U.S. patent application number 10/075411 was filed with the patent office on 2002-09-26 for tooth whitening device and method of using same.
This patent application is currently assigned to BriteSmile, Inc.. Invention is credited to Cipolla, Anthony J., Prey, John E., Warner, John W., Williams, Michael A..
Application Number | 20020137001 10/075411 |
Document ID | / |
Family ID | 27372532 |
Filed Date | 2002-09-26 |
United States Patent
Application |
20020137001 |
Kind Code |
A1 |
Cipolla, Anthony J. ; et
al. |
September 26, 2002 |
Tooth whitening device and method of using same
Abstract
The present invention provides a device for tooth whitening
which has a light source, at least one optical output a projection
means for holding and positioning said optical output outside of a
patient's mouth in a manner to so as to provide approximately
simultaneous and uniform illumination of a patient's front teeth by
said optical output; and a connection means for connecting said
light source to said optical output. Also provided are methods of
using the tooth whitening device with a tooth-whitening composition
containing a transparent carrier compound and a transparent
oxidizing compound which when in contact with the surface of a
stained tooth and exposed to actinic light is activated to
facilitate tooth whitening.
Inventors: |
Cipolla, Anthony J.; (Trout
Run, PA) ; Warner, John W.; (Warner, NH) ;
Williams, Michael A.; (Midvale, UT) ; Prey, John
E.; (Tower Lakes, IL) |
Correspondence
Address: |
KALOW & SPRINGUT LLP
488 MADISON AVENUE
19TH FLOOR
NEW YORK
NY
10022
US
|
Assignee: |
BriteSmile, Inc.
Walnut Creek
US
94598
|
Family ID: |
27372532 |
Appl. No.: |
10/075411 |
Filed: |
February 14, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10075411 |
Feb 14, 2002 |
|
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09233793 |
Jan 19, 1999 |
|
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60074708 |
Feb 13, 1998 |
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60075222 |
Feb 19, 1998 |
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Current U.S.
Class: |
433/29 |
Current CPC
Class: |
A61C 19/066 20130101;
A61Q 11/00 20130101; A61K 2800/262 20130101; A61K 2800/81 20130101;
A61K 8/22 20130101 |
Class at
Publication: |
433/29 |
International
Class: |
A61C 001/00 |
Claims
What is claimed is:
1. A tooth whitening device comprising: a light source; at least
one optical output; projection means for holding and positioning
said optical output outside of a patient's mouth in a manner to so
as to provide approximately simultaneous and uniform illumination
of a patient's front teeth by said optical output; and connection
means for connecting said light source to said optical output.
2. A tooth whitening device as in claim 1, wherein there are three
optical outputs.
3. A tooth whitening device as in claim 1, wherein there are six
optical outputs.
4. A tooth whitening device as in claim 1, wherein the projection
means has a shape approximately that of a convex arch.
5. A tooth whitening device as in claim 1, wherein said means for
connecting the light source to said optical output is at least one
fiber optic bundle.
6. A tooth whitening device as in claim 1, wherein said means for
connecting said light source to said optical output is at least two
fiber optic bundles.
7. A tooth whitening device as in claim 5, wherein said fiber optic
bundle is glass or plastic.
8. A tooth whitening device as in claim 1, wherein said optical
output is of a shape selected from the group consisting of
circular, triangular and linear.
9. A tooth whitening device as in claim 1, when said optical output
is linear in shape.
10. A method for tooth whitening comprising the steps of: applying
a tooth-whitening composition to a patient's teeth; and exposing
said composition to light projected from the device of claim 1.
Description
[0001] The present application claims priority from provisional
Application Serial Nos. 60/074,708, filed Feb. 13, 1998 and
60/075,222, filed Feb. 19, 1998, the contents of which are hereby
incorporated by reference into the present disclosure.
BACKGROUND OF THE INVENTION
[0002] This invention relates to improvements in tooth whitening
compositions and methods of using same. In particular, the
invention provides novel tooth whitening compositions and methods
that use light energy to achieve a faster and improved level of
tooth whitening.
[0003] White teeth have long been considered cosmetically
desirable. Unfortunately, due to the presence of chromogenic
(color-causing) substances in food, beverages, tobacco, and
salivary fluid, in addition to internal sources such as blood,
amalgam restoratives, and antibiotics such as tetracycline, teeth
become almost invariably discolored in the absence of intervention.
The tooth structures that are generally responsible for presenting
a stained appearance are enamel, dentin, and the acquired pellicle.
Tooth enamel is predominantly formed from inorganic material,
mostly in the form of hydroxyapatite crystals, and farther contains
approximately 5% organic material primarily in the form of
collagen. In contrast, dentin is composed of about 20% protein
including collagen, the balance consisting of inorganic material,
predominantly hydroxyapatite crystals, similar to that found in
enamel. The acquired pellicle is a proteinaceous layer on the
surface of tooth enamel which reforms rapidly after an intensive
tooth cleaning.
[0004] A tooth stain classification system, termed the N (Nathoo)
Classification System, has been proposed (J. of the Amer. Dental
Asso., Vol. 128, Special Supplement, April 1997). One form of
direct dental stain is the N1 type stain which occurs when a
chromogenic material binds to the tooth surface to cause
discoloration similar in color to that of the unbound chromogen.
Another type of direct dental stain is the N2 type stain, in which
a chromogenic material binds to the toothsurface and subsequently
undergoes a color change after binding to the tooth. Finally, an N3
stain is an indirect dental stain, caused by the binding of a
colorless material (prechromogen) to the tooth, said prechromogen
undergoing a chemical reaction that converts it into a chromogen
that causes tooth stain. Tooth stains may be either extrinsic or
intrinsic, depending upon their location Within the tooth
structure. For example, extrinsic staining of the acquired pellicle
arises as a result of compounds such as tannins and other
polyphenolic compounds which become trapped in and tightly bound to
the proteinaceous layer on the surface of the teeth. This type of
staining can usually be removed by mechanical methods of tooth
cleaning that remove all or part of the acquired pellicle together
with the associated stain. In contrast, intrinsic staining occurs
when chromogens or prechromogens penetrate the enamel and dentin
and become tightly bound to the tooth structure. Intrinsic staining
may also arise from systemic sources of chromogens or
prechromogens, for instance, when excess fluoride intake during
enamel development leads to the mottled yellow or brown spots
typical of fluorosis staining. Intrinsic staining is not amenable
to mechanical methods of tooth cleaning and generally requires the
use of chemicals, such as hydrogen peroxide, that can penetrate
into the tooth structure, in order to affect a change in the light
absorptivity of the chromogen. Intrinsic tooth staining is
generally more intractable and difficult to remove than extrinsic
tooth staining.
[0005] Consequently, tooth-bleaching compositions generally fall
into two categories: (1) gels, pastes, or liquids, including
toothpastes that are mechanically agitated at the stained tooth
surface in order to affect tooth stain removal through abrasive
erosion of stained acquired pellicle; and (2) gels, pastes, or
liquids that accomplish the tooth-bleaching effect by a chemical
process while in contact with the stained tooth surface for a
specified period, after which the formulation is removed. In some
cases, an auxiliary chemical process or additive, which may be
oxidative or enzymatic, supplements the mechanical process.
[0006] Among the chemical strategies available for removing or
destroying tooth stains, the most effective compositions contain an
oxidizing agent, such as hydrogen peroxide, in order to attack the
chromogen molecules in such a way as to render them colorless,
water-soluble, or both. In one of the most popular approaches to
whitening a patient's teeth, a dental professional will construct a
custom-made tooth-bleaching tray for the patient from an Impression
made of the patient's dentition and prescribe the use of an
oxidizing gel to be dispensed into the tooth-bleaching tray and
worn intermittently over a period of time ranging from about 2
weeks to about 6 months, depending upon the severity of tooth
staining. These oxidizing compositions, usually packaged in small
plastic sages, are dispensed directly by the patient, into the
custom-made tooth-bleaching tray, held in place in the mouth for
contact times of greater than about 60 minutes, and sometimes as
long as 8 to 12 hours. The slow rate of bleaching is in large part
the consequence of the very nature of formulations that are
developed to maintain stability of the oxidizing composition. The
most commonly used oxidative compositions contain the hydrogen
peroxide precursor carbamide peroxide which is mixed with an
anhydrous or low-water content, hygroscopic viscous carrier
containing glycerin and/or propylene glycol and/or polyethylene
glycol. When contacted by water, carbamide peroxide dissociates
into urea and hydrogen peroxide. Associated with the slow rate of
bleaching in the hygroscopic carrier, the currently available
tooth-bleaching compositions cause tooth sensitization in over 50%
of patients. Tooth sensitivity is believed to result from the
movement of fluid through the dentinal tubules, which is sensed by
nerve endings in the tooth. The carriers for the carbamide peroxide
enhance this movement. In fact, it has been determined that
glycerin, propylene glycol and polyethylene glycol can each give
rise to varying amounts of tooth sensitivity following exposure of
the teeth to heat, cold, overly sweet substances, and other
causative agents.
[0007] Prolonged exposure of teeth to bleaching compositions, as
practiced at present, has a number of adverse effects in addition
to that of tooth sensitivity. These include: solubilization of
calcium from the enamel layer at a pH less than 5.5 with associated
demineralization; penetration of the intact enamel and dentin by
the bleaching agents, so as to reach the pulp chamber of a vital
tooth thereby risking damage to pulpal tissue; and dilution of the
bleaching compositions with saliva resulting in leaching from the
dental tray and subsequent ingestion.
[0008] Alternatively, there are oxidizing compositions (generally
those with relatively high concentrations of oxidizers) which are
applied directly to the tooth surface of a patient in a dental
office setting under the supervision of a dentist or dental
hygienist. Theoretically, such tooth whitening strategies have the
advantage of yielding faster results and better overall patient
satisfaction; however, due to the high concentration of oxidizing
agents contained in these so called "in-office" compositions, they
can be hazardous to the patient and practitioner alike if not
handled with care. The patient's soft tissues (the gingiva, lips,
and other mucosal surfaces) must first be isolated from potential
exposure to the active oxidizing agent by the use of a perforated
rubber sheet (known as a rubber dam), through which only the teeth
protrude. Alternatively, the soft tissue may be isolated from the
oxidizers to be used in the whitening process by covering said soft
tissue with a polymerizable composition that is shaped to conform
to the gingival contours and subsequently cured by exposure to a
high intensity light source. Once the soft tissue has been isolated
and protected, the practitioner may apply the oxidizing agent
directly onto the stained tooth surfaces for a specified period of
time or until a sufficient change in tooth color has occurred.
Typical results obtained through the use of a in-office tooth
whitener, with or without activation by heat, range from about 2 to
3 shades (as measured with the VITA.RTM. Shade Guide, VITAE.RTM.
Zahnfarbik, Bad Sackingen, Germany).
[0009] The range of tooth shades in the VITA.RTM. Shade Guide
varies from very light (B1) to very dark (C4). A total of 16 tooth
shades constitute the entire range of colors between these two
endpoints on a scale of brightness. Patient satisfaction with a
tooth whitening procedure increases with the number of tooth shade
changes achieved. Typically, the minimum generally accepted change
is about 4 to 5 VITA.RTM. shades.
[0010] Attempts have been made to activate peroxides with heat
and/or light for the purpose of whitening teeth. U.S. Pat. No.
4,661,070 discloses a method of whitening stained teeth which
includes the application of a concentrated solution of hydrogen
peroxide within the pulp chamber or upon the surface of a
discolored tooth, followed by exposing the discolored tooth to
optical energy consisting of both ultraviolet and infrared light.
The preferred wavelengths of light disclosed by this patent are
from 320 to 420 nanometers and from 700 to 1200 nanometers, with
light in the visible spectrum (wavelengths from 500 and 700
nanometers) being suppressed. The disclosed method suffers from two
serious drawbacks: (1) ultraviolet light can be hazardous to the
patient and practitioner alike and (2) infrared Right may cause
irreversible pulpitis if not handled with care.
[0011] These drawbacks are partially addressed in U.S. Pat. No.
4,952,143 which discloses a dental bleaching instrument which
filters out ultraviolet light and has a temperature regulation
mechanism. This patent also discloses the use of visible light with
wavelengths ranging from 450 to 500 and 650 to 750 nanometers to
produce a dark reddish/purple beam which facilitates the aiming and
focusing of the instrument.
[0012] U.S. Pat. No. 5,032, 178 discloses compositions and methods
to improved tooth whitening efficacy which uses exposure to
"optical energy", preferably in the visible spectrum wavelength
range of 400 to 700 nanometers. The compositions disclosed in this
patent require the use of (1) an inert silica gelling agent, (2) a
catalytic accelerator (either manganese sulfate monohydrate or
ferrous sulfate), (3) an agent for providing thixoplasticity and
thickening properties to the composition, such as cellulose ethers
and methyl vinyl ethers, and (4) a means for indicating completion
of the bleaching treatment of the teeth, comprising a redox color
indicator for transforming from one color to another in response to
the dissociation of hydrogen peroxide over a given time period.
Compositions described therein are mixed homogeneously prior to use
and all of the required components, including the catalyst, are
dispersed evenly throughout the mixture. The compositions described
are not highly transparent to light energy in the range of 400 to
700 nm, due to the presence of the high levels of inorganic silica
particles. Commercial mixtures based on this patent (available
under the trade name Shofu Hi-Lite.RTM. from Shofu Dental
Corporation, Menlo Park, Calif.) confirm that these preparations
are not transparent to visible light, but rather are quite opaque.
Typical results obtained using such compositions and methods are
about 2 to 3 VITA.RTM. shades improvement in tooth color, similar
to that achieved with compositions that do not employ light energy
in the process of bleaching teeth.
[0013] U.S. Pat. No. 5,240,415 discloses a dental bleaching system
comprising a multi-component kit, one of the required components of
said kit being fumed silica. As described above, silica renders an
aqueous composition relatively opaque to visible light energy.
Again, a tooth shade improvement of about 2 to 3 VITA.RTM. shades
can be expected through the use of this type of composition.
[0014] A commercial product called Opalescence Xtra available for
bleaching teeth in the controlled environment of a dental office
has recently been introduced by Ultradent Products, Inc, South
Jordan, Utah. This product is believed to be based on the
disclosure of U.S. Pat. No. 5,785,527. The commercial product is
supplied in a plastic syringe and is described in the accompanying
literature as a fight-activated tooth whitening gel, which contains
approximately 35% hydrogen peroxide. A pH determination showed the
product to have a neat pH at 25.degree. C. of about 4.0. The
product is thickened to a loose, gel-like consistency with a
polymer. Additionally, the product as sold, and as disclosed in
U.S. Pat. No. 5,785,527, contains a bright orange pigment or dye
(carotene), which presumably serves as the "photosensitizer". The
manufacturer also claims that the photosensitizer is able to absorb
light energy and convert it into heat energy, thereby increasing
the activity of the peroxide as a tooth bleaching agent. The
presence of a photoabsorber in the aforementioned composition
renders it relatively opaque to wavelengths from about 400 to 700
nm. Exposure of this composition to light energy between 400 and
700 nm results in a gradual fading of the orange color, presumably
due to a photobleaching effect in the presence of the hydrogen
peroxide. Comparative clinical results show an improvement in tooth
color of from about 3 to 4 VITA shades, which is highly dependent
upon the contact time of the composition on the tooth surface,
rather than any particular light or heat activation regimen. In
addition, the low pH of the commercial product may cause a
reduction in the microhardness of tooth enamel, due to the
dissolution of hydroxyapatite crystals (which can occur at a pH of
around 5.5 or less).
[0015] Devices for use in light/heat-activated tooth whitening
procedures include the commercially available Union Broach
Illuminator System, from Union Broach, a Health/Chem Company, New
York N.Y. This device, as described by the manufacturer, provides
direct, full spectrum illumination to all of the teeth found in the
front of the average adult's mouth. However, this device does not
uniformly illuminate all sixteen central teeth in the front upper
and lower arches because of the curvature of the dentition. This
potentially gives rise to uneven results. In addition, the Union
Broach device generates a great deal of heat which is both
uncomfortable for the patient and potentially damaging to the
teeth.
[0016] There is thus a need for improved compositions, methods and
devices for whitening teeth that overcome the limitations of the
prior art described above. In particular, there is a need for tooth
whitening compositions and methods capable of whitening teeth
quickly and safely, without harm to tooth enamel, dentin, or pulp.
The compositions and methods of the present invention described
herein satisfy these and other needs.
[0017] It is an object of this invention to provide fast and safe
tooth whitening compositions and methods that can be activated or
accelerated by the use of light energy.
[0018] It is a further object of this invention to provide a tooth
whitening composition that shortens the treatment time required to
obtain a given level of tooth whitening that is satisfactory to
both the patient and the dentist.
[0019] It is another object of the present invention to provide
tooth whitening compositions that are relatively transparent to
light energy in the wavelength range at which tooth chromogens
absorb in order to allow exposure of the tooth enamel surface to
said light energy while in contact with said tooth whitening
compositions.
[0020] It is yet another object of this invention to provide
compositions and methods for whitening teeth whereby the extent of
tooth whitening, addition to the types of tooth stains removed, can
be controlled by the duration, intensity and wavelength of actinic
radiation exposure at the tooth surface.
SUMMARY OF THE INVENTION
[0021] The present invention encompasses methods for whitening
teeth, wherein a stained tooth surface is contacted with (i) a
tooth whitening composition that is transparent to photoactive
light and (ii) a photosensitive agent that is responsive to the
wavelengths of light that are transmitted through the whitening
composition and, after contacting with the composition and agent,
the tooth is exposed to a biologically safe and effective level of
photoactinic light in order to enhance the ability of the oxidizing
compound in the whitening composition to effect rapid tooth
whitening.
[0022] Also disclosed and contemplated within the scope of this
invention are methods for whitening teeth, wherein a stained tooth
surface is contacted with an oxidizing compound that is transparent
to the wavelengths of light that are absorbed by tooth stain
chromogens, and then exposing the treated tooth to a biologically
safe and effective level of those same wavelengths of alight in
order to effect rapid tooth whitening.
[0023] Also disclosed and contemplated within the scope of this
invention are the compositions and compounds described above and
devices for whitening teeth, wherein a minimum of eight central
teeth in both the upper and lower arches in an adult are
simultaneously and uniformly illuminated with a biologically safe
and effective level of actinic light to effect rapid tooth
whitening.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1: A diagram of a device for illuminating the eight
central teeth in both the upper and lower arches of an adult for
use in a light-activated tooth whitening procedure.
[0025] FIG. 2: A diagram illustrating the position of two devices
for illuminating the eight central teeth in both the upper and
lower arches of an adult for use in a light-activated tooth
whitening procedure.
[0026] FIG. 3: Graph of Comparative Spectra
[0027] FIG. 4: Spectral Curves of Light Attenuation
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] This section details the preferred embodiments of the
subject invention. These embodiments are set forth to illustrate
the invention, but are not to be construed as limiting. Since the
present disclosure is directed to those skilled in the art field
and is not primer on the manufacture of tooth whitening
compositions or their use or on devices for using such
compositions, basic concepts and standard features known to those
skilled in the art are not set forth in detail. Details for
concepts such as choosing appropriate construction materials or
ingredients, operating conditions or manufacturing techniques, etc.
are known or readily determinable to those skilled in the art.
Attention is directed to the appropriate texts and references known
to those skilled in the art for details regarding these and other
concepts which may be required in the practice of the invention;
see, for example, Kirk-Othmer Encyclopedia of Chemical Technology,
4th Edition, Volumes 4 (1992), 13 (1995), 18 (1996), John Wiley
& Sons, NY; Goldstein and Garber, Complete Dental Bleaching,
Quintessence Publishing Co. 1995; and the aforementioned Journal of
the American Dental Association, Vol. 128, Special Supplement,
April 1997, the disclosures of which are hereby incorporated by
reference into the present disclosure to aid in the practice of the
invention. The development of the inventive compositions and
methods described herein resulted from the unexpected discovery
that extremely rapid tooth whitening occurs by allowing actinic
radiation to penetrate through the oxidizing compound, which is
placed directly onto the tooth surface to be whitened. This
discovery is antithetical to all prior art compositions that
include a light (or heat) absorbing additive dispersed directly in
and homogeneously throughout the oxidizing compound. The inventive
compositions, on the other hand, allow actinic radiation to reach
the stained tooth surface at higher power densities than prior art
compositions that are specifically designed to absorb light.
Actinic radiation is thus more effectively utilized compared to
prior art compositions and methods in which compositions are both
opaque to most wavelengths of light and are activated directly by
the actinic radiation. As the greatest oxidizing activity is
required in the few millimeters of enamel and dentin at the tooth
surface, the present inventive compositions and methods are more
effective at removing tooth stains, in many cases with lower levels
of active oxidizing agents, thereby resulting in safer compositions
for use in the oral cavity.
[0029] For the purpose of this disclosure, the term actinic
radiation shall mean light energy capable of being absorbed by
either an exogenous photosensitizing agent or an indigenous tooth
chromogen. Also for the purpose of this disclosure,
photosensitizing actinic radiation will mean light absorbed by a
specific photosensitive agent, where as chromosensitizing actinic
radiation will mean light absorbed by one or more tooth chromogens.
The terms "actinic radiation" and "actinic light" will be referred
to interchangeably.
[0030] Also for the purposes of this disclosure, the term
"transparent" shall mean having greater than 70% transmission of
light at a specified wavelength or within a wavelength range. In
addition, all composition ingredient percentages are by weight
unless otherwise stated.
[0031] Various modes of application of the inventive tooth
bleaching compositions are effective, although methods that allow
for the accumulation or concentration of the photosensitizer within
the acquired pellicle, enamel, and dentin (the three tooth
structure primarily associated with the majority of tooth staining)
are most preferred. This is best accomplished by contacting the
stained tooth surface with the photosensitizer prior to contacting
the same stained tooth surface with the oxidizing composition. In
this way, the photosensitizer is able to penetrate into the tooth
structure, thus being present at the site of the tooth chromogen(s)
prior to contact with the oxidizing composition and prior to
exposure to the actinic radiation source.
[0032] Photosensitizing agents useful in accomplishing the desired
tooth whitening effect include any compounds capable of absorbing
light energy at biologically acceptable wavelengths prescribed by
the limits of safety for use in the oral cavity. In general, such
wavelengths are from about 350 nanometers (nm) to about 700 nm,
encompassing a portion of the UVA spectrum (300 to 400 nm) and most
of the visible light spectrum (400 to 700 nm). Examples of
compounds which may convert light energy to either heat of chemical
energy, include semiconductor particles (particularly
nanometer-scale titanium dioxide and zinc oxide), benzophenone
derivatives, benzotriazole derivatives, diketones (such as
camphorquinone and benzil), metal- ligand complexes (such as ferric
potassium oxalate, manganese gluconate, and various metal
bisphosphonate chelates), phthalocyanin-metal complexes, and
others. A specific example of a suitable photosensitizing
composition is an aqueous dispersion of zinc oxide with particle
sizes between 5 and 20 nanometers. Any molecule capable of
absorbing a photon of light in the wavelength range of from about
350 nm to about 700 nm and subsequently converting the energy in
said photon of light into the useful energy of oxidation either
alone or in the presence of an auxilliary oxidizing agent, is
contemplated to have utility in the practice of the present
invention.
[0033] It is preferred that the inventive photosensitizers are of a
molecular size, charge, pH and hydrophobicity/hydrophilicity to
allow for effective penetration into the deeper structures of
enamel and dentin. The more readily a photosensitizer penetrates
the tooth structure, the more likely that, upon exposure of the
photosensitizer to actinic radiation at the appropriate wavelength
and energy, said energy will be converted into oxidative activity
at the site of, or in close proximity to, the chromogen itself.
Photosensitizers having a molecular size, net charge, pH, and/or a
hydrophobicity/hydrophilicity which prevent or limit penetration
into deeper tooth structures are of utility in the practice of the
present invention, but may be limited to the removal and/or
destruction of chromogens located at the outer tooth surface
(extrinsic stains).
[0034] Especially prefer ed photosensitizers belong to the general
class of water-soluble metal-ligand complexes which absorb light in
the range of from about 3:50 nm to about 700 nm. For the purposes
of the present disclosure, the term "ligand" will mean an organic
molecule capable of complexing or associating with a metal ion in
aqueous solution, such that the reactivity, solubility, or any
other physical property of said metal ion is changed. Such
metal-ligand complexes are also known as metal-coordination
complexes. Suitable metals ions include iron, manganese, copper,
and other transition metal ions. Various valence states may be used
or may be present simultaneously. The metal ions may be present in
saliva, plaque, or the acquired pellicle on the tooth surface.
Metal ions may also contribute, through formation of oxides, to
certain types of tooth stains. Suitable metal ion ligands include
chelating agents capable of associating with the metal ions above
in aqueous solution, resulting in a water-soluble metal-chelate
complex that absorbs light between about 350 and 700 nm.
Illustrative, but by no means limiting, examples of
metal-coordination complexes are formed from the association of
iron, manganese and copper with chelators such as ethylenediamine
tetraacetic acid (EDTA), diethylenetriamine pentaacetic acid
(DETPA), nitrilotriacetic acid (NTA),
1-hydroxyethylidene-1,1-diphio- sphonic acid, ethylenediamine
tetra(methylenephosphonic acid), diethylenetriamine
penta(methylenephosphonic acid), and polyols such as sorbitol,
xylitol, mannitol, maltitol, lactitol and other non-carboxylated
polyhydroxy compounds more fully described in EP 443,651, such
description being incorporated herein by reference. Any organic
multidentate chelating agent capable of forming a photoabsorbing
coordination complex with a metal ion can be presumed to have
utility in the present inventive compositions for and methods of
whitening stained teeth.
[0035] A number of the inventive metal-ligand complexes have an
absorption spectrum that is pH-dependent; in general, such
complexes will display a greater degree of absorption between 350
and 700 nm at a pH of greater than about 4.0, light absorption in
this range increasing with increasing pH. For instance, the aqueous
complex formed between 1-hydroxyethylidene-1,1-diphosphonic acid
and ferrous ions is virtually transparent to visible light at pH
3.0, but absorbs strongly in the spectral region between 350 and
500 nm as the pH is raised to 7.0.
[0036] In some cases, a photosensitizer precursor may be included
directly within the oxidizing composition, where it does not
readily absorb light in the visible region of the spectrum from 400
to 700 m. However, upon contact with the tooth surface (when placed
there with the oxidizing composition), the photosensitizer
precursor may combine, for instance, with a metal ion such as iron
present in saliva or found in the interstitial fluid of enamel and
dentin, resulting in the formation, in situ, of an active
photosensitizer capable of activating the oxidizing compound upon
exposure to actinic radiation. Obviously, only those compounds that
are stable in a highly oxidative environment are suitable for
inclusion directly in the oxidizing composition. An example of such
a compound is 1-hydroxyethylidene-1,1-diphosphonic acid (available
commercially under the trade name Dequest 2010 and sold as a 60%
active solution by Monsanto Corporation, St. Louis, Mo.).
[0037] The ability of certain metal chelates to act as
photosensitizers has been noted in the literature by various
workers. For example, Van der Zee, et al ("Hydroxyl Radical
Generation by a Light-Dependent Fenton Reaction" in Free Radical
Biology & Medicine, Vol. 14, pp 105-113, 1993) described the
light-mediated conversion of Fe (II) to Fe (II) in the presence of
a chelating agent and hydrogen peroxide. The reduction of Fe (III)
chelates by light at 300 nanometers to yield Fe (II) was shown to
proceed steadily over a period of about 30 minutes, with
conversions to Fe (I) ranging from about 40% to about 80%,
depending upon the particular chelating compound studied. The Fe
(II) thus created initiated a Fenton-type degradation of the
hydrogen peroxide, yielding hydroxyl radicals that were
spin-trapped and detected by electron spin resonance ESR). It was
not suggested or implied by the authors that this photochemical
reaction would have utility in the oxidation of chromophores, such
as those found in a human tooth.
[0038] Useful oxidizing compounds include liquids and gels,
preferably containing a peroxide or peroxyacid known in the art.
Such oxidizing compounds include, but are not limited to, hydrogen
peroxide, carbamide peroxide, alkali metal peroxides, alkali metal
percarbonates, and alkali metal perborates. Often, it may be
desirable to utilize a peroxyacid compound, such as peroxyacetic
acid (for instance, when attempting to eliminate highly intractable
tooth stains caused by tetracycline) in the tooth whitening
composition. The peroxyacid may be included directly within the
oxidizing composition providing that transparency to light energy
between about 350 and about 700 nanometers is maintained).
Alternatively, the peroxyacid may be formed by combining two or
more separate phases (one of which contains a peroxyacid precursor,
such as glyceryl triacetate and a second that contains one of the
oxidizing compounds listed above) prior to application to the tooth
surface. Preferably, the peroxyacid is formed in situ, by
contacting the tooth surface with a peroxyacid precursor prior to
the application of an oxidizing compound; the peroxyacid is thus
formed only on and within the stained tooth structure, where it is
most beneficial to the tooth whitening process. Suitable peroxyacid
precursors include, but are not limited to, glyceryl triacetate,
acetylated amino acids, acetylsalicylic acid, and
N,N,N',N'-tetraacetyl ethylenediamine, vinyl acetate polymers and
copolymers, acetylcholine, and other biologically acceptable
acetylated compounds.
[0039] The oxidizing compounds are liquid, gel, or solid
compositions transparent to the wavelength(s) of light capable of
activating the photosensitizing agent at the tooth surface; light
energy otherwise will be attenuated by the film or layer of
oxidizing compound between the actinic radiation source and the
photosensitizer at the tooth enamel surface. As the tooth enamel
surface is the location of the tooth discoloration, the most
effective method of whitening teeth will occur when most or all of
the light energy reaches the photosensitizer at the tooth enamel
surface. An example of a suitable composition that is transparent
to light energy between 380 and 500 nm is a 6% hydrogen peroxide
gel with a pH of about 7.0 that has been thickened to approximately
100,000 cps with neutralized carboxypolymethylene.
[0040] Another unexpected benefit of utilizing an oxidizing
composition transparent to photosensitizing actinic radiation is
that certain wavelengths of light seem to be absorbed by tooth
chromogens in a manner that promotes their oxidation to a
non-chromogenic state. Reflectance studies show that dentin and
enamel transmit green light, reflect yellow/red light and absorb
blue light Although not wishing to be bound by any particular
theory, light is absorbed by the molecules responsible For tooth
discoloration; thus, tooth chromogens may act in a manner similar
to that of photosensitizers. In particular, exposure to certain
wavelengths may raise the energy state level of pi electrons
carbonyl (C.dbd.O), double bond (C.dbd.C) and conjugated double
bond (C.dbd.C_C.dbd.C) moieties, making them more susceptible to
attack by active oxidizing species such as perhydroxyl anion
(HOO--), peroxyacid anions (RCCOOO--), and radical species such as
hydroxyl radical (HO*) and perhydroxyl radical (HOO*). In order to
destroy or solubilize chromogenic substances, the activation energy
of the reaction between one of the above light-absorbing moieties
and an active oxidizing species must be overcome; thus, light
assisted chromogen attack leads to more efficient destruction of
the molecular moieties responsible for the appearance of tooth
discoloration by raising the energy state of electrons in specific
chemical bonds within a light-absorbing molecule from a normal pi
bonding orbital to a pi antibonding orbital. Whilst in the less
stable pi antibonding orbital, a light absorbing double bond has
considerable single bond character and is much more easily attacked
by oxidizing agents such as peroxides and peroxyacids. In theory,
actinic light of a specific energy and wavelength, simply through
the process described above, may utilize a tooth chromogen molecule
as a photosensitizer in order to improve the efficacy of a given
oxidative composition in contact with said tooth chromogen.
[0041] A light-activated tooth whitening method, in accordance with
a specific embodiment of the invention includes contacting the
tooth enamel surface with the photosensitizing agent, then
contacting the photosensitizer-treated tooth surface with the
oxidizing compound, and, thereafter, exposing the tooth surface to
light energy capable of activating the photosensitizer which, in
turn, activates the oxidizing compounds at the tooth enamel
surface.
[0042] Another light-activated tooth whitening method, in
accordance with another embodiment of the invention includes
contacting the tooth enamel surface with an oxidizing compound
which contains a photosensitizer precursor, whereby said precursor
is seen to absorb actinic radiation in the range of 350 to 700 nm
only after contact with said tooth surface. Once the
photosensitizer precursor becomes light absorbent, the tooth
surface is exposed to light energy capable of activating the now
absorbent photosensitizer, which in turn activates the oxidizing
compound at the tooth surface to whiten the tooth.
[0043] A Further light-activated tooth whitening method, in
accordance with another embodiment of the invention includes
contacting the tooth enamel surface with an oxidizing compound and
thereafter exposing said tooth enamel surface to actinic radiation
corresponding to a tooth chromogen molecule absorption wavelength.
The preferred wavelengths of light in this embodiment include those
between about 350 and about 700 nanometers, a more preferred
embodiment include those between about 380 and about 550 nanometers
with the most preferred wavelengths being between about 400 and
about 505 nanometers. As in all of the methods described above, the
oxidizing composition must be transparent to the actinic radiation
utilized in order to allow the wavelength-specific light energy to
reach the tooth surface and underlying structure.
[0044] Yet another light-activated tooth whitening method, in
accordance with another Weal embodiment of the invention includes
contacting the tooth enamel surface with a peroxyacid precursor
prior to contacting said tooth enamel surface with an oxidizing
compound and subsequently exposing to actinic radiation as
described above. The peroxyacid precursor may be placed on the
tooth surface together with or separately from a
photosensitizer.
[0045] Stained teeth may be treated individually, for instance, by
directing the light to a single tooth surface by means of a fiber
optic light guide. In this manner, several stained teeth are
exposed to light in sequence, the dentist or hygienist moving the
light guide from tooth to tooth during the procedure. This process
is both labor intensive and time consuming for the dentist or
hygienist as well as tedious for the patient. Alternatively, all of
the stained teeth may be exposed to light simultaneously either by
direct illumination from a light source shaped substantially like
the dental arch or by indirect illumination from a light guide or
device that is capable of illuminating all of the front teeth at
once.
[0046] One such device for the simultaneous and uniform
illumination of at least eight central teeth in both the upper and
lower arches is illustrated in FIG. 1. This preferred embodiment
has three linear optical outputs 11, 12, and 13 precisely
positioned on three front (patient facing surfaces 1, 2, and 3. In
a more preferred six bar embodiment, two three bar devices are
stacked one on the other resulting in six optical outputs on the
front patient facing surfaces as illustrated in FIG. 2.
[0047] Although FIGS. 1 and 2 illustrate embodiments having 3
outputs and 6 outputs, respectively, it is contemplated that the
device may have any number of outputs or emitters, from one to a
high multiple of outputs. Each output consisting of an individual
fiber or fiber bundle that ultimately is connected to a light
source. Embodiments having 3 or 6 outputs are presently preferred
for the device because they achieve fairly uniform illumination of
the eight or more central teeth without excessive manufacturing
problems or costs. More than six output, of course are feasible and
may in fact be beneficial in terms of uniformity of
illumination.
[0048] The front surfaces of the device are positioned to give an
output configuration such that the combined beams from each optical
output converge to illuminate at least the eight central teeth in
both the upper and lower arches or the area from the incisors to
the first pre-molars in each half arch, a total area of about 10.4
cm.sup.2 in the average male. Although depicted mi FIG. 1 as linear
in form, these outputs may be of any shape, e.g., circular,
triangular or linear. Linear forms are preferred. The preferred
embodiments have six linear outputs, each output having a length to
width ratio of about 16.+-.20%--i.e., ratios of 12.8 to 19.2. In
the most preferred embodiment, 80% of the light projected from the
outputs onto the 8 upper and lower central teeth is within an area
between about 0.9 and about 1.5 inches wide, the approximate
distance from the top of the enamel of the top teeth to the bottom
of the enamel of the bottom teeth. Each optical output preferably
is connected to a distal light source by two glass or plastic fiber
optic bundles which originate at the distal light source, enter the
device through a socket 20 and terminate at the trifurcated linear
output window. Non-uniformity in fiber transmission is generally
observed to be minor in the absence of actually breaks in the
fibers. Variation in optical output from point to point at the
surface of each output or emitter should be no more than about
.+-.10%.
[0049] Whether illumination of the stained teeth is performed
individually or as a whole, the light emerging from a direct or
indirect source may be continuous ("on" the entire procedure),
interrupted continuous (primary "on" with short rest
interruptions), pulsed ("on" and "off" in a predetermined timed
sequence and intensity), or a combination of continuous,
interrupted continuous and pulse. In a preferred embodiment from
about 10 to about 200 milliWatt/cm.sup.2 of light is applied
continuously to the front surface of the teeth for a total period
of time from about 10 to about 90 minutes. In a more preferred
embodiment from about 100 to about 160 milliWatt/cm.sup.2 of light
is applied continuously or continuously with short interruptions to
the front surface of the teeth for a period of time from about 10
minutes to about 30 minutes followed by an interruption or "off"
period of about 1 to 10 minutes, with the cycle repeated for a
total time of approximately 40-60 minutes. In one envisioned
embodiment of the invention a feed-back mechanism based on
reflectance would be used to monitor bleaching efficiency and
regulate the total amount of actinic radiation applied. In all
embodiments of the invention the positioning of the light source
affects the energy density applied to the teeth as power density
decreases with distance. The preferred placement of the light
source will vary depending on the precise nature of the device. For
the device described above, the preferred distance for placement of
the device is from directly in front of the surface of the teeth up
to about 2.0" in front of the surface of the teeth (when measured
from the middle of the light source to the central tooth), with a
distance of about 1.75" being most preferred.
[0050] A number of different sources of actinic radiation have been
shown to have utility in the practice of the present invention. In
general, any light source capable of emitting actinic radiation in
the wavelength range necessary to activate either the inventive
photosensitizer(s) or otherwise raise the energy state of tooth
chromogens, is contemplated to have utility in the practice of this
invention. In particular, light sources capable of emitting actinic
radiation that is both biologically safe and effective are
preferred, especially those sources which emit limited amounts of
infrared light (700 nm and above). Infrared light more readily
penetrates the tooth structure and may cause an excessive
temperature rise in pulpal tissue. It is preferred that light
sources (combined with filters) emitting only those wavelengths
necessary for the activation of the inventive photosensitizer
and/or the activation of a tooth stain chromophores be used in the
process of whitening teeth with the inventive compositions. It is
generally accepted that a pulpal temperature rise of more than
5.5.degree. C. for a significant period of time can be irreversibly
damaging to the tooth structure.
[0051] More specifically, light sources which emit actinic
radiation in the wavelength range from about 350 nanometers to
about 700 nanometers are especially preferred, in that both the
photosensitizers described herein and the tooth chromogen molecules
responsible for tooth staining absorb primarily in this region of
the spectrum. Light sources which emit actinic radiation in the
wavelength ranges from about 400 and about 505 nanometers are most
preferred. Output uniformity should be about +/-10% over the area
of the beam once transmitted through a glass or plastic fiber to
the optical output which may be placed in front of a patient's
teeth. Although there are no limitations on the input and length
dimensions of such a fiber, one of about 10 millimeters in diameter
and 3 meters in length is preferred. Such energy may be provided by
a source which generates a continuous electromagnetic spectrum
filtered to the preferred wavelengths with a variation of no more
than about +/-10%, or by a source which generates an emission line
spectrum, or a combination of both. Suitable lamps which emit
actinic radiation in the preferred range of wavelengths include
linear flash lamps, tungsten halogen, metal halide, Xenon short
arc, Mercury short arc, Mercury Xenon short arc, Argon plasma arc,
and Argon short arc lamps, among others. The output of two Mejiro
By 250 watt metal halide lamps filtered through dichroic filters to
between about 400 and 505 nanometers meet these criteria.
[0052] The following examples set forth preferred embodiments of
the invention. These embodiments are merely illustrative and are
not intended to, and should not be construed to, limit the claimed
invention in any way.
Example I
[0053] In order to determine the ability of the inventive
compositions to eliminate tooth stain, a preliminary in vitro study
on stained bovine enamel was performed. Squares of dental enamel 4
mm on a side were cut, using a diamond-cutting disk, from bovine
permanent incisors. Using a mold, the enamel squares were embedded
in clear polyester casting resin NATCOL Crafts Inc., Redlands,
Calif.) to provide 1.5 cm square blocks with the labial surface
exposed. The top surface Of the polyester blocks was ground flush
with the leveled labial surface of the enamel squares by means of a
dental model trimmer. The surface was then smoothed by hand sanding
on 400-grit emery paper using water as the lubricant until all
grinding marks were removed. Finally, the top surface of the blocks
was hand polished to a mirror finish using a water slurry of GK1072
calcined kaolin (median particle size=1.2 microns) on a cotton
cloth. The finished specimens were examined under a dissecting
microscope and were discarded if they had surface
imperfections.
[0054] In preparation for the formation of artificial stained
pellicle on the enamel, the specimens were etched for 60 seconds in
0.2M HC1 followed by a 30-second immersion in a saturated solution
of sodium carbonate. A final etch was performed with 1% phytic acid
for 60 seconds, then the specimens were rinsed with deionized water
and attached to the staining apparatus.
[0055] The pellicle staining apparatus was constructed to provide
alternate immersion into the staining broth and air-drying of the
specimens. The apparatus consisted of an aluminum platform base
which supported a Teflon rod (3/4 inch in diameter) connected to an
electric motor, which by means of a speed reduction box, rotated
the rod at a constant rate of 1.5 rpm. Threaded screw holes were
spaced at regular intervals along the length of the rod. The tooth
specimens were attached to the rod by first gluing the head of a
plastic screw to the back of a specimen. The screw is then
tightened within a screw hole in the rod. Beneath the rod was a
removable, 300-ml capacity trough, which held the pellicle,
staining broth.
[0056] The pellicle staining broth was prepared by adding 1.02
grams of instant coffee, 1.02 grams of instant tea, and 0.75 grams
of gastric mucin (Nutritional Biochemcals Corp., Cleveland Ohio
44128) to 250 ml of sterilized trypticase soy broth. Approximately
50 ml of a 24-hour Micrococcs luteus culture was also added to the
stain broth. The apparatus, with the enamel specimens attached and
the staining broth in the trough, was then placed in an incubator
at 370 C. with the specimens rotating continuously through the
staining broth and air. The staining broth was replaced once every
24 hours for ten consecutive days. With each broth change the
trough and specimens were rinsed and brushed with deionized water
to remove any loose deposits. Or the eleventh day the staining
broth as modified by the addition of 0.03 grams of
FeCl.sub.3.multidot.6H.sub.2O, and this was continued with daily
broth changes until the stained pellicle in on the specimens was
sufficiently dark. Then the specimens were removed from the
staining broth, brushed thoroughly with deionized water, and
refrigerated in a humidor until used.
[0057] Absorbance measurements over the entire visible spectrum
were obtained using the CIELAB color scale (Commission
International de L'Eclairage, Recommendations on uniform color
spaces, color difference equations, and psychometric color terms,
Supplement 2 to CIE publication 15 (F-133.1) 1971 (TC-1.3), 1978,
Paris: Beaurea Central de la CIE, 1978). The CIELAB color scale
evaluates color in terms of three axes of a color sphere, called L,
a, and b. The "L" value is the as in the color sphere which relates
lightness and darkness on a scale from 0 (black) to 100 (white).
The "a" value is the axis which relates color on a yellow to blue
scale, with a 0 value in the center of the sphere, positive values
toward the yellow, and negative values toward the blue. The "b"
value is the axis which relates color on a red to green scale, with
a 0 value in the center of the sphere, positive values toward the
red, and negative values toward the green.
[0058] The stained enamel specimens were allowed to air-dry at room
temperature for at least one hour before absorbance measurements
were made. Measurements were conducted by aligning the center of a
4-nm square segment of stained enamel directly over the 3-mm
aperture of the Minolta spectrophotometer. An average of 3
absorbance readings using the L*a*b* factors were taken for each
specimen.
[0059] The difference between the pre-treatment (baseline) and
post-treatment readings for each color factor (L*, a*, and b*)
represented the ability of a test solution to eliminate chromogens
from the stained teeth.
[0060] The overall change in color of stained pellicle was
calculated using the CIELAB equation
.DELTA.E=[(.DELTA.L*).sup.2+(.DELTA.a*).sup.2+(.DELTA.b*).sup.2].sup.1/2
[0061] A "Corrected .DELTA.E" value was calculated by eliminating
from the above formulation the contribution of any positive
.DELTA.a or .DELTA.b values (positive .DELTA.a and .DELTA.b values
are changes in tooth color in the opposite direction from zero, and
hence construed to add color, rather than remove it).
[0062] The following oxidizing composition was prepared, which
contained approximately 15% by weight hydrogen peroxide and 1
percent by weight of the photosensitizer precursor
1-hydroxyethylidene-1,1-diphosphonic acid (Dequest 2010, Monsanto
Corp., St. Louis, Mo.). Highly purified water (18.2 megaohm,
filtered through a 0.2 micron filter) was utilized in order to
maintain good stability of the composition during storage. The
composition was thickened with a carboxypolymethylene polymer
(Carbopol 974P, B.F. Goodrich Co., Cleveland, Ohio) to the
consistency of a light, non-runny gel. Glycerin was added in a
small percentage as a humectant and stabilizer (as a free radical
scavenger), and the Carbopol 974P was neutralized to a pH of 5.00
with ammonium hydroxide, resulting in the formation of a
transparent and thixotropic gel.
1 Ingredient Percentage Distilled water 49.400
1-hydroxyethylidene-1,1-diphosphonic acid 1.000 Glycerin 99.7%
5.000 Hydrogen peroxide 35% 42.900 Carbopol 974P 1.700 Ammonium
hydroxide 29% to pH 5.5 TOTAL 100.000
[0063] The above composition was prepared in a plastic mixing
chamber by combining, under agitation with a Teflon-coated mixing
paddle until a clear solution was obtained, the distilled water,
the 1-hydroxyethylidene-1,1-diphosphonic acid, and the glycerin.
The Carbopol 974P was then sifted slowly into the vortex created by
the mixing paddle and allowed to mix until a homogeneous slurry of
the polymer was obtained. Finally, the ammonium hydroxide was added
in a constant, dropwise fashion over a period of about 5 minutes
until thickening and clarification of the slurry occurred. A pH
probe was inserted periodically and the ammonium hydroxide addition
proceeded until a pH of exactly 5.00 was obtained. The resulting
gel contained 15% by weight hydrogen peroxide, and was highly
transparent and thixotropic (non-slumping) in character.
[0064] Each stained bovine enamel slab was coated with a 1-2 m film
of the composition in Example I above for a specified period of
time and exposed to actinic radiation from one of several light
sources. Table 1 below shows some comparative results obtained by
exposing gel treated enamel slabs to either Argon plasma arc (AR)
or tungsten halogen (TH) light sources. This particular protocol
called for the fiber optic light guide to be placed 5 mm from the
surface of the enamel during light exposures. The energy of each
pulse was adjusted with a power density meter prior to each
exposure regimen and measured again after each regimen to verify
consistent output of the light source over the duration of the
test. The results are listed in Table IL below:
2TABLE 1 Bovine Light Total Gel Number of Energy/Pulse Corrected
Tooth # Source Contact Time Pulses (Joules) Delta E* B311 None 30
min 0 0.00 12.76 B388 AR None 30 1.66 1.41 B277 AR 30 min 30 1.66
29.28 B214 AR 30 min 30 3.35 29.75 B283 AR 10 min 10 3.29 18.62
B147 AR 10 min 10 4.90 25.98 B401 AR 10 min 30 4.97 32.18 B211 AR 5
min 15 4.84 20.05 B213 AR 5 min 30 4.93 31.02 B35 TH 5 min 15 1.29
12.88 B35 TH 5 min 15 1.29 19.39 B35 TH 5 min 15 1.29 20.01 B35 TH
5 min 15 1.29 23.61 B35 TH 5 min 15 1.29 25.35 B35 TH 5 min 15 1.29
26.41 *Elimination of positive .DELTA.a and .DELTA.b values from
calculation
[0065] The data in Table 1 demonstrates that:
[0066] (1) in the in vitro model described, exposure of bovine
enamel slabs, contacted with the inventive gel composition above,
to pulsed actinic radiation from a Argon plasma arc light source
resulted in significantly reduced tooth stain as compared to slabs
treated either with just gel alone (and not exposed to the light
source) or light source exposure only (no gel).
[0067] (2) Six sequential treatments (over 30 mutes) of a single
stained bovine enamel slab B35) with gel and concurrent exposure of
said slab to pulsed actinic radiation from a tungsten halogen light
source (5 minute exposure periods) resulted in an increasing level
of tooth stain removal over the period of the test. The result was
significantly lighter in color than that achieved in tooth number
B311, which was also in contact with de inventive gel composition,
but did not get exposed to a light source.
Example II
[0068] A comparative study of light transmission through various
light and/or heat activated tooth whitening gels was undertaken.
Spectral energy curves were generated using an Ocean Optics
spectrometer with a 50 micron fiber for gather emission data. Light
transmission through a glass microscope slide was used as a control
and the test consisted of coating the slide with a 1-2 mm thick
layer of each tooth whitening gel and illuminating with a metal
halide light source connected to an 8 mm glass fiber optic light
guide. The light was filtered through a 505 nm short pass filter
only wavelengths less than 505 nm pass through) prior to entering
the light guide. The spectrometer's fiber optic probe was placed
against the opposite side of the slide from the gel in order to
detect the wavelengths of light allowed to pass through the gel on
the slide. The spectral curves of FIGS. 4A-E clearly demonstrate
the degree of light attenuation caused by all of the commercially
available compositions. The spectral curves of FIGS. 4A-E clearly
demonstrate the degree of light attenuation caused by all of the
commercially available compositions: FIG. 4A-Control; FIG.
4B-Inventive Example I; FIG. 4C-Shofu Hi-Lite; FIG. 4D-QuasarBrite;
Figure E-Opalescence Xtra.
[0069] The attenuation of power density, measured in mW/cm.sup.2,
was determined for the same four compositions by again placing a
1-2 mm layer of each gel or paste on a glass microscope slide and
placing the slide/gel assembly in the path between the light source
and the detector well of the power density meter. Due to the depth
and shape of the detector well, the slide was 7 nm above the actual
detector surface, rather than directly in contact with it. The
power density was recorded at the beginning (B) and at the end of a
60 minute light exposure (E). The power density without slide or
gel in the light path was adjusted to 175 mW/cm.sup.2. The results
are shown in Table 2 below.
3 TABLE 2 Energy Density Composition U.S. Pat. No. (mW/cm.sup.2)
Control (slide only) -- 165 Example I (B) + (E) -- 160 & So
Shofu Hi-Lite (B) 5,032,178 25 Shofu Hi-Lite (E) 5,032,178 50
QuasarBrite (B) 5,240,415 110 QuasarBrite (E) 5,249,415 111
Opalescence Xtra (B) 5,785,527 65 Opalescence Xtra (E) 5,785,527
94
Example III
[0070] Another transparent hydrogen peroxide gel was prepared that
had a lower concentration of oxidizer (3% by weight of
H.sub.2O.sub.2), but at a pH of 7.0 and a much higher viscosity
(approximately 1,000,000 cps). The gel below was prepared in
accordance with the procedure in Example I, except that a Kynar
coated Ross Double Planetary vacuum mixer (Charles Ross & Sons,
Haupaugge, N.Y.) was used to handle the elevated viscosity achieved
during and after neutralization with the ammonium hydroxide. Sodium
stannate was added as an additional stabilizer for the hydrogen
peroxide.
4 Ingredient Percentage Distilled water 81.010 Glycerin 99.7% 5.000
1-hydroxyethylidene-1,1-diphosphonic acid 0.400 Sodium stannate
0.015 Hydrogen peroxide 35% 8.570 Carbopol 974P 5.000 Ammonium
hydroxide 29% to pH 7.0 TOTAL 100.000
[0071] The ability of the 3% hydrogen peroxide gel, transparent to
visible light between the wavelengths of 380 and 700 nanometers, is
demonstrated in Table 3 below.
5TABLE 3 Wavelength Power Energy/ Bovine Oxidizing Time Light Range
Pulses/ Density Pulse Tooth # Gel Period Source (nanometers) Period
(mW/cm2) (Joules) Delta E* B388 Example II 5 min AR 380-505 15 4.84
19.67 B388 Example II 5 min AR 380-505 15 4.84 29.43 B388 Example
II 5 min AR 380-505 15 4.84 32.74 B365 Example II 5 min None -- 0 0
3.41 B365 Example II 5 min None -- 0 0 4.23 B365 Example II 5 min
None -- 0 0 5.78 B365 Example II 5 min AR 380-505 15 4.84 23.49
B365 Example II 5 min AR 380-505 15 4.84 30.27 B367 Example I 30
min TH 400-520 Continuous 250 32.26 *Elimination of positive
.DELTA.a and .DELTA.b values from calculation.
Example IV
[0072] Extracted human teeth (EH) that were non-carious and free of
amalgam or resin-based restorative materials were utilized to study
the ability of the inventive compositions to eliminate the stains
from human enamel and dentin. The teeth were coated with a 1-2 mm
thick film of an oxidizing gel and irradiated according to the
regimens shown in Table IV below. The resulting change in tooth
color (.DELTA. Shades) was recorded as the number of VITA.RTM.
shade difference between the original baseline VITA.RTM. shade
value and the final VITA.RTM. shade value.
6TABLE 4 Light Exposure Pulses/ Joules/ Shade Shade .DELTA. Tooth #
Gel Source Time (min) Minute Pulse (Initial) (Final) Shade HE2
Example I AR 30 1 4.84 B4 C2 6 HE3 Example I AR 30 1 4.84 A4 A3.5 3
HE4 Example I AR 30 1 4.84 A3 B2 6 HE5 Example I AR 30 1 4.84 B3 D4
3 HE6 Example I AR 30 1 4.84 B3 B2 8 HE7 Example I AR 30 1 4.84 A3
A1 7 HE8 Example I AR 30 1 4.84 A3.5 A2 7 HE9 Example I AR 30 1
4.84 A3 A1 7 HE10 Example I AR 30 1 4.84 A4 A3.5 6 HE11 Example I
AR 30 1 4.84 A3.5 A2 7 HE12 Example I AR 30 2 4.84 A3.5 A2 7 HE13
Example I AR 30 2 4.84 B3 B2 8 HE14 Example I AR 30 2 4.84 A3.5 B2
9 HE15 Example I AR 30 2 4.84 A4 A1 13 HE16 Example I AR 30 2 4.84
B4 B1 12 HE17 Example I AR 30 1 1.64 A3 A2 4 HE18 Example I AR 30 1
1.64 B4 B2 10 HE19 Example I AR 30 1 1.64 C4 D3 6 HE20 Example I AR
30 1 1.64 B3 A2 6 HE21 Example I AR 30 1 1.64 B3 B2 8 HE22 Example
I No light 30 0 0 B3 A2 2 HE23 Example I No light 30 0 0 A3 A2 4
HE24 Example I No light 30 0 0 B3 D4 3 HE25 Example I No light 30 0
0 D3 B2 7 HE26 Example I No light 30 0 0 B3 A2 6 HE27 Example I
Tungsten 60 Continuous 250 B3 A1 9 Halogen mW/cm2
Example V
[0073] Human extracted teeth were whitened as follows by applying a
1-2 mm thick film of gel on the enamel surface and exposing he same
surface to varying power densities from a metal halide light source
with a 505 nm short pass internal filter. Comparisons were done to
two controls, one of which was Gel exposure only (no light) and
light exposure only (no Gel). Exposure regimens, consisting of gel
application (except in the case of light only/no Gel), followed by
20 minutes of continuous light exposure, were repeated three times
(3.times.20 minutes).
7TABLE 5 Power Light Density Test Initial Final Shade Tooth # Gel
Source (mW/cm2) Filter Duration Shade Shade Change HE101 Example I
MH 250 505 3 .times. 20 min A3.5 A1 7 HE102 Example I MH 250 505 3
.times. 20 min B4 A2 8 HE103 Example I MH 175 505 3 .times. 20 min
A3 B1+ 8 HE104 Example I MH 175 505 3 .times. 20 min A4 B2 12 HE105
Example I MH 175 505 3 .times. 20 min B3 B2 8 HE106 Example I MH
175 505 3 .times. 20 min A3 B1+ 8 HE107 Example I MH 175 505 3
.times. 20 min A4 A2 10 HE108 Example I No light 3 .times. 20 min
A3.5 A3 3 HE109 Example I No light 3 .times. 20 min A4 D3 5 HE110
Example I No light 3 .times. 20 min A3.5 A3.5 0 HE111 Example I No
light 3 .times. 20 min A4 A3 6 HE112 Example I No light 3 .times.
20 min A4 A3.5 3 HE113 None MH 175 505 3 .times. 20 min A3 A3 0
HE114 None MH 175 505 3 .times. 20 min A4 A4 0 HE115 None MH 175
505 3 .times. 20 min A3.5 A3 3 HE116 None MH 175 505 3 .times. 20
min B3 B3 0
Example VI
[0074] A pulpal chamber of an endo-tooth in a cooperative and
informed patient was wired using a thermal probe and
thermo-conducting paste. Pulpal temperatures were measuring during
an actual whitening procedure, in which the illumination was
supplied using the currently available Union Broach Illuminator and
the device described in the instant application used at the most
preferred wavelengths of 400 to 505 nanometers. Measurements of the
energy densities at the tooth surface showed comparable energy
densities for each device (230 milliwatts/cm.sup.2 for the Union
Broach Illuminator and 200 milliwatts/cm.sup.2 for the device
described in the instant application, respectively). The results
are shown below in Table 6.
[0075] Illumination using the device described in the instant
application in the preferred wavelength range from about 400 to 505
nanometers raised pulpal chamber temperature less than did the
Union Broach device. In this experiment, temperatures rose to a
maximum by twenty minutes and were then stable. In contrast to the
temperature rise seen with the Union Broach device, at no time did
the temperature using the device disclosed in the instant
application rise above the 5.5.degree. C. which could result in
thermally induced pulpitis if maintained for a significant period
of time. The temperature changes seen are likely to be greater than
those seen with vital teeth as endo-teeth have no blood supply to
provide additional cooling.
8 Time Temperature Rise (deg. C. from ambient) (min.) Union Broach
BriteSmile 2000 5 4 2.9 10 8 4.5 15 9 5.3 20 9 4.2 25 9.5 4.5 30 9
4.3
[0076] Upon reading the subject application, various alternative
constructions and embodiments will become obvious to those skilled
in the art. These variations are to be considered within the scope
and spirit of the subject invention. The subject invention is only
to be limited by the claims which follow and their equivalents.
* * * * *