Device and method to treat oral disease in felines

A laser system and method are described that will effectively interrupt the progression of periodontal disease in felines, particularly in situations where the disease has progressed to advanced stages of periodontitis and feline lymphocytic-plasmacytic gingivitis stomatitis. A laser system is employed to achieve precision in surgical procedures where the working field is limited due to the anatomical structure of a feline's mouth. The laser system is also capable of effectively sealing tubules and of eradicating bacteria in the periodontium to significantly reduce the risk of infection. Additionally, the laser therapy can be preceded by pretreatment methods to effectively interrupt the progression of periodontal diseases.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a device and method to treat periodontal 
disease in felines, particularly in situations where the disease has 
progressed to advanced stages of periodontitis and feline 
lymphocytic-plasmacytic gingivitis (commonly referred to as feline 
lymphocytic-plasmacytic stomatitis). 
2. Information Disclosure Statement 
Oral diseases are especially prevalent in cats. Periodontal disease can 
range from a localized inflammation of the gingiva (gingivitis) to 
inflamation and destruction of the gingiva, alveolar bone, the periodontal 
ligament, and tooth structure (periodontitis). Etiology of the disease can 
involve plaque, calculus, and systemic inflammatory response. 
Generally, the protocol for treating periodontal disease focuses on 
cleaning the oral cavity, repairing the tissue, and stopping the 
progression of the disease. However, the available treatment methods, 
which include scalping, polishing, curettage, dental extractions, root 
planing, gingivectomies and in extreme cases, gingival flaps or grafts, 
are inadequate when treating advanced periodontitis and feline 
lymphocytic-plasmacytic gingivitis/stomatitis. 
Root planing is often necessary to remove necrotic tissue from the roots of 
periodontally involved teeth. A curette or Orban file is applied to the 
root surface and withdrawn in overlapping strokes using sufficient 
pressure to scrape necrotic cementum and debris from the root and smooth 
its surface. However, due to the anatomical structure of a cat's mouth, it 
is very difficult to remove the necrotic debris without affecting the 
surrounding soft tissue. 
A gingivectomy is often performed to eliminate gingival sulcus, in an 
effort to facilitate plaque control and oral hygiene. A gingivectomy is 
required where pocket depths exceed 4 mm, the epithelial attachment is 
still above bone level, and resection can be contained within the attached 
gingiva. The level of epithelial attachment is determined using a 
periodontal probe and is marked on the buccal surface of the gingiva. The 
gingival tissue is then excised using a periodontal knife. Digital 
pressure is usually sufficient to effect hemostasis. However, the gingiva 
is especially narrow in cats therefore, it is very difficult to limit 
resection to the attached gingiva. Additionally, the anatomical structure 
of a feline's mouth limits the available working area and restricts 
maneuverability of instruments within the mouth thereby reducing the 
precision by which the procedure can be performed. 
Cats exhibit particular manifestations of periodontal disease that are 
unique to the feline species. For example, a chronic problem in cats that 
is commonly associated with both chronic gingivitis/periodontitis and 
feline lymphocytic-plasmacytic stomatitis is external root resorption. 
Inflammatory resorption occurs at the cementoenamel junction. The presence 
of exuberant gingival tissue often conceals extensive cavitations in the 
tooth that undermine the crown eventually causing it to fracture and 
crumble thereby exposing the dentin. Exposed dentin is sensitive and 
extremely painful. 
Typically, a fluoride gel is administered to treat this condition to 
desensitize the dentin. However, restoration has not been very successful 
and in many circumstances all of the teeth must be extracted. Extraction 
of involved teeth is often difficult because the crowns are weakened and 
therefore tend to fracture easily. Additionally, the roots are usually 
ankylosed and hard to separate from the surrounding bone. The long-term 
therapeutic response for treating external root resorption has typically 
been poor. 
The cats are also placed on systemic antibiotics and long-term 
corticosteroids to reduce the risk of infection and to reduce 
inflammation. However, antibiotic treatments are usually not effective in 
treating feline lymphocytic-plasmacytic gingivitis/stomatitis because a 
primary bacterial causative agent has not yet been identified and 
long-term corticosteroid use can lead to serious secondary systemic side 
effects such as kidney failure. 
Thus there is a need for a device and method that will improve treatment 
for cats with periodontal disease, particularly in the advanced stages of 
periodontitis and feline lymphocytic-plasmacytic stomatitis without the 
complications associated with the prior art. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a laser system and 
treatment method that will eliminate the complications associated with the 
prior art. 
It is another aim of the present invention to eliminate the chronic 
symptoms associated with periodontal disease in cats. 
It is another aim of the present invention to employ a laser system to 
achieve enhanced precision in surgical procedures. 
It is a further aim of the present invention to seal the tubules in 
surrounding tissue and eradicate bacteria to significantly reduce the risk 
of infection. 
Briefly stated, the present invention describes a laser system and method 
that will effectively interrupt the progression of periodontal disease in 
cats, particularly in situations where the disease has progressed to 
advanced stages of periodontitis and feline lymphocytic-plasmacytic 
stomatitis. A laser system is employed to achieve precision in surgical 
procedures where the working field is limited due to the anatomical 
structure of a cat's mouth. The laser system is also capable of 
effectively sealing tubules and of eradicating bacteria in the 
periodontium to significantly reduce the risk of infection. Additionally, 
the laser therapy can be preceded by pre-treatment methods to effectively 
interrupt the progression of periodontal diseases. 
The above, and other objects, features, and advantages of the present 
invention will become apparent from the following detailed description 
read in conjunction with the accompanying drawings.

DISCLOSURE OF PREFERRED EMBODIMENTS 
The present invention describes a new device and method to treat 
periodontal disease, particularly in situations where the disease has 
progressed to periodontitis and feline lymphocytic-plasmacytic stomatitis. 
A preferred embodiment of the present invention employs a 980 nm diode 
laser to achieve high precision, low penetration cutting. The graph in 
FIG. 1 illustrates a peak in the absorption of light in water in the 
vicinity of 980 nm. As a result, 980 nm radiation is preferred over 1064 
nm radiation for medical procedures involving soft tissue because greater 
absorption is achieved when 980 nm light is employed on the tissue. 
FIGS. 2 and 3 illustrate an example and preferred embodiment in which the 
present invention was used to treat feline lymphocytic-plasmacytic 
gingivitis/stomatitis. Feline lymphocytic-plasmacytic gingivitis (also 
known as feline plasma cell gingivitis-pharyngitis and chronic feline 
gingivitis-stomatitis) is an oral disease of unknown etiology that is 
frequently encountered in cats. Cats with feline lymphocytic-plasmacytic 
gingivitis stomatitis have proliferative and ulcerated gingiva that 
extends into the soft palate and oropharnyx. The gingiva may recede, there 
may be bone loss, the roots may become exposed, and abscesses may form. 
Cats with feline lymphocytic-plasmacytic gingivitis/stomatitis suffer from 
intense oral pain that is typically attributable to external root 
resorption. 
FIG. 2 is a cross-sectional view of a mandibular molar that is afflicted 
with external root resorption. The presence of exuberant gingival tissue 
202 conceals extensive cavitations 206 in tooth 200 that undermines crown 
210 eventually causing it to fracture and crumble. In typical current 
treatments, tooth 200 would be extracted. Generally, the response to 
extractions is favorable. However, extractions are not always successful 
for treating external root resorption when the cat has feline 
lymphocytic-plasmacytic stomatitis. Approximately 20% of the cats with 
feline lymphocytic-plasmacytic stomatitis experience a relapse following 
the extraction and the long-term response is typically poor. 
FIG. 3 shows a preferred embodiment of the present invention in which a 980 
nm diode laser 310 was used to treat a cat with feline 
lymphocytic-plasmacytic gingivitis stomatitis who had relapsed following 
extraction. Laser 310 was set to deliver an optical power of 2 W to resect 
gingiva 302 to the cementoenamel junction 308 and effectively eliminate 
the affected tissue. A 600 .mu.m flat tip optical fiber 302 delivered 
radiation to the affected tissue in a continuous mode. A small spot size 
was used to concentrate high amounts of energy into the tissue to achieve 
rapid vaporization. 
After the resection, the laser was then set to 1 W (pulsed 1 sec on/1 sec 
off) to seal the tubules thereby preventing the osmotic action of the 
tubules from replanting bacteria, present at the time of the procedure, 
into the newly grown tissue. 
In another example and preferred embodiment of the present invention, a 
diode laser system with multi-wavelength sources may be employed in 
conjunction with a photosensitizer to stop the progression of 
periodontitis. Generally, 980 nm light may be employed to resect the 
affected tissue and a wavelength that is suitable to activate the 
photosensitizer may be used to eradicate the gram-negative bacteria in the 
periodontium. 
The photosensitizer liquid or paste, when activated by an appropriate laser 
wavelength, produces hyperactive singlet oxygen that are capable of 
destroying bacteria. The oxygen singlets will destroy the gram-negative 
bacteria that are reacting with the inflammatory cells in the periodontium 
to mediate the inflammatory response. Specifically, the plasma cells 
elaborate antibodies against endotoxins, produced by the gram-negative 
bacteria, thereby producing antigen-antibody complexes that activate the 
complement system of the cat The result of complement activation is the 
production of biologically active substances such as anaphylatoxins, which 
mediate various aspects of the inflammatory response. By eradicating the 
gram-negative bacteria, the antigen-antibody complex that is responsible 
for initiating the inflammatory response is destroyed thereby effectively 
interrupting the chronic progression of the disease. 
Particular pretreatment methods can be especially advantageous in treating 
periodontitis when used in conjunction with the present laser system. The 
laser treatment may be preceded by mechanically cleansing the surface of 
the teeth and by disinfecting the oral cavity with an antiplaque substance 
to remove the gram-negative bacteria on the surface of the teeth. 
Antimicrobial agents such as chloramphenicol, clindamycin, tetracycline or 
metronidazole may also be of some benefit prior to the dental procedure 
when the feline's immune system is suppressed due to a systemic illness. 
The photosensitizer may then be applied to the periodontium and a 
multi-wavelength laser system can be employed to activate the 
photosensitizer and to resect necrotic tissue at the roots of the 
periodontially involved teeth to eliminate the chronic symptoms associated 
with the condition. Additionally, the tubules may be sealed to further 
reduce the risk of infection. 
Having described the preferred embodiments of the invention with reference 
to the accompanying drawings, it is to be understood that the invention is 
not limited to these precise embodiments, and that various changes and 
modifications may be effected therein by one skilled in the art without 
departing from the scope or spirit of the invention as defined in the 
appended claims.