port may include a nipple or hose barb on or extending outwardly from an outer surface  795  of the wall portion (e.g.,  782 ) for receiving a lubricant delivery tube whereby lubricant is delivered to a surface of the tool (e.g.,  104 ,  204 ,  304 ,  404 ) by automatic and/or continuous delivery means or by a hand operated hypodermic connect to a remote end of the delivery tube. 
         [0039]    The disk stop or protrusion  794  is located adjacent to, or in close proximity to, an inner portion (e.g.,  796 ) of the lubrication port, tube or well  790 . For instance, the disk stop protrudes from an inner surface (e.g.,  798 ) of the wall portion  782  of the guard (e.g.,  700 ) at an elevation on that wall surface  798  that positions the stop  794  behind the work element or disk (e.g.,  104 ,  204 ,  304 ,  404 ) when the work element is installed within the guard (e.g.,  700 ). For instance, when the work element is a disk (e.g.,  104 ,  204 ,  304 ,  404 ), the work element may be relatively thin and flexible. Accordingly, the work element may tend to warp or flex so that it appears to wobble up and down as it is rotated or spun by the dental tool. The disk stop  794  may urge portions of the disk that are warped downward and away from the lubrication port back toward the lubrication port, thereby ensuring that all portions of the disk or dental tool are properly positioned to receive lubrication. 
         [0040]    In  FIG. 7 , the disk or tool stop  794  is depicted as a continuous shelf protruding from the inner surface  798  of one portion of the wall portion  782 . However, in some embodiments, the stop  794  protrudes from the inner surface  798  of the entire wall portion  782 . Alternatively, the stop  794  is implemented as one or more discrete protrusions that extend from the inner surface  798  of the wall portion  782  at least in a region that is in close proximity to the inner portion  796  of the lubrication orifice, port or tube  790  in order to ensure that the disk or work element is close enough to the lubrication well  790  to draw away lubricant by capillary action or other similar means. 
         [0041]    Any of the previously described guards (e.g.,  100 ,  200 ,  300 ,  400 ,  500 ) can include one or more of the features (e.g.,  780 ,  790 ,  794 ) described with particular reference to the sixth embodiment  700 . Furthermore, any of the features described with reference to the first through fifth guards (e.g.,  100 ,  200 ,  300 ,  400 ,  500 ) can be included guards such as that depicted in  FIG. 7 . 
         [0042]    Referring to  FIG. 8  and  FIG. 9 , some guards (e.g.,  400 ,  500 ) include attachment mechanisms  452 ,  582  for attaching the guards (e.g.,  400 ,  500 ) to contra-angles (e.g.,  810 ,  910 ) of dental drive elements or hand tools. For instance, as explained above, portions of the attachment mechanisms  452 ,  582  may be resilient or flex when receiving or mating with an associated contra-angle (e.g.,  810 ,  910 ). Such flexure may create a resilient force for gripping the associated contra-angle (e.g.,  810 ,  910 ), which may stabilize the guard (e.g.,  400 ,  500 ) during a working element ( 404 ,  504 ) and drive shaft or mandrel (e.g.,  444 ) installation process, with the guard (e.g.,  400 ,  500 ) being captured between the working element (e.g.,  404 ,  504 ) and the contra-angle (e.g.,  810 ,  910 ) when a drive shaft (e.g.,  444 ) or mandrel of the working element ( 404 ,  504 ) is captured in the chuck or other shaft grasping mechanism of the contra-angle (e.g.,  810 ,  910 ). Alternatively, the contra-angle grip or attachment mechanism (e.g.,  452 ,  582 ) may secure the guard (e.g.,  400 ,  500 ) to the contra-angle (e.g.,  810 ,  910 ) independent of the installation of the working element ( 404 ,  504 ). 
         [0043]    As indicated with respect to  FIG. 1 ,  FIG. 2  and  FIG. 3 , guard portions may include finger grips or grip enhancing means. For instance, the guard portions  412 ,  512  of the fourth  400  and fifth  500  guards may include knurled edges (e.g.,  176 ), finger plates (e.g.,  276 ) or finger cups (e.g.,  376 ,  776 ) carried approximately tangentially on spaced portions of outer surfaces of the wall portions (e.g.,  428 ) of the guards (e.g.,  400 ,  500 ,  700 ). 
         [0044]    Guards (e.g.,  100 ,  200 ,  300 ,  400 ,  500 ,  700 ) may be unitary in construction. That is, the guards ( 100 ,  200 ,  300 ,  400 ,  500 ,  700 ) may be molded or machined from metal or plastic and formed as a single contiguous piece. Alternatively, individual components such as guards, shafts, attachment mechanisms, finger plates and/or finger grips may be manufactured separately and assembled together through attachment mechanisms such as, but not limited to, adhesives, bonding, welds, rivets, screws and bolts. 
         [0045]    Preferably, the guards are made of plastic such as, for example, acrylonitrilebutadiene-styrenes (ABS), styrene-butadiene copolymers (SBC), acrylics, and polyproplyenes. The plastic might be selected to be an injection moldable plastic. The plastic might be selected to be sterilizable, at least one time, through known or as yet to be developed sterilization processes. Preferably, the plastic is inexpensive, thereby allowing the guard (e.g.,  100 ,  200 ,  300 ,  400 ,  500 ,  700 ) to be properly disposed of after a single use. In some instances it might be desirable to select a plastic that has a melting point or glass transition temperature at or below standard autoclave chamber or cavity operating temperatures (e.g., below about 250° F. or 121° C.) and/or pressures. For example, it might be desirable to prevent unauthorized reuse through autoclaving by manufacturing the guard from a plastic that melts or softens so that the guard will deform if exposed to sterilizing temperature and/or pressures used in an autoclave. In other instances it may be desirable to select a plastic having a higher melting point or glass transition temperature, thereby allowing reuse through autoclaving. Polycarbonates and nylons that have such higher melting points/glass transition temperatures are available. The manufacture of the guard (e.g.,  100 ,  200 ,  300 ,  400 ,  500 ,  700 ) from transparent plastic may allow a dentist to see more of a work area or target tooth than would be afforded by the use of other materials. Furthermore, a guard made from a transparent plastic can allow light from an illumination source, such as, for example, light delivered to the work area via a fiber optic cable, to pass through and better illuminate the work area. Indeed, at least some transparent plastics have indexes of refraction such that they act as optical fibers. A guard made of one of these plastics could conduct or guide light from a light source to the work area, through edges of the guard. Transparent ABSs, SBCs, acrylics, and polypropylenes, polycarbonates and nylons are available. 
         [0046]    Referring to  FIG. 10 , an improved dental working element such as a grinding wheel or disk  1004  includes a grinding or work portion  1008  and a pilot or safety region  1012 . The disk  1004  can have a diameter of about 0.5 cm to about 3 cm in diameter and has a thickness of about 0.2 mm to about 1.5 mm. For example, the pilot or safety region  1012  is an outer ring portion of the grinding disk  1004  that is devoid of abrasive material. The work or grinding portion  1008  carries an abrasive such as a diamond dust or grit impregnated adhesive. While a top surface  1016  of the disk  1004  is visible in  FIG. 10 , a bottom or under surface  1020  of the disk  1004  may be similarly configured with a working surface and safety or pilot region. Alternatively, the bottom or under surface  1020  may be completely devoid of grinding or cutting material. The disk  1004  includes a means (not shown) for attaching the disk to a shaft or mandrel. For example, the disk  1004  may include an opening or orifice that is centered on the disk. A portion of a fastener (not shown) such as screw, bolt, rivet or snap may be placed through the whole and screwed, bolted, riveted or snapped into the shaft or mandrel. Alternatively, the substrate may be unitary with an attachment means, such as a treaded element or snap. Furthermore, the disk may be unitary with the shaft or mandrel. In yet other embodiments the disk may be secured to the shaft or mandrel with an adhesive or weld (e.g. ultrasonic) 
         [0047]    The pilot or safety area  1012  may be a ring extending from an outer edge  1024  radially inward to a work portion  1008  boundary  1028 . For instance, the radial distance between the outer edge  1024  and the boundary  1028  may be from about 0.1 mm to about 2.0 mm. That is, the abrasive or aggregate including an abrasive material adhered to the disk shaped region of at least the first or top surface of the substrate. The disk shaped region is centered on the disk shaped substrate and has a diameter that is smaller than the radius of the disk shaped substrate by about 0.2 mm to about 4 mm. The pilot or safety region  1012  allows the user to, for example, guide the disk between teeth to be cut or ground with a reduced level of risk of damaging tooth structure that might otherwise be inadvertently cut while the user or dentist attempts to line up or properly position a disk in the tight space between two adjacent teeth. 
         [0048]    A grinding disk, such as the grinding disk  1004 , with a pilot or safety region (e.g.,  1012 ) can be used in conjunction with any of the guards (e.g.,  100 ,  200 ,  300 ,  400 ,  500 ,  700 ) described above. 
         [0049]    It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different guards or shields. Various alternatives, modifications, variations or improvements are intended to be encompassed by the following claims.