Abstract:
A dental mirror comprising a handle, a mirror, a tubular member inside the handle, a light source inside the tubular member, a light transmitting element coupled to the light source, a thermally conductive fluid conduit coiled around the tubular member, a fluid discharge manifold, a manifold support member for supporting the manifold adjacent to the mirror, a first connector attached to one end of the handle, a second connector attached to the first connector, and a combined electric/air supply line coupled to the second connector. The supply line couples electrical energy and compressed air to the handle via the connectors. The compressed air is coupled to the fluid conduit to aid in cooling the handle while the light source is energized. The air, having been warmed during the cooling process, is then channeled to the mirror to clean and defog the mirror.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to hand-held dental instruments, and more particularly to hand-held dental mirrors which are illuminated by fiber optic light sources. 
     2. Background Art 
     The dental mirror has long been and continues to be a prolific instrument in the clinical fields of dentistry. In the last 30 years, the dental industry has sought to develop a mirror with its own illumination system. Examples of such mirrors are disclosed in U.S. Pat. Nos.: 3,638,013 to Keller; 4,279,594 to Rigutto; 4,629,425 to Detsch; 4,993,945 to Kimmelman et al.; 5,139,420 to Walker; 5,139,421 to Verderber; and 5,457,611 to Verderber. The most successful of these mirrors have been those which contain a light source built in the handle of the mirror. The mirror disclosed in U.S. Pat. No. 5,457,611 to Verderber is such a device; it is the only known illuminated mirror that has been succesfully marketed. The Verderber mirror is currently produced and marketed by Welch-Allyn, Inc., of Skaneateles, N.Y. 
     The problem with illuminated mirrors having built-in light sources is that the handle or handpiece supporting the mirror heats up to a temperature that is uncomfortable to the user. As a result, the user (e.g., a dental clinician) may have a tendency to put the mirror down repeatedly during clinical procedures. Also, the clinician may be inclined to alternate mirrors during longer procedures to avoid the discomfort. These practices invariably prolong procedures, distract the clinician, and compromise accuracy, all to the detriment of the patient. 
     A solution to the heat problem is proposed in U.S. Pat. No. 5,457,611 to Verderber. In Verderber, a high intensity lamp is contained in a heat sink mounted within the dental mirror handle. The handle contains multiple vents spaced from and surrounding the heat sink. Heat from the lamp radiates out through the vents from the heat sink. This convection creates a thermal current, causing heated air to exhaust through the vents and be replaced by cooler air from the surrounding atmosphere (hereinafter referred to as “ambient cooling”). Even with the aid of ambient cooling, the heat generated by the lamp becomes particularly noticeable within 15 minutes. Handle temperatures for the Verderber mirror have reached 134° F., which are uncomfortable and distracting to the clinician. 
     Another approach to cooling a dental handpiece is disclosed in U.S. Pat. Nos.: 4,334,863 to Magid et al.; 4,477,252 to Lieb et al. and 3,634,938 to Hutchinson. Magid et al. discloses cooling the lamp, in part, by passing water and air through parallel channels adjacent to the lamp (FIG.  4 ). This approach is not sufficient by itself to prevent the handpiece from becoming uncomfortably hot—a critically dimensioned air gap and shield are also required. Lieb et al. discloses cooling the lamp (FIGS. 4 and 6) with exhaust air from a turbine drill; the exhaust air passes adjacent to and around the lamp. 
     In Hutchinson, cooling is accomplished by a water coil around the lamp (FIG. 3) and an air circulating chamber; water and air used for operating a turbine drill is passed through the coil and chamber, respectively, to effect the cooling. None of these approaches are particularly suitable for improving or retrofitting with the commercially produced dental mirror disclosed in U.S. Pat. No. 5,457,611 to Verderber. 
     A longstanding shortcoming inherent in a dental mirror is the tendency of the reflective surface to become obscured during clinical procedures. Fog, mist, spray from dental drills, tooth debris, dental materials, etc., collect on the mirror&#39;s reflective surface, impairing the visibility of the image from the mirror. The need for clear mirrors in dental and otolaryngology offices is immense. The affected procedures range from hygiene procedures (which are an important and constant activity in the dental office) to extensive oral surgeries as well as medical office examinations. 
     Clinicians are forced to repeatedly clean or wipe the reflective surface, which requires repositioning of the mirror. This repeated repositioning, however, can disrupt the concentration of the clinician, leading to reduced accuracy. Furthermore, much time is lost by the clinician in removing the mirror from the patient&#39;s mouth, cleaning or wiping the surface, then repositioning the mirror in order to continue with the procedure. 
     As a result of all of this, some clinicians opt not to use a dental mirror at all. Instead, they position the patient at an angle that allows for a more clear and direct view of the procedure. However, the clinicians must awkwardly position their heads, necks and backs to achieve such a view. Discomfort and strain are often experienced by both the clinician and the patient. Clinicians may develop temporary or even permanent neck and back problems as a result of such practices. 
     Attempts have been made to automatically clear (or “self-clean”) the mirror with a flow of air and/or water. Examples of such attempts are disclosed in U.S. Pat. Nos.: 5,449,290 to Reitz; 5,139,420 to Walker; 4,925,391 to Berlin; 4,629,425 to Detsch; 4,279,594 to Rigutto; and 3,969,824 to Widen et al. The mirrors disclosed in these patents do not contain a light source in the handle; and thus, there is no suggestion that the air and/or water used to clean the mirror may also be used to cool the handle. In addition, there is no coincidental warming of the air/water by an onboard light source before the air/water is applied to the mirror. While these self-cleaning approaches are theoretically sound, they have not, to this inventor&#39;s knowledge, been commercially successful. Further, there is no suggestion that such approaches be especially adapted for the commercially produced dental mirror disclosed in U.S. Pat. No. 5,457,611 to Verderber. Verderber discloses no provision for self-cleaning or defogging the mirror. 
     Another problem with dental mirrors is that their reflective surfaces are susceptible to marring by tooth debris, dental materials, or aluminum oxide powder from air-abrasion systems. When such marring occurs, the mirror must be replaced. This adds to the cost of treating a patient, which cost is passed on to the patient. In self-cleaning systems using a flow of water, the mirror is coincidentally protected from abrasion, to some degree, by the water; however, water, as a protection mechanism, creates two new problems—(1) distortion of the image from the mirror, and (2) the need to evacuate the water. 
     In some situations, it may be desirable or necessary to quickly replace the handle of an illuminated dental mirror during a procedure (e.g., if the lamp burns out or some other electrical malfunction occurs). As disclosed in U.S. Pat. No. 5,457,611 to Verderber, the handle of the mirror is connected to an electrical cord which supplies electrical power to the lamp. In order to separate the handle from the cord, a rear end cap must be unsnapped (FIG. 2) or unscrewed (FIG. 5) from the body of the handle. Such separation mechanisms are not expedient when a quick handle replacement is necessary during a clinical procedure. 
     A further problem with dental mirrors is the risk of transmitting germs from one patient to another (i.e., “cross contamination”). Cross contamination is possible because the handle of the mirror is exposed to the patient during clinical procedures. The recommended approach for preventing cross contamination is to autoclave the mirror handle after each use. Such an approach is time consuming and requires access to and handling of autoclave equipment and materials. Further, the autoclave process increases the wear-and-tear on the mirror handle. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide display apparatus and methods that avoid the limits and problems associated with the prior art. 
     It is another object of the present invention to maintain the temperature of a dental handpiece, containing a light source, at comfortable levels during clinical procedures. 
     It is a further object of the present invention to improve upon the dental mirror disclosed in U.S. Pat. No. 5,457,611 to Verderber. 
     It is yet another object of the present invention to provide certain retrofittable components for the dental mirror of U.S. Pat. No. 5,457,611. 
     It is yet a further object of the present invention to provide a self-cleaning and self-defogging dental mirror. 
     It is still another object of the present invention to cool a dental handpiece, containing a light source, using compressed air from a standard dental office air-supply. 
     It is still a further object of the present invention to utilize the compressed air, after it has been warmed during the cooling process, to also clean and defog the mirror. 
     It is yet still another object of the present invention to reduce marring of the reflective surface of the dental mirror by directing the compressed air onto the reflective surface in a fan-like pattern. 
     It is yet still a further object of the present invention to provide an expedient means for interchanging dental mirror handles. 
     It is yet still a further object of the present invention to effectively eliminate the risk of cross-contamination associated with the use of dental mirrors. 
     These and other objects are attained in accordance with the present invention wherein there is provided an illuminated dental mirror instrument comprising a handle, a mirror, an elongated tubular member, an electric light source, a light transmitting element, a thermally conductive fluid conduit, a fluid discharge manifold, a manifold support member, first and second complementary connectors, and a combined electrical and fluid supply line. 
     The handle of the instrument is defined as having front and rear ends. The mirror contains a reflective surface and includes a shank portion which is releasably attached to the front end of the handle. The elongated tubular member is located within the handle. The light source is contained within the elongated tubular member. The light transmitting element transmits light from the light source to the front end of the handle. The thermally conductive fluid conduit is coiled around the elongated tubular member, and the conduit is defined as having an intake end and a discharge end. 
     The fluid discharge manifold of the instrument is coupled to the discharge end of the fluid conduit via a fluid tube. The manifold support member is removably secured to the shank of the mirror and supports the manifold adjacent to the reflective surface of the mirror. The fluid tube is supported by the support member. The manifold is configured to discharge fluid in a fan-like pattern over the reflective surface of the mirror. 
     The first connector of the instrument is removably connected to the rear end of the handle, and it contains a fluid passage removably coupled to the intake end of the fluid conduit. The light source is mounted to the first connector. 
     The second connector of the instrument is removably connected to and mates with the first connector. The second connector contains a fluid passage removably coupled to the fluid passage of the first connector. The second connector includes electrical conductors which are removably electrically coupled to the light source. 
     The combined electric and fluid supply line is coupled to the second connector and serves to couple electrical energy and fluid to the electrical conductors and fluid passage, respectively, of the second connector. 
     In another aspect of the present invention, there is provided a method of retrofitting a dental mirror instrument. The instrument is of the type having: (i) a handle containing a plurality of vents; (ii) a mirror with a reflective surface coupled to the handle; (iii) an elongated tubular member located within the handle; (iv) an electric light source contained within the elongated tubular member; (v) a light transmitting element for transmitting light from the light source to the mirror; (vi) an end cap removably attached to the handle; and (vii) an electrical cord, secured to the end cap, which includes a pair of wires coupled to the light source. 
     The method of retrofitting the instrument comprises the steps of: (a) removing the light source, end cap and electrical cord from the handle; (b) removing the elongated tubular member from the handle; (c) placing a thermally conductive, helical-shaped, fluid conduit around the elongated tubular member to create a subassembly, the fluid conduit having an intake end and a discharge end; (d) installing the subassembly in the handle, such that the discharge end of the fluid conduit is accessible through a vent in the handle; (e) coupling a fluid discharge manifold to the discharge end of the fluid conduit; (f) attaching a support member to the instrument and using the member to support the discharge manifold adjacent to the reflective surface of the mirror; (g) replacing the light source, end cap, and electrical cord of the instrument with a replacement light source, first and second connectors, and a supply line, the replacement light source being mounted to the first connector and the supply line being mounted to the second connector; (h) inserting the replacement light source into the elongated tubular member; (i) connecting the first connector to the handle, in place of the end cap; and (j) connecting the second connector to the first connector. 
     In a further aspect of the present invention, a protective contaminant-resistant sheath assembly for a dental instrument is provided. The assembly comprises a support and an elongated protective sheath. The support is adapted to be coupled to the dental instrument. The protective sheath is made from a flexible contaminant-resistant material. The sheath has a first end secured to the support and a second end. The second end is open and free to allow manual deployment of the sheath over and around at least a portion of the dental instrument. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Further objects of the present invention will become apparent from the following description of the preferred embodiment with reference to the accompanying drawing, in which: 
     FIG. 1 is a perspective view of an illuminated dental mirror with associated components, constructed in accordance with the present invention; 
     FIG. 2 is a top plan view of the illuminated dental mirror of the present invention, shown without a protective sheath; 
     FIG. 3 is a side elevation view of the illuminated dental mirror of FIG. 2, shown with the mirror and associated components detached; 
     FIG. 4 is an enlarged exploded view, in partial section, of a handpiece for the illuminated dental mirror of the present invention; 
     FIG. 5 is an elevation view, along line  5 — 5  in FIG. 4, of a male connector of a quick-disconnect coupler, which coupler forms part of the handpiece of FIG. 4; 
     FIG. 6 is a perspective view of a female connector of the quick-disconnect coupler and a lamp socket attached thereto; 
     FIG. 7 is an exploded view of the handle portion of the handpiece of FIG. 4; 
     FIG. 8 is an enlarged elevation view of a support member, which is a component of the illuminated dental mirror of FIG. 2; 
     FIG. 9 is an enlarged fragmentary view of that portion of the illuminated dental mirror of FIG. 2, that is encircled by a dashed line in FIG. 2; 
     FIG. 10 is a side elevation view of a prior art dental mirror; 
     FIG. 11 is a side elevation view of the illuminated dental mirror of the present invention, employing a protective sheath, which is shown in an undeployed position; 
     FIG. 12 is a side elevation view of the illuminated dental mirror of FIG. 11, showing the protective sheath in a partially deployed position; and 
     FIG. 13 is a side elevation view of the illuminated dental mirror of FIG. 11, showing the protective sheath in a fully deployed position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown an illuminated dental mirror instrument  10  constructed in accordance with the present invention. Instrument  10  is shown with an optional protective sheath  11  covering most of the instrument. As will be described in detail below, electrical energy and compressed air are supplied to instrument  10  via a supply line  12 . Supply line  12  contains, within an outer casing  13 , an electrical cord  12   a  and a compressed air line  12   b  (FIG.  4 ). Supply line  12  is coupled to an instrument holder  14 . Holder  14  is suitably configured to releasably hold instrument  10 . 
     As shown in FIG. 1, holder  14  is configured to be removably secured to a mounting block  16 . Block  16  is mounted on a suitable support structure  18 . An electrical power supply  20  supplies electrical energy to mounting block  16 . Holder  14  and block  16  each contain a pair of electrical contacts. The contacts of block  16  ( 16   a,    16   b ) are in physical contact with the contacts of holder  14  (not shown) when block  16  and holder  14  are secured together. The electrical energy from power source  20  is coupled to instrument  10  via the assembly comprising block  16 , holder  14 , and electrical cord  12   a . The construction and electrical operation of the assembly is well known and fully described in U.S. Pat. No. 5,385,468 to Verderber (“Verderber I”), which is incorporated herein by reference. 
     In accordance with the present invention, instrument holder  14  (FIG. 1) has been modified from what is shown in Verderber I. Holder  14  includes a compressed air fitting  22  which is directly coupled to and in fluid communication with (not shown) the compressed air line in supply line  12 . A typical dental office air supply  24  can be coupled to fitting  22  to provide compressed air to instrument  10 . As suggested in FIG. 1, a compressed air filter/regulator  26  may be inserted between air supply  24  and fitting  22  to remove most liquids and solid particles from the air and regulate air pressure to instrument  10 . The preferred air pressure level to be delivered to instrument  10  is about 40-60 PSI. A quick-disconnect connector  28  is used to connect the filtered and regulated air supply to fitting  22 . 
     A manual shutoff valve (not shown) may also be included between filter/regulator  26  and fitting  22 . In an alternative implementation, an automatic shutoff valve may be employed inside holder  14 . As described in Verderber I, an electrical switch contact ( 14   a  in my FIG. 1) is located on holder  14 . Switch contact  14   a  functions to turn off the electric power to instrument  10  when the instrument is held in holder  14 , and to turn on the electric power when instrument  10  is removed from holder  14 . This same electrical switch can be employed for turning on and shutting off the compressed air. Swith contact  14   a  can be used with an electrically powered automatic shutoff valve (e.g., a solenoid actuated valve) located in holder  14 , for the compressed air. 
     Referring now to FIGS. 2-4, the construction of instrument  10  will now be more fully described. Instrument  10  is a modification of an existing dental instrument disclosed in U.S. Pat. No. 5,457,611 to Verderber (“Verderber II”), which is incorporated herein by reference. Familiarity with Verderber II is assumed in the following description of instrument  10 . Instrument  10  includes a handle  32  having a front end  32   a  and a rear end  32   b . A front cap  34  is threaded onto front end  32   a  (FIG.  4 ), and a quick-disconnect coupler  36  is removably attached to rear end  32   b . The downstream end of supply line  12  is connected to coupler  36  to supply compressed air and electricity to instrument  10 .  32  Handle  32 , cap  34 , and coupler  36  are preferably made of low heat absorbing material. 
     Handle  32  contains a plurality of air vents  37  through the wall of handle  32 , which allows ambient air to circulate in and out of the handle. The wall of handle  32  defines an interior volume  33  (FIG.  4 ). A mirror  38  is inserted into front cap  34  and is secured in place by tightening cap  34  on the threaded portion of handle  32 . This securement mechanism is more fully explained in Verderber II. Mirror  38  includes a shank portion  38   a , a heel portion  38   b , a face portion  38   c , and a reflective surface  38   d . Mirror  38  is a fiber optic disposable mirror of the type in which light transmitted into shank portion  38   a  is emitted from heel portion  38   b  and face portion  38   c . Such a mirror is commercially available and supplied by Welch-Allyn, Inc. Skaneateles, N.Y. 
     With further reference to FIGS. 2-4, instrument  10  contains an air discharge manifold  40  connected to an air tube  42  which is, in turn, connected to a flexible connector hose  44 . A support member  46  (see also FIG. 8) is removably secured to mirror shank  38   a . Support member  46  may be configured as a clip-on or slip-on device, where an engagement portion  46   a  (FIG. 8) is either open to clip onto or closed to slip onto the mirror shank. Support member  46  contains a hole  46   b  through which air tube  42  passes, and air tube  42  is supported thereby. Air tube  42  is preferably firm enough to support manifold  40  adjacent to reflective surface  38   d  of mirror  38 . Manifold  40 , air tube  42 , connector hose  44 , and support member  46  are all disposal parts, made of an inexpensive material. Manifold  40  and support  46  may be made from Delrin® material. 
     As shown in FIG. 9, an intake port  40   a  of manifold  40  is inserted into air tube  42 , to make the fluid connection thereto. In an alternative implementation, intake port  40   a  and air tube  42  are adapted so that air tube  42  can be inserted into intake port  40   a . Also, on the other end of air tube  42 , connector hose  44  may be eliminated if air tube  42  is flexible enough, at that end, to be inserted into the interior volume of handle  32 . 
     As shown in FIG. 2, manifold  40  is positioned such that it does not completely block the light emitted from front face  38   c of mirror  38 . As shown in FIG. 9, manifold  40  is positioned above reflective surface  38   d  and discharges streams of air, in a fan-like pattern, down and over reflective surface  38   d . Manifold  40  contains a plurality of air branch lines  40   b  and discharge openings  40   c , respectively. Discharge openings  40   c  are contained in a front face  40   d  of manifold  40 . Branch lines  40   b  converge into and are in fluid communication with intake port  40   a.    
     In some cases, it may be desirable to alter the direction of the air streams from manifold  40  from what is shown in FIG.  9 . It may be preferable to make the air streams geometrically normal to the curvature of the mirror. This can be accomplished, e.g., by reconfiguring manifold  40  and matching the curvature of face  40   d  with the curvature of mirror  38 . Also, it may be preferable to aim face  40   d  of manifold  40  slightly “upward” (in the orientation shown in FIG.  3 ). The alternate position for manifold  40  is shown phantom lines in FIG. 3, and is referenced by numeral  40 ′. In this alternate orientation, the air streams from manifold  40 ′are incident on reflective surface  38   d  at a more shallow angle. It is not desirable to make this angle zero (i.e., air streams parallel to reflective surface  38   d ). 
     The internal components of instrument  10  will now be described with reference to FIGS. 4-7. Again, familiarity with the disclosure in Verderber II is assumed in the following description. A heat sink  50 , configured as an elongated tubular member, is contained within interior volume  33  of handle  32 . Heat sink  50  is made of a thermally conductive material, such as aluminum or copper. A light transmission rod  52  is located within the front end of heat sink  50 , and is secured therein by means of an adhesive or interference fit. Rod  52  may made of any material having a high light transmission capability, such high quality quartz glass. 
     A light source  54  is located within the rear end of heat sink  50 . Light source  54  includes a high intensity halogen lamp  56  having a pair of leads  57  inserted into a lamp base or socket  58  (FIG.  4 ). Socket  58  includes a pair of electrical socket contacts  59  in which leads  57  are inserted. Socket  58  also includes a pair of electrical conductors or pins  60  electrically connected to contacts  59 , respectively. Socket  58  contains an external circumferential groove in which an O-ring  61  or other elastomeric seal is seated. When light source  54  is inserted into heat sink  50 , O-ring  61  is compressed by the interior wall of heat sink  50 , effecting a moisture resistant seal. 
     Light source  54  is positioned within heat sink  50  at close proximity to a rear end  52   a  of rod  52 , such that light emitted from lamp  56  is optically coupled into rod  52 . Lamp  56  may also include a lens  56   a  for focusing light into end  52   a . Light coupled into rod  52  is transmitted to a front end  52   b  of rod  52  and then optically coupled into mirror shank  38   a.    
     The front end of heat sink  50  is secured in handle  32  by virtue of rod  52  closely engaging an inner surface  55  of end  32   a  of the handle. The rear end of heat sink  50  is secured by its engagement with O-ring  61  and socket  58 . Of course, other well known securement or mounting approaches may me employed. The claimed invention is not limited to any particular approach. 
     In accordance with the present invention, a thermally conductive, helical-shaped, fluid conduit  62  is located around heat sink  50  (see FIGS.  4  and  5 ). Preferably, conduit  62  is made of thin-walled stainless steel and is in close contact with heat sink  50 . Conduit  62  includes an intake end  62   a  and a discharge end  62   b . Connector hose  44  is inserted into housing  32 , through a vent  37 , and slipped over discharge end  62   b  of conduit  62  (FIG.  4 ). Discharge end  62   b  is preferably slightly tapered to facilitate the union of hose  44  with the discharge end. From the description thus far, it understood that a complete fluid channel is established through conduit  62 , connector hose  44 , tube  42 , and discharge manifold  40 . 
     With further reference to FIGS. 4-6, quick-disconnect coupler  36  comprises a female connector  64  and a male connector  66 . Light source  54  is rigidly mounted to female connector  64 ; however, in an alternative embodiment, light source  54  may be threaded into connector  64 . Conductor pins  60  of light source  54  project into the interior of connector  64  (FIG.  4 ). In an alternative arrangement, connector  64  could be configured with its own pair of conductor pins, which would be, in turn, electrically coupled to light source  54 . The claimed invention is not limited to any particular conductor pin approach. 
     As shown in FIG. 4, female connector  64  contains a fluid passage  68  having a front coupling section  68   a  and a rear coupling section  68   b . Connector  64  is removably attached to rear end  32   b  of handle  32 . The removable attachment is established by means of a pair of resilient locking snaps  70   a  and  70   b  (see FIGS. 2 and 6) snapping into slots  72   a  and  72   b , respectively. Female connector  64  is made resilient enough to allow manual depression of the connector to a sufficient degree to disengage snaps  70   a  and  70   b  from slots  72   a  (FIG. 4) and  72   b  (FIG.  7 ). When connector  64  is properly attached to handle  32 , coupling section  68   a  of fluid passage  68  is coupled to intake end  62   a  of conduit  62 . 
     With further reference to FIGS. 4-6, male connector  66  includes a fluid coupling tube  74  and a pair of pin sockets  76   a  and  76   b . Connector  66  is removably connected to female connector  64  in a well known manner. When connectors  64  and  66  are connected together, pins  60  mate with pin sockets  76   a  and  76   b , respectively, and coupling tube  74  mates with rear coupling section  68   b  of fluid passage  68 . The connection of connectors  66 ,  64  is locked by sliding a locking ring  78  to the position shown in FIG.  4 . In a well-known manner, a locking O-ring  80  is urged down into a groove  82  to effect the lock of these couplers. 
     As shown in FIG. 4, the downstream end of supply line  12  is mounted in male connector  66 . Such mounting may be accomplished by any suitable well-known means. Electrical cord  12   a  contains a pair of electrical wires (not shown). These wires are routed through connection  66  and electrically coupled to pin sockets  76   a  and  76   b , respectively. Compressed air line  12   b  is coupled to tube  74  via an internal tube or fluid channel (not shown) contained in connector  66 . Alternatively, air line  12   b  may extend through connector  66  and be directly connected to tube  74 . 
     From the above description, it can be understood that a complete electric circuit is established between power source  20  and lamp  56 . In addition, a complete fluid path is established between air supply  24  and discharge manifold  40 . The compressed air supplied to instrument  10  flows through conduit  62  while lamp  56  is energized. This flow of air greatly aids in the cooling of handle  32  during extended operation of instrument  10  (e.g., exceeding 10-12 minutes). Preliminary tests have suggested that the temperature of handle  32  can be maintained below 80° F. for extended periods of use of instrument  10  (e.g., 10-12 minutes). The air (warmed from heat sink  50 ) continues from conduit  62 , through connector hose  44  and air tube  42 , and is discharged out of manifold  40 . The same air that aided in the cooling of handle  32  is also forced over reflective surface  38   d . The warm air defogs surface  38   d  and substantially clears surface  38   d  of water, debris, etc. The forced air also acts as a barrier which, at least in part, may protect surface  38   d  from tooth debris, dental materials, or aluminum oxide powder from air-abrasion systems. 
     The weight of instrument  10  is almost the same as a traditional stainless steel handle and mirror. The size (diameter) of handle  32  is far more ergonomically configured than the heavier, smaller diameter stainless steel handle that millions of dental clinicians use daily. 
     A method of retrofitting an existing dental mirror  100 , in accordance with the present invention, will now be described with reference to FIG. 10 (prior art) and FIGS. 2-9. As shown in FIG. 10, instrument  100  is essentially constructed as the instrument disclosed in FIG. 1 of Verderber II. 
     As shown in FIG. 10, instrument  100  comprises a handle  112  containing a plurality of vents  117 . A mirror  118 , having a reflective surface  118   b , is coupled to handle  112 . An elongated tubular heat sink  130  is located within handle  112 . An electric light source, similar to that shown in FIG. 4 (herein), is contained within heat sink  130 . A light transmitting rod (not shown) is located in heat sink  130 . An end cap  116  is removably attached to handle  112 . Finally, an electrical cord  120  is secured to end cap  116 . Cord  120  contains a pair of wires (not shown) coupled to the light source. 
     The preferred retrofitting method of the present invention comprises the steps of: (a) removing the light source, end cap  116 , and electrical cord  120  from handle  112 ; (b) removing heat sink  130  from handle  112 ; (c) placing fluid conduit  62  (FIGS. 4 and 7) around heat sink  130 ; (d) installing the assembly of conduit  62  and heat sink  130  in handle  112 ; (e) coupling fluid discharge manifold  40  (FIGS. 2 and 3) to fluid conduit  62 , via tube  42  and hose  44 ; (f) attaching support member  46  to the shank of mirror  118  and using member  46  to support manifold  40  adjacent to reflective surface  118   b  of mirror  118 ; (g) replacing the light source, end cap  116 , and electrical cord  120  with light source  54 , male and female quick-disconnect connectors  64 ,  66 , and supply line  12 ; (h) inserting light source  54  into heat sink  130 ; (i) attaching connector  64  to handle  112 , in place of end cap  116 ; and (j) connecting connector  66  to connector  64 . 
     Referring now to FIGS. 11-13, there is shown a dental mirror instrument  200  employing an elongated protective sheath  202 . FIG. 11 shows sheath  202  in an undeployed position; FIG. 12 shows sheath  202  in a partially deployed position; and FIG. 13 shows sheath  202  in a fully deployed position. Instrument  200  is identical to instrument  10 , thus the details of its construction will not be presented here. Instrument  200  includes a handle  232 . A quick-disconnect coupler  236  is removably attached to the rear end of handle  232 . A dental implement, such as a disposable fiber optic mirror  238 , is releasably attached to the front end of handle  232 , as previously described. Mirror  238  includes a shank  238   a . A support member  246 , constructed as shown in FIG. 8, is secured to shank  238   a  of mirror  238 . 
     In the preferred embodiment, protective sheath  202  is an elongated tubular sheath having two open ends  202   a  and  202   b  (FIG.  13 ). End  202   a  is affixed to support member  246 , around the perimeter of member  246 , as shown. End  202   b  remains open and free to allow manual deployment of sheath  202  over and around handle  232  (FIG.  13 ). In the embodiment shown, instrument  200  also includes a discharge manifold  240 , an air tube  242 , and a connector hose  244 , all constructed and operational as previously described with respect to instrument  10 . 
     In the undeployed position, sheath  202  is rolled up upon itself, from end  202   b  to end  202   a , as shown in FIG.  11 . This rolled up configuration facilitates the deployment of sheath  202  over handle  232 , because the sheath can simply be unrolled over the handle, as illustrated in FIGS. 12 and 13. Sheath  202  is made from a flexible contaminant-resistant material, such as, for example, Vinyl, Latex, Nitrile or Polyethylene. Once sheath  202  is fully deployed, a protective contaminant-resistant barrier is established from support member  246 , over handle  232 , to and including coupler  236 . In the preferred embodiment, mirror  238 , manifold  240 , air tube  242 , connector hose  244 , support member  246 , and protective sheath  202  are all disposable items, and are collectively referred to as a disposable assembly  204  (FIG.  11 ). Thus, after using instrument  200 , sheath  202  is rolled back up into its undeployed configuration (FIG.  11 ), and disposable assembly  204  is discarded. No increase in the temperature of handle  232  was experienced when sheath  202  was fully deployed as shown in FIG.  13 . 
     While the preferred embodiments of the invention have been particularly described in the specification and illustrated in the drawings, it should be understood that the invention is not so limited. Many modifications, equivalents and adaptations of the invention will become apparent to those skilled in the art without departing from the spirit and scope of the invention, as defined in the appended claims.