Patent Publication Number: US-2007099154-A1

Title: Method of treating dental patients with ultraviolet C range light

Description:
FIELD OF THE INVENTION  
      The present invention relates generally to dental treatments, and more specifically to the prevention of blood borne infectious agents introduced into the body during a dental procedure.  
     BACKGROUND OF THE INVENTION  
      The dental profession is well aware of the possibility of introducing bacteria into a patient&#39;s circulatory system while performing normal routine procedures. In routine procedures, such as cleaning a patient&#39;s teeth, it is not uncommon to have the gums bleed; bacteria in the mouth can then enter the open wound and infect the patient. The bacteria can then lodge in host organs and replicate itself, resulting in septicemia, endocarditis, and even heart attacks and strokes.  
      Dental practitioners routinely have the patient swish a germicidal wash in his/her mouth prior to beginning any procedure that can be invasive or result in any blood loss. After the procedure is initiated, generally no proactive procedure is performed to arrest the possibility of infection. During the time the procedure is being performed the patient may be vulnerable to infection by airborne pathogens as well as the recolonization of bacteria from the patient&#39;s own mouth. The recolonization may actually be more prolific than the original bacteria colonization, as in open wounds typically the recolonization count is higher than the original.  
      There may also be a high risk in the dental procedures of cross-contamination from patients. During some procedures, body fluids can spread from the patient&#39;s mouth to the face, eyes, nostrils, etc. of the treating professional. Dental instruments often use pressure to dislodge and expel the mouth contents, thus allowing the fluids and bacteria to vaporize and/or become airborne.  
      It has been known for some time that ultraviolet (UV) light can have antimicrobial effects. See, e.g., Licht, Therapeutic Electricity and Ultraviolet Radiation (Waverly Press, 1967). Early experiments demonstrated that properties of sunlight (either a heating effect or a property of the sun&#39;s rays itself) could prevent bacterial growth. Later, UV light was shown to be bacteriocidal to many bacteria, including  Mycobacterium tuberculosis, Staphlococcus, Streptococcus, Bacillus anthrasis , and  Shigella dysenteriae . UV light has also been a common treatment for tuberculosis of the skin. Id.  
      UV light can be divided into different classes based on wavelength, including ultraviolet A (UVA) at about 350 nm, ultraviolet B (UVB) at about 300 nm, and ultraviolet C (UVC) at about 250 nm. Not unexpectedly, the effectiveness of UV light in producing biological changes can differ at different wavelengths.  
      For wound healing, the use of UV light is attractive in that it is a non-pharmalogical treatment that is non-invasive to the wound. It has been demonstrated that UV light can increase epithelial cell turnover, release prostaglandin precursors and histamines, increase vascular permeability, accelerate DNA synthesis, and inactivate bacterial cells. However, UVA and UVB have been shown to cause damage to the skin, particularly in the form of sunburn and blistering, each of which would be undesirable, particularly to an open wound; also, these forms of UV radiation have been demonstrated to be carcinogenic. The use of UVC in the treatment of open wounds is described in U.S. Pat. No. 6,283,986 to Johnson, the disclosure of which is hereby incorporated herein in its entirety.  
     SUMMARY OF THE INVENTION  
      As a first aspect, embodiments of the present invention are directed to a method of treating a dental patient. The method comprises applying ultraviolet C radiation to the mouth of the patient for a time and at a proximity and intensity sufficient to have a bacteriocidal effect. With this method, the risk of bacterial infection to both the patient and the dentist/oral surgeon can be reduced.  
      As a second aspect, embodiments of the present invention are directed to a dental instrument with bacteriocidal capability. The dental instrument comprises: a handle; a tool portion attached to the handle and configured to be applied to the mouth of a patient; and a UVC lamp mounted on one of the handle and tool portion to illuminate a portion of the patient&#39;s mouth during a dental procedure. The dental instrument can be employed during a dental procedure to reduce the risk of bacterial infection.  
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       FIG. 1  is a perspective view of a dental mirror that includes a lamp for illuminating the patient&#39;s mouth with UVC radiation according to embodiments of the present invention.  
       FIG. 2  is a perspective view of a dental drill that includes a lamp for illuminating the patient&#39;s mouth with UVC radiation according to embodiments of the present invention.  
       FIG. 3  is a perspective view of a root canal tool that includes a lamp for illuminating the patient&#39;s mouth with UVC radiation according to embodiments of the present invention.  
       FIG. 4  is a perspective view of a pair of pliers that includes a lamp for illuminating the patient&#39;s mouth with UVC radiation according to embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION  
      The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.  
      As noted above, the present invention employs UVC radiation in dental treatments. As used herein, “UVC radiation” is intended to encompass ultraviolet radiation having a wavelength of between about 240 and 260 nm. UVC radiation having with a wavelength of between about 243 and 255 nm may be employed in some embodiments; in certain embodiments, a wavelength of between about 245 and 247 nm may be used, as it has been observed that the bacteriocidal effect of the UVC radiation tends to peak at this wavelength range. In other embodiments, a wavelength of between about 253 and 255 nm may be used.  
      In dental treatments suitable for use with the present invention, UVC radiation may be applied to the mouth of a subject. It is also contemplated that the treatment can be used on both human subjects and non-human subjects (i.e., for veterinary use).  
      In some embodiments, the UVC radiation may be applied to the mouth with a UVC germicidal lamp, although other UVC radiation sources may also be suitable. A germicidal UVC lamp is generally of the configuration of a fluorescent lamp and operates with the same type of peripheral or auxiliary equipment. A UVC lamp typically contains no phosphor, but has a drop of liquid mercury dispersed in an argon gas vacuum. The mercury floats within the argon; when electricity is introduced, the mercury atoms discharge UVC radiation at approximately 260 nm. The UVC lamp will typically include a special glass bulb, cover or lens that allows transmission of most of the UVC radiation generated by the mercury arc (up to 74 percent of the UVC energy can be transmitted through the glass). A particularly suitable UVC lamp is the V-254 lamp, available from MedFaxx, Inc., Raleigh, N.C.  
      Because of the varied treatment regimes for different microorganisms, it may be desirable for the UVC radiation source to include components for varying intensity and/or wavelength within the UVC range. Also, an integral timer can be included to time the duration of UVC radiation application. In some embodiments, the UVC radiation may be applied prior to beginning any oral treatment, during a procedure, and/or post-procedure.  
      The UVC lamp or other UVC radiation source should provide UVC radiation at an intensity that enables it to have a bacteriocidal effect on the microorganism(s) to which it is applied. Typically, an intensity of between about 5 and 20 μW/cm 2  is suitable, with an intensity of between about 15 and 16 μW/cm 2  being preferred.  
      During application of UVC radiation to the mouth of the subject, the UVC lamp or other UVC radiation source should be positioned sufficiently proximate to or within the mouth so as to have a bactericidal effect. This position is typically between about ¼ and  3  inches from the desired treatment area, with a distance of between about ½ and 1 inches being suitable for certain embodiments. This typically positions the lamp inside the subject&#39;s mouth. The UVC radiation may be sufficiently diffuse to treat the air inside the patient&#39;s mouth during the procedure.  
      Alternatively, the UVC radiation may be applied to treat particulate matter that is expelled from the mouth and lodges outside the mouth in an area that can be exposed to the radiation.  
      Application of UVC radiation to the patient&#39;s mouth may be performed for a time sufficient to have a bacteriocidal effect therein. Typically, the duration of application is between about 5 seconds and 1 minute, with a duration of between about 5 and 30 seconds being preferred. The invention may be a continuous light or may be pulsed at intervals. Of course, the duration may be varied depending on the type and character of the treatment, any specific microorganisms to be eliminated, and the intensity and position of the UVC source. The UVC radiation may be incorporated into instruments presently used by the dental profession, or may be incorporated into a new instrument specific for the dental profession. Such instruments are illustrated in  FIGS. 1-4 .  FIG. 1  shows a dental mirror  10  that includes a lamp  20  for illuminating the patient&#39;s mouth with UVC radiation.  FIG. 2  shows a dental drill  50  with a lamp  60 .  FIG. 3  shows a root canal tool  100  with a lamp  110 .  FIG. 4  shows a pair of pliers  150  with a lamp  160 . Those skilled in this art will recognize that other dental instruments, typically comprising a handle and a tool portion attached to the handle for performing a dental procedure, may also include a UVC lamp.  
      Exemplary dental procedures that may be preceded, followed, or accompanied by application of UVC radiation include tooth scaling, dental implantation, extractions, procedures known to cause mucosal or gingival bleeding, reimplantation of avulsed teeth, root canal surgery, and professional cleaning of high risk patients. High risk patients include, but are not limited to, HIV-positive, diabetic, and hemophiliac patients as well as those with recent hip replacements.  
      The types of microorganisms that can be treated with the treatment method of the present invention include bacteria, yeast, mold spores, viri, and protozoa. Exemplary lists of microorganisms are set forth in Tables 1-5; those skilled in this art will appreciate that these lists are exemplary only and that other microorganisms may also be suitable for treatment.  
                           TABLE 1                                      ENERGY               (μW-s/cm 2 )                         ORGANISM   90% kill   100% kill                                   Bacillus anthracis     4520   8700         S. enteritidis     4000   7600         B. Megaterium sp.  (veg.)   1300   2500         B. Megaterium sp.  (spores)   2730   5200         B. paratyphusus     3200   6100         B. subtilis     5800   11000         B. subtilis  spores   11600   22000         Clostridium tetani     13000   22000         Corynebacterium diphtheriae     3370   6500         Eberthella typosa     2140   4100         Escherichia coli     3000   6600         Micrococcus candidus     6050   12300         Micrococcus sphaeroides     10000   15400         Myrobacterium tuberculosis     6200   10000         Neisseria catarrhalis     4400   8500         Phtomonas tumeficiens     4400   8500         Proteus vulgaris     3000   6600         Pseudomonas aeruginosa     5500   10500         Pseudomonas fluorescens     3500   6600         S. typhimurium     8000   15200         Salmonella typhosa -typhoid Fever   2150   4100         Salmonella paratyphi -enteric Fever   3200   6100         Sarcina lutea     19700   4200         Serratia marcescens     2420   3400         Shigella dysenteriae -Dysentery   2200   4200         Shigella flexneri -Dysentery   1700   3400         Shigella paradysenteriae     1680   3400         Spirillum rubrum     4400   6160         Staphylococcus albus     1840   5720         Staphylococcus aureus     2600   6600         Streptococcus hemolyticus     2160   5500         Streptococcus lactis     6150   8800         Streptococcus viridans     2000   3800         Vibrio comma -Cholera   3375   6500         Leptospira canicola -Infectious Jaundice   3150   6000                 *tests carried out at 253.7 nm UVC             
 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                   
               
               
                   
                 ENERGY 
                   
               
               
                   
                 (μW-s/cm 2 ) 
               
            
           
           
               
               
               
               
            
               
                   
                 YEAST 
                 90% kill 
                 100% kill 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 
                   Saccharomyces ellipsoideus 
                 
                 6000 
                 13200 
               
               
                   
                 
                   Saccharomyces sp. 
                 
                 8000 
                 17600 
               
               
                   
                 
                   Saccharamyces carevisiae 
                 
                 6000 
                 13200 
               
               
                   
                 Brewers Yeast 
                 3300 
                 6600 
               
               
                   
                 Bakers Yeast 
                 3900 
                 8800 
               
               
                   
                 Common yeast cake 
                 6000 
                 13200 
               
               
                   
                   
               
               
                   
                   *tests carried out at 253.7 nm UVC    
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                   
                 TABLE 3 
               
             
            
               
                   
                   
               
               
                   
                   
               
               
                   
                 ENERGY 
               
               
                   
                 (μW-s/cm 2 ) 
               
            
           
           
               
               
               
               
            
               
                 MOLD SPORES 
                 COLOR 
                 90% kill 
                 100% kill 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 
                   Penicillium roqueforti 
                 
                 Green 
                 13000 
                 26400 
               
               
                 
                   Penicillium expansum 
                 
                 Olive 
                 13000 
                 22000 
               
               
                 
                   Penicillium digitatum 
                 
                 Olive 
                 44000 
                 88000 
               
               
                 
                   Aspergillus glaucus 
                 
                 Bluish green 
                 44000 
                 88000 
               
               
                 
                   Aspergillus flavus 
                 
                 Yellowish green 
                 60000 
                 99000 
               
               
                 
                   Aspergillis niger 
                 
                 Black 
                 132000 
                 330000 
               
               
                 
                   Rhisopus nigricans 
                 
                 Black 
                 111000 
                 220000 
               
               
                   Mucor racemosus  A 
                 White gray 
                 17000 
                 352000 
               
               
                   Mucor racemosus  B 
                 White gray 
                 17000 
                 352000 
               
               
                 
                   Oospora lactis 
                 
                 White 
                 5000 
                 11000 
               
               
                   
               
               
                   *tests carried out at 253.7 nm UVC    
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 4 
               
             
            
               
                   
                   
               
               
                   
                   
               
               
                   
                 ENERGY 
                   
               
               
                   
                 (μW-s/cm 2 ) 
               
            
           
           
               
               
               
               
            
               
                   
                 VIRUS 
                 90% kill 
                 100% kill 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Bacteriophage ( E. Coli ) 
                 2600 
                 6600 
               
               
                   
                 Infectious Hepatitis 
                 5800 
                 8000 
               
               
                   
                 Influenza 
                 3400 
                 6600 
               
               
                   
                 Poliovirus-Poliomyelitis 
                 3150 
                 6000 
               
               
                   
                 Tobacco mosaic 
                 240000 
                 440000 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 5 
               
             
            
               
                   
                   
               
               
                   
                   
               
               
                   
                 ENERGY 
                   
               
               
                   
                 (μW-s/cm 2 ) 
               
            
           
           
               
               
               
               
            
               
                   
                 PROTOZOA 
                 90% kill 
                 100% kill 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 
                   Paramecium 
                 
                 110000 
                 200000 
               
               
                   
                 Nematode eggs 
                 4000 
                 92000 
               
               
                   
                   Chlorella vulgaris . 
                 12000 
                 22000 
               
               
                   
                   
               
               
                   
                   *tests carried out at 253.7 nm UVC    
               
            
           
         
       
     
      It has been observed that different microorganisms may be more susceptible to eradication by different wavelengths within the UVC radiation range. For example, vancomycin-resistant  Enterococcus faecalis  (VRE) and methicillin-resistant  Staphlococcus aureus  (MRSA) have both proven to be very susceptible to UVC having a wavelength of 246 nm.  
      Note that Tables 1-5 also include recommended UVC radiation energy levels to destroy 90 percent and 100 percent of these microorganisms. This information can be used to calculate application duration and frequency. For example, according to Table 3 the mold spore  Aspergillis niger  requires 330,000 μW-s/cm 2  for complete destruction. Assuming a UVC output of 2,250 μW per cm 2  of treatment area, a 146 second application interval is needed for total destruction of the microorganism. This can be accomplished in a single 146 second treatment, or, alternatively, in three 49 second treatments.  
      The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention.