Sâu răng là một vấn đề sức khỏe răng
miệng chính ở hầu hết các nước trên thế giới và
là nguyên nhân chính gây mất răng. Việc chẩn
đoán sớm bệnh sâu răng là rất quan trọng đối
với trẻ em và người lớn trong điều trị và phòng
ngừa bệnh tật. Trong nghiên cứu này, một
camera huỳnh quang đã được thiết kế và sản
xuất cho mục đích trên. Thiết bị này bao gồm
một đèn LED 380 nm có khả năng kích thích
porphyrins (một loại sản phẩm trao đổi chất của
vi khuẩn gây sâu răng) phát ra huỳnh quang, và
một máy ảnh nhỏ gọn ghi hình huỳnh quang
theo thời gian thực. Thiết bị được kết nối với
máy tính thông qua cổng usb. Một phần mềm
lưu trữ giúp lưu ảnh và video. Trọng lượng và
kích thước của thiết bị phù hợp cho việc kiểm
tra lâm sàng trong khoang miệng và có thể được
sử dụng trong thực hành nha khoa hàng ngày.
Các kết quả kiểm tra cho thấy camera huỳnh
quang có thể phát hiện một số loại tổn thương
bao gồm mảng bám răng, sâu răng, sâu ẩn và
sâu giai đoạn sớm. Bên cạnh đó, công cụ này có
một số ưu điểm như không xâm lấn, an toàn
(không sử dụng bức xạ ion hóa), cơ động, thời
gian thử nghiệm nhanh chóng, và giá thành
thấp.
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84 SCIENCE & TECHNOLOGY DEVELOPMENT, Vol 20, No.K2- 2017
Abstract—Dental caries is a major oral health
problem in most industrialised countries and is still a
major cause of tooth loss. The early diagnostics of
caries is of great importance for children and adults
to facilitate the treatment and prevention of the
diseases. In this study, a fluorescence camera was
designed and manufactured for this purpose. This
device includes a 380-nm LED, which stimulates
porphyrins - metabolic products of the life cycle of
caries-inducing bacteria to emit fluorescence, and a
compact camera recording fluorescence images in
real time. The device is connected to computer via usb
cable. An archiving software helps save shots as image
or video. The weight and size of this device are
suitable for the visual inspection in oral cavity and
can be used in daily dental practice. The test results
showed that this fluorescence camera can detect some
types of carious lesions including dental plaque,
dental caries, hidden caries and early caries. Besides,
this tool has a number of advantages such as non-
invasiveness, safety (non-ionizing radiation), mobility,
rapid test time, and economical..
Index Terms—Camera, dental caries, fluorescence,
LED.
Manuscript Received on July 13th, 2016. Manuscript Revised
December 06th, 2016.
This research is funded by Ho Chi Minh City University of
Technology – VNU-HCM under grant number T-KHUD-2017-
36.
Pham Thi Hai Mien is with Ho Chi Minh City University of
Technology - VNU-HCM, Ho Chi Minh City, Viet Nam (e-mail:
phamhaimien@ hcmut.com.vn).
Nguyen Tien Dat is with Ho Chi Minh City University of
Technology - VNU-HCM, Ho Chi Minh City, Viet Nam (e-mail:
ntdat.211@gmail.com).
Duong Ngoc Khanh Vy is with Ho Chi Minh City University
of Technology - VNU-HCM, Ho Chi Minh City, Viet Nam (e-
mail: dnkvy95@gmail.com).
Huynh Thi Hoang Vy is with Ho Chi Minh City University
of Technology - VNU-HCM, Ho Chi Minh City, Viet Nam (e-
mail: k1304947@hcmut.com.vn).
1 INTRODUCTION
Dental caries is the most prevalent of the oral
diseases worldwide. Traditionally, dental
professionals rely mostly on subjective
interpretation of clinical-tactile inspection, aided by
dental radiography for caries detection [1].
However, these methods often show low
sensitivity, and can be difficult to objectively
measure mineral loss, meaning that a large number
of lesions may be missed [2, 3]. Subjective
interpretation can also lead to widely varying
diagnoses depending on the test conditions and
examiner experience [4]. Furthermore, because of
the possible hazardous effects of ionizing radiation,
X-ray based methods can be unsuitable for patient
groups such as children and pregnant women, the
subjective judgement of this method is neither
quantitative nor sensitive enough to detect early
enamel caries lesions [5].
Today, the demand for accuracy and early
diagnosis of caries is higher than before. The lesion
needs to be assessed as to whether the caries is
limited to enamel or if it has progressed to dentin.
A determination of whether the lesion is cavitated
needs to be made since cavitated lesions continue
to trap bacterial plaque and need to be restored. So
that several new diagnostic tools are constantly
being investigated and obtain promising results.
One of the newly developed diagnostic procedures
employs fluorescence diagnostics. Quantitative
light-induced fluorescence (QLF) is based on the
autofluorescence of teeth. When teeth are
illuminated with high intensity blue light, they will
start to emit light in the green part of the spectrum.
The fluorescence of the dental material has a direct
relation with the mineral content of the enamel [6].
It is important to emphasize that QLF can be
influenced by some factors, such as stains, dental
plaque, dental fluorosis or hypomineralization.
Another fluorescence technique – laser-induced
fluorescence is based on the quantification of
emitted fluorescence from organic components of
Design, manufacture and test of a dental camera
using fluorescence technique
Pham Thi Hai Mien, Duong Ngoc Khanh Vy,
Nguyen Tien Dat, Huynh Thi Hoang Vy.
TẠP CHÍ PHÁT TRIỂN KH&CN, TẬP 20, SỐ K2-2017
85
dental tissues when excited by a 655 nm laser diode
located on the red range from the visible spectrum.
The laser is able to excite either the hard dental
tissue, resulting in the tissue autofluorescence, or
fluorophores present in the caries lesions. This
device has shown good results in the detection of
occlusal caries, however, it might not be used as the
only method for treatment decision-making process
[7]. The other investigators have shown that under
UVA light (near ultraviolet) sound teeth emit blue
– green color, while caries teeth emit the red
fluorescence [8-14]. Based on the difference in the
color of the teeth fluorescence caries lesions can be
detected.
Fluorescence technique using 380-nm light is
non-destructive, non-invasive, and non-ionizing
radiation. This method also shows high sensitivity
in the detection of early demineralization and early
dental caries lesion. In this paper, the fluorescence
technique was applied to design and create a device
model for detecting the appearance of bacteria
causing caries. The in vitro testing method was
conducted to analyze and evaluate the device.
2 MATERIALS AND METHODS
2.1 LEDs
The device for detection of dental caries is a
system that consists of two LEDs: one white LED
PLCC-6 Oval for the general examination, one
SMD 380-nm LED with 1W-power for exciting
teeth fluorescence. The field of view of white LED
must provide the full overview of the oral cavity in
the inspection process. For that request, a white
LED with three integrated diodes was used.
With 380-nm LED, the wavelength and power
play aimportant role in stimulating fluorescence.
According to the research results of the thesis of
Duong Van Hung and Nguyen Van Tuan [11], the
UVA or violet light (365 nm, 380 nm and 405 nm)
are suitable for exciting teeth fluorescence. The
fluorescence images stimulated by 380 nm
wavelength hadhigh contrast between the blue and
red fluorescence better than by 365 nm and 405
nm. With 1W power LED the fluorescence
intensity of all obtained images was available for
the unaided eye observation. Therefore, the 380-nm
LED with 1W power was chosen in this study.
2.2 Source and stable voltage ciruit
Two LEDs are provided with 3,3 V DC power
from batteries or USB port of the computer through
a stable voltage circuit and source selector switch.
The power of LEDs is controlled by hand in a
flexible manner. The stable voltage circuit receives
input from the battery or the computer and the
output voltage is 3,3 V to match the performance
parameters of the LEDs.
Figure 1. Stable voltage ciruit
2.3 Camera
The recorded image can be directly observed
with the naked eye or through the camera. Due to
the poorness of the lightand space condition in the
oral cavity the camera should have a short focal
length ~ 1 cm and high sensitive ~ 5 Mps to
appropriate to record fluorescence image of the
teeth. This camera is connected to computer with
usb cable 2.0.
2.4 Filters
The light emitted from the 380-nm LED is not
monochromatic with a spectrum from 370 nm to
390 nm. The edge of the LED spectrum in the
visible region causes the overlap with the
fluorescence spectrum of teeth. In this case, one
UV bandpass filter (UG-1, Edmund Optics) was
used for passing only wavelength shorter than 400
nm and eliminating unwanted visible light from the
LED.
The 380-nm LED is arranged close to the
camera so the LED light can scatter and decrease
the quality of fluorescence images recorded by
camera. Therefore, a JB490 filter was placed in
front of the camera to block the scattered light from
LED and pass the fluorescence signals from teeth.
2.5 Radiator for LEDs
The heat emitted in the working process of
device is mainly due to the LEDs. The temperature
does not affect the course of the survey and the
quanlity of fluorescence images but shortens the
life span of LEDs. A radiator base plate for LEDs
was designed and placed at the back of the white
and 380-nm LEDs.
3 RESULTS AND DISCUSSION
3.1 Design – build process
The aim ofthis study was to design a portable
fluorescence camera forobservation in the oral
86 SCIENCE & TECHNOLOGY DEVELOPMENT, Vol 20, No.K2- 2017
cavity. Therefore, the device must be easy to use:
the camera header is small for comfortable
manipulation in the visual inspection, the body of
device should be light and fit for hand, and the
LED controler in a convenient location for
controlling LED intensity. The device was modeled
by SolidWorks software and builded by 3D
printing.
Figure 2. Device structure: 1 - Battery cover, 2 - Upper
body, 3 – Camera, 4 – Circuit, 5 – Filters, 6 – Lower body, 7 –
Battery
Figure 3. Fluorescence camera
3.2 Safety equipment
In any electrical and radiation equipment, the
most important requirement is safeness. By using
low voltage (under 5V), and plastic
materialfordevicecasing, dental caries detection
device is perfectly safe. Besides, the light-emitting
diodes operating in the near ultraviolet (UVA), the
lowest photon energy of the three ultraviolet
wavebands, has virtually no effect on human tissue
with short-term exposures [15]. In this research, we
had tested the power LEDs emitting 380-nm peak
in exciting human tissue in 1 minute and below.
3.3 Test of device
3.3.1 Tooth samples
The experiments were made on extracted teeth
(in vitro) and in vivo. All samples, without dental
restorations to ensure the presence of
questionable occlusal caries, were classified
according to the visual criteria of the International
Caries Detection & Assessment System (ICDAS)
[16].
3.3.2 The results of device testing
All samples of thesound and lesion teeth were
observed under white light and 380-nm LED of
designed fluorescence camera.
Fig. 4 shows a sound teeth specimen (sample 1).
Under UVA excitation, as can be seen in Fig. 4B,
this sample emitted the blue-green color on a white
background. As known that the healthy teeth emits
blue or green fluorescence when irradiated with
near ultraviolet or violet-blue light,respectively
[17-18]. In this work the 380-nm LED emitting
band from 370 nm to 390 nm was used that was
capable of stimulating a broad emission band in the
visible region with maximum located at blue –
green wavelengths. For many years, researchers
have studied the origin of natural fluorescence in
dental hard tissue. While the chromophores of
fluorescence at 350–400 nm (in UVA wavelength)
with excitation wavelength shorter than 300 – 325
nm have been identified (traces of trypthophan and
hydroxypyridinium [19], the other fluorescence
colors in visible region remain unidentified. Thus,
the determination of fluorophores emitting blue –
green color in sound teeth requires further
investigation.
Besides blue-green fluorescence observed in
sound teeth, the red color appeared in the samples
with different types of lesions. Sample 2 with
dental calculus is presented in Fig. 5, where the
calculus illuminated the strong red fluorescence.
Calculus is a form of hardened dental plaque. It is
caused by precipitation of minerals from saliva and
gingival crevicular fluid in plaque on the teeth.
There are about 1,000 out of the 25,000 species of
bacteria that are involved with the formation of
dental plaque, but microorganisms that form the
plaque are mainly Streptococcus mutans and
anaerobes, with the composition varying by
location in the mouth [10]. It has long been
recognized that the bacteria Streptococcus mutans
produces special metabolites called porphyrins.
Porphyrins are the native fluorophores that strongly
emits red light under UVA excitation. This
fluorescence is detected in some studies [11-13, 20-
21]. The denser the bacterial colonization, the more
intense the red fluorescent signal will be.
The red fluorescence was also found in more
advanced lesions (dentinal lesions) as can be seen
in Fig. 6 (sample 3). The caries in of this sample
was scored as International Caries Detection &
Assessment System Code 6 (extensive distinct
cavity with visible dentin). Dental caries, also
known as tooth decay, cavities, or caries, is
breakdown of teeth due to the activities of bacteria.
The mouth contains a wide variety of oral bacteria,
but only a few specific species of bacteria are
believed to cause dental caries: Streptococcus
mutans and Lactobacillus species among them.
These organisms break down the hard tissues of the
teeth (enamel, dentin and cementum) by making
TẠP CHÍ PHÁT TRIỂN KH&CN, TẬP 20, SỐ K2-2017
87
acid from food debris on the tooth surface [8]. As
mentioned above, the bacteria Streptococcus
mutans produces porphyrins, which have red
fluorescence observed in Fig. 6.
Figure 4. Sample 1: white light image (A),
fluorescence image (B)
Figure 5. Sample 2: white light image (A),
fluorescence image (B)
Figure 6. Sample 3: white light image (A),
fluorescence image (B)
Figure 7. Sample 4: white light image before and after grinding
(A, B), magnified white light and fluorescence images before
grinding (C, D)
However, the caries expression is not always
cavitated as in the case of sample 3. The base of a
pit or fissure, which is usually the most susceptible
to acid attack, often exhibits caries without any
visual occlusal evidence other than stain. For
example, Fig. 7A presents sample 4 scored as
International Caries Detection & Assessment
System Code 0 (sound tooth). No mark of caries of
this sample was found in lit room with normal
white light illumination. However under UVA
stimulation a small red spot, with careful attention,
was caught. This spot was magnified 10 times for
more detailed observation (Fig. 7D) by using a 10x-
magnification multiple lens system. Doubting about
the presence of a caries hiding under the enamel
layer at an early stage, this area was ground from
the surface to the dentin layer until the cavity was
appeared (Fig. 7B). The result showed not an initial
caries but a distinct cavity in the dentin layer.
The question is “Where is this caries cavity
from”? Note that the enamel layer (thickness 1-3
mm) is a filtering membrane allowing the transit of
substances from the exterior to the interior, and
vice versa. These zones allow the flow of acids
from bacterial plaque, giving rise to disintegration
of the organic material and posteriorly conditioning
demineralization of the inorganic component-thus
supporting the proteolysis-chelation theory of
dental caries. These enamel areas with
disintegration of the organic material, and the large
structural defects such as cracks, which are rich in
organic material, can facilitate the penetration of
bacteria into deep areas of the enamel, without the
existence of superficial cavitation [22].
The next question is “How can the excited light
penetrate into the dentin layerat the depth of about
1-2 mm, and on the other hand, the emission light
escape from the tooth surface?”. In the visible
region, dentin and enamel weakly absorb light and
light scattering plays an important role in
determining the deposited energy distribution in the
tissue [23]. From the tooth surface to the end of
enamel layer, the photon density slowly decreases.
The fluence at the end of enamel layer is over 95%
of the value on the surface. The photons are almost
completely absorbed at the depth of 3.7 mm. In the
case of sample 4, the caries was found at the depth
of 1-2 mm. At this depth, the excited light can
completely penetrate into the carious area for
stimulating, and vice versa, the emission light can
escape to the surface for observing.
The other interesting tooth (sample 5), presented
in Fig. 8, need to be attended. For this sample, in
white lighting condition we can see the tooth
surface without any damage or plaque, but there
was a brownish-yellow area circled in Fig. 8A.
88 SCIENCE & TECHNOLOGY DEVELOPMENT, Vol 20, No.K2- 2017
When stimulated by 380 nm LED this area showed
the reddish color. Brown spots on teeth could be
stains, enamel demineralization or they could be a
symptom of tooth decay at the early stage. The
lesion itself may first become noticeable as a dark
spot or blemish that grows in size over time
(typically months to years), frequently involving
obvious tooth destruction. In this case, reddish
color of brown area under 380 nm demonstrates the
presence of bacteria, so the symptom of early
caries.
Figure 8. Sample 5: white light image (A), fluorescence image
(B)
4 CONCLUSION
Many studies have shown that fluorescence
property of sound teeth was different from of lesion
teeth. Based on the difference in the color of the
teeth fluorescence caries lesions can be detected.
The aim of the present research was to design and
manufacture a portable device for early diagnosis
of dental caries using fluorescence imaging
techniques, with small size and can be easily used
in oral cavity. This device was used to investigate
the fluorescence property of sound and lesion teeth.
The test results showed that fluorescence images
can give interesting information about hidden
caries and caries at the early stage. At this time it is
maybe too early to base solely on this diagnostic
technology, but it shows the possibility to apply
fluorescence technique in the development of a
specificity and sensitivity dental screening tool
without the use of ionizing radiation, and owning a
number of advantages such as safety, mobility, low
cost and rapid test time.
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[11]. Duong Phan Hung and Nguyen Van Tuan, “Design of
optical system for studying emission properties of tissue”,
M.S. thesis, Ho Chi Minh City University of Technology
- VNU-HCM., Ho Chi Minh, Viet Nam, 2014.
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1102, Jul. 1983.
[14]. T. S. Uzunov, T. Uzunov, R. Grozdanova and D.
Kosturkov, "Diagnosis of Dentin Caries – Ultraviolet
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[15]. J. W. Laurence and FardadShakibaie, “Ultraviolet-
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asessement system (ICDAS): an intergrateed system for
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I. Volkova and V. B. Loschenov, “Fluorescence
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[20]. R. Hibst and R. Paulus, “New approach on fluorescence
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Manuela Herrera and Rafael Llamas, “How to Diagnose
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Contemporary Approach to Dental Caries. InTech –
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Pham Thi Hai Mien was born in Vietnam in
1983. She received the PhD. degree in Optics from
Voronezh State University, Russian Federation, in
2011. She is the lecturer of Faculty of Applied
Science, Ho Chi Minh City University of
Technology - VNU-HCM, Vietnam. Her research
interest includes the application of optical
techniques in diagnostic imaging.
Duong Ngoc Khanh Vy was born Vietnam in
1995. She is a senior student at Ho Chi Minh
University of Technology. Her research relates the
application of fluorescence technique in detecting
dental caries.
Nguyen Tien Dat was born in Vietnam in 1995.
He is a senior student at Ho Chi Minh University of
Technology. His research relates the application of
fluorescence technique in detecting dental caries.
Huynh Thi Hoang Vy was born in Vietnam in
1995. She is a senior student at Ho Chi Minh
University of Technology. Her research relates the
application of fluorescence technique in detecting
dental caries.
90 SCIENCE & TECHNOLOGY DEVELOPMENT, Vol 20, No.K2- 2017
Tóm tắt - Sâu răng là một vấn đề sức khỏe răng
miệng chính ở hầu hết các nước trên thế giới và
là nguyên nhân chính gây mất răng. Việc chẩn
đoán sớm bệnh sâu răng là rất quan trọng đối
với trẻ em và người lớn trong điều trị và phòng
ngừa bệnh tật. Trong nghiên cứu này, một
camera huỳnh quang đã được thiết kế và sản
xuất cho mục đích trên. Thiết bị này bao gồm
một đèn LED 380 nm có khả năng kích thích
porphyrins (một loại sản phẩm trao đổi chất của
vi khuẩn gây sâu răng) phát ra huỳnh quang, và
một máy ảnh nhỏ gọn ghi hình huỳnh quang
theo thời gian thực. Thiết bị được kết nối với
máy tính thông qua cổng usb. Một phần mềm
lưu trữ giúp lưu ảnh và video. Trọng lượng và
kích thước của thiết bị phù hợp cho việc kiểm
tra lâm sàng trong khoang miệng và có thể được
sử dụng trong thực hành nha khoa hàng ngày.
Các kết quả kiểm tra cho thấy camera huỳnh
quang có thể phát hiện một số loại tổn thương
bao gồm mảng bám răng, sâu răng, sâu ẩn và
sâu giai đoạn sớm. Bên cạnh đó, công cụ này có
một số ưu điểm như không xâm lấn, an toàn
(không sử dụng bức xạ ion hóa), cơ động, thời
gian thử nghiệm nhanh chóng, và giá thành
thấp.
Từ khóa - sâu răng, huỳnh quang, LED, camera.
Thiết kế, chế tạo và thử nghiệm camera nha khoa
sử dụng kỹ thuật huỳnh quang
Phạm Thị Hải Miền, Dương Ngọc Khánh Vy, Nguyễn Tiến Đạt,
Hoàng Gia Cát, Huỳnh Thị Hoàng Vy
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