WO2009047669A2

WO2009047669A2 - A light-activated dentifrice and associated light irradiating toothbrush

Info

Publication number: WO2009047669A2
Application number: PCT/IB2008/054000
Authority: WO
Inventors: Yukiko Furukawa; Bart Gottenbos; Jozef Johannes Maria Janssen
Original assignee: Koninklijke Philips Electronics NV; US Philips Corp
Current assignee: Koninklijke Philips NV; US Philips Corp
Priority date: 2007-10-08
Filing date: 2008-10-01
Publication date: 2009-04-16
Anticipated expiration: 2010-04-08
Also published as: WO2009047669A3

Abstract

A combination of a treatment device (10) having a light source in a head end portion emitting light in the visible range for use inside the mouth with a dentifrice (21) which comprises a mixture of a liquid medium and a powder comprising particles (13) having a titanium nitride (TiN) core (15) with a titanium oxide (TiO2) outer shell (17). The mixture when applied to the teeth and irradiated by the light source in the mouth results in the activation of the TiO2, resulting in up to 90% and more of the oral bacteria in contact with the dentifrice and exposed to the light being killed within a given time period.

Description

A LIGHT- ACTIVATED DENTIFRICE AND ASSOCIATED LIGHT IRRADIATING TOOTHBRUSH

This invention relates generally to dentifrices and more specifically concerns a light- activated dentifrice for killing oral bacteria and the combination of such a dentifrice with a light irradiating toothbrush.

The use of photocatalyst material activated by ultraviolet light for killing of bacteria, including oral bacteria, is well known. Titanium Oxide (TiO₂) is one example of such a material. However, the use of ultraviolet (UV) light inside the mouth is seriously restricted due to safety concerns. Accordingly, it is desirable to have a light-activated dentifrice which is capable of killing bacteria but which can be activated by light in the visible spectrum which is safe for use in the mouth of a human user.

An oral care combination is disclosed which comprises: a treatment device having a source of light in the visible spectrum, safe for use in the mouth, and capable of activating photocatalysts to kill oral bacteria; and a dentifrice for use with the treatment device, comprising as one ingredient thereof photoactive particles comprising a core substantially of titanium nitride (TiN) and a shell of titanium oxide (TiO₂), wherein the relative amounts of TiN and TiO₂ in the active particles are such that the light activates the TiO₂ to the extent that substantially more than 50% of the oral bacteria coming into contact with the dentifrice and exposed to the light for a selected time are killed.

A dentifrice is disclosed which comprises: a mixture comprising a liquid medium and a powder comprising particles having a core of titanium nitride (TiN) and an outer shell of titanium oxide (TiO₂), the particles responding to light in the visible spectrum to kill oral bacteria when the mixture is used in the mouth.

A method is disclosed for making a powder for use in a dentifrice for killing oral bacterial irradiated by light in the visible spectrum, longer in wavelength than ultraviolet light, comprising the steps of: oxidizing a particle of original TiN material sufficiently to produce an end particle comprising a core of TiN and a shell of

TiO₂, wherein the relative amounts of TiN and TiO₂ in the end particle are such that oral bacteria are killed when exposed to a dentifrice which includes said end particles and irradiated by said light. Figure 1 is an elevational view of a treatment device/toothbrush capable of emitting visible light in combination with a particular dentifrice in a conventional dentifrice tube.

Figure 2 is an elevational view showing a treatment device/toothbrush arrangement capable of emitting visible light for activating a particular dentifrice which is stored in the device/toothbrush itself.

Figure 3 is a diagram illustrating the effectiveness of two dentifrice embodiments in killing oral bacteria.

Figure 4 is a top plan view of a portion of a mouthguard using the particular dentifrice and visible light sources.

Figure 5 is a diagram of a particle used in the dentifrice.

Titanium Oxide (TiO₂) is known to function as a photocatalyst under ultraviolet light (UV). Under UV irradiation, it acts as a strong oxidant and can oxidize organic material directly. Further, as TiO₂ is exposed to UV light, it becomes increasingly hydrophilic and can be used in a number of general cleaning applications, as well as for killing bacteria, including oral bacteria. Hence, TiO₂ could be used as a component in oral care compositions such as toothpaste, mouthwash and whitening coatings for teeth. However, the actual use of TiO₂ in oral care is extremely limited, because, as noted above, it requires the use of ultraviolet light, which is subject to safety concerns, including the possibility of inducing oral cancers with extended use. Heretofore, visible light, which is safe for use in the mouth, could not be used to activate TiO₂.

In the present embodiment, a dentifrice powder is used for oral care applications which comprises particles 13 which have a titanium nitride (TiN) core 15 and a TiO₂ shell 17 around the TiN core. Such a particle can be readily produced by partially oxidizing a TiN particle to produce an outer shell of TiO₂ around a remaining inner core of TiN. A number of different TiN core/TiO₂ shell arrangements have been discovered to be useful and safe in oral care applications as set forth below. In one embodiment, the individual particles comprise 4% TiN and 96% TiO₂ by weight. The particles of this embodiment absorb light having wavelengths less than 550nm, which is higher than the wavelength of ultraviolet light, which is less than 400nm. The particles of another embodiment comprise 84% TiN and 16% TiO₂ which absorb visible light having wavelengths less than 850nm. Both of the above particles, but especially the higher TiN content embodiment, absorb a wide range of visible light having wavelengths greater than 400nm. Both of the above powder particles, when used in a dentifrice, have been shown to be effective in killing bacteria when irradiated with visible light at the wavelengths noted above. In one dentifrice arrangement, the powder particles are used in a water suspension with a powder concentration of 5-100mg/l. Different powder mixtures can, however, be used. Applying the dentifrice to biofilms on teeth containing bacteria and then exposing the dentifrice to light in a safe wavelength spectrum produces results shown in Figure 3, in which the powder embodiment (line 30) comprising 96% TiO₂ results in close to 90% of the bacteria being killed using 190 j/cm² of light exposure (dose), while the 16% TiO₂ powder (line 32) killed close to 100% of the bacteria at the same light exposure. Figure 3 also shows that a 100% TiO₂ powder only produced a 40% killing level, which is about the level of killing produced by the light alone. The data shows the effectiveness of a dentifrice powder/water mixture using a TiN core/TiO₂ shell arrangement in killing oral bacteria.

Figure 1 shows an oral treatment device 10. Treatment device 10 includes a light source 12 which can be located in a head portion 14, or in a handle portion 16. In the handle embodiment, light proceeds through a light pipe to and then out from head portion 14. On-off button 24 controls the operation of light source 12. Treatment device 10 can include bristles 18 for scrubbing of the teeth, if desired. Bristles, however, are not necessary for effective operation of the treatment device. Device 10 can be a manual toothbrush, or it could be a power toothbrush which provides a desired motion to the toothbrush head portion, including, for instance, lateral

(side-to-side) motion, longitudinal motion or more complex movements. Motor/drivers 23 to produce such various motions are well known and are thus not disclosed in detail herein. One such arrangement is shown in U.S. Patent No. 5,378,153, owned by the assignee of the present invention. Motion actuation is controlled by a separate button 25. In the embodiment of Figure 1, dentifrice 21, which includes the desired TiNVTiO₂ particles, is applied to the teeth by a user from a separate storage member, such as a dentifrice tube 20. Light source 12 in one embodiment shown is an LED powered by a battery 22. The light source 12 is controlled by user-operated on-off switch 24. In one example, the wavelength of the LED is between 400-500nm. Dental LEDs are presently available in wavelengths in that range. Furthermore, the existing dental LEDs have been designed for power outputs of up to lW/cm², which is sufficient to provide the desired activation for the TiNVTiO₂ particles.

In operation, the user applies a desired amount of dentifrice to a section of teeth. The user can use the brush to scrub the teeth, if desired. The light source is then actuated by operation of switch 24. The light irradiates the dentifrice to kill the oral bacteria. The visible light produced by the light source is advantageously absorbed by the TiN core and then transferred to the TiO₂ shell, activating the TiO₂ material, which produces the desired killing effect on the oral bacteria. The present particle arrangement results in the TiO₂ being activated by the use of visible light. Since the light is in the visible spectrum, using dental approved LEDs, no harm is done to the user.

Figure 2 shows another treatment device embodiment 30, in which a source of dentifrice 32 is contained within handle 34 of the device. By means of a pump 36 or similar member, the dentifrice is directed to the teeth through openings 38 in the head portion 40 of the treatment device. The embodiment of Figure 2 can use light activation alone, or bristles could be provided on the head portion for scrubbing of the teeth, with the toothbrush being manually or power operated. The light source is actuated by on-off button switch 42. Motion can be provided to the head portion 40 by a motor/driver 44, controlled by a button witch 46.

In operation of the embodiments of Figures 1 and 2, the time of light exposure to produce the desired killing rates could be 2 seconds per tooth, and several minutes, up to 10 or even 15 minutes, for the whole mouth, although 2-5 minutes would be more typical. Although Figures 1 and 2 show hand-held treatment device embodiments, another useful embodiment could be in the form of a fully illuminating mouthguard, which treats all of the teeth at the same time. The dentifrice composition with the TiNVTiO₂ particles could be positioned in the mouthguard before use. This embodiment is illustrated in Figure 4, which shows a mouthguard portion 50, i.e. a lower half of a full mouthguard, with a light source 52 and an on-off control button 54. The light source 54 is connected via a light pipe or similar element 56 to a plurality of light outlets 58-58 in the body of the mouthguard. With the mouthguard embodiment, the entire mouth could be treated in a very short time, e.g. 2 minutes or less, depending on the arrangement of light sources in the mouthguard. The light source could also be located away from the mouthguard itself, with the light proceeding through a flexible light tube to the mouthguard. Although a preferred embodiment of the invention has been disclosed here for the purposes of illustration, it should be understood that various changes, modifications and substitutions may be incorporated in the embodiment without departing from the spirit of the invention, which is defined by the claims which follow.

Claims

1. An oral care combination, comprising a treatment device (10) having a source of light (12) in the visible spectrum, safe for use in the mouth, capable of activating photocatalysts to kill oral bacteria; and a dentifrice (21) for use with the treatment device, comprising as one ingredient thereof photoactive particles (13) comprising a core (15) substantially of titanium nitride (TiN) and an outer shell (17) of titanium oxide (TiO₂), wherein the relative amounts of TiN and TiO₂ in the active particles are such that the light activates the TiO₂ to the extent that substantially more than 50% of the oral bacteria coming into contact with the dentifrice and exposed to the light for a selected time are killed.

2. The combination of claim 1, wherein substantially at least 80% of the oral bacteria are killed.

3. The combination of claim 1, wherein the selected time is in the range of 2 seconds per tooth to 15 minutes for the entire mouth

4. The combination of claim 1, wherein the selected time is in the range of 2 seconds per tooth to 120 seconds for the entire mouth.

5. The combination of claim 1, wherein the treatment device includes a head portion (14) from which the light is delivered.

6. The combination of claim 1, wherein the light source is an LED having a wavelength greater than ultraviolet light and below 850nm.

7. The combination of claim 1, wherein the dentifrice is delivered to the teeth from a reservoir source (32) thereof in the treatment device.

8. The combination of claim 1, wherein the dentifrice is present in a reservoir (20) separate from the treatment device for application by a user.

9. The combination of claim 1, wherein the treatment device is a toothbrush which includes a brushhead portion with bristles (18) for scrubbing of the teeth.

10. The combination of claim 9, including a system (23) for moving the brushhead with a selected motion.

11. The combination of claim 1, wherein the treatment device is a mouthguard (50) having a plurality of sources of light (58) along the mouthguard.

12. A dentifrice, comprising: a mixture comprising a liquid medium and a powder comprising particles (13) having a core (15) of titanium nitride (TiN) and an outer shell (17) of titanium oxide (TiO₂), the particles responding to light in the visible spectrum to kill oral bacteria, when the mixture is used in the mouth.

13. The dentifrice of claim 12, wherein the light has a wavelength greater than the wavelength of ultraviolet light and less than 850nm.

14. The dentifrice of claim 12, wherein the powder comprises approximately 4%-95% TiN and approximately 96%-5% TiO₂, respectively.

15. The dentifrice of claim 12, wherein the powder comprises approximately 84% TiN and 16% TiO₂.

16. The dentifrice of claim 12, wherein the powder comprises approximately 4% TiN and 96% TiO₂.

17. A method for making a powder for use in a dentifrice for killing oral bacteria when irradiated by light in the visible spectrum, longer in wavelength than ultraviolet light, comprising the steps of: oxidizing a particle of original TiN material sufficiently to produce an end particle (13) comprising a core (15) of TiN and a shell (17) of TiO₂, wherein the relative amounts of TiN and TiO₂ in the end particle are such that oral bacteria are killed when exposed to a dentifrice which includes said end particles and irradiated by said light.

18. The method of claim 17, wherein the end article comprises approximately 4%-95% TiN and approximately 96%-5% TiO₂, respectively.