Search

Background: Various oral health management programs in Korea affect the oral health improvement in the elderly Several studies have been conducted to date; however, those studies have not shown uniform results due to the differences in research methods or designs. Hence, this study aimed to review the overall research trends of the reported oral health care programs for the elderly in Korea, verify their effects, and clarify them based on the systematic literature review. Methods: The literature search selected intervention studies that applied the oral health care program for the elderly in Korea from 2001 to 2020. Following the COre, Standard, and Ideal (COSI) models presented by the US National Library of Medicine, we selected databases including Korean studies Information Service System (KISS), ScienceOn, Research Information Sharing Service (RISS), DBpia, PubMed, and Google Scholar. Of the 1,335 studies searched using keywords, titles, and abstracts, 21 were finally selected based on primary and secondary exclusion criteria. Results: The most frequent intervention period was 4 weeks, and the number of interventions varied between 2 and 90 times. As for the type of intervention, 14 studies that conducted both theory and practice were the most frequent. Significant differences in the clinical indicators, such as calculus, halitosis, salivation rate, swallowing function, and dry mouth, were found in most oral health care programs. Conclusion: Based on the results of this study, the intervention program needs further verification using multiple indicators in future studies. In addition, a study extending the intervention period and the number of samples is considered necessary for verifying continuous effectiveness of the intervention program.

To accurately evaluate the protective effects of titanium dioxide-based emulsion from infrared-A rays (IRA) irradiation in daily life, we assessed the harmful effects of natural level of IRA irradiation on human skin cells. Using a well-defined solar IRA simulator, short-term (less than seven days) IRA irradiation on fibroblasts at 34°C elicited an increase in the matrix metalloproteinase-1 (MMP1) mRNA level and decrease in the collagen type-1 α-1 (COL1A1) mRNA level. While short-term IRA exposure showed negligible effects on cell proliferation at 34°C, long-term (24 days) IRA irradiation significantly decreased the proliferation of fibroblasts at the same temperature. However, in the presence of heat stress at 43°C, short-term IRA exposure also elicited severe damage including reduction in cell proliferation and procollagen type 1 C-terminal peptide (PIP) level. In addition, formulated titanium dioxide-based emulsion (IRA protective cream; IRC) with an infrared-A protection factor value of ten could successfully protect cells from damage by short-term and long-term IRA exposures. In this study, we demonstrated that IRC reduces mild and severe damages elicited by natural level of IRA irradiation mimicking system after short-term and long-term exposures.

Considering the potent immune stimulation by CpG oligodeoxynucleotides (CpGs), the development of CpG carriers is a prerequisite for efficient cancer immunotherapy. In this study, we conjugated 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[hydroxyl succinimidyl (polyethylene glycol)] (DSPE-PEG-NHS) with polyethylenimine (PEI) to develop a PEI-PEG-DSPE conjugate that can serve as a biocompatible and efficient CpG carrier. Five types of PEIPEG-DSPE conjugates were developed, each with different molecular weights of PEI and different degrees of DSPEPEG modification, and all exhibited significantly lower cytotoxicity. In particular, compared to CpG delivery via natural PEI, delivery with PEI (25 kDa)-PEG-DSPE and DSPE-PEG-NHS/(amine groups of PEI) at a molar ratio of 0.1 resulted in a higher uptake of CpGs into RAW264.7 cells, probably because of the presence of a hydrophobic lipid moiety. In addition, PEI-PEG-DSPE/CpG complexes triggered significant cytokine secretion (TNF-α) from RAW264.7 cells, comparable to that triggered by PEI/CpG complexes. Thus, PEI-PEG-DSPE conjugates could serve as biocompatible and efficient carriers of the immune stimulator CpG to the macrophages.

The city of Seoul will limit the maximum particulate matter (PM10) concentration to ≤35 μg/m3 (from 2024). Herein, a numerical parametric study was conducted on the PM removal efficiency of the heating, ventilation, and air conditioning (HVAC) filters installed in the ceiling of subway cabins. The PM10 concentration distribution was explored according to the flow rate and flow rate ratio of the air introduced into the cabin. Under the current ventilation conditions of the subway train HVAC system, the PM10 concentration was highest in the cabin central area where exhaust outlets are located and decreased toward both ends of the cabin. The indoor airflow was improved and the PM10 concentration was reduced by increasing the flow rate of the supplied air at both ends of the cabin while decreasing it in the central area. It was found that the strengthened PM10 concentration criterion of Seoul can be met by increasing the ventilation flow rate to 700 CMH (currently, 500 CMH) and the filter efficiency to 85% (currently, 70%) while maintaining the current flow rate ratio. These results are expected to be used as important reference data for reducing the PM concentration in subway cabins and thereby improving indoor air quality.

The city of Seoul will limit the maximum particulate matter (PM

A conical-shaped Si dioxide nano-pattern was employed to sapphire substrate in order to improve the light extraction efficiency of light-emitting diodes. The conical-shaped Si dioxide nano-patterns were fabricated on a 2-inch sapphire wafer using direct imprinting of hydrogen silsesquioxane material. A blue-LED structure was grown on conical-shaped silicon-dioxide nano-patterned sapphire substrates. Photoluminescence and electroluminescence measurements were used to confirm the effectiveness of the nanoscale Si oxide patterned sapphire. An improvement in the luminescence efficiency was observed when nanoscale Si oxide patterned sapphire substrate was used. 1.5 times higher PL intensity and 1.6 times higher EL intensity were observed for GaN LED structure grown on nanoscale Si oxide patterned sapphire, compared to LED structure grown on conventional flat sapphire wafer.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the cause of the COVID-19 outbreaks, is transmitted by respiratory droplets and has become a life-threatening viral pandemic worldwide. The aim of this study was to evaluate the effects of different chemical (chlorine dioxide [ClO

In this study, two different conical-shape nano-patterns were fabricated on the 2-inch diameter sapphire wafer in order to improve the efficiency of light-emitting diodes. The conical-shape nano-patterns were fabricated on the sapphire wafer using a nanoimprint technique and dry etching method. A blue LED structure was grown on the nanoscale-patterned sapphire substrates. The photoluminescence and electroluminescence were measured to confirm the effectiveness of the nano-scale patterns. An improvement in the luminescence efficiency was observed in case that nano-patterned sapphire substrate was used; a 1.44 times-higher photoluminescence intensity and a 1.5 times-higher electroluminescence intensity were observed, compared to those of the light-emitting diodes structure grown on a conventional flat sapphire wafer.

We propose an all-optical phase-shifting method using Yb-doped optical fibers and demonstrate its potential in on-axis digital holography microscopy (DHM) system. The Yb-doped optical fiber induces a phase change under optical pumping conditions. The induced phase shift shows a good linear response to applied pumping currents, and N-step phase-shifting up to 2p can be properly performed. Four-, six-, and eight-step phase-shifting methods are performed, and the phase retrievals from their phase-shifted interferograms are achieved using an interframe correlation matrix method. An 8-step phase shifting-based reconstruction, which is effective for background noise reduction, is used for 3D imaging of an indium tin oxide (ITO) thin film and an organic light-emitting diode (OLED) thin film. The reconstructed surface profile was in agreement with the step structure of the samples. The proposed all-optical phase-shifting method is expected to be applied to various optical imaging systems using fiber-based phase-shifting interferometers.

We present spectral characteristics of the phase shifts in refractive index based phase-shifting interferometer. The conventional mechanical movement method cannot provide the same phase change for different wavelengths, which occurs phase information distortion in the incoherent interferometer. The refractive index-based phase-shifting method can adjust the uniform phase shift over a wide spectral window. Spectral phase-shifting errors of the proposed method were compared with those of the mechanical phase-shift method. The proposed method can be applied to eliminate unwanted phase-shifting errors and to obtain correct phase information of optical tomographic images.

In this study, we compared the antioxidant activities of curcumin (Cur) and a Cur formulation using a fluorescence analysis assay. The Cur formulation was prepared by a simple incorporation of Cur into exosomes (EXO) to produce Cur/EXOs. Free Cur had a low fluorescence intensity in aqueous solution because of its poor stability as a result of its autoxidation, whereas a significantly higher fluorescence intensity was observed for Cur/EXOs. Compared to free Cur, the increased level of intact Cur in EXOs allowed for enhanced antioxidant activity in H2O2 scavenging activity and DPPH assays. Compared to Cur at high concentration (200 μM), Cur/ EXOs were significantly less cytotoxic. The antioxidant activity of Cur or Cur/EXOs in cells could be easily demonstrated by monitoring decreases in their fluorescence intensity. Following subcutaneous injection, the fluorescence intensities of Cur/EXOs were much higher than that of Cur, suggesting that Cur/EXOs improve Cur stability in vivo. Taken together, we have demonstrated the superiority of Cur/EXOs over free Cur in terms of aqueous stability and antioxidant activity using fluorescence monitoring both in vitro and in vivo.

Nanoimprint lithography (NIL) is the next-generation alternative to conventional photolithography involving an inexpensive and high throughput process. However, conventional NIL equipment requires a bulky air compressor which possesses a large area. This study aims to overcome this limitation by introducing a novel hydraulic ultra-violet (UV) imprint system. Hydraulic UV imprint system can be used to conduct the UV NIL process by using a simple, low-cost materials without needing complex equipment. To form various patterned layers, UV NIL was conducted with various master stamps.(diameter: micro-cones:3 μm, nanopillars:200 nm, nanoholes: 200 nm) The performance of the imprint system was verified by using scanning electron microscopy analysis of samples fabricated by new system. The results showed that the performance of the new imprint system was comparable to that of a conventional air-pressure UV imprint system.

We proposed novel phase-shifting interferometry using a fiber-optic vibration sensor. The Doppler shift in the coiled fiber caused by vibrations can be used to detect the vibrations by using a fiber-optic interferometer. The principle can be applied to induce phase shifts. While applying vibrations to the coiled fiber at various vibration frequencies, we recorded the variations in the interference fringes. The interference fringe moved to longer wavelengths when a vibration frequency was increased from 38.00 to 38.40 kHz. Phase variations of 3.59 rad/kHz were obtained. The ability to accurately control the phase by using the vibrations in the coiled fiber was demonstrated by the elimination of the depth degeneracy using the complex signal generated by the phase-shifted interference fringes. Using vibrations to control phase shifting can be an acceptable alternative to conventional methods and can be applied to resolve the depth ambiguity in Fourier domain optical coherence tomography.

In this study, activated platelet-derived vesicles (Act-VEs) are developed as a novel hemostatic biomaterial. Spherical Act-VEs (114.40 ± 11.69 nm in size) with surface charges of -24.73 ± 1.32 mV are successfully prepared from thrombin-activated murine platelets with high surface expression of active glycoprotein IIb/IIIa (GP IIb/IIIa, also known as αIIbβ3) and P-selectin. Although nanosized vesicles from resting platelets (VEs) and Act-VEs showed similar sizes and surface charges, Act-VEs formed much larger aggregates in the presence of thrombin and CaCl2 , compared to VEs. After incubation with fibrinogen, Act-VEs formed much denser fibrin networks compared to platelets or VEs, probably due to active αIIbβ3 on the surfaces of the Act-VEs. After intravenous injection of the Act-VEs, tail bleeding time and the blood loss are greatly reduced by Act-VEs in vivo. In addition, Act-VEs showed approximately sevenfold lower release of pro-inflammatory interleukin-1β (IL-1β) during incubation for 4 days, compared to platelets. Taken together, the formulated Act-VEs can serve as a promising hemostatic biomaterial for the efficient formation of fibrin clots without releasing pro-inflammatory cytokine.

We designed and fabricated a telecentric f-theta imaging lens (TFL) to improve the imaging performance of spectral domain optical coherence tomography (SD-OCT). By tailoring the field curvature aberration of the TFL, the flattened focal surface was well matched to the detector plane. Simulation results showed that the spot in the focal plane fitted well within a single pixel and the modulation transfer function at high spatial frequencies showed higher values compared with those of an achromatic doublet imaging lens, which are commonly used in SD-OCT spectrometers. The spectrometer using the TFL had an axial resolution of 7.8 μm, which was similar to the theoretical value of 6.2 μm. The spectrometer was constructed so that the achromatic doublet lens was replaced by the TFL. As a result, the SD-OCT imaging depth was improved by 13% (1.85 mm) on a 10 dB basis in the roll-off curve and showed better sensitivity at the same depth. The SD-OCT images of a multi-layered tape and a human palm proved that the TFL was able to achieve deeper imaging depth and better contrast. This feature was seen very clearly in the depth profile of the image. SD-OCT imaging performance can be improved simply by changing the spectrometer’s imaging lens. By optimizing the imaging lens, deeper SD-OCT imaging can be achieved with improved sensitivity.

Exosomes (EXO) are considered to be versatile carriers for biomolecules; however, the delivery of therapeutic peptides using EXOs poses several challenges. In this study, the efficiency of serum-derived EXOs in delivering tyrosinase-related protein-2 (TRP2) peptides to lymph nodes is determined. TRP2 peptides are successfully incorporated into EXOs, which show a uniform and narrow size distribution of around 45 nm. The TRP2-incorporated exosomes (EXO-TRP2) are efficiently internalized into macrophages and dendritic cells, and are seen to display a punctate distribution. EXOs loaded with TRP2 together with MPLA, (EXO-MPLA-TRP2) result in a strong release of proinflammatory cytokines (TNF-α and IL-6) from both RAW264.7 and DC2.4 cells. Finally, subcutaneous injection of fluorescently labeled EXO-TRP2 followed by ex vivo imaging using in vivo imaging system (IVIS) show a strong fluorescent signal in the lymph nodes after only 1 h, which is maintained until at least 4 h after injection. Taken together, the findings suggest that serum-derived EXOs can serve as promising carriers to deliver therapeutic peptides to lymph nodes for immunotherapy.

We present a balanced detection method for spectral domain optical coherence tomography (SD-OCT) using a fiberoptic phase shifter. SD-OCT systems typically use a single line scan camera to detect the spectrogram, and noninterfered signals are not excluded from the recorded signal. That limits dynamic range and reduces image quality. Balanced detection methods are used to overcome these problems in swept-source OCT system. Detection using two line scan cameras or multi line camera was proposed to perform the balanced detection in SD-OCT systems. Time delayed replica generated by long optical fiber have been made for that purpose. To induce a phase shift in interference signal, we used a phase shifting interferometry based on an optically tunable phase shifter. The proposed phase shifter can control refractive index variations using the optical power of the pumping beam incident on the rare-earth doped optical fiber. Phase shifts on the optical power represent non-linear behavior and require optimized tuning for proper phase shift. We measured the spectrogram and analyzed the phase change characteristics. By subtracting the phase-shifted replica from the original interference signal, the amplitude of the interference signal is doubled and sensitivity is improved. We prove balanced detection performance based on a phase shifting interferometer.

While some studies have examined the concave and convex regular polygons respectively, very little work has been done to integrate and restructure polygon shapes. Therefore, this study aims to systematically reclassify the regular polygons on the through a comprehensive analysis of previous studies on the convex and concave regular polygons. For this study, the polygon`s consistency with respect to the number of sides and angles was examined. Second, the consistency on the number of diagonals was also examined. Third, the size of the interior and exterior angels of regular polygons was investigated in order to discover the consistent properties. Fourth, the consistency concerning the area in regular polygons was inspected. Last, the consistency of the central figure number in the "k-th" regular polygons was examined. Given these examinations, this study suggests a way to create a concave regular polygon from a convex regular polygon.

We proposed a cell-counting method using optical fiber interferometer and demonstrated the performance of the proposed method. The cell counting means the counting or the quantification of individual cells. Its application ranges from the biological research to practical disease diagnosis. As a conventional approach for cell counting, various methods are employed. Among them, flow cytometry is quite accurate and exact method but it uses bulk and expensive optical equipment. When image-based methods are exploited, the limited field of view obtained by microscope is considered for cell counting. From this reason, problem of time consuming for whole cell counting is to be solved. The proposed method utilized single-mode optical fiber and high-speed spectrometer. Light beam having broad spectral bandwidth over 100 nm at 850-nm central wavelength is irradiated to a flow channel through fiber from top to bottom. Different optical path length differences are made whether the cell is passing though the flow channel across the beam area or not. The difference of optical path lengths in the beam area due to the cell induces interference signal depending on optical thickness of the cell. By measuring a series of interferences, the number of cells can be analyzed. The proposed system can be implemented without any expensive and perform the cell counting in the absence of complex image analysis. Interferometer-based cell counting can be a good alternative to the reported cell-counting methods.

In this paper, we propose and demonstrate a Fabry-Perot interferometer (FPI) optical fiber tip sensor fabricated by a blade-sawing technique using a fiber optic patch cord for high-resolution temperature measurement. The sensor head consists of a short air FP cavity near the tip of a single-mode fiber patch cord tip. The temperature which we can measure is determined through a phase variation of the interference fringes in the reflective spectrum of the sensor. The fiber optic FPI sensor in this work can monitor the environmental temperature very accurately from 40 to 120 o C. As a result, the temperature sensitivity is obtained as 38.2 pm/ o C.

In this study, conical-shaped hollow-patterned sapphire substrates (HPSSs) with three different sizes, were fabricated and used as substrates for blue light emitting diode (LED). The HPSSs were fabricated on 2-inch diameter sapphire wafers by nanoimprint technique. Blue LED structures were grown on the HPSS and flat sapphire wafer, in order to investigate the effect of hollow patterns on sapphire substrate. The photoluminescence (PL), electroluminescence (EL) and X-ray diffraction analysis were used to characterize the blue LED structures. Luminescence efficiency of LED structure, grown on HPSS wafer was improved, compared to identical LED structure grown on conventional flat sapphire wafer. 4.5 times stronger PL and 1.7 times stronger EL intensities were observed from GaN based LED structures grown on HPSS.

The surface of bovine serum-derived exosomes (EXOs) are modified with α-d-mannose for facile interaction with mannose receptors on dendritic cells (DCs) and for efficient delivery of immune stimulators to the DCs. The surface of the EXOs is modified with polyethylene glycol (PEG) without particle aggregation (≈50 nm) via the incorporation of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) into the lipid layer of the EXO, compared to chemical conjugation by N-hydroxysuccinimide activated PEG (NHS-PEG). PEG modification onto the exosomal surface significantly decreases the non-specific cellular uptake of the EXOs into the DCs. However, the EXOs with mannose-conjugated PEG-DSPE (EXO-PEG-man) exhibit excellent intracellular uptake into the DCs and boost the immune response by the incorporation of adjuvant, monophosphoryl lipid A (MPLA) within the EXO. After an intradermal injection, a higher retention of EXO-PEG-man is observed in the lymph nodes, which could be used for the efficient delivery of immune stimulators and antigens to the lymph nodes in vivo.

We have developed a surgical microscope-integrated optical coherence tomography (MI-OCT) system based on an active feedback method to obtain uniform optimal OCT image contrast along the depth of focus (DOF) of a surgical microscope. Conventional MI-OCT systems use a shorter DOF objective lens than those of surgical microscopes for OCT imaging. The existing MI-OCT system was developed to overcome sensitivity roll-off by using an electrically tunable lens (ETL). However, active change in the focus position through the ETL cannot cope with the sensitivity decrease due to optical path length difference (OPD) mismatch. The proposed active feedback method was able to maintain high sensitivity by actively performing OPD matching using a linear motor in the reference arm while tuning the focal position in the sample arm using the ETL. The optical system designed to maintain the OCT resolution and a retroreflector used for ensuring regular reflection intensity in the reference arm during OPD compensation contributed to the uniform sensitivity and stable OCT imaging performance. The simultaneous and automatic actuation of the ETL and linear motor provided sensitivity variation of 3 dB from 17 dB for 10-mm sample displacement corresponding to the DOF of the surgical microscope used in the MI-OCT system. By using an infrared detection card and a mouse brain tumor model, it was demonstrated that the proposed MI-OCT system could acquire OCT images with optimal sensitivity without the limitations due to short OCT DOF.

In this paper, the characteristics of a humidity sensor implemented by Mach Zehnder Interferometer (MZI) in a Planar Lightwave Circuit (PLC) have been designed and demonstrated. The humidity outside is detected with polyvinylpyrrolidone (PVP) coated on the etched arm of the MZI. The length of the etched arm is 10 mm and the PVP was coated by dip-coating into the etched region. As the refractive index of the PVP changes with the surrounding humidity, the PVP-coated humidity sensor presented changes in the interferogram depending on RH (Relative Humidity) around the PLC. The measured results show that the proposed humidity sensor works successfully in the range of 30% to 80% of RH.

We demonstrate fiber-optic sensor applications to full-range complex optical coherence tomography (OCT). To extend imaging range in OCT, real value or interferogram measured from an interferometer is needed to convert into complex value. For the purpose, various treatments such as mechanical, electro-optical, optical and programming based methods have been exploited in the interferometer. To make complex signal in fiber-optic interferometer, we propose vibrationbased optical phase shifting method. The proposed method utilizes optical fiber sensors that are for the detection of vibration using optical fiber. When coiled fiber was exposed to vibration, interferogram presents fringe shift without periodicity variations, which means that vibration induces phase shift in the interferometer. Therefore, intentionally generated vibration could be applicable to controlling of the optical phase shift and retrieval of the complex signal. As a result, the vibrations applied to coiled fiber were able to remove mirror image in Fourier domain. This result proved the feasibility of the proposed method on the extending of optical imaging range.

We proposed complex conjugate-free optical coherence tomography imaging method and demonstrated its performance on mirror image suppression operating in fiber-based interferometer. Artifact image given by twin peaks after the Fourier transform of real interferogram could be removed by using the Doppler shift induced by vibrations, which is utilized for the retrieval of complex signal. To induce the Doppler shift, in the experiment, piezoelectric transducer(PZT) was attached on coiled fiber in reference arm. With adjusting vibration conditions of the PZT, quantity of the phase shift obtained by the Doppler shift could be controlled in the fiber-based interferometer. With changing vibration frequencies, the performance of mirror image suppression was observed. Although small frequency changes of 15 Hz were adjusted, the complex conjugate-free results could be achieved easily. Because the proposed method could be easily adapted to the fiber-based interferometer, required phase control in fiber-based phase shifted interferometer or interferometer-based imaging system would be performed properly by simple implementation of vibration module.

Light guiding panel (LGP) is major device in back light unit (BLU) of liquid crystal display (LCD) and determines the optical property of the LCD in terms of average luminance and uniformity. Previously proposed scatterer patterns had problem of non-uniform luminance such as high concentration of luminance near an entrance of a light source. In this paper, V-groove based scatterer patterns were proposed to improve the performance of the LGP. With changing interval between V-grooves and depth of V-groove itself, various patterns were prepared. The feasibility of the designed model was checked with simulation, which calculates luminance value over the LGP surface based on ray tracing technique, and the obtained results were analyzed to determine optimized fabrication conditions in experimental implementation. In modeling of the scatterer patterns, two different kinds of the patterns were considered: one is the pattern composed with regular V-groove interdistance at the same depth along the LGP length, and the other has regular arrangement along the length but different depth. From the results of simulation, experimental inscription with CO 2 laser was done. The implemented pattern consisting of V-grooves with linearly increasing depth of the slope of 3.2° has proved good possibility. The proposed LGP pattern is expected to be a good alternative to expensive and time consuming fabrication process, which could be a good solution for highly efficient LGP for LCD in the near future.

Bioluminescence imaging (BLI) is the most sensitive animal imaging technique for molecular imaging research. Generally, highly sensitive CCD is used to detect an optical probe introduced in a living mouse. However, in many cases, the light signal emitted from a probe is too small to detect because it is scattered and attenuated by the tissue prior to being detected. The problem is that scattering and attenuation not only inhibit accurate measurement but also make image quality down. Thus we introduced a new method to reduce noise by using property of CCD and method to improve image quality of bioluminescence image by using two steps Gaussian blurring.

We demonstrated the performance of a fiber sensor based on a photonic crystal fiber (PCF) for the detection of high temperatures. The proposed fiber sensor was implemented by collapsing the air holes of the PCF with an arc discharge and forming an in-fiber Mach-Zehnder interferometer. The intentionally collapsed parts in the PCF cause coupling between the core mode and the cladding modes, which produces interference fringes in the transmission spectrum. The spectral response was observed while changing the ambient temperature. The fiber sensor operated properly at high temperatures up to 1000 C. The proposed fiber sensor presented good reliability after repeated temperature variation cycles and showed low hysteresis over wide temperature range. We expect this compact fiber sensor to be applied to monitoring the high-temperature distribution around a thin film sensor and to be an alternative for a strain/pressure thin film sensor under high temperatures in harsh conditions.

Introduction Optical coherence tomography (OCT) is a diagnostic tool that can make near-histologic tomographic images without a biohazard. Due to its high resolution (average, 4 μm) and safety (using light as the source), it has been applied widely in medical fields to replace invasive biopsies. But the trials in dentistry have been restricted to mainly detecting dental caries and oral cancer. In this preliminary study for successive human studies, we tried to evaluate whether OCT can be helpful in determining tooth movement under light orthodontic forces. Methods Orthodontic distraction forces (0, 5, and 10 g) were applied to the mandibular incisors of 6 white rats (10 weeks old) for 5 days by using individualized loop springs (round Elgiloy, 0.018-in diameter, Rocky Mountain Orthodontics, Denver, Colo). The changed periodontal ligaments were imaged with OCT and digital intraoral radiography 2 dimensionally. Both tensile and compressive ligaments were measured and compared. Results With OCT images, we could measure changed ligaments from all directions; radiography could not show the portions overlapped by teeth. The averages of measured ligament width in OCT were larger than those from radiography in all groups. Conclusions This preliminary study shows the possible evaluation and prediction of precise tooth responses under orthodontic forces by using real-time OCT.