Note: Descriptions are shown in the official language in which they were submitted.
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NON-VOLATILE DENTAL COMPOSITIONS
FIELD OF THE INVENTION
[0001] The invention relates to dental composite materials, and more
specifically, to dental
composite materials containing multifunctional acrylate compounds while
lacking volatile
compounds such as methyl methacrylate.
BACKGROUND OF THE INVENTION
[0002] Dental sealants and adhesives are widely used in clinical settings.
Desirable properties
include safety, efficacy, durability, and favorable cosmetic properties. It is
preferred that dental
compositions be shelf stable, easy to formulate, and that they do not set so
rapidly as to make
them difficult to apply to a patient.
[0003] Dental compositions frequently contain monomers which are polymerized
by the dentist
or technician (e.g. by light, self cure, or dual-cure). However, many dental
compositions form a
problematic "oxygen inhibited layer" (OIL) or "uncured layer" on their
surface. This layer's
polymerization is inhibited due to the presence of molecular oxygen radicals
in ambient air. As a
result, incomplete polymerization occurs. Such layer often render the surface
sticky or tacky,
making the dental composition more difficult to mold or shape. Such incomplete
polymerization
also tends to lead to lower hardness of the surface and/or no curing if a thin
surface is present.
[0004] Extoral is a visible-light cured dental resin formulation sold by AFR
Imaging Corp.
(Portland, Oregon). Extoral can be used for surface treatment or as a denture
resin. Extoral
cures rapidly and produces a glossy, hard surface upon irradiation with normal
dental light.
Extoral is significant in that it does not have an "oxygen inhibited layer",
even when cured with
low intensity light. One difficulty with using Extoral is its volatility,
leading to a very strong
odor. The smell is objectionable to both patients and dentists/technicians,
making it difficult to
use in a laboratory, and nearly impossible to use in a clinical setting.
Another difficulty is the
very brittle surface created by Extoral, which may limit its use in certain
dental applications such
as surfaces subject to compressive forces.
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[0005] Extoral's odor is suggestive of the presence of methyl methacrylate.
Methyl
methacrylate is a volatile compound used in several dental products. In
addition to its unpleasant
smell, exposure to methyl methacrylate has been linked to various health
concerns. Numbness,
paraesthesia, reduced pulmonary function, and reduced respiratory function
have been observed
in dental technicians who have been chronically exposed to methyl methacrylate
(Sadoh, D.R. et
al., British Dental J. 186(8): 380-381, 1999; Nishiwaki, Y. et al., J. Occup.
Health 43: 375-378,
2001). The U.S. Environmental Protection Agency describes methyl methacrylate
as an irritant
of the nose and throat, and mentions that exposure for short periods of time
can cause headache
and fatigue (EPA 749-F-95-014 Fact Sheet, November 1994).
[0006] It would be of great value to develop a dental composition that does
not have an "oxygen
inhibited layer" and that does not contain methyl methacrylate or other
volatile compounds that
are irritating and potentially dangerous to dentists, dental technicians, and
their patients.
SUMMARY OF THE INVENTION
[0007] An embodiment of the invention is directed towards dental acrylic
compositions
containing a multiacrylate compound and an initiator. Curing of the
compositions results in
surfaces lacking an oxygen inhibition layer ("OIL"). The formulations do not
contain methyl
methacrylate, an irritating and potentially harmful material found in many
dental formulations.
The multiacrylate compound contains at least three acrylate units per
molecule. The
formulations can further comprise other acrylate compounds, solvents, fillers,
nanofillers,
diluents, or other materials useful in dental formulations. The formulations
are useful in
applications such as dental coatings, dental sealants, and fingernail /
toenail repair.
DETAILED DESCRIPTION OF THE INVENTION
[0008] An embodiment of the invention is directed towards dental acrylic
material compositions
that cure to form surfaces that lack an oxygen inhibition layer ("OIL"). The
compositions
preferably do not contain methyl methacrylate. The compositions preferably
cure rapidly to
form stable, hard, glossy surfaces.
[0009] One embodiment of the invention is a dental composition comprising a
multiacrylate
compound and an initiator. The multiacrylate compound is a chemical compound
comprising at
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least three acrylate functionalities per molecule. The composition preferably
does not contain
methyl methacrylate. The composition, upon curing, preferably does not form an
oxygen
inhibition layer.
[0010] Presently preferred initiators are phosphine oxide photoinitiators and
camphorquinone.
Examples of such initiators include 2,4,6-trimethylbenzoyldiphenylphosphine
oxide (TPO),
TPO-L, Irgacure 819, Darocure 4265, and camphorquinone. It is expected that
other initiators
capable of photocleavage with or without the need for amine co-initiators will
have utility
according to the present invention. The initiator can generally be present at
any concentration in
the composition. The initiator is preferably present at a concentration that
will not noticeably
discolor the cured composition. Example concentration ranges of the initiator
include about 1
weight percent of the composition or less, at least about 1 weight percent of
the composition, at
least about 2 weight percent of the composition, at least about 3 weight
percent of the
composition, at least about 4 weight percent of the composition, at least
about 5 weight percent
of the composition, at least about 6 weight percent of the composition, or at
least about 7 weight
percent of the composition up to saturation levels of initiator in the
composition. Example
concentrations of the initiator include about 3 weight percent of the
composition, about 6 weight
percent of the composition, and about 7 weight percent of the composition up
to saturation levels
of initiator in the composition. It is also expected that lower concentrations
can be provided in
the presence of a volatile dental solvent such as acetone that, upon
evaporation, provides the
desired higher effective initiator concentration in the composition.
[0011] The multiacrylate compound can generally be any multiacrylate compound
having at
least three acrylate functionalities per molecule in relatively close spatial
proximity to one
another. Examples of such multiacrylate compounds include a hexafunctional
aromatic urethane
acrylate oligomer, a caprolactone modified dipentaerythritol hexaacrylate,
dipentaerythritol
pentaacrylate, di-trimethylolpropane tetraacrylate, trimethylolpropane
triacrylate, and
ethoxylated trimethylolpropane triacrylate. Other multiacrylate compounds
comprising three
acrylate functionalities per molecule, compounds comprising four acrylate
functionalities per
molecule, compounds comprising five acrylate functionalities per molecule,
compounds
comprising six acrylate functionalities per molecule, compounds comprising
seven acrylate
functionalities per molecule, compounds comprising eight acrylate
functionalities per molecule,
compounds comprising nine acrylate functionalities per molecule, and compounds
comprising
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ten acrylate functionalities per molecule in relatively close spatial
proximity to one another are
also expected to have utility according to the present invention. Larger
number of oligo-
acrylates or polyacrylates could be added to the compositions.
[0012] The multiacrylate compound can generally be present at any
concentration of the
composition. Example concentration ranges include at least about 20 weight
percent of the
composition and at least about 30 weight percent of the composition. Specific
concentration
examples include about 20 weight percent, about 30 weight percent, about 40
weight percent,
about 50 weight percent, about 60 weight percent, about 70 weight percent,
about 80 weight
percent, about 90 weight percent, and about 95 weight percent of the
composition.
[0013] The compositions can further comprise a co-monomer. The co-monomer
preferably
polymerizes with the multiacrylate compound. The co-monomer can generally be
any type of
co-monomer, and preferably is a non-volatile acrylate compound with a surface
tension that is
similar to or higher than that of the selected multifunctional acrylate
compounds) present in the
composition. Presently preferred co-monomers include a monoacrylate compound,
diacrylate
compound, a triacrylate compound, or a tetraacrylate compound. An example
monoacrylate is
caprolactone acrylate. Example diacrylate compounds are tripropylene glycol
diacrylate,
ethoxylated bisphenol A diacrylate, polyethylene glycol diacrylate, epoxy
diacrylate, urethane
dimethacrylate, and urethane diacrylate. An example triacrylate compound is
trimethylolpropane
triacrylate. An example tetraacrylate is ditrimethylolpropane tetraacrylate.
Ethoxylated forms of
such acrylates may be preferred due to their relatively higher surface
tension.
[0014] The composition can further include a volatile, non-reactive solvent.
Examples of such
solvents include acetone, ethanol and mixtures of acetone and water, ethanol
and water and/or
acetone, ethanol and water.
[0015] The compositions can further comprise fillers, nanofillers, glass
particles, or other dental
materials. Examples of such fillers include Ox-50, silane-treated Ox-50, glass
ionomer powder
IXG 1944 RGW from Ferro, which is also a fluoride release agent.
[0016] An additional embodiment of the invention is directed towards methods
of using the
above-described compositions. A method of sealing a surface can comprise
obtaining a surface;
applying to the surface a composition comprising a multiacrylate compound and
an initiator; and
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curing the composition to obtain a sealed surface. The sealed surface
preferably does not contain
an oxygen inhibition layer.
[0017] The surface can generally be any surface to be sealed, and is presently
preferred to be a
dental surface, a tooth, a dental implant, an artificial tooth, a bone, a
fingernail, or a toenail.
Additionally, the surface may be that of a previously applied dental
composition such as a dental
composite.
[0018] The curing can generally be performed by any means sufficient to
rapidly cure the
composition to form a non-oxygen inhibited layer (MOIL). The curing step is
presently preferred
to comprise light curing. The light curing can be performed at low light
intensity or at high light
intensity. The intensity of light is preferably an intensity suitable for use
in a dental laboratory or
in a dentist's office. Examples of light intensity ranges include less than
about 50 mW/cm2, less
than about 100 mW/cm2, about 200 mW/cm2 or less, about 300 mW/cm2 or less,
about 400
mW/cm2 or less, about 500 mW/cm2 or less, about 600 mW/cmaor less, about 800
mWlcm2 or
less, and about 2000 mW/cma or less, it being understood that higher light
intensities can also be
employed. Specific examples of light intensities include about 50 mW/cm2,
about 100 mW/cm2,
about 150 mW/cm2, about 200 mW/cm2, about 250 mW/cm2, about 300 mW/cm2, about
350
mW/cm2, about 400 mW/cma, about 450 mW/cm2, about 500 mW/cm2, about 600
mW/cm2°
about 800 mW/cmz, and about 2000 mW/cm2. Higher light intensities may also be
used. For
example, Bisco's VIPT"" Dental Light Curing system using a blue wavelength
light source may be
employed by the dentist. Light-curing systems for dental laboratories such as
the Jeneric-
Pentron Cure-Lite Plus light box system or the Triad light box system from
Dentsply, Inc. may
also be used for dental appliances. Bisco's NTLT"" System utilizing its light
source without the
nitrogen environment may also be used. The time of light curing can generally
be any time.
Presently preferred time ranges include about two minutes or less, about one
minute or less, less
than about 30 seconds, less than about 20 seconds, less than about 15 seconds,
less than about 10
seconds, and less than about 5 seconds. Specific examples of light curing
times include about
one minute, about 30 seconds, about 20 seconds, about 15 seconds, about 10
seconds, about 5
seconds, about 3 seconds, about 2 seconds, and about 1 second. Shorter light
cure times are
generally preferably to shorten patient time for the procedure and for the
convenience of the
dental practitioner.
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[0019] The following examples are included to demonstrate preferred
embodiments of the
invention. It should be appreciated by those of skill in the art that the
techniques disclosed in the
examples which follow represent techniques discovered by the inventors to
function well in the
practice of the invention, and thus can be considered to constitute preferred
modes for its
practice. However, those of skill in the art should, in light of the present
disclosure, appreciate
that many changes can be made in the specific embodiments which are disclosed
and still obtain
a like or similar result without departing from the spirit and scope of the
invention.
EXAMPLES
Example 1: Abbreviations used in the Examples
[0020] The following table lists the chemical compounds and abbreviations used
throughout the
Examples section.
Abbreviation / Chemical name Commercial source
product
BZ Benzophenone Sartomer (Eaton,
PA)
CQ Camphorquinone Aldrich Chemical
CTXO 2-Chlorotioxanthen-9-oneAldrich Chemical
EDMAB Ethyl (4-dimethylamino)benzoateEsschem Company
MEHQ Methylhydroquinone, a Aldrich Chemical
polymerization inhibitor
MMA Methyl methacrylate Aldrich Chemical
OX-50 Fumed silicon dioxide Degussa
filler
TMPTMA Trimethylopropane Esschem Company
trimethacrylate
TPO Lucirin TPO photoinitiator;BASF (Mount Olive,
2,4,6- NJ)
trimethylbenzoyldiphenylphosphi
ne oxide
UDMA Urethane dimethacrylate Esschem
CD 9052 Trifunctional acid esterSartomer (Eaton,
PA)
CN 120 Epoxy diacrylate Sartomer (Eaton,
PA)
CN 383 Monofunctional acrylatedSartomer (Eaton,
amine PA)
coinitiator
CN 975 Hexafunctional aromatic Sartomer (Eaton,
urethane PA)
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acrylate oligomer
CN 983 Urethane diacrylate Sartomer (Eaton,
PA)
l~ayarad DPCA20 Caprolactone modified Sartomer (Eaton,
(DP20) dipentaerythritol hexaacrylatePA)
I~ayarad DPCA60 Caprolactone modified Sartomer (Eaton,
(DP60) dipentaerythritol hexaacrylatePA)
SR 259 Polyethylene glycol (200)Sartomer (Eaton,
diacrylate PA)
SR 306 Tripropylene glycol diacrylateSartomer (Eaton,
PA)
SR 344 Polyethylene glycol 400 Sartomer (Eaton,
diacrylate PA)
SR 349 Ethoxylated bisphenol Sartomer (Eaton,
A PA)
diacrylate
SR 350 Trimethylolpropane Sartomer (Eaton,
trimethacrylate PA)
SR 351 Trimethylolpropane triacrylateSartomer (Eaton,
PA)
SR 355 Ditrimethylolpropane Sartomer (Eaton,
tetraacrylate PA)
SR 399 Dipentaerythritol pentaacrylateSartomer (Eaton,
PA)
SR 459 Caprolactone acrylate Sartomer (Eaton,
PA)
SR 495 Caprolactone acrylate Sartomer (Eaton,
PA)
SR 502 Ethoxylated trimethylolpropaneSartomer (Eaton,
triacrylate PA)
SR 610 Polyethylene glycol (600)Sartomer (Eaton,
diacrylate PA)
Example 2: Analysis of Extoral composition
[0021] While Extoral is a commercial product, its composition and ingredients
are not publicly
known. The strong objectionable odor suggested that Extoral contains methyl
methacrylate. The
following analytical experiments were performed in an attempt to determine the
chemical
composition of Extoral.
[0022] Evaporation of the volatile components of Extoral produced a viscous
resin. About 40%
by weight of the composition evaporated. This was assumed to be primarily
methyl
methacrylate.
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_g_
[0023] FTIR assays of pre- and post-evaporation Extoral revealed several
transitions. A peak at
1620 cm 1 grows larger upon evaporation of methyl methacrylate. This peak is
present in butyl
acrylate, but not in butyl methacrylate. An aliphatic double-bond peak shifts
from 1635.0 cm 1 to
1633.8 cm 1 upon evaporation, indicating a transition from a methacrylate-like
character to a
more acrylate-like character. The FTIR spectrum of Extoral does not suggest
the presence of
amines.
[0024] UV/Vis spectra comparing Extoral with a TPO standard allowed estimated
identification
and quantification of TPO in Extoral to be about 4%.
Example 3: Addition of a hexafunctional acrylate
[0025] Compositions were prepared using CN-975, a hexafunctional aromatic
urethane acrylate,
MMA, and other compounds. Numbers represent the amount of each compound in the
composition by weight percent.
Composition
Compound AC-10 AC-l0A AC-11 AC-11A
CN 975 17.2 16.7 68.7 67.0
CN 120Z 51.5 50.3
MMA 29.5 28.7 29.5 28.7
TPO 1.8 4.3 1.8 4.3
[0026] Compositions AC-10 and AC-11 had sticky surfaces upon curing at 500
mW/cm2 for 5
seconds. FTIR showed that the surface conversion was 47.3% for AC-10 and 47.5%
for AC-11,
about 16% lower than for Extoral (63.2%). The higher TPO concentration in AC-
l0A and AC-
11A enhanced the curability. The surface conversion was 65.7% for AC-l0A and
58.7% for
AC-1 lA.
[0027] The surface of cured AC-11A resembles cured Extoral: non-sticky, slick,
hard, and
glossy.
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Example 4: Preparation of "no oxygen inhibited layer" (MOIL) compositions
[0028] NOIL compositions contain at least two components: a multifunctional
acrylate and a
photo-initiator (such as phosphine oxide). A diluent (such as ethoxylated di-
or tri-acrylate) may
also be added to enhance handling of the multiacrylate and / or solubility of
the initiator. The
compositions can contain additional materials such as solvents, polymerizable
co-monomers,
inhibitors, surfactants, glass filler, fluorescent or phosphorescent
compounds, dyes, colorants,
fluoride compounds, and other materials used in the dental and orthodontic
fields.
Examples: Preparation of unfilled resin compositions
[0029] A mixture of multifunctional-acrylate, diluents, TPO or other
initiator, and optionally
MEHQ are blended together. The mixture may be heated at 60 °C - 62
°C for four hours with
stirring or shaking to afford a clear or hazy solution. The haziness, if any,
will fade over a few
days.
Example 6: Preparation of filled resin compositions
[0030] Unfilled resin and filler such as OX 50 are combined as a slurry. The
slurry is ground for
30 minutes. The grinding process often introduces air bubbles into the
mixture. The bubbles can
be removed by centrifugation at >1000 x g for 30 minutes to afford an
essentially clear solution.
Example 7: Monomers for use in "No Oxygen Inhibited Layer" (MOIL) compositions
[0031 ] Multifunctional acrylates and acrylated diluent co-monomers have been
found to be
effective ingredients in NOIL compositions. The following table lists
exemplary compounds
that have been found to be useful.
Trade name Chemical descriptionCharacteristics
Multifunctional Acrylates
CN 975 Hexafunctional axomaticFast curing, high
urethane acrylate hardness
I~ayarad DPCA20 (DP20)Acrylate of caprolactoneFast curing, lower
modified dipentaerythritolviscosity
I~ayarad DPCA60 (DP60)Acrylate of caprolactoneFast curing, flexibility
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modified dipentaerythritol
Acrylated Co-Monomers
SR 344 Polyethylene glycol Hydrophobicity, hardness
400
diacrylate
SR 349 Ethoxylated bisphenolHydrophobicity, hardness
A
diacrylate esters
SR 610 Polyethylene glycol Low viscosity, flexibility
(600)
diacrylate
SR 459 Caprolactone acrylateFlexibility, hydrophobicity
CN 383 Monofunctional acrylatedVery low viscosity,
amine polymerizing rate
promoter
CD 9052 Trifunctional acid Adhesion promoter
ester
Example 8: Preparation of volatile MMA compositions containing a
tetrafunctional acrd
AC-23 and -33
[0032] A composition containing 3g SR355 (ditrimethylolpropane tetraacrylate),
2g MMA
volatile co-monomer, 0.25g TPO, and 3.Smg MEHQ was prepared ("AC-23"). The
composition
had the characteristic strong odor of a composition containing methyl
methacrylate (MMA). The
composition was coated on white paper and exposed to VIP light source set at
600 mW/cm2
intensity for an exposure time of 30 seconds. An oxygen inhibition layer was
detected by finger
touch, which revealed a soft surface even after waiting 10 minutes after
exposure to the light
source. These results suggest that a tetrafunctional acrylate in the presence
of a volatile co-
monomer MMA was insufficient to prevent formation of an oxygen inhibition
layer.
[0033] An additional composition containing lg CN975, 4g SR355
(ditrimethylolpropane
tetraacrylate), 0.35g TPO, and 2.Smg MEHQ was prepared ("AC-33"). The
composition had the
characteristic strong odor of a composition containing methyl methacrylate
(MMA). This
composition could not be cured tack-free in less than 60 seconds exposure to
the VIP light gun
set at 600 mW/cm2, and was easily scratchable even after exposure to that
intensity light for 60
seconds.
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Example 9: Preparation of a volatile MMA composition containin~i a
pentafunctional acrylate
AC-24
[0034] A composition containing 3g SR399 (dipentaerythritol pentaacrylate
esters), 2g MMA
volatile co-monomer, 0.25g TPO, and 3.Smg MEHQ was prepared. The composition
had the
characteristic strong odor of a composition containing methyl methacrylate
(MMA). The
composition was coated on Pyramid composite, shade 3.5 (Bisco, Inc.) and cured
by exposure to
the VIP light gun output for 10 seconds at 300 mW/cm2. No oxygen inhibition
layer was
detected by finger touch, suggesting that a pentafunctional acrylate in the
presence of a volatile
co-monomer MMA is sufficient to prevent formation of an oxygen inhibition
layer.
Example 10: Preparation of non-volatile NOIL compositions AC-15C and filled
and colored AC-
15C
[0035] A composition containing 2.7g CN975, 3.3g SR344, 0.333g TPO, and 3mg
MEHQ was
prepared ("AC-15C"). A filled mixture of 75% AC-15C and 25% OX50 filler by
weight was
also prepared. The AC-15C compositions contain a hexafunctional diacrylate (CN
975) and no
MMA. No MMA odor or other appreciable odor was detected. AC-15C exhibited
better light
curing sensitivity than Extoral, with twice the double-bond conversion rate.
AC-15 was curable
scratch-free and mar free after 20 seconds exposure to 500 mW/cm2 light source
using VIP, or
40 seconds at 200 mW/cm2 using the same curing light source. Addition of 10%
methyl blue
colorant in ethanol did not adversely affect the curing. The conversion rate
of AC-15C in air and
in a nitrogen environment was the same, indicating that it lacked an OIL
layer. The Barcol
hardness of AC-15C was 77 after curing 40 seconds at 200 mW/cm2 exposure using
the Cure-
Lite Plus light box system.
Example 11: Preparation of non-volatile, NOIL composition AC-35
[0036] A composition containing 3.22g CN975, 1.38g CN383, 0.4g TPO, and 2.Smg
MEHQ
was prepared. AC-35 formed a scratch-free to human fingernail and tack-free
surface to touch
after 10 seconds cured at 300 mW/cm2 on Pyramid shade 3.5 composite using the
VIP system.
AC-36, prepared containing the same amounts of TPO and MEHQ but 2.76g CN 975
and 1.848
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CN 383, was curable scratch-free to fingernail scratching and tack-free to
touch using the same
composite base and light cure system after 20 seconds exposure at 300 mW/cm2.
Example 12: Preparation of non-volatile NOIL compositions AC-40 and AC-40A
[0037] A composition containing 8.9g CN975, 10.3g SR349, 7.8g SR610, 0.9g
CD9052, 2.1g
TPO, and l5mg MEHQ was prepared. The composition cured into a scratch-free
surface after
20 seconds exposure on Pyramid shade 3.5 composite using the VIP curing system
set at 500
mW/cm2. The AC-40 composition also exhibited good stability after storage
under water at 60
°C, curing in 20 seconds at 300 mW/cm2 on Pyramid composite shade 3.5
after 30 days and 47
days, the latter being comparable to storage for 472 days at 20 °C.
Addition of 5% CN 383 to
the composition (AC-40A) caused a scratch-free surface to form after curing at
300 mW/cm2 for
15-20 seconds, or 10 seconds at 500 mW/cma exposure on Pyramid composite using
the VIP
curing light system. In addition to sealing applications, this composition may
also be attractive
as a deep cavity filler due to its relatively high viscosity (around 1200 cps
at 22 °C).
[0038] AC-40 also exhibits good compressive strength of about 282MPa +/- 27
MPa.
Compressive strength is determined by preparing a sample in a 6mm high by
4rrun diameter
stainless steel split mold. The sample is cured at 500 ~ 50 mW/cm2 for 60
seconds per side. The
disc is heated at 37 °C for 15 minutes. The disc is placed in a 30 ml
Nalgene bottle filled with
deionized water, and heated for 23 hours at 37 °C. The disc is removed,
blotted dry, and cooled
to room temperature for one hour. An Instron Universal Testing Instrument
(model 4465) is
used to determine the load reading (kg) at which the sample breaks. The
compressive strength is
calculated as (load reading (kg) x 0.0624) / sample diameter (cm).
[0039] AC-40 passed a cytotoxicity assay performed with mouse fibroblast cells
on a solid
agarose surface. Toxicity, or the lack thereof, was determined by measuring
the zone of lysis (if
any) around the test sample after incubation at 37 °C in 5% carbon
dioxide for 24 hours.
Example 13: Preparation of a non-volatile NOIL composition DP20-5
[0040] A composition containing 5.2g DP20, l.Sg CN383, 2.1g SR610, O.Sg
CD9052, 0.7g
TPO, and 4.4mg MEHQ was prepared. The composition cured very rapidly, forming
a scratch-
free surface after 3-6 seconds at 500 mW/cm2, 5-10 seconds at 300 mW/cm2, and
60 seconds at
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50-100 mW/cm2 on white paper using the VIP curing light system The DP-20-5
compound also
had good compressive strength (51 +/-9 MPa as determined using the Instron
test system
described in the previous Example). It also exhibits a relatively lower
viscosity (410cps at 22
°C) than AC-40. This composition is attractive for use as a protective
coating under and around
orthodontic application on enamel, or as a margin sealant where rapid curing
and flowablity are
important considerations
Example 14: Preparation of non-volatile, NOIL composition filled DP20-5
[0041] Compositions of 10% filler, 20% filler, 30% filler, and 40% filler, and
90%, 80%, 70%
and 60% DP-20-5 were made by mixing the appropriate weight amount of filler
with the DP20-5
composition described in Example 13 above. The filler used was OX-50 or
silanated OX-50.
The sample containing 20% OX-50 filled DP20-5 was scratch free after
irradiation for 5 seconds
at 300 mW/cm2 or for 2 seconds at 500 mW/cm2. The pencil hardness was > SH.
These results
are similar to those obtained with the neat resin lacking filler. The filler
had no noticeable effect
on the curability of the resin.
Example 15: Preparation of non-volatile, NOIL composition DP60-5
[0042] A composition containing 15g DP60, 4.Sg SR349, 4.Sg SR459, 3g CN383,
0.9g CD9052,
2.1 g TPO, and 1 Smg MEHQ was prepared. The composition cured to a scratch-
free surface in
15 seconds at 500 mW/cma and 20 seconds at 300 mW/cm2 exposure using the VIP
light gun and
after coating the composition on Pyramid shade 3.5 composite. This composition
can be used as
a flexible coating on dental prosthetic devices, or on dentures. The
composition can also be used
as a narrow gap filler, where flexibility is desirable.
Example 16: Preparation of non-volatile NOIL compositions AC-25 containing
pentaacrylate
and AC-26
[0043] A pentaacrylate and two diacrylate composition containing 3g SR 399, 3g
SR349, 3g
SR610, 0.3g CD9052, 0.7g TPO, and Smg MEHQ was prepared (AC-25). A similar
composition containing a hexaacrylate and two diacrylates was prepared by
combining 3g
CN975, 3g SR349, 3g SR610, 0.3g CD9052, 0.7g TPO, and Smg MEHQ (AC-26). Both
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compositions AC-25 and AC-26 were scratch free after irradiation at 300 mW/cm2
for 20
seconds, or 500 mW/cm2 for 10 seconds. The pencil hardness of both materials
was 1H.
Example 17: Evaluation of di-, tri-, and tetra-acrylates in preparation of
NOIL surfaces
[0044] Five resins were selected to compare the ability of diacrylates,
triacrylates, and
tetraacrylates to prepare NOIL surfaces. Monomer resins were solubilized in
acetone at a l:l
ratio by weight. TPO initiator was added, and the acetone was allowed to
evaporate in air for
about 60 seconds or more. After 20 seconds evaporation, the acetone was not
detectable in terms
of weight loss. The compositions were irradiated using either a blue light at
500 mW/cm2 or a
bright white light at 200 mW/cm2. The produced surfaces were evaluated as
described in the
following Table.
Monomer (# TPO Irradiation time and Coating surface
intensity
acrylates/molecule)weight
SR-355 (4) 5.6 120 sec., 500 mW/cm2 Marrable
120 sec., 200 mW/cm2 Almost scratch
free
SR-355 (4) 7 120 seconds, 500 mW/cm2Scratchable
60 sec., 200 mW/cm2 Scratch free
SR-351 (3) 6 100 seconds, 500 mW/cm2Scratch free
40 sec., 200 mW/cm2 Scratch free
SR-502 (3) 6 120 seconds, 500 mW/cm2Scratch free
60 sec., 200 mW/cm2 Scratch free
SR-350 (3) 8 120 seconds, 500 mW/cm2Thick OIL
120 sec., 200 mW/cm2 Thick OIL
SR-259 (2) 10 120 seconds, 500 mW/cm2Slightly tacky,
thin
OIL
[0045] As used in this table, "Scratch free" also indicates that the surface
was mar free and tack
free; "Mar free" also indicates that the surface was tack free but was
scratchable. The actual
concentration of the TPO is double that shown in the table due to the
evaporation of the acetone
solvent. Resins made from tri-acrylates or tetra-acrylates could be
polymerized to prepare a
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surface lacking an oxygen inhibition layer. The triacrylate and diacrylate
tested under these
conditions were not able to produce an acceptable surface.
Example 18: Scratch resistance assay of non-volatile NOIL sealants
[0046] The suitability of NOIL sealants as orthodontic sealants was evaluated
using a scratch
resistance assay. A surface is rubbed using pencils containing graphite of
different hardnesses in
an attempt to scratch the surface. The surface is evaluated by what hardness
of graphite is
required to create a detectable scratch.
[0047] This assay is based on ASTM D 3383-00. The sealant was brushed onto a
composite
disc, and was cured. The pencils were obtained from a Kimberly Graphite
Drawing Kit, and had
hardnesses according to the following table.
II Softest
Hardest II
II SB I 7B I 6B I SB I 4B I 3B I 2B I B I HB I F I H I 2H I 3H I 4H I SH II
[0048] The assay further distinguishes between gouges and scratches.
Scratching refers to the
hardness needed to indent the surface. Gouging refers to the hardness required
to scrape the
adhesive from the surface. Oxygen inhibition layers often are easier to
scratch than the rest of
the cured adhesive, so the scratch/gouge assay is useful to detect the
presence of an air inhibition
layer on a surface.
[0049] The following adhesive compositions were evaluated: (DP20-5, DP-20-5
with a
fluorescing agent (DP-20-SF), DP-20-5 with a fluorescing agent and 20% glass
ionomer (DP-20-
5-FG), Bisco One Step Adhesive System, Filled L/C Sealant, and L/C Sealant.
The adhesive
compositions were brushed on composite disks made from Bisco Renew Shade A2
Translucent
and cured for 2, 5, 10, 20 30, and 40 seconds using the VIP curing light
system before
evaluating. The first value in the table is for gouging, the second value is
for scratching.
Product 2 sec 5 sec 10 sec 20 sec 30 sec 40 sec
DP-20-5 >SH / >SH / >SH / >SH l >SH / >SH /
>SH >SH >SH >SH >SH >SH
DP-20-SF >SH / >SH / >SH / >SH / >SH / >SH l
>SH >SH >SH >SH >SH >SH
DP-20- >SH / >SH / >SH / >SH / >SH / >SH /
SFG >SH >SH >SH >SH >SH >SH
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One Step <8B / >SH / >SH / >SH / >SH / >SH /
<8B <8B <8B <8B <8B <8B
Filled <8B / <8B / >SH / >SH / >SH l >SH /
L/C <8B <8B <8B <8B <8B <8B
Sealant
L/C <8B / HB / <8B SH / <8B >SH / >SH / >SH /
<8B <8B <8B <8B
Sealant
[0050] Conventional adhesives had significant oxygen inhibition at the surface
since the softest
pencil used (8B) was able to scratch it. The NOIL DP-20-5 compositions did not
have oxygen
inhibition layers since even the hardest pencil used (SH) had difficulty
scratching the surface.
The addition of a fluorescing agent and glass ionomer filler did not
detrimentally affect the
hardness of the DP-20-5 compositions. These NOIL compositions light cured very
quickly, as
evidenced by their consistent assay results across the range of time periods
tested.
Example 19: Evaluation of photoinitiators for the preparation of a NOIL
surface
[0051] Six photoinitiators were individually added to a common resin
containing SOg CN-795
(hexafunctional acrylate), SOg acetone (volatile solvent), O.lg Flourad FC-431
(surfactant for
leveling), and 0.02g MEHQ (inhibitor for storage). The following Table lists
the initiators.
Initiator Chemical name Absorbance x 10-3
Lucirin TPO (TPO) 2,4,6-trimethylbenzoyl-6
diphenylphosphinate
Lucirin TPO-L (TPOL) ethyl-2,4,6- 4
trimethylbenzoyl-
phenylphosphinate
Irgacure 819 (819) bis(2,4,6-trimethylbenzoyl)-23
phenylphosphineoxide
Camphorquinone (CQ) camphorquinone 11
H-Nu 470 (HNu) 5,7-diiodo-3-butoxy-6-2960
fluorone
PAQ phenanthrenequinone 466
[0052] The absorptivity is the absorbance in the range of 400-500 nm in
acetonitrile normalized
by mass. The higher the value, the higher the absorption in the visible light
range. The first
three initiators undergo unimolecular bond cleavage upon irradiation. The last
three initiators
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require a co-initiator, such as an amine, to undergo a bimolecular reaction.
The initiators (and
EDMAB amine if required) were added to the resin. Samples were coated on a
white mixing
pad, evaporated for greater than 60 seconds, and irradiated at 500 mWlcm2
using a Bisco VIP
light curing system. Samples were irradiated for 5 seconds, 10 seconds, 30
seconds, and 10
seconds in the absence of air. The "no air" cure was performed between two
Mylar slips, each
0.25mm thick. The actual concentration of initiator in the resin was double
that shown in the
table due to the evaporation of the acetone. The surface was evaluated for
percent degree of
conversion as indicated in the following table.
DC,
InitiatorInitiator,EDMAB % 5 sec 10 sec 30 sec 10 sec (no
% air)
CQ 1 1 24 27 30 47
CQ 3 3 43 50 58 65
TPO 2 0 30 39 39 64
TPO 3 0 29 52 52 53
819 1.5 0 44 47 47 57
819 3 0 49 55 58 65
TPOL 3 0 29 38 57 56
HNu 0.2 1 0 0 0 23
PAQ 0.2 1 0 0 0 33
[0053] To confirm the observation that the presence of air leads to lower DC
values, triplicate
samples of resin containing TPO at 3% were irradiated in the presence and
absence of air.
Average DC values, and the standard deviation were determined as shown in the
following
Table.
Irradiation time Air DC (std. dev.)
seconds Present 46.9% (3.0%)
30 seconds Present 51.6% (4.3%)
10 seconds Absent 57.4% (1.3%)
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[0054] Resins were prepared and coated on composite disks. After evaporation
of the acetone
for greater than 60 seconds, the coatings were irradiated for 30 seconds at
300 mW/cma bright
light. The pencil hardness was measured, as shown in the following Table. All
surfaces were
found to be tack and fingernail scratch free.
InitiatorInitiator,EDMAB % Pencil hardness
%
CQ 1 1 1H
CQ 3 3 > SH
TPO 2 0 4H
TPO 3 0 SH
819 1.5 0 4H
819 3 0 > SH
TPOL 3 0 4H
[0055] These results show that initiators other than phosphine oxide, such as
camphorquinone,
can be used to successfully prepare a NOIL surface.
Example 20: Ortho Shear Bond Stren_ h assay
[0056] DP-20-5 NOIL compositions and L/C Bonding resins were evaluated for
their shear
strength. NOIL DP20-5 was prepared with and without 0.75 Lumilux Blue (a
fluorescent
additive) and 20% glass ionomer (X1B44RWG). Bond strength was compared against
unfilled
and filled L/C Bonding resins.
[0057] Human tooth enamel was etched with 37% phosphoric acid semi-gel for 15
seconds. The
etchant was washed away with a jet of water, and dried thoroughly with a
stream of air. One
coat of the aforementioned compositions was applied as a sealant over the
etched area by
brushing onto the etched enamel surface, and was light cured for 10 seconds at
500 mW/cm2
intensity using the Bisco VIP curing light system. An orthodontic bracket was
bonded to the
sealed area using bracket adhesive (Lightbond or Phase II) and cured. Bonded
samples were
placed in a 37 °C deionized water bath for two hours before testing.
The shear test results are
shown in the following table.
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Bracket LlC Sealant Filled L/C Unfilled Filled DP-20-5
adhesive Sealant DP-20-5 with Flourescer
Lightbond 22.85 2.0 23.04 6.4 23.08 1.7 20.96 1.3
MPa MPa MPa MPa
Phase II 23.23 5.7 25.02 5.9 20.27 2.8 21.12 1.8
MPa MPa MPa MPa
[0058] Bond strengths of the tested samples were fairly similar. These results
indicate that
unfilled and filled NOIL compositions display shear bond strength values
suitable for use in
orthodontic applications.
Example 21: Fluoride release assay
[0059] The fluoride release properties of NOIL compositions were compared
against L/C
sealants. The NOIL sample was DP20-5 containing 20% glass ionomer for fluoride
release and
0.75% Lumilux blue for phosphorescence.
[0060] Shade disks of DP-20-5 and LC Sealant were prepared as follows. A round
stainless steel
mold held between polyethylene sheets and glass slabs were used to prepare
discs of a fixed size.
The discs were cured using two light guns set at 500 ~ 50 mW/cm2. A single
light gun was
positioned over the center of the disc, and irradiated the disc for 20
seconds. Next, the two light
guns were positioned at opposing ends of the circle (across the diameter), and
irradiated the disc
for 10 seconds. The two light guns were moved around the circle to irradiate
the disc for a total
of four times of 10 seconds (position of the two light guns around the
circular discs: 0 and 180
degrees, then 90 and 270 degrees, then 135 and 315 degrees, and finally 45 and
225 degrees), in
addition to the 20 second irradiation in the center). The top glass plate was
removed, and the
curing process repeated. The specimen was heated at 37 ~ 3 °C for 15 ~
1 minutes. A diamond
burr was used to drill a hole near the edge of the disks. The disk was
sonicated in acetone to
remove any air inhibited layer that may be present. The diameter and height of
the disk was
measured with a caliper, and the mass of the disk was determined using an
analytical balance. A
wire was threaded through the hole and twisted/turned such that the disk can
be propped upright
within a vial. An aqueous solution of sodium chloride (0.2M, 10 ml) was added
to each vial, the
vials were capped, and placed at 37 °C for 1 hour. Fluoride release was
determined using a
fluoride sensitive electrode immersed in a 50/50 TISAB/sample mixture. Three
tests of each
sample were performed. The results are shown in the following table.
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Sample Fluoride release (~,g/cma)
L/C Sealant test #1 0.178
L/C Sealant test #2 0.172
L/C Sealant test #3 0.153
DP-20-Stest #1 0.286
DP-20-Stest #2 0.262
DP-20-Stest #3 0.280
[0061] These results show that the NOIL sealants such as DP-20-5 with fluoride
glass can
release significantly more fluoride than the conventional L/C sealant. NOIL
sealants can
therefore be used in applications where fluoride release is desirable or
required.
Example 22: Use of NOIL as a top surface over a composite
[0062] A composite can be placed appropriately in a dental restoration
procedure according to
the manufacturer's instructions. The final layer of composite is placed and
adapted to the
cavosurface margin, shaped, and contoured to the desired final form. A thin
coating of a NOIL
composition such as AC-40 or DP-20-5 is gently applied using a soft brush over
the surface of
the composite and the surrounding enamel. The NOIL-coated surface is then
light cured using
an appropriate light source and time of irradiation (e.g. visible blue light
from a VIP light gun at
600 mW/sec2 for 20-40 seconds or less). The produced surface will have a
smooth, glossy
surface. Further, such surface can be obtained without the need for shaping
the composite with
burs or abrasives as required in conventional composite applications, thereby
avoiding potential
damage to surrounding tooth tissue structure while also further minimizing
patient time in the
treatment room.
Example 23: Use of NOIL over a low viscosity composite
[0063] A low viscosity or flowable composite can be placed appropriately in a
dental restoration
procedure. The final layer of composite is placed and adapted to the
cavosurface margin,
shaped, and contoured to the desired final form. The composite is light cured
for a short period
of time such as 5 seconds to eliminate flow of the composite material. A thin
coating of NOIL
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(such as DP-20-5) is gently applied using a soft brush over the surface of the
composite and the
surrounding enamel. The surface is then light cured using an appropriate light
source and time
of irradiation (e.g. visible blue light at 600 mW/sec2). The produced surface
will have a smooth,
glossy surface.
Example 24: Use of NOIL as a root surface coatin
[0064] A root surface requiring desensitization can be isolated, and scrubbed
with a pumice and
cavity cleanser slurry using a cotton pellet, foam pellet, or microbrush. The
root surface can
additionally be etched with phosphoric acid for 15 seconds if desired. A thin
coating of NOIL
(such as DP-20-5) or a filled sample for non-slumping purposes is gently
applied using a soft
brush over the root surface. The NOIL surface is thinned with a gentle stream
of air, and light
cured using an appropriate light source and time of irradiation (e.g. for 10
seconds with visible
blue light at 600 mW/sec2 using the VIP curing light system)
Example 25: Use of NOIL on Dental Annliances
[0065] Shear bond strength (SBS) of NOIL formulas AC-40 and DP20-5 were tested
and
compared to that of Fortify Plus. The following substrates were tested:
enamel, dentin,
composite, uncured composite, Rex III, porcelain, amalgam, acrylic, and
Itself. The following
techniques were used.
[0066] Enamel -- Enamel was pumiced, rinsed and dried. Enamel was etched with
37%
phosphoric acid semi-gel for 15 seconds before rinsing and drying. One coat of
Fortify Plus,
AC-40 or DP20-5 was applied and light cured for 20 seconds, 20 seconds and 5
seconds
respectively at 500 mW/cm~. Post was bonded and sheared after being stored in
37 °C water for
two hours.
[0067] Dentin -- Dentin was polished on moistened 600 grit sanding paper for
30 seconds, rinsed
and dried. Dentin was etched for 15 seconds using 32% phosphoric acid semi-
gel. Dentin was
rinsed and kept moist. 5-7 coats of All Bond 2 Primer A&B mixture were applied
to moist
dentin. Primed surface was lightly air-dried. One coat of Fortify Plus, AC-40
or DP20-5 was
applied and light cured for 20 seconds at 500 mW/cm2. Post was bonded and
sheared after being
stored in 37 °C water for two hours.
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[0068] Amalgam and RexIII -- Amalgam and Rex III were polished on moistened
600 grit
sanding paper for 30 seconds, rinsed and dried. Surface was microetched using
the Accuprep to
achieve a uniform surface. One coat of Fortify Plus, AC-40 or DP20-5 was
applied and light
cured for 20 seconds, 20 seconds and 5 seconds respectively at 500 mW/cm2.
Post was bonded
and sheared after being stored in 37 °C water for two hours.
[0069] Composite and Acrylic -- Composite and acrylic were polished on
moistened 600 grit
sanding paper for 30 seconds, rinsed and dried. Surface was microetched using
the Accuprep to
achieve a uniform surface. Surface was etched with 32% phosphoric acid semi-
gel for 15
seconds before rinsing and drying. One coat of Fortify Plus, AC-40 or DP20-5
was applied and
light cured for 20s, 20s and Ss respectively at 500 mWlcm2. Post was bonded
and sheared after
being stored in 37 °C water for two hours.
[0070] Porcelain -- Porcelain was polished on moistened 600 grit sanding paper
for 30 seconds,
rinsed and dried. The surface was microetched using the Accuprep to achieve a
uniform surface.
The surface was etched with 4% hydrofluoric acid semi gel for 4 minutes,
rinsed and dried.
Generous amounts of porcelain primer was applied to the surface and allowed to
air-dry. One
coat of Fortify Plus, AC-40 or DP20-5 was applied and light cured for 20
seconds, 20 seconds
and 5 seconds respectively at 500 mW/cma. Post was bonded and sheared after
being stored in
37 °C water for two hours.
[0071 ] Uncured composite -- A preparation was done in acrylic using a high
speed handpiece
and burr. The preparation was etched with Accuprep and 32% phosphoric acid
semi-gel. Etched
surface was treated with One Step according to manufacturers instructions.
Renew A2
Translucent was filled into the preparation. One coat of Fortify Plus, AC-40
or DP20-5 was
applied and light cured for 40s at 500 mW/cm2. Post was bonded and sheared
after being stored
in 37 °C water for two hours.
[0072] Itself - Substrates of cured Fortify Plus, AC-40 and DP20-5 were set
into acrylic.
Composite and acrylic were polished on moistened 600 grit sanding paper for 30
seconds, rinsed
and dried. Surface was microetched using the Accuprep to achieve a uniform
surface. Surface
was etched with 32% phosphoric acid semi-gel for 15 seconds before rinsing and
drying. One
coat of Fortify Plus, AC-40 or DP20-5 was applied to their respective
substrates and light cured
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for 20 seconds, 20 seconds and 5 seconds respectively at SOOmW/cm2. Post was
bonded and
sheared after being stored in 37 °C water for two hours.
[0073] The results of the shear bond strength (SBS) assays are shown in the
following table,
where numerical values are in MPa. A #5 gel cap (bonding area 0.1684 cm2) was
used in each of
the foregoing tests along with an Instron (Model 4466) shear bond machine set
to a crosshead
speed of Smm/min, and the shear bond strength (SBS) was calculated in MPa by
dividing the
peak load by bonding area. The mean and standard deviations were calculated
for five
replications (N=5) for each test.
Substrate DP20-5 AC-40 Fortify +
Dentin 13.81 2.9 19.122.7 14.829.5
Enamel 21.58 4.4 25.51 3.3 24.25 3.1
Acrylic 11.81 4.5 17.62 2.0 12.82 1.8
RexIII 12.631.2 17.800.1 11.411.9
Amalgam 11.84 1.4 14.98 2.3 11.47 1.9
Itself 9.21 3.2 14.97 3.7 18.28 3.3
Composite 17.37 3.1 15.35 7.7 16.83 4.7
Porcelain 17.72 1.7 17.58 3.2 14.50 1.2
Uncured composite16.74 3.1 13.69 3.0 22.13 7.5
[0074] In general, DP20-5 and AC-40 performed as well or better than Fortify
+, within
experimental error.
[0075] The location of failure has been of particular interest in comparing
the performance of
dental products. Sample sets consisted of 5 specimens. Most failures occurred
in the substrate
(SUB) or at the interface of the substrate and sealant (S/S). There are a few
occasions where it
appears that there was failure at the sealant layer (SEAL). There is one case
in which there
appears to be a failure at the sealant and post interface (S/P). These
observations are
summarized in the following table.
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Substrate DP20-5 AC-40 Fortify +
Dentin 1 SEAL;4S/S 2SUB;2S/S;1 SEAL1 SUB;4S/S
Enamel 1SUB;4S/S 2SUB;3S/S 3SUB;2S/S
Acrylic 3S/S;2SEAL 4S/S;1SEAL SS/S
Rex III SS/S SS/S SS/S
Amalgam SSIS 3SUB;2S/S 1SUB;4S/S
Itself 4SUB;1 S/S 4SUB;1 S/S 5 SUB
Composite 5 SUB 5 SUB 5 SUB
Porcelain SSUB SSUB SSUB
Uncured composite5 SUB 3 SUB; l S/S; 5 SUB
l S/P
Example 26: Use of NOIL in fingernail or toenail repair applications
[0076] DP-20-5 was tested as a fingernail repair composition as follows. A
thin layer of DP20-5
was coated on a human fingernail with brushing until a smooth surface was
obtained. The
composition was exposed to 500 mW/cm2 light intensity using VIP curing light
system for about
seconds. The composition cured into a smooth shiny surface that was hard to
the touch.
[0077] All of the compositions and/or methods disclosed and claimed herein can
be made and
executed without undue experimentation in light of the present disclosure.
While the
compositions and methods of this invention have been described in terms of
preferred
embodiments, it will be apparent to those of skill in the ant that variations
may be applied to the
compositions and/or methods and in the steps or in the sequence of steps of
the methods
described herein without departing from the concept, spirit and scope of the
invention. More
specifically, it will be apparent that certain agents which are both
chemically and physiologically
related may be substituted for the agents described herein while the same or
similar results would
be achieved. All such similar substitutes and modifications apparent to those
skilled in the art
are deemed to be within the spirit, scope and concept of the invention.
