SCI ENTI F IC R EVI EW
Near-Infrared Imaging of
Dental Decay at 1310 nm
Daniel Fried, PhD*, Michal Staninec, DDS, Cynthia L. Darling, PhD
University of California San Francisco (UCSF) School of Dentistry, San Francisco, California
* Principal and corresponding author
J Laser Dent 2010;18(1):8-16
Editor’s note: Dr. Daniel Fried is the Academy of Laser Dentistry’s 2009
T.H. Maiman award winner for dental research. His article gives a
summary of his work at the University of California San Francisco School
of Dentistry on using a 1310-nm laser for imaging dental carious lesions.
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CAR I ES DETECTION
AND NEW OPTICAL
DIAGNOSTIC
T EC H N O LO G I ES
8
During the past century, the nature
of dental decay or dental caries in
the United States has changed
markedly due to the introduction of
fluoride to drinking water, the use
of fluoride dentifrices and rinses,
application of topical fluoride in the
dental office, and improved dental
hygiene. In spite of these advances,
dental decay continues to be the
leading cause of tooth loss in the
United States. The nature of the
caries problem has changed
dramatically with the majority of
newly discovered carious lesions
being highly localized to the
occlusal pits and fissures of the
posterior dentition and the proximal contact sites. These early
carious lesions are often obscured
or “hidden” in the complex and
convoluted topography of the pits
and fissures or are concealed by
debris that frequently accumulates
in those regions of the posterior
teeth. Moreover, such lesions are
difficult to detect in the early
stages of development.
Over the past 30 years there has
been an effort to develop optical
methods for the detection and
imaging of proximal and occlusal
dental decay.1-2 These methods
include fiber-optic transillumination (FOTI), fluorescence-based
Fried et. al
methods, and optical coherence
tomography. There has been
renewed interest in optical transillumination, with the availability
of high-intensity, fiber-optic-based
illumination systems for the detection of proximal lesions.3-6 During
fiber-optic transillumination, a
carious lesion appears dark upon
transillumination because of
decreased transmission due to
increased scattering and absorption
of light by the lesion. However, the
strong light scattering of sound
dental enamel at visible wavelengths, 400-700 nm, inhibits
imaging through the entire tooth.
OPTICAL P ROP ERTI ES
O F D E N TA L E N A M E L
AND DENTIN
The near-infrared (NIR) is the
region of the electromagnetic spectrum between 0.7 to 2.0
micrometers (µm). NIR light can
penetrate much further without
scattering through all the tooth
enamel, due to the reduced scattering coefficient in normal enamel.
Figure 1 graphically depicts that
the attenuation coefficient of
enamel is markedly less in the
investigative wavelength of 1310
nm (approximately 2-3 cm-1) than
at visible red light, at around 600
nm (approximately 50-60 cm-1). The
absorption coefficients (µa) and
scattering coefficients (µs) for
normal enamel and dentin have
AB STR ACT
In this review paper we present an
overview of our research which
has shown that dental enamel
manifests high transparency in the
near-infrared (NIR) and suggests
that NIR light at 1310 nm is ideally
suited for the imaging of carious
lesions on proximal and occlusal
tooth surfaces. NIR-sensitive
imaging systems with broadband
light sources centered at 1310 nm
were used to acquire NIR images
of lesions in extracted teeth and
proximal lesions in vivo. Stains
and noncalcified plaque are not
visible in the NIR, enabling better
discrimination of defects, cracks,
and demineralized areas. Carious
lesions were visible in the NIR
with high contrast and can be
viewed from multiple surfaces to
aid in diagnosis. These studies
indicate that NIR imaging may
offer significant advantages over
the conventional visual, tactile,
and radiographic caries-detection
methods.
been reported between the wavelength range of 200-1550 nm. For
enamel, absorption is very weak in
the visible range (µa < 1 cm-l, Ï =
400-700 nm).7 For dentin in the
400-700 nm wavelength range, the
absorption coefficient is essentially
wavelength-independent with a
value of µa ~ 4 cm-1.8 Scattering in
enamel is strong in the visible (µs
= 60 cm-1 at 632 nm) and decreases
~ Ï-3 with increasing wavelength to
a value of only 2-3 cm-1 at 1310 nm
and 1550 nm in the NIR.9-10
Therefore, enamel is virtually
transparent in the NIR with optical
attenuation 1-2 orders of magnitude less than in the visible range.
SCI ENTI F IC R EVI EW
for imaging caries lesions is where
scattering is at a minimum in
sound enamel. However, the scattering coefficient of enamel should
increase markedly with demineralization to provide high contrast of
the lesion. Figure 2 shows how the
optical attenuation of dental
enamel increases at 1310 nm as a
function of mineral loss in natural
lesions. These transmission measurements through demineralized
tissue sections at 1310 nm show
that the demineralized tissue
attenuates the NIR light by a
factor of 20-50 times greater than
the sound enamel.12-13
Figure 2: Optical attenuation (cm-1) at 100 points taken from 10 natural enamel caries
lesions (10 points per lesion) produced by 1310-nm laser emission. The solid line represents the best exponential fit, r2 = 0.74 to the attenuation coefficient vs. volume %
mineral loss. (From reference #11)
In contrast, scattering in dentin is
strong throughout the visible and
near-IR due to forward (Mie) scattering by the dentinal tubules.
Longer NIR wavelengths have
decreased transmission due to
water absorption (see Figure 1).
The optimum wavelength region
Fried et. al
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Figure 1: Plot of the mean ± standard deviations of the attenuation coefficient for dental
enamel (filled circles) and the absorption coefficient of water (open circles) vs. wavelength. (From references #2, 9, 11-12)
In our NIR imaging studies, we
have employed three different NIR
imaging technologies with different
spectral responsivities to acquire
images of lesions: Indium-GalliumArsenide (InGaAs) focal plane
arrays (FPAs) that operate from
1000-1600 nm with high sensitivity,
a conventional silicon-based
charge-coupled device (CCD)
camera with the NIR filter
removed which is sensitive in the
visible range out to 1000 nm, and a
new Germanium (Ge)-enhanced
complementary metal-oxide-semiconductor (CMOS)-based camera
that is sensitive from 500-1600 nm.
Various light sources were investigated for NIR imaging including
Fabry-Pérot NIR diode lasers, tungsten-halogen lamps, and broadband
superluminescent diodes (SLDs).
The SLDs provided a high-intensity, uniform illumination source
from an optical fiber, and the high
bandwidth avoided the production
of laser speckle that produces interference patterns because of the
light’s scattering after striking
irregular surfaces. The use of SLDs
resulted in the acquisition of better
images. Various setups were
employed in these studies that
were optimized for imaging proximal and occlusal lesions through
transillumination of occlusal
2010 VO L 18 , N O . 1
N I R I MAGI NG
M ETHODS
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lesions through reflection (Figure 3).
These setups employed one or two
NIR light sources to provide illumination as uniform as possible and
probes were developed for clinical
use. The following four imaging
devices were used: two high-sensitivity InGaAs FPAs (318 x 252
pixels) (Model SU320KTSX, Sensors
Unlimited, Princeton, N.J., and
Model Alpha NIRTM, Indigo Systems,
Goleta, Calif.); a Ge-enhanced
CMOS image sensor (Model NPEC700M-01 evaluation camera,
NoblePeak Vision, Wakefield, Mass.);
and a near-IR sensitive CCD camera
(DMK-3002-IR, Imaging Source,
Charlotte, N.C.). NIR light was
provided by a λ = 1310 nm superluminescent diode with an output
power of 15 mW and a 35-nm bandwidth (Model SLED1300D20A, Opto
Speed, Zurich, Switzerland) or a
tungsten-halogen 150-W fiber-optic
illuminator (FOI-1, E. Licht
Company, Denver, Colo.) with 90-nm
band-pass filters centered at 1310
nm or 830 nm.
Figure 3: Top image is a depiction of NIR-trans imaging (laterally through the tooth). The
bottom image shows the NIR-occlusal imaging mode. Dashed lines show that the light
source (blue) and detector (black) or the light source alone can be moved around the
tooth (green) for different angles of illumination and imaging. (From reference #21)
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N I R I MAGI NG OF
P ROXI MAL LESIONS
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At 1310 nm the dental enamel
resembles the appearance of a
transparent ice cube. In our early
transillumination measurements,
we employed cross polarizers to
avoid saturation of the InGaAs
FPA by the light that did not pass
through the tooth. However, in
later studies we found that the
crossed polarizers were not necessary with more diffuse illumination
sources. In our first comprehensive
study we used tooth sections of
varying thickness with small simulated lesions ~ 1 mm in diameter to
determine the image contrast at
various wavelengths as a function
of enamel thickness. High contrast
was measured between simulated
and natural caries lesions and
sound tissues14 and we were able to
acquire high contrast through the
sections of greatest thickness and
whole teeth at 1310 nm. Images
taken through plano-parallel tooth
Fried et. al
Figure 4: Contrast ratio between sound enamel and the simulated lesion for the three
imaging systems for varying section thickness: triangles show 1310 nm, squares 830
nm, and circles visible, standard CCD, no filters. (From reference #15)
sections of up to 7-mm thickness
show that the simulated lesions
can be resolved through the
maximum possible thickness of
enamel at 1310 nm. The contrast
was also measured in the visible
region and at 830 nm (Figure 4).15
The performance at visible wave-
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Figure 6: Radiograph (A) and in vivo NIR images of two small lesions taken from the
facial (B) and lingual (C) views. The boxes demarcate the position of the lesions in each
image. The opaque areas represent amalgam restorations. (From reference #16)
images were acquired in vivo from
three directions and the majority of
lesions examined were too small to
require restoration, based on
accepted bitewing radiograph
criteria. All but one of the 33
lesions examined were successfully
imaged from at least one direction.
Figure 7 shows in vivo NIR images
taken from multiple perspectives,
along with a radiograph. Many
other lesions were visible in the
NIR images that were not visible in
radiographs; however, since the
teeth were not extracted and such
lesions were not restored, there
was no histological confirmation of
the nature of those lesions.
N I R I MAGI NG OF
O CC LU SA L L ES I O N S
Our first occlusal images were
acquired by illuminating the tooth
with a “sheet of 1310-nm light” just
above the gingiva from one side
using a cylindrical lens, and the NIR
camera was positioned directly
above the occlusal surface as shown
in Figure 3 (bottom), so that diffuse
light propagates up through the
enamel of the crown from the under-
Fried et. al
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tooth near the cementoenamel
junction (CEJ), proximal lesions
could be viewed directly from the
occlusal surface. Figure 6 shows in
vivo NIR images and a radiograph
of a tooth with a small proximal
lesion. This is particularly advantageous since multiple views can be
acquired of each lesion to aid in
diagnosis.
Recently, we completed our first
in vivo imaging study.16 In this
study only proximal lesions that
were of sufficient severity to show
up on an X-ray were investigated.
The carious lesions were
discernible on bitewing radiographs, but were not visible upon
clinical examination.
NIR imaging handpieces were
developed and attached to a
compact InGaAs focal plane array
and subsequently used to acquire
in vivo NIR images of 33 caries
lesions on 18 test subjects. NIR
images were acquired by transillumination through the tooth
(faciolingual orientation) or by
viewing the lesion from the occlusal
surface while delivering the light
near the CEJ of the tooth. NIR
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lengths was very poor. The imaging
system operating in the NIR
around 830 nm, utilizing a silicon
CCD optimized for the NIR, was
capable of significantly higher
performance than the visible
system, but it did not provide as
high a contrast as that attainable
at 1310 nm and could not detect
the lesions through the full thickness of the enamel.15
Later studies demonstrated that
we could see natural caries lesions
through whole teeth. Figure 5
shows visible and NIR images of
two extracted teeth in contact. One
of the teeth has a proximal lesion
that is clearly visible in the NIR
image. The incremental growth
lines are also visible in the higherresolution 640 x 400 pixel image.
We also noticed that if the tooth
were rotated back and forth while
imaging the interior of the tooth,
we acquired a stereoscopic (3-D)
view through the transparent
enamel. This stereoscopic effect
could also be replicated clinically
by slightly rotating the probe
during imaging.
If the tooth were illuminated
with NIR light delivered low on the
Figure 7: In vivo NIR images of an interproximal lesion from multiple views, occlusal (A)
and buccolingual (B). An X-ray of the lesion is shown in (C), taken with D-speed film.
JOU R NAL OF L ASER DENTI STRY
Figure 5: In vitro interproximal lesion
imaged from the faciolingual orientation.
Visible light image of teeth (A) and nearIR image (B) with the lesion indicated in
yellow. (From reference #16)
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lying dentin.17 Figure 8 shows a
lesion in the pit and fissure area of
the tooth. In the NIR in vitro image
there is a dark gray/black area at
the center of the lesion with very
sharp contrast indicative of
demineralization near the surface
and a larger lighter gray area that is
more diffuse in appearance, indicative of deep subsurface decay
(Figure 8A). The radiograph of the
tooth is shown in Figure 8B. It is
difficult to determine from the radiograph whether the tooth contains a
lesion because the defect on the Xray overlaps into the enamel. The
histology is shown in Figure 8C and
the lesion is present in the enamel
as well as into the dentin.
One quickly notices that
staining and pigmentation do not
interfere in the NIR images and we
were easily able to discriminate
between stains and plaque and
demineralization since the plaque
and stains are not visible in the
NIR. Dental calculus, accumulated
plaque, and organic stains and
debris have been found to interfere
12
Figure 8: In vitro NIR image (A), X-ray (D-speed film) (B), and histology (C) of a tooth
with a deep occlusal lesion penetrating into the dentin.
significantly with visual diagnosis
and fluorescence-based caries
detection schemes in occlusal
surfaces. For example, to use the
DIAGNOdent® (KaVo Dental
GmbH, Biberach/Riß, Germany),
such confounding factors typically
have to be removed by prophylaxis
(abrasive cleaning) before reliable
measurements can be taken.18
Surface staining at visible wavelengths greatly compounds that
problem and it is very difficult to
determine whether pits and
fissures are simply stained or
demineralized. Staining and
pigmentation do not interfere with
NIR imaging at
1310 nm because
the highly conjugated molecules
such as melanin
and porphyrins
produced by
bacteria and
those found in
food dyes that
accumulate in
dental plaque
and are responsible for the
pigmentation in
the visible range,
do not absorb
light in the
NIR.17, 19 Calculus
or calcified
plaque, on the
other hand, is
mineralized and
highly scatters
Figure 9: In vitro visible light images of the occlusal surfaces of
NIR light. Figure
two teeth with stains (A and C). Demineralized areas are visible
9 contains in
in the NIR image of left tooth in (B), while the NIR image shows
vitro images of
the right tooth is sound (D).
Fried et. al
two teeth; one is highly stained but
sound (C), while the other is
stained with demineralization (A).
In the visible images it is not easy
to determine whether there is any
decay in the occlusal surfaces of
either of these teeth because the
pit and fissures are highly stained,
obscuring the areas of demineralization. In the NIR images the
observer is easily able to determine
exactly where the demineralized
areas are localized since the stain
is not visible and the demineralized
areas are more opaque than the
sound enamel.
Developmental defects such as
fluorosis that appear as white spots
on tooth surfaces frequently appear
white in NIR transillumination
images of the occlusal surface. This
reverse in contrast allows discrimination between these
developmental defects and deeper
areas of demineralization due to
caries. In vitro images of a tooth
with occlusal lesions that penetrate
to the dentinoenamel junction
(DEJ) are shown in Figure 10 along
with polarized light micrographs
(PLMs) of two thin sections cut for
histological examination. This tooth
is interesting because in addition to
the lesions, large areas of the
occlusal surface appear with opposite contrast; namely, they appear
whiter or with higher intensity
than the sound enamel areas. We
have observed this phenomenon in
previous transillumination images
of shallow, artificially demineralized areas in the occlusal surfaces20
and from shallow developmental
defects.21 The PLMs show a dark
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(brown) band of hypomineralization
near the enamel surface (see yellow
arrows) with an outer layer of
higher mineral content that is
transparent, which is typical of
mild development defects or fluorosis.21
N I R R E F L E C TA N C E
I MAGI NG
N I R I MAGI NG
DURING SURGICAL
INTERVENTION
Over the past two years we have
presented work showing that NIR
imaging can be used to monitor the
evolution of ablation craters during
laser ablation (drilling) through the
transparent enamel.23-25 Laser-abla-
tion events can be observed in real
time to assess safe laser operating
parameters by imaging thermal and
stress-induced damage, elaborate the
mechanisms involved in ablation
such as dehydration, monitor
removal of demineralized enamel,
and investigate the dynamic changes
in the transparency of enamel with
water loss. If water cooling is not
used, excessive heat accumulation
near the laser incisions causes loss of
transparency in the enamel at 1310
nm, and dynamic changes in the
enamel transparency were directly
visible during laser irradiation.
Figure 12 shows in vitro images
produced during drilling by a rapidly
scanned 9300-nm CO2 laser and by a
high-speed handpiece. As expected in
this experiment, crack formation can
be seen in real time around the
periphery of the preparation and
thermal damage due to excessive
heating causes loss of transparency
of the enamel. Therefore, NIR
imaging can be used to directly
assess the safety of different laser
parameters and removal rates and
Figure 10: In vitro images of a tooth sample with both lesions
and areas of hypomineralization on the occlusal surface. Visiblelight reflectance image (A), NIR transillumination image captured
with the Ge-enhanced CMOS camera (B), PLM images (C, D) of
the sections cut along the yellow dotted lines in Figure 10A. The
yellow arrows in the PLM images indicate the position of
hypomineralization.
Figure 11: In vitro buccal lesion images are shown for one
sample. Visible reflectance with crossed polarizers (A), NIR
reflectance with crossed polarizers (B), fluorescence (C), and NIR
transillumination with crossed polarizers (D). Note the position
of the fiducial marks cut by a CO2 laser at the midway point of
each 2 x 2-mm window. These marks demarcate the position of
the line profiles used for calculating the image contrast on each
sample. (From reference #20)
Fried et. al
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Since the light scattering from
sound enamel is a minimum which
reduces the diffuse reflectance from
the sound enamel, NIR reflectance
imaging has great potential for
imaging early demineralization. In
a recent study, we compared the
image contrast of four imaging
modalities for shallow areas of
demineralization on buccal and
occlusal tooth surfaces. Lesions
were imaged using NIR transillumination, NIR and visible light
reflectance, and fluorescence
imaging methods.20 Crossed polarizers were used where appropriate
to improve contrast. NIR
reflectance imaging had the
highest image contrast for both the
buccal and occlusal groups and it
provided significantly higher
contrast than visible light
reflectance (P < 0.05). Figure 11
shows in vitro images of the buccal
surface of a tooth using the four
imaging modalities. Very little
reflectance is visible in the NIR
reflectance image from the sound
enamel areas which results in high
contrast between sound and
demineralized enamel. Zakian et
al.22 recently reported multispectral
reflectance measurements of
occlusal caries lesions which
confirm that the NIR wavelengths
are well-suited for imaging caries
lesions and that stains do not interfere at these wavelengths.
13
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the damage is not
reversible and
cracks are also
visible.
Nonreversible
changes to
protein, lipid, and
mineral are
possible at higher
temperatures.
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S U M M A RY
AND
FUTURE
WOR K
14
viewing of both occlusal and proximal caries lesions. The clinician can
also acquire multiple images of
dental caries by using various orientations of the imaging system and
the illumination source to avoid the
influence of overlapping teeth,
confirm lesion depth, and avoid false
positives. Since light scattering
provides the high contrast between
sound and demineralized enamel,
areas that are not as severely
demineralized or cavitated are
visible with high contrast.
NIR images of occlusal caries
demonstrate that NIR imaging can
also be used for the detection and
imaging of caries lesions in occlusal
surfaces where most new decay
develops. It is particularly advantageous that pigmentation and
staining do not significantly interfere with imaging demineralization
in the NIR.27 This novel and
straightforward method exploits
the high transparency of dental
enamel and the strong scattering
and weak absorption of the underlying dentin to deliver a uniform
distribution of diffuse NIR light
underneath the transparent
enamel of the crowns to facilitate
high-contrast NIR imaging of the
occlusal decay and detect hidden
lesions beneath the surface. We
have shown that this NIR technology can be used to acquire
images of natural occlusal caries
lesions, both shallow and deep, that
are not detectable by conventional
Initial studies
suggest that NIR
imaging has
considerable
Figure 12: Real-time NIR images of in vitro enamel samples
potential for the
during drilling with a high-speed handpiece (A and B) and a
nondestructive
mechanically scanned 9300-nm CO2 laser (C and D). Cracks are
imaging of dental
formed (white circles) peripheral to the site of removal during
caries. Several
drilling for both devices.
modes of imaging
were investigated
make sure sufficient cooling mechausing imaging geometries optimized
nisms are in place. It can also be
for imaging either proximal or
occlusal lesions. Lesions on proximal
used to assess the rate of material
surfaces were visible with high
removal and the uniformity of the
contrast with transillumination
crater produced by the laser. Since
through the facial or lingual tooth
enamel is highly transparent at 1310
surfaces. Moreover, the enamel is so
nm, subtle changes in the optical
transparent at 1310 nm, that
properties of the enamel can be seen
natural proximal lesions can be
such as dehydration. Heating by the
imaged from the occlusal surfaces.
laser or an external heat source
This offers the advantage of being
without a water spray can cause
able to illuminate from the buccal
dehydration which increases the
(facial) surface of the tooth and
opacity of the enamel by 2-3 times.26
We postulate the filling of the pores
image from the occlusal surface (top)
left by loss of the water with air
with the possibility of simultaneous
results in higher scattering. Figure
13 shows three in vitro images of a
tooth section irradiated by a CO2
laser, also operating at 9300 nm,
without water cooling at a low
fluence to deliberately overheat the
enamel. A large area of the enamel
becomes opaque (dark) after laser
irradiation. After immersion of water
some of the heated areas become
transparent again, indicating that
the changes are reversible, likely due
to the refilling of the pores with
Figure 13: In vitro NIR image (A) showing the high initial transparency of enamel
through a 3-mm thick tooth section prior to CO2 laser irradiation. NIR image (B) of
water. In some of the areas close to
section after irradiation with nonablative CO2 laser, pulses at a repetition rate of 100 Hz.
the surface that were heated to the
Tooth section after immersion in water for 24 hours (C). (From reference #23)
highest temperatures by the laser,
Fried et. al
SCI ENTI F IC R EVI EW
Dr. Daniel Fried is a professor in
the Division of Biomaterials and
Bioengineering in the Department
of Preventative and Restorative
Dental Sciences at the University
of California, San Francisco School
of Dentistry. He received his PhD
in Physical Chemistry from Wayne
State University in 1992 and his
thesis work involved laser ablation
and spectroscopy. Dr. Fried has
been a researcher in the field of
laser dentistry for the past 15
Dr. Cynthia Darling is an assistant professor in the Division of
Biomaterials and Bioengineering in
the Department of Preventative
and Restorative Dental Sciences at
the University of California, San
Francisco School of Dentistry. She
received her PhD in Physical
Chemistry from Wayne State
University in 1993 and her thesis
work involved electronic structure
theory in quantum mechanics. She
has authored and coauthored 50
research papers in conference
proceedings and peer-reviewed
journals. Dr. Darling has been a
researcher in the field of biophotonics for the past 8 years and has
made contributions to the development of digital microradiography
for the assessment of enamel and
dentin mineral content, near-IR
imaging for caries detection, and
polarization-resolved optical property measurements. She may be
contacted by e-mail at
[email protected].
None of the authors have any
commercial disclosures relative to
this article. Their work was
supported by the NIH Grant 1-R0114698.
2010 VO L 18 , N O . 1
Dr. Michal Staninec received a
bachelor’s degree in biochemistry
from the University of California
Berkeley in 1974, his DDS from
UCSF in 1980, then spent one year
in Japan as a researcher in dental
materials and operative dentistry.
Since 1982 he has been teaching
restorative dentistry at UCSF on a
half-time basis, while maintaining
a private practice in San Francisco.
He is currently a clinical professor
in the Department of Preventive
and Restorative Dental Sciences. In
1999 he received his PhD in
Medical Sciences with a thesis in
restorative dentistry from the
University of Nijmegen in Holland.
He has authored and coauthored 50
articles in peer-reviewed journals
and lectured on restorative
dentistry in the United States,
Japan, and Europe. His research
interests include dental adhesion,
conservative restorative techniques, clinical testing of adhesive
techniques, secondary caries, laser
interactions with dental hard
tissues, and effects of fatigue on
dentin. He is a Fellow of the
Academy of Dental Materials,
Academy of Dentistry
International, and a past president
of the Dental Materials Group
Chapter of the American
Association for Dental Research.
He may be contacted by e-mail at
[email protected].
ACKNOWLEDGEM ENTS
Supported by the NIH/NIDCR
Grant 1-R01 DE14698. The authors
would also like to thank Robert
Jones, Graham Jones, Christopher
Bühler, Patara Ngaotheppitak, Gigi
Huynh, Chulsung Lee, Dennis Hsu,
Jen Wu, Ken Fan, Ken Chan, Hobin
Kang, Shane Douglas, Dustin Lee,
Chulsung Lee, Krista Hirasuna,
Kathy Tao, Linn Maung, and John
Featherstone.
Fried et. al
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AUTHOR B IOGR AP H I ES
years and his contributions in this
field include fundamental measurements of the optical properties of
dental hard tissues from the ultraviolet to the infrared, studies of the
interaction of carbon dioxide lasers
with dental hard tissues for laser
ablation of caries and the surface
modification of enamel for caries
prevention, the use of lasers for the
selective removal of caries and
composite restorative materials,
the assessment of demineralization
and remineralization with polarization-sensitive optical coherence
tomography, and the development
of near-IR imaging for caries detection. In 2009, he received the T. H.
Maiman Award from the Academy
of Laser Dentistry. He may be
contacted by e-mail at
[email protected].
JOU R NAL OF L ASER DENTI STRY
means either radiographically or by
visual/tactile examination. These
studies suggest that NIR imaging
has considerable potential as a tool
for routine caries screening of the
entire dentition. Moreover, this new
imaging tool that does not require
ionizing radiation may enable the
dentist to treat and monitor early
dental decay effectively in a
nonsurgical manner. The dentist
may be able to acquire multiple
NIR images of teeth during subsequent visits to determine whether
fluoride therapy is effective in
arresting the lesion or whether the
lesion has expanded, requiring
more aggressive intervention. Such
an approach is not as practical
with radiographic methods due to
repeated X-ray exposure. These
initial images demonstrate the
potential of the NIR for imaging
dental decay and for overcoming
some of the limitations of conventional methods of caries detection,
namely, visual, tactile, and radiographic. Although these
preliminary NIR images are very
exciting, extensive clinical studies
will be needed to assess the diagnostic performance of any devices
developed based on NIR technology.
The diagnostic performance is
likely to be dependent on the
training and experience of the operator and there are likely to be false
negatives, false positives, and
imaging artifacts just like there are
for other similar technologies.
15
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