WO1998006456A1

WO1998006456A1 - Method and apparatus to treat gingival and periodontal disease

Info

Publication number: WO1998006456A1
Application number: PCT/US1997/011052
Authority: WO
Inventors: James C. Chen; Brent Wiscombe
Original assignee: Light Sciences Limited Partnership
Priority date: 1996-08-08
Filing date: 1997-06-26
Publication date: 1998-02-19
Also published as: AU3578497A

Abstract

Method and apparatus employing light therapy to destroy organisms causing oral diseases. A fixture (20) is formed in a U shape and having a trough or cavity (24) with a generally inverted U-shaped cross section open along a lower surface. Light is emitted from spaced-apart points disposed adjacent to inner walls (28) of the fixture so that the light is incident upon a gum line of a patient. A photoreactive agent is applied to the gum line of the patient prior to initiating administration of the light therapy. Since the light has substantially the same range of wavelengths or waveband as an absorption waveband of the photoreactive agent, disease-causing organisms that exist along the gum line and which preferentially absorb the photoreactive agent are destroyed by the light administered using the fixture. An external light source can be employed by using a bundle (30a, 30b) of optical fibers (32) to convey the light from outside the oral cavity to spaced-apart points along the inner wall of the fixture at which ends (34) of individual cleaved optical fibers are directed toward the gum line. Alternatively, a plurality of spaced-apart light emitting devices (52/62) can be mounted adjacent the inner walls of the fixture so that the light the devices emit is directed along the gum line. Since the light intensity of these various types of light sources is relatively low, the duration of the PDT is likely to range from minutes to hours.

Description

METHOD AND APPARATUS TO TREAT GINGIVAL AND

PERIODONTAL DISEASE

Field of the Invention

This invention generally relates to a method and apparatus for treating diseases of the oral cavity, and more specifically, to the use of photodynamic therapy (PDT) for treatment of gingival and periodontal diseases and for destroying organisms that cause caries.

Background of the Invention

The field of dentistry has undergone significant changes due to improvements in personal hygiene products, improvements in dental care technology, and greater awareness by the public of appropriate preventive measures to avoid dental disease and loss of teeth. However, many dental problems resulting in the extraction of teeth are still caused by periodontal and gingival diseases of the tissue supporting the teeth, in some cases because of a refusal to floss and apply other personal hygiene habits that will minimize the formation of plaque. While antibiotic therapy is sometimes useful in destroying the organisms that cause periodontal and gingival diseases, in many cases, the diseases advance to the point at which teeth must be extracted.

As an alternative to antibiotics, the use of photosensitizers in connection with relatively lower power laser light sources for treating oral pathogens in vitro is disclosed in several papers, including: "Sensitization of Oral Bacteria to Killing by Low-Power Laser Radiation," by Michael Wilson, John Dobson, and Wilson Harvery, pp. 77-81 , Current Microbiology, Vol. 25 (1992); "Lethal Photosensitization of Bacteria in Subgingival Plaque from Patients with Chronic Periodontitis," by S. Sarkar and M. Wilson, pp. 204-210, Journal of Periodontal Research, Vol. 28 (1993); and "Sensitization of Periodontopathogenic Bacteria to Killing by Light from a Low-Power Laser," by M. Wilson, J. Dobson, and S. Sarkar, pp. 182-187, Oral Microbiology and Immunology, Vol. 8 (1993). Each of these papers describes how a low power He/Ne gas laser having an output of about 7.3 mW was used to destroy cultivated colonies of oral pathogens (ex vivo) that had been sensitized with various photoreactive agents. Laser light was administered to the photosensitized bacterial colonies for short periods of time to achieve substantial reduction in the viable organisms in such colonies. In "Targetable Photoactivatable Drugs - Synthesis of Water-Soluble Galactosamine Containing Polymeric Carriers of Chlorin e₆ and Their Photodynamic Effect on PLC Cells in vitro " by Krinik et al., pp. 70-83, SPIE Vol. 997 Advances in Photochemotherapy (1988), it is demonstrated that tumor cells can be destroyed with a low irradiance light source (i.e., 0.77 mW/cm²) if the period of irradiance is sufficient long (i.e., up to 24 hours). It is possible that other low power light sources such as LEDs can be employed for administering PDT to treat pathogenic gingival and periodontal organisms if the low level light is applied for time periods of thirty minutes or longer.

Several different embodiments of light emitting probes designed to be transcutaneously introduced into the body of a patient and disposed at a desired treatment site to administer PDT using low light level sources for extended periods of time are taught in commonly assigned U.S. Patent No. 5,445,608, the drawings and disclosure of which are specifically incorporated herein by reference. Each of the probes disclosed in this patent reference includes a plurality of light sources that are mounted so that the light emitted thereby is transmitted to the tumor or other cells to be destroyed by PDT. The light sources used on the probes taught by this reference are preferably light emitting diodes (LEDs). By transcutaneously placing one of these probes at an internal treatment site and applying PDT for an extended time, abnormal tissue at the treatment site can be destroyed without adverse impact on surrounding normal tissue.

The design and shapes of probes disclosed in the above-referenced patent are not well suited for use in administering PDT for extended periods of time inside a patient's mouth. What is required is a method and apparatus that applies light of the desired waveband to a treatment site extending along a patient's gum line where undesirable organisms that cause oral disease principally reside. The application of light should ideally be provided by a source that can comfortably be left inside a patient's mouth for times ranging from, for example, thirty minutes to many hours. For example, it may be desirable to provide apparatus to administer PDT that can be left inside a patient's mouth overnight, to minimize the affect of the treatment on the patient.

Summary of the Invention In accord with the present invention, apparatus is provided for administering light therapy inside a patient's oral cavity. The apparatus includes a generally U-shaped fixture, sized to fit adjacent to a gum line of teeth, disposed inside the patient's oral cavity. A light source is coupled to the fixture and produces light having a predefined waveband. Means are also included for directing the light produced by the light source onto the gum line to administer the light therapy thereto.

The fixture preferably includes a groove that is seated over the teeth to administer the light therapy to the gum line. In one embodiment, the light source is coupled to the fixture by an optical fiber, and the means for directing the light comprise an end of the optical fiber that is disposed so that the end is adjacent to the gum line when the fixture is fitted to the teeth of the patient. Light emitted from the end of the optical fiber is then incident on the gum line. More specifically, the means for directing the light comprise a plurality of optical fibers that convey light from the light source, which is disposed outside of the patient's oral cavity, to a plurality of spaced-apart points disposed on the fixture at the gum line.

In another embodiment, the light source comprises a plurality of light emitting devices disposed in spaced-apart array on the fixture, so that said light emitting devices are substantially aligned with the gum line when the fixture is positioned in the patient's oral cavity. Optionally, the means for directing the light can comprise a diffusing material that diffuses light produced by the source, so that the light is incident more continuously along the gum line.

In each of the preferred embodiments, the means for directing the light are disposed along the two facing portions of the fixture so that the light is directed at the gum line along both an inner and an outer side of the teeth. The light source may comprise an LED, a laser diode, a vertical cavity surface emitting laser (VCSEL), a light emitting semiconductor, a gas discharge source, a light emitting polymer, or a filament bulb.

A further aspect of the present invention is directed to a method for applying a light therapy to treat disease in an oral cavity of a patient. The method includes steps that are generally consistent with the functions performed by the elements of the apparatus described above. Bricf Description of the Drawing Figures

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is an isometric view of an fixture in accord with the present invention, for administering PDT to treat diseases of the oral cavity;

FIGURE 2 is an isometric view of the fixture of FIGURE 1 , with hidden lines to show a recessed groove in the fixture that is adapted to fit over either the upper or lower teeth in a patient's mouth during administration of PDT;

FIGURE 3 is a plan view of the fixture shown in FIGURES 1 and 2; FIGURE 4 is a cross-sectional view of the fixture, taken along section line 4-4 in FIGURE 3;

FIGURE 5 is a partial cut-away plan view of the fixture, showing the optical fibers that convey light to a plurality of spaced-apart points along an inner surface of the fixture;

FIGURE 5 A is an enlarged portion of the fixture shown in FIGURE 5; FIGURE 6 is a partial cut-away plan view of a second embodiment of the fixture, showing a plurality of light emitting devices positioned at points along an inner surface of the fixture;

FIGURE 6A is an enlarged portion of the fixture shown in FIGURE 6; FIGURE 7 is a partial cut-away plan view of a third embodiment of the fixture, showing a plurality of light emitting devices mounted to a conductive strip that is embedded in a wall of the fixture; FIGURE 7A is an enlarged portion of the fixture shown in FIGURE 7, showing an optional diffuser strip that is embedded in the inner wall of the fixture; FIGURE 8 is a partial cut-away plan view of a fourth embodiment of the fixture, showing placement of an optical fiber used to convey light within the fixture; and FIGURE 8A is an enlarged portion of the fixture shown in FIGURE 8, illustrating spaced-apart nicks in the cladding of the optical fiber that emit light directed toward the interior cavity of the fixture.

Description of the Preferred Embodiment Several different embodiments of fixtures useful for administering PDT for extended periods of time inside a patient's mouth to destroy undesirable oral organisms are illustrated in the drawings. FIGURES 1 and 2 illustrate details of a fixture 20 in accord with the present invention. Except as noted, fixture 20 is the same in each of the embodiments described below. The embodiments of the present invention differ primarily in the manner in which light is delivered to a treatment site extending along the gum line in a patient's mouth. As shown in FIGURES 1 and 2, fixture 20 is generally U-shaped, appearing similar to a mouth guard of the type that is used for protecting teeth against bruxism or from injury during participation in sports activities such as football or boxing. An elastomeric biocompatible material such as a silicone or a soft polyurethane or other plastic is used to form fixture 20 into the desired shape. It is contemplated that a variety of sizes and shapes of fixture 20 may be made commercially available to accommodate the individual shape of a specific patient's oral cavity, since substantial variation exists in the dental configuration of teeth and gingival tissue among individuals within the general population.

As more clearly shown in FIGURE 2, fixture 20 includes an open trough or cavity 24 that is generally an inverted "U" shape in cross section and which has open ends 21 , so that trough 24 in fixture 20 is seated over the teeth in a patient's mouth. Ideally, fixture 20 will be sized to fit the dental structure in a particular patient's oral cavity, and open ends 21 will be disposed adjacent the intramandible tissue, i.e., behind the point at which the patient's wisdom teeth are normally disposed. By providing the appropriate size fixture 20 fitted to a specific individual's mouth and dental structure, full exposure of the gum line on the lower and upper sets of teeth can be achieved.

While it is possible that two fixtures 20 may be used for simultaneously administering PDT to both the lower and upper sets of teeth within a patient's mouth, it will likely be more comfortable for the patient if the treatment is applied only to the upper or lower set of teeth at a time. In one preferred form of fixture 20, a lead 22 extends from the fixture to a point outside the patient's oral cavity. Depending upon the type of light source employed, lead 22 may convey an electrical current from an external power supply (not shown), such as a battery pack, that is fastened to the patient's clothing, or fixed behind the patient's ear (e.g., in the same manner as some hearing aids). Alternatively, as illustrated by the dashed line in FIGURE 1, instead of supplying electrical current to fixture 20 from an external power source, an internal battery 25, accessible by removing a cover 23 on the front of the fixture can be used to provide power to energize the light source contained within fixture 20. Internal battery 25 is less desirable, however, since it is likely to add to the bulk of fixture 20, and because the materials used in batteries are potentially toxic, should any leakage occur from the internal battery that escapes past cover 23.

In FIGURE 3, a plan view of fixture 20 shows the position of a cross- sectional view taken along cross section lines 4-4. This cross-sectional view is illustrated in FIGURE 4. In the particular embodiment shown in FIGURE 4, fixture 20 includes a plurality of optical fibers in hexagonal shaped bundles 30a and 30b that are embedded within the structural body of the fixture, between an outer wall 26 and an inner wall 28. FIGURE 4 shows how the fixture is seated over the teeth of a patient, so that, for example, a molar 36 extends into trough 24 adjacent to and between facing inner walls 28 of the fixture. Bundles 30a and 30b are disposed at an elevation within fixture 20 so they are generally adjacent a gum line 38 in the patient's mouth when the fixture is seated on the patient's teeth.

As shown in FIGURES 5 and 5A, at spaced-apart intervals along inner walls 28 of the fixture, ends 34 of cleaved optical fibers 32 are deflected away from bundles 30a and 30b toward gum line 38. Light conveyed through optical fibers 32 from an external light source (not shown) is directed from ends 34 of the optical fibers onto gum line 38 to administer PDT that is intended to destroy undesirable disease-causing organisms at the gum line treatment site. Optical fibers in bundle 30a direct light onto the gum line on one side of molar 36, while optical fibers in bundle 30b direct light onto the gum line on the opposite side of molar 36. It will be apparent that bundle 30a is substantially larger and includes a greater number of optical fibers than bundle 30b, since fewer optical fibers remain in bundle 30b. The optical fibers comprising the bundles extend from fixture 20 through lead 22 to the external light source, e.g., to a low-powered laser or to one or more laser diodes. Alternatively, for exposures over even longer periods of time, light can also be supplied at a relatively lower intensity from lower power sources such as LEDs, VCSELs, or even filament bulbs. Light from one or more such sources is conveyed through lead 22 and distributed along the gum line by optical fibers 32, so that the entire gum line of the lower or upper set of teeth (both inner and outer sides) is exposed to the light to administer PDT.

As noted in the Background of the Invention above, PDT is preferably administered to a treatment site to which a photoreactive agent has already been applied; the photoreactive agent is preferentially absorbed by the organisms intended to be destroyed by the PDT. Any of the photoreactive agents that are described in the papers listed in the Background of the Invention or other photoreactive agents suitable for this purpose can be applied along the gum line of the patient prior to insertion of the fixture in accord with the present invention, to effect PDT. Each type of photoreactive agent has a characteristic absorption waveband or range of wavelengths that are absorbed. Light having a corresponding waveband or range of wavelengths is then applied by fixture 20. Depending upon the concentration of the photoreactive agent, the type of organism intended to be destroyed, the intensity of the light at the treatment site, and various other parameters, which vary from individual to individual, fixture 20 may be left in place to provide the treatment for periods of time ranging from minutes to hours. After one set of teeth has been treated, the photoreactive agent can be applied along the gum line of the other set of teeth and the fixture applied to the other set of teeth to complete the therapy.

FIGURES 6 and 6A illustrate a second embodiment of the present invention that comprises a fixture 20' in which a plurality of LEDs, VCSELs, laser diodes, or other light emitting devices 52 are embedded within the walls of the fixture at spaced-apart intervals and oriented so that they emit light directed along the gum line of a patient. Fixture 20' is placed into a patient's mouth, with either the upper or lower set of teeth inserted into trough 24. Since the light emitting devices are embedded within the elastomeric material comprising the supporting body of fixture 20', the material preferably comprises an optically transparent polyurethane or other comparable plastic material. In addition, it is contemplated that the inner side of outer wall 26 can be made highly light reflective to improve the intensity of light applied to the gum line.

Electrical power to energize light emitting devices 52 is supplied through a lead 50 that extends from a lead 22', which is connected to an external power source. Alternatively, lead 50 may be connected to internal battery 25 (as indicated in FIGURE 1).

Yet another embodiment is represented by fixture 20" shown in FIGURES 7 and 7A. In this embodiment, a plurality of light emitting devices 62, including any of the various types of light sources noted above, are mounted on a substrate 60 that includes conductive traces 63a and 63b on its surface for conveying electrical current to energize the light emitting devices. Substrate 60 is sufficiently flexible to conform to a relatively small radius of curvature without damage, enabling it to curve around the radius of curvature of the fixture. Preferably, the surface of substrate 60 on which light emitting devices 62 are mounted is made highly light reflective to increase the intensity of light applied to the gum light. In addition, the inner surface of outer wall 26 is also preferably highly light reflective, for the same purpose.

A pair of conductors 56 extends through external lead 22" and connects the external power supply to conductive traces 63a and 63b on substrate 60. Alternatively, as noted above, power may be supplied to the conductive traces from internal battery 25, which is located within the fixture.

In FIGURE 7A, a further optional detail is illustrated that is applicable to each of the embodiments of the present invention. Specifically, this drawing shows a diffuser 64 that is mounted within inner wall 28 of the fixture between the light emitting devices and the location of the gum line when the fixture is in use within a patient's mouth. Diffuser 64 has a relatively high index of refraction, at least along its linear axis, so that it disperses light emitted by the light emitting devices or by the optical fibers to provide a more even distribution of the light along the gum line. It is also contemplated that instead of diffuser 64, a simple linear lens assembly can be used for directing the light and dispersing it along the gum line of the patient.

The fourth embodiment of the present invention comprises a fixture 20'", as shown in FIGURES 8 and 8A. In this embodiment, an optical fiber 70 is disposed adjacent inner wall 28 at an elevation corresponding to the disposition of the patient's gum line when fixture 20'" is inserted over the teeth of the patient. Optical fiber 70 includes a cladding 72 that is applied to maximize internal reflections along the length of the optical fiber. However, at spaced-apart intervals, a plurality of nicks 82 are formed in cladding 72 on a side of the optical fiber directed toward inner wall 28. The material comprising the wall of fixture 20'" is optically transparent. At each point where a nick 82 is applied to the cladding along the length of the optical fiber, light escapes from inside the optical fiber to illuminate the gum line of the patient. Alternatively, cladding 72 can be textured (not shown) so that is has scratches, dimples, or grooves on its surface, or can include embedded particles, to facilitate light transmission through the cladding.

While not specifically shown as a separate drawing figure, it is also contemplated that an electroluminescent strip (generally appearing like optical fiber 70 in FIGURE 8) could also be used for producing light that is employed to administer PDT to the gum line of a patient. However, the light intensity of an electroluminescent strip is substantially lower than that emitted by the other types of light sources discussed above. Accordingly, it is likely that a substantially longer period of treatment would be required to achieve the same beneficial results, i.e., the destruction of undesirable oral disease-causing organisms within the oral cavity. Other types of light sources are contemplated for use with this invention, including light emitting semiconductor materials and gas discharge light sources.

Although the present invention has been described in connection with several preferred forms, those of ordinary skill in the art will understand that many other modifications can be made thereto within the scope of the claims that follow. Accordingly, it is not intended that the scope of the invention in any way be limited by the above description, but instead be determined entirely by reference to the claims that follow.

Claims

The invention in which an exclusive right is claimed is defined by the following:

1. Apparatus for administering light therapy inside a patient's oral cavity, comprising:

(a) a substantially U-shaped fixture sized to fit adjacent a gum line of teeth disposed inside the patient's oral cavity;

(b) a light source coupled to the fixture, said light source producing light having a predefined waveband; and

(c) means for directing the light produced by the light source onto the gum line to administer the light therapy thereto.

2. The apparatus of Claim 1 , wherein the fixture includes a groove that is seated over the teeth to administer the light therapy to the gum line.

3. The apparatus of Claim 1, wherein the light source is coupled to the fixture by an optical fiber, said means for directing the light comprising an end of said optical fiber disposed so that said end is adjacent to the gum line when the fixture is fitted to the teeth of the patient, light emitted from the end of the optical fiber being incident on the gum line.

4. The apparatus of Claim 1 , wherein the light source comprises a plurality of light emitting devices disposed in spaced-apart array on the fixture, so that said light emitting devices are substantially aligned with the gum line when the fixture is positioned in the patient's oral cavity.

5. The apparatus of Claim 1, wherein the means for directing the light comprise a plurality of optical fibers that convey light from the light source outside of the patient's oral cavity, to a plurality of spaced-apart points disposed on the fixture.

6. The apparatus of Claim 1 , wherein the means for directing the light comprise a diffusing material that diffuses light produced by the source, along the gum line.

7. The apparatus of Claim 1 , wherein the means for directing the light are disposed along inner facing portions of the fixture so that the light is directed at the gum line along both an inner and an outer side of the teeth.

8. The apparatus of Claim 1 , wherein the light source comprises one of a light emitting diode, a laser diode, a vertical cavity surface emitting laser, a light emitting polymer, a light emitting semiconductor, a gas discharge light source, and a filament bulb.

9. A fixture for administering photodynamic therapy within a patient's oral cavity, comprising:

(a) a supporting body having a generally U-shaped cross section, said supporting body being formed of a biocompatible material and being adapted to remain within the patient's oral cavity while administering the photodynamic therapy;

(b) a light source that emits light from the supporting body so that when the fixture is employed to administer the photodynamic therapy, light emitted by the light source is incident on a treatment site within the patient's oral cavity; and

(c) a lead coupled to the light source and adapted to connect to a power source, for supplying electrical power to energize the light source to administer the photodynamic therapy.

10. The fixture of Claim 9, wherein the light source comprises a plurality of light emitting devices that are spaced apart within the supporting body to emit light along an inner surface of the supporting body, said plurality of light emitting devices extending generally along a line aligned with a gum line in the patient's oral cavity when the fixture is being used to administer the photodynamic therapy.

1 1. The fixture of Claim 10, wherein the light emitting devices are coupled to a conductive trace that extends through the supporting body of the fixture.

12. The fixture of Claim 9, wherein the light source comprises an external light emitting device that is coupled to the supporting body through a plurality of optical fibers, said plurality of optical fibers terminating at spaced-apart points along an inner surface of the supporting body, so that when the fixture is employed to administer the photodynamic therapy to a gum line within the patient's oral cavity, light emitted by ends of the optical fibers is incident on the gum line.

13. The fixture of Claim 9, wherein the light source emits light within a predefined waveband.

14. The fixture of Claim 9, further comprising a diffuser supported by the supporting body of the fixture, for diffusing light emitted by the light source, thereby increasing an area over which the light is incident.

15. A method for applying a light therapy to treat disease in an oral cavity of a patient, comprising the steps of:

(a) providing a fixture adapted to fit within the oral cavity of the patient, said fixture being sized and shaped to be held adjacent teeth of the patient;

(b) producing light having a predefined waveband; and

(c) directing the light at a gum line of the patient to administer the light therapy to the patient.

16. The method of Claim 15, wherein the light therapy destroys organisms that cause gingival and periodontal diseases.

17. The method of Claim 15, further comprising the step of applying a photoreactive agent to the gum line, said photoreactive agent having a characteristic light absoφtion waveband that is substantially equal to the predefined waveband of the light directed at the gum line.

18. The method of Claim 15, wherein the step of directing the light comprises the step of diffusing the light to spread the light along the gum line.

19. The method of Claim 15, wherein the step of directing the light comprises the step of conveying the light into the oral cavity from an external source.

20. The method of Claim 19, wherein the light is conveyed by a plurality of optical fibers having ends disposed in a spaced-apart array along the gum line, so that the light emitted from the ends of the optical fibers is directed along the gum line.

21. The method of Claim 15, wherein the step of producing the light comprises the step of energizing a plurality of light emitting devices that are disposed in spaced-apart array adjacent to the gum line of the patient. AMENDED CLAIMS

[received by the International Bureau on 7 November 1997 (07.11.97); original claims 1,4,6-11,13-18 and 21 amended and renumbered as claims 1 and 3-16; original claims 3,5,12,19 and 20 cancelled; new claims 17-20 added; remaining claim 2 unchanged (5 pages)]

(b) a plurality of light sources mounted on the fixture in a spaced-apart array, said light sources producing light having a predefined waveband that is substantially equal to a characteristic light absoφtion waveband of a photoreactive agent; and

(c) means for directing the light produced by the light sources onto tissue disposed along the gum line, so that light therapy can be administered to tissue that has absorbed the photoreactive agent.

3. The apparatus of Claim 1, wherein the plurality of light sources comprises a plurality of light emitting devices substantially aligned with the gum line when the fixture is positioned in the patient's oral cavity.

4. The apparatus of Claim 1 , wherein the means for directing the light comprise a diffusing material that diffuses light produced by the plurality of light sources, along the gum line.

5. The apparatus of Claim 1, wherein the means for directing the light are disposed along inner facing portions of the fixture so that the light is directed at the gum line along both .an inner and an outer side of the teeth.

6. The apparatus of Claim 1, wherein each of the plurality of light sources comprises one of a light emitting diode, a laser diode, a vertical cavity surface emitting laser, a light emitting polymer, a light emitting semiconductor, a gas discharge light source, and a filament bulb.

7. A fixture for administering photodynamic therapy within a patient's or.al cavity, comprising:

(a) a supporting body having a generally U-shaped cross section, said supporting body being formed of a biocompatible material and being adapted to remain within the patient's oral cavity while administering the photodynamic therapy; (b) a plurality of low intensity light sources that emits light having a predefined waveband, said plurality of low intensity light sources being mounted in the supporting body in a spaced-apart array, so that when the fixture is employed to administer the photodynamic therapy, light emitted by the light sources is incident on tissue at a treatment site within the patient's oral cavity, and the predefined waveband of the light is substantially equal to a characteristic light absoφtion waveband of a photoreactive agent that has been absorbed by said tissue; and

8. The fixture of Claim 7, wherein the plurality of low intensity light sources comprises a plurality of light emitting devices that emit light along an inner surface of the supporting body, said plurality of light emitting devices extending generally along a line aligned with a gum line in the patient's oral cavity when the fixture is being used to administer the photodynamic therapy.

9. The fixture of Claim 8, wherein the light emitting devices are coupled to a conductive trace that extends through the supporting body of the fixture.

10. The fixture of Claim 7, wherein the plurality of low intensity light sources emits light within a predefined waveband.

11. The fixture of Claim 7, further comprising a diffuser supported by the supporting body of the fixture, for diffusing light emitted by the plurality of low intensity light sources, thereby increasing an area over which the light is incident.

12. A method for applying a light therapy to treat disease in an oral cavity of a patient, comprising the steps of:

(b) producing light from a plurality of sources disposed at spaced-apart points on the fixture, said light having a predefined waveband that is substantially equal to a characteristic light absoφtion waveband of a photoreactive agent; (c) applying the photoreactive agent to tissue along a gum line of the patient diseased tissue and undesirable organisms disposed along the gum line preferentially absorbing the photoreactive agent; and

(d) directing the light produced by the plurality of sources at tissue along the gum line of the patient to administer the light therapy to the gum line in oral cavity of the patient, thereby destroying said diseased tissue and undesirable organisms.

13. The method of Claim 12, wherein the light therapy destroys organisms that cause gingival and periodontal diseases.

14. The method of Claim 12, further comprising the step of applying a photoreactive agent to the gum line, said photoreactive agent having a characteristic light absoφtion waveband that is substantially equal to the predefined waveband of the light directed at the gum line.

15. The method of Claim 12, wherein the step of directing the light comprises the step of diffusing the light to spread the light along the gum line.

16. The method of Claim 12, wherein the step of producing the light comprises the step of energizing a plurality of light emitting devices that .are disposed adjacent to the gum line of the patient.

17. Apparatus for administering light therapy inside a patient's oral cavity, comprising:

(a) a generally U-shaped fixture sized to fit adjacent a gum line of teeth disposed inside the patient's oral cavity; and

(b) a solid state light source coupled to the fixture, said solid state light source producing light having a predefined waveband that is substantially equal to a characteristic light absoφtion waveband of a photoreactive agent applied to tissue at the gum line, said solid state light source being positioned to emit light directly onto a treatment site disposed along the gum line, so that light therapy can be administered to destroy diseased tissue and undesirable organisms that have preferentially absorbed the photoreactive agent.

18. Apparatus for administering light therapy inside an oral cavity of a patient, comprising:

(a) a substantially U-shaped fixture sized to fit adjacent a gum line of teeth disposed inside the oral cavity; (b) a light source coupled to the fixture, said light source producing light having a predefined waveband that is substantially equal to a characteristic light absoφtion waveband of a photoreactive agent administered to the patient and absorbed by tissue along the gum line; and

(c) an inner reflective surface disposed in said fixture, said inner reflective surface reflecting the light produced by said light source onto the tissue disposed along the gum line with an enhanced intensity, so that light therapy can be administered to said tissue that has absorbed the photoreactive agent.

19. A fixture for administering a photodynamic therapy within a patient's oral cavity, comprising:

(a) a supporting body having a generally U-shaped cross section, said supporting body being formed of a biocompatible material and being adapted to remain within the patient's oral cavity while administering the photodynamic therapy, said body having an inner surface that is light reflective, said inner surface being disposed on the supporting body so that the inner surface faces towards tissue at a treatment site within the patient's oral cavity;

(b) a light source disposed on the supporting body, said light source emitting light having a predefined waveband appropriate to administer the photodynamic therapy, so that when inserted in the patient's oral cavity, light emitted by the light source is reflected by said inner surface onto tissue at the treatment site within the patient's oral cavity, thereby enheincing an intensity of light incident on the treatment site; and

20. A method for applying a light therapy to treat disease in an oral cavity of a patient, comprising d e steps of:

(b) producing light having a predefined waveband that is substantially equal to a characteristic light absoφtion waveband of a photoreactive agent; (c) applying the photoreactive agent to tissue along a gum line of the patient diseased tissue and undesirable organisms disposed along the gum line preferentially absorbing the photoreactive agent; and

(d) reflecting the light at tissue along the gum line of the patient from an inner surface of said fixture that is light reflective, said inner surface being disposed along the gum line and adjacent to the diseased tissue and undesirable organisms, so that said diseased tissue and undesirable organisms are destroyed by the light therapy.

AMENDED SHEET (ARTICLE 19