Attempting near-infrared transillumination imaging with simple instrumentation for studying dental lesions

During the past decades, near-infrared (NIR) methods have been applied to many aspects of life, particularly in dentistry. X-ray methods involve reliable techniques that dentists use to evaluate tooth structure lesions. However, X-ray methods still have some limitations, such as affecting patient health and dentists. In addition, early demineralised enamel is barely detected by X-ray methods. Many studies have demonstrated the usefulness of NIR light for observing tooth structure due to the differences of the optical properties between sound and demineralised tooth tissues under NIR wavelengths. Early demineralisation located under the enamel layer can be observed by NIR imaging (780-1,300 nm). The areas suspected to be demineralised enamel are distinct from the stain and pigmentation because stain and pigmentation do not appear in NIR images. The demineralised areas are substantially darker than the surrounding sound tissues under NIR light. In this study, two optical systems with transillumination and scattering techniques using NIR light (940 nm) were built for capturing occlusal and approximal images of teeth. The systems fulfill some requirements, such as simple setup, safety, and affordable price for the purpose of the replacement of imported equipment.

Physical Sciences | Engineering Doi: 10.31276/VJSTE.61(2).42-46 Attempting near-infrared transillumination imaging with simple instrumentation for studying dental lesions Thi Hai Mien Pham*, Phu Duong Le, Thi Kim Tham Ta University of Technology, Vietnam National University, Ho Chi Minh city Received 13 November 2018; accepted 20 March 2019 Abstract: Introduction During the past decades, near-infrared (NIR) methods have been applied to many aspects of life, particularly in dentistry X-ray methods involve reliable techniques that dentists use to evaluate tooth structure lesions However, X-ray methods still have some limitations, such as affecting patient health and dentists In addition, early demineralised enamel is barely detected by X-ray methods Many studies have demonstrated the usefulness of NIR light for observing tooth structure due to the differences of the optical properties between sound and demineralised tooth tissues under NIR wavelengths Early demineralisation located under the enamel layer can be observed by NIR imaging (780-1,300 nm) The areas suspected to be demineralised enamel are distinct from the stain and pigmentation because stain and pigmentation not appear in NIR images The demineralised areas are substantially darker than the surrounding sound tissues under NIR light In this study, two optical systems with transillumination and scattering techniques using NIR light (940 nm) were built for capturing occlusal and approximal images of teeth The systems fulfill some requirements, such as simple setup, safety, and affordable price for the purpose of the replacement of imported equipment Dental lesions are one of the most common diseases, affecting people of all ages across the world, and particularly children Diagnoses of damaged structures of teeth in general and early dental present challenges for dentistry Some available diagnostic methods for dental lesions include X-rays, clinical visual inspection, caries indicator dyes, fluorescent methods, electrical conductance measurements (ECM), etc Keywords: approximal lesion, demineralisation, near-infrared, occlusal, teeth The visual method is the most popular diagnostic method in dentistry because it can detect most occlusal lesions, cavitated enamel, and dentine lesions with high specificity However, with low sensitivity, this method has trouble detecting early enamel lesions and proximal and hidden caries [1, 2] In addition to the visual method, X-rays are commonly used as a diagnostic tool in dentistry When X-rays pass through the oral cavity, much of the X-rays are absorbed by hard tissues such as teeth and bones [3] The absorbed X-rays will pass through the film or a digital sensor, creating a radiographic image of the tooth This method makes it possible to observe the structure of hard tissue and surrounding soft tissues that cannot be observed by clinical examination methods, such as proximal tooth surfaces or hidden caries However, this method also produces many adverse effects, particularly for children and pregnant women, through the use of ionising radiation Today, in dentistry, near-infrared technology has been studied for decades and is being applied to the detection of early damages without use of ionising radiation [3, 4] The NIR method yields tooth structure images detected by NIR camera The images created are based on the optical properties of the tooth due to the transmission, absorption, and scattering of dental tissues in NIR wavelength Because the absorption coefficients are exceptionally small in visible Classification number: 2.3 *Corresponding author: Email: phamhaimien@hcmut.edu.vn 42 Vietnam Journal of Science, Technology and Engineering JUne 2019 • Vol.61 Number Physical sciences | Engineering and NIR light, while scattering is strong in visible light and weak in NIR, enamel is translucent in the near infrared light For dentin, the absorption coefficient depends upon the wavelength in the visible region with a value of µa ~ cm-1, while the scattering is strong throughout the visible and NIR regions Therefore, NIR light is the optimum wavelength for imaging dental lesions, particularly dentin caries [5] The damaged tooth structure is mostly demineralised enamel, in which mineral density is reduced As a result, demineralisation creates gaps in enamel and dentin tissues Near-infrared light is scattered at the wall of these gaps and substantially attenuated by the absorption with the elongated pathlength due to multiple scattering [6] For demineralisation, the scattering coefficient of demineralised enamel increases by one to two orders of magnitude at a wavelength of 1,300 nm [7] According to the difference in optical properties between sound and demineralised enamel, their contrast in NIR images is rather pronounced Notably, X-rays not distinguish between sound enamel and demineralised enamel [4, 6] symmetrical light sources on two opposite sides of the sample The scattering system was used to observe the occlusal surface This method is an effective means of observing molar teeth because of their thickness The camera was placed above the tooth and perpendicularly to the light path The quality of the tooth structure image depends upon the position of the camera, the light sources, and tooth The distance between the sample and the camera is about to 1.5 cm, and the light sources were located below the gum line of the teeth The power of the light sources is an important factor as well If LED power is overly high, the recorded images will be overwhelmed by light, and no details of teeth can be seen For this system, the power of each LED was 1.5 W Technical specifications of 940-nm LED: consumption power 1.5/3 W, input voltage 2.0 to 2.4 V, forward current 0.3-0.6 A, lumen efficiency 100 lm/W, and emitting angle 1400 Technical specifications of camera: sensor type CMOS, spectral range 350-1,000 nm, resolution 2Mpx, image rate NIR technology has been investigated for several 15 fps, focal length to cm, input voltage V, temperature decades around the world, and some NIR dental diagnostic range 10-750C, and outer dimensions of 17 cm (height) devices have been commercialised This study has aimed to cm (width) cm (depth) With the purpose of designing a build simple optical systems with reasonable prices Many dental diagnostic device in the future, the size and the focal length the selected camera for intraoral in vivo researchers have indicated that a wavelength of 1,300 nm the the future, sizeof and the focal lengthareofsuitable the selected camera are suitable for examination is more effective than 940 nm due to the higher contrast of intraoral in vivo examination images at 1,300 nm, but performance is challenging because the future, the size and the focal length of the selected camera are suitable for of the limited equipment (LED and camera) Therefore, the intraoral in vivo examination system used a 940-nm wavelength of which the extinction is lower than 40 cm-1 in enamel, and absorption of water is negligible [4] 940-nm LED and NIR cameras are available at an affordable cost This study has designed the transillumination and scattering NIR optical systems to record the approximal and occlusal images of teeth Materials and methods The transillumination system illustrated in Fig 1A (B) (A)(A) (A) (B)(B) consists of a light source, a tooth sample, and an NIR Fig Schematic diagram of transillumination (A) and scattering camera An approximal image of tooth was observedFig clearly Fig Schematic diagram of of transillumination (A) and scattering systems 1.systems Schematic transillumination (A) and scattering systems (B) (B) (B).diagram by this system The transillumination method suits thin teeth such as incisors and canines Samples were illuminated in visible light and 940-nm wavelengths and operated with an LED An oral camera was used for capturing images The camera was connected to a computer with a USB cable 2.0 The LED intensity and source-to-sample distance (about 1-1.5 cm) were adjusted for each sample to control image quality Tooth samples were placed on a 3600-rotating table to capture all sides of samples (Fig 2A) (A) (B) (B) The optical scattering system is illustrated schematically in Figs 1B and 2B It consists of two 940-nm LEDs, Fig a 2.Fig Appearance of transillumination (A) and scattering Appearance of transillumination (A) and scattering systems (B) (A) (B) specimen, and an NIR camera This system used two systems (B) Results and discussion Fig Appearance of transillumination (A) and scattering systems (B) White-spot lesions Results and discussion Vietnam Journal of Science, many Number causes of 2forming white spot lesions which JUneThere 2019 are • Vol.61 43are often Technology and Engineering fluorosis, overlooked in clinical observation, such as demineralisation, enamel White-spot lesions hypoplasia, etc Although X-rays are the gold standard in dentistry, but it is unable to detect white spot lesions at early stages [8] Substantial research has Physical Sciences | Engineering Results and discussion White-spot lesions There are many causes of forming white spot lesions which are often overlooked in clinical observation, such as demineralisation, fluorosis, enamel hypoplasia, etc Although X-rays are the gold standard in dentistry, but it Sample under light (A), NIR light and(C) X-rays is unable to detect white spot lesions at early stages [8] Fig 5.Fig Sample under visible visible light (A), NIR light (B), and(B), X-rays (C) Substantial research has demonstrated that the observation Occlusal lesions of early tooth lesions is more effective by NIR imaging Occlusal lesions Under NIR light, many lesions appear with high contrast Occlusal lesion is a type of injury that can easily be observed by infrared Occlusal typedebris of injury can occlusal easily be light scattering It is lesion formed is by afood insertedthat between pits and because the scattering coefficient of damaged tissue is confused with dental plaque or fluorosis or enamel hypoplasia In the NIR image, observed by infrared light scattering It is formed by food lower than that of healthy enamel [5] This is the sign occlusal lesion is not mistaken for plaque or stains on the tooth of demineralisation appearing at the first stage of the debris inserted between occlusal pits and confused with Figure 6plaque demonstrates a tooth sample having a large area of dental or fluorosis or enamel hypoplasia Indemineralisation the NIR progression of tooth lesion on the occlusal surface However, this lesion is not clear on the X-ray film (Fig image, occlusal lesion is not mistaken for plaque or stains 6C), but in the NIR image (Fig 6B) The NIR image displays a high-contrast area, Figure depicts a tooth sample with white-spot lesions on the darker tooth.than the surrounding area For this sample, demineralisation substantially Under visible light (Fig 3A), at the center of the chewing occurred in a large area so that a deep hole was formed Substantial research has demonstrates a tooth sample having a large indicated Figure that the6 broken crystal structure of demineralised tissue area can cause surface, relative to more translucent, healthy enamel, an of demineralisation on precipitates the occlusal surface.ofHowever, this In unkeeping of water in tissue and the creation gaps in the enamel opaque white area appeared According to the doctor’s thisFig thevisible is attenuated more by the absorption theNIR elongated Fig Sample area, under light (A), light (B), and X-rays Sample under visible light (A), NIR light (B), and X-rays (C) lesion islight not clear on theNIR X-ray film (Fig 6C), butwith in(C) the scattering coefficient based of damaged tissue isobservations lower than thatand of healthy enamel [5] due to multiple scattering [9, 10] Therefore, the demineralised tissue is conclusions on clinical X-ray (Fig pathlength tering coefficient of damaged tissue tissue is lower than of healthy enamel scattering of damaged is lower thatstage of healthy enamel [5] [5] image (Fig 6B) The tissue NIR under image a high-contrast This is thecoefficient sign of demineralisation appearing at than the that first of theOcclusal progression of Occlusal lesions darker than surrounding healthy NIRdisplays light thisof sample has positive However, onprogression the NIR s is the sign ofis3C), demineralisation appearing at status the first stage ofthe the progression of This the sign demineralisation appearing at the first stage of oflesions tooth lesion area, substantially darker than the surrounding area For this h lesion tooth lesion image (Fig 3B), the contrast of circled area is higherOcclusal than the lesion is a lesion type is ofa injury that that can can easily observed by infrared Occlusal type of injury easilybe be observed by infrared demineralisation inbetween abetween large area sopits that Figure depicts a tooth sample with white-spot lesions Under visible light light light scattering Itsample, is formed foodbydebris inserted occlusal pits scattering It isby formed food occurred debris inserted occlusal anda and surrounding enamel, which has demonstrated that Figure depicts sample with white-spot lesions Under visible Figurea3 tooth depictshealthy a tooth sample with white-spot lesions Under visible light light confused withhealthy dental plaque or fluorosis orSubstantial enamel hypoplasia NIR image, confused with dental plaque or fluorosis or enamel hypoplasia InIn thethe NIR image, (Fig 3A), at the center of the chewing surface, relative to more translucent, deep hole was formed research has indicated 3A), at the of chewing surface, translucent, healthy (Fig.center 3A), the the center of thelesion chewing relativetotomore moreocclusal translucent, healthy theanatorigin this issurface, notrelative fluorosis fluorinated lesion is not mistaken plaque or stains on on the occlusal lesion is notfor mistaken for plaque or stains thetooth tooth enamel, opaqueofwhite area appeared Accordingbecause to the doctor's conclusions that the broken crystal structure of demineralised tissue mel, an opaque white area appeared According doctor'sconclusions conclusions enamel, an opaque white area appeared Accordingtoto the the doctor's based enamel on clinical observations and NIR X-ray and (Fig.visible 3C), thisimages sample [4] hasFigure positive white both Thisstatus is6status demonstrates a tooth sample having a large ofdemineralisation demineralisation Figure demonstrates a tooth sample having a largearea area of ed on clinical and in X-ray (Fig.(Fig 3C), this haspositive positive status basedobservations on clinicalisobservations and X-ray 3C), thissample sample has canocclusal cause unkeeping of tissue precipitates on the occlusal surface However, this lesion is not clear theX-ray X-ray on the NIR image (Fig.3B), 3B), theNIR contrast of circled area ishigher higher than the on the surface However, this water lesion isin not clear on on and the filmfilm (Fig (Fig oneon ofthe the advantages of the which is useful wever, on However, the NIR image (Fig 3B), contrast ofmethod, circled is than the However, NIR image (Fig.the the contrast of circled area area is higher than the 6C), but in the NIR image (Fig 6B) The NIR image displays high-contrast 6C),the but in the NIR image (Fig 6B) The NIR image displays aahigh-contrast area, area, creation of gaps in the enamel In this area, the light surrounding healthy enamel, which has demonstrated that the origin of this lesion is ounding healthy enamel, which has demonstrated that the origin of this lesion is surrounding healthy enamel, which has demonstrated that the origin of this lesion is substantially darker than darker the surrounding area.area ForFor this demineralisation substantially than the surrounding thissample, sample, demineralisation to observe disease progression andin improve diagnostic not fluorosis because fluorinated enamel is white both NIR and visible images is area attenuated more thewas absorption the research elongated fluorosis not because fluorinated enamel is white in in both andvisible visible fluorosis because fluorinated enamel is white bothNIR NIRoccurred and inimages a images large that a so deep formed Substantial research occurred in aso large area thatby ahole deep hole was formed with Substantial has has [4] This is one one of the theadvantages advantages ofthe theNIR NIRmethod, method, which isuseful useful to observe accuracy indicated that thepathlength broken of demineralised tissue indicated that thecrystal brokentostructure crystal structure of demineralised tissue can can causecause This is one the advantages of theofNIR method, which is useful to observe [4] of This is of which is to observe due multiple scattering [9, 10] Therefore, (C) disease progression andimprove improvediagnostic diagnostic accuracy unkeeping of water precipitates in enamel In unkeeping of waterand in tissue and precipitates the creationof of gaps gaps in thethe enamel In (A) in tissue (B) the creation ase progression and improve diagnostic accuracy disease progression and accuracy the demineralised tissuemore is darker than surrounding healthy The similar results of white spot lesions are in this thisdepicted area, the light is attenuated more by the absorption withthethe elongated area, the light is attenuated by the absorption with elongated The similar results whitelesions spotlesions lesions aredepicted depicted samples 22 and 3 due to pathlength to scattering [9, 10] is pathlength multiple scattering [9, Therefore, 10] Therefore,the the demineralised demineralised tissuetissue is The similarsamples results white inin samples and The similar results ofofspot white in samples 2due and 6.multiple tissue under NIR light 2ofand (Figs 4,spot 5) arearedepicted Fig Sample under visible lightunder (A), NIR light (B), and X-ray (C) (Figs 4, 5) darker than surrounding healthy tissue under NIR light darker than surrounding healthy tissue NIR light s 4, 5) (A) (Figs 4, 5) (A) (A) (B) (B) (B) (C) (C)(C) (A) (B) (A) (C) (C) (B) Fig Sample under visible light (A), NIR light (B), and X-rays Fig Sample under visible light (A), NIR light (B), and X-ray Fig Sample under visible light (A),NIR NIR light (B), and X-rays (C) Fig Sample under visible light (A), NIR light (B), X-ray (C) Fig Sample under visible light (A), NIR light (B),and and X-ray (C) Sample under visible light (A), NIR light (B), and X-rays (C) Fig Sample 11 under visible light (A), light (B), and X-rays (C) (C) (C) 1 (A) (A) (A) (B) (B) (B) (C) (C)(C) (A) (A) 1 22 3 (B)(B) (C) (C) Fig Sample under visible light (A), NIR light (B), and X-ray Fig Sample under visible light (A), NIR light (B), and X-rays Sample under visible light (A),NIR NIRlight light (B), (C).(C) Fig Fig Sample under visible light (A), (B),and andX-ray X-ray (C) (C) Sample under visible light (A), NIR light (B), and X-rays (C) Fig Sample under visible light (A), NIR light (B), and X-rays (C) Fig Sample under visible light (A), NIR light (B), and X-rays (C) 44 Vietnam Journal of Science, Technology and Engineering illustrates a sample withthe theappearance appearance ofofananearly cariuos lesion FigureFigure illustrates a sample with early cariuos lesion circledarea area2)2) on on the occlusal a large area area Under Under visiblevisible light light (Fig.(Fig 7A,7A, circled occlusalsurface, surface, a large regarded as a lesion appeared in the occlusalgrooves grooves However, in in thethe NIRNIR image regarded as a lesion appeared in the occlusal However, image (Fig.this 7B),area this area exhibit moresevere severe lesion to to other regions (Fig 7B), doesdoes not not exhibit a amore lesionrelative relative other regions andbecause 3) because concentrateddental dental plaque occlusal surface (circled(circled area 1area and13) thethe concentrated plaqueininthethe occlusal surface confused lesions undervisible visible light light The of these is easily confused withwith lesions under Thedisappearance disappearance of these JUne 2019 • Vol.61 Number is easily infrared demonstratesthe the effectiveness effectiveness ofofthethe NIR method for for plaquesplaques under under infrared lightlight demonstrates NIR method the diagnosis of dental lesions addition,inin the the NIR circled region 1 the diagnosis of dental lesions In In addition, NIR image, image,thethe circled region a higher contrast than surrounding enamel; it isitregarded appearsappears with awith higher contrast than thethesurrounding enamel;however, however, is regarded as a minor under visible light Thecircled circled area area 33appears clearly under bothboth as a minor injuryinjury under visible light The appears clearly under Recurrent caries under fillings Fillings are frequently used in the treatment of cavities at the stages of enamel or dentin decay After fillings, the lesions can be relapsed, and they are referred to as „recurrent caries under fillings‟ The proportion of secondary caries is exceptionally high after filling in permanent teeth or primary teeth Secondary caries primarily occur because of the formation of micro cracks after filling When | Engineering Physical the micro crack width exceeds 50 micron,sciences saliva enters the micro cracks between the filling and the tooth tissue The cariogenic bacteria in the saliva grow when the environment of micro cracks is appropriate, thereby producing secondary caries [11] Figure illustrates a 1sample 2with the appearance of an early cariuos2 lesion Under visible light (Fig 7A, circled area 2) 3on the occlusal surface, a large area regarded as a lesion appeared in the occlusal grooves However, in the (C) (B) (A) NIR image (Fig 7B), this area does not exhibit a more severe lesion relative to other regions (circled area and Fig Sample under visible light (A), NIR light (B), and X-ray (C) (C) (A) (B) 3) because the concentrated dental plaque in the occlusal surface easily confused with under light Figure is illustrates a sample with the lesions appearance of an visible early cariuos lesion Fig Sample under visible light (A), NIR light (B), and X-ray Fig Sample under visible light (A), NIR light (B), and X-ray (C) Under visible light (Fig 7A, circled area 2) on the occlusal surface, a large area (C) The disappearance of these plaques under infrared light regarded as a lesion appeared in the occlusal grooves However, in the NIR image Figure depicts a tooth sample with a filling on the occlusal surface Under demonstrates the effectiveness of the NIR method for the (Fig 7B), this area does not exhibit a more severe lesion relative to other regions visible light (Fig 9A, circled area), there were some dark areas around the filling, depicts a tooth sample with a filling on the diagnosis of 3)dental In addition, in the NIR image, (circled area and becauselesions the concentrated dental plaque in the occlusal surface whichFigure rendered it difficult to distinguish between plaque and demineralisation, is easily confused with lesions under with visiblea light Thecontrast disappearance occlusal surface Under (Fig 9A, the circled region appears higher than of thethese while the X-ray image (Fig 9C) did visible not providelight any information of the circled suspected plaques under infrared light demonstrates the effectiveness of the NIR method for lesion under filling because of the limitation of X-ray in scanning the occlusal surrounding enamel; however, it is regarded as a minor area), there were some dark areas around the filling, which the diagnosis of dental lesions In addition, in the NIR image, the circled region surface Because plaques not absorb NIR light and disappear completely in NIR injury under visible light The circled area appears clearly appears with a higher contrast than the surrounding enamel; however, it is regarded images [5], the area in 9B demonstrated the clearplaque appearance rendered it darker difficult to Fig distinguish between andof lesion as aunder minor injury visible The circled areaIn3 appears both under visible andlight infrared light X-ray clearly films under (Fig.both demineralised demineralisation, while the X-ray image (Fig 9C) did not visible and infrared light In X-ray films (Fig 7C), there is no recognition of the Tooth discolorisation and plaque 7C), there is no recognition of the existence of these lesions provide any information of the suspected lesion under filling existence of these lesions because of the limitation of X-ray in scanning the occlusal surface Because plaques not absorb NIR light and disappear completely in NIR images [5], the darker area in Fig 9B demonstrated the clear appearance of demineralised 2 lesion (A) (B) Tooth discolorisation and plaque (C) Fig Sample under visible light (A), NIR light (B), and X-ray (C) Figure 10 illustrates a discolored sample with a cavity on the enamel surface and calculus Under visible light, it is For teeth with many signs of injury on the occlusal surface, as illustrated in easy to recognise that the color of tooth changed to black Fig 8, For the teeth NIR method has exhibited efficiency determining the exact with many signs ofhigh injury on theinocclusal surface, position of lesion Under visible light (Fig 8A), the brown regions are suspected of as illustrated in Fig 8, the NIR method has exhibited high Fig 10B displays a NIR image captured by the transmission the demineralisation, which cannot be observed in the X-ray image (Fig 8C) method, in which calculus and discolored areas appeared as efficiency in determining the exact position of lesion Under visible light (Fig 8A), the brown regions are suspected of black However, as mentioned above, infrared light cannot the demineralisation, which cannot be observed in the X-ray be absorbed by plaque and discolored area; therefore, they image (Fig 8C) However, some brown stains, such as are not apparent in the NIR image This means that in this 10 illustrates a discolored sample with aunder cavitythe on the enamel surface sample, the demineralisation occurred calculus area 1, were apparent under NIR illumination In addition, Figure and calculus Under visible light, it is easy to recognise that the color of tooth and discolored area Notably, even the X-ray films (Fig another region of injury (circled area number 2) could be to black Fig 10B displays a NIR image captured by the changed transmission allow the definition of theareas presence of caries without observed clearly in the infrared image, while in visiblemethod, light, in10C) which calculus and discolored appeared as black However, as above, infrared be absorbed by plaque area; detection of light earlycannot damages This property of and the discolored tooth it is difficult to be distinguished because of the similarmentioned color the therefore, they are not apparent in the NIR image This means that in this sample, relative to healthy enamel and NIR light interaction can be applied to distinguish the demineralisation occurred under the calculus and discolored area Notably, even fromthe discoloration the X-ray demineralisation films (Fig 10C) allow definition ofand the calculus presence of caries without the Recurrent caries under fillings Fig Sample under visible light (A), NIR light (B), and X-ray (C) detection of early damages This property of the tooth and NIR light interaction can The same demineralisation results were recorded with other be applied to distinguish from discoloration and samples calculus cavities Fillings are frequently used in the treatment of 11, 12).were recorded with other samples (Figs 11, 12) same results at the stages of enamel or dentin decay After fillings, the The(Figs lesions can be relapsed, and they are referred to as ‘recurrent caries under fillings’ The proportion of secondary caries is exceptionally high after filling in permanent teeth or primary teeth Secondary caries primarily occur because of the formation of micro cracks after filling When the micro crack width exceeds 50 micron, saliva enters the micro cracks between the filling and the tooth tissue The (A) (B) (C) cariogenic bacteria in the saliva grow when the environment of micro cracks is appropriate, thereby producing secondary Fig 10 Sample under visible light (A), NIR light (B), and Fig 10 Sample under visible light (A), NIR light (B), and X-rays (C) X-rays (C) caries [11] JUne 2019 • Vol.61 Number Vietnam Journal of Science, Technology and Engineering 45 (A) (B) | Engineering (C) Physical Sciences Fig 10 Sample under visible light (A), NIR light (B), and X-rays (C) REFERENCES [1] Zangooei Booshehry (2010), “Dental caries diagnostic methods”, DJH, 2(1), pp.1-12 [2] Mirela Marinova-Takorova, et al (2016), “Effectiveness of near-infrared transillumination in early caries diagnoisis”, (A) (B) (C) Biotechnology & Biotechnological Equipment, 30(6), pp.1207-1211 [3] D.G Bussaneli, et al (2015), “Assessment of a new infrared Fig 11.9 Sample under visible lightlight (A), (B), NIRand lightX-rays (B), and Fig 11 Sample under visible light (A), NIR (C) laser transillumination technology (808 nm) for the detection of X-rays (C) occlusal caries - an in vitro study”, Lasers Med Sci., 30(7), pp.18731879 [4] C.M Buhler, Patara Ngaotheppitak, and Daniel Fried (2005), “Imaging of occlusal dental caries (decay) with near-IR light at 1310nm”, Optics Express, 13(2), pp.573-582 (A) (B) (C) 12 Sample 10 under visible light (A), NIR light (B), and Fig 12.Fig Sample 10 under visible light (A), NIR light (B), and X rays (C) X-rays (C) [5] Daniel Fried, Michal Staninec, Cynthia L Darling (2010), “Near-infrared imaging of dental decay at 1,310 nm”, J Laser Dent., 18(1), pp.8-16 [6] S.J Robert, et al (2003), “Near-infrared transillumination Conclusions Conclusions at 1,310-nm for the imaging of early dental decay”, Optics Express, With the purpose of studying, designing, and 11(18), pp.2258-2265 With the purposea ofdental studying, designing, and with manufacturing a dental manufacturing diagnostic device advantages diagnostic device with advantages such as simple setup, safety, and affordable such as simple setup, safety, and affordable price, in this [7] C.S Jacob, et al (2016), “Near-IR transillumination and price, instudy, this study, optical systemswith with transillumination transillumination andand scattering two two optical systems reflectance imaging at 1,300 nm and 1,500-1,700 nm for in vivo caries techniques using 940techniques nm LED were designed andLED built.were Thesedesigned systems were to scattering using 940 nm anduseddetection”, Lasers in Surgery and Medicine, 48(9), pp.828-836 observebuilt the approximal and occlusal teeth,toand they were to discriminate These systems were ofused observe the able approximal betweenand the demineralised and discolored teeth Theable resulttoindicates the possibility [8] Keith Angelino, David A Edlund, and Pratik Shah (2017), occlusal of teeth, and they were discriminate of applying the NIR in the development of a teeth specificity sensitivity between thetechnique demineralised and discolored Theand result “Near infrared imaging for detecting caries and structural deformities dental screening without the use ofofionising radiation This method can support indicatestoolthe possibility applying the NIR technique in teeth”, Journal of Translational Engineering in Health and in inthedetecting development a specificity sensitivity dental of the clinicians the earlyofdental lesions In and the future, the hardware Medicine, 5, p.e2300107 screening tool further without the use ofand ionising radiation software This will optical systems requires improvement, a photo processing method can support clinicians be developed to increase the image quality in detecting the early dental [9] F Daniel, et al (1995), “Nature of light scattering in dental lesions In the future, the hardware of the optical systems enamel and dentin at visible and near-infrared wavelengths”, Applied requires further improvement, and a photo processing Optics, 34(7), pp.1278-1285 ACKNOWLEDGEMENTS software will be developed to increase the image quality This research is funded by Vietnam National University in Ho Chi Minh city [10] Soojeong ACKNOWLEDGEMENTS (VNU-HCM) under grant number C2018-20-04 Cynthia L Darling Chung, Daniel Fried, Michal Staninec, and (2011), “Multispectral near-IR reflectance and This research is funded by Vietnam National University transillumination imaging of teeth”, Biomedical Optics Express, The authors declare that there is no conflict of interest regarding the in Ho Chi Minh city (VNU-HCM) under grant number publication of this article 2(10), pp.2804-2814 C2018-20-04 The authors declare that there is no conflict of interest regarding REFERENCES the publication of this article [11] X Feng (2014), “Cause of secondary caries and prevention”, West China Journal of Stomatology, 32(2), pp.107-116 [1] Zangooei Booshehry (2010), “Dental caries diagnostic methods”, DJH, 2(1), pp.1-12 [2] Mirela Marinova-Takorova, et al (2016), “Effectiveness of near-infrared transillumination in early caries diagnoisis”, Biotechnology & Biotechnological Equipment, 30(6), pp.1207-1211 46 Vietnam Journal of Science, Technology and Engineering JUne 2019 • Vol.61 Number ... imaging of early dental decay”, Optics Express, With the purpose of studying, designing, and 11(18), pp.2258-2265 With the purposea ofdental studying, designing, and with manufacturing a dental manufacturing... Near-infrared imaging of dental decay at 1,310 nm”, J Laser Dent., 18(1), pp.8-16 [6] S.J Robert, et al (2003), Near-infrared transillumination Conclusions Conclusions at 1,310-nm for the imaging. .. Figure depicts sample with white-spot lesions Under visible Figurea3 tooth depictshealthy a tooth sample with white-spot lesions Under visible light light confused withhealthy dental plaque or fluorosis