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The concept and configuration of a plasmonic cascadable full adder are proposed, whose logic operation is carried out by interference of surface plasmons and whose circuits are formed only with single- and multiple-mode plasmonic waveguides. This full adder is fabricated by patterning a SiO2 film deposited on a metal film using complementary metal-oxide-semiconductor-compatible processes except for the material of metal. The redundant surface plasmons present after interference are drained from the waveguides by forming radiation ports, and metal bumps are formed in the circuits to prevent stray light recoupling with the waveguides. The logic operation of the circuits is numerically confirmed by the three-dimensional finite-difference time domain method, and the difference in surface plasmon intensity between logic level “0” and “1” is numerically estimated to be 1.5 dB even for the worst case. These simulations were experimentally confirmed for some input signal patterns using scanning near-field microscopy, and the surface plasmon intensity distributions monitored coincide well with those simulated.

Feasibility of fabricating plasmonic circuits by complementary metal–oxidesemiconductor (CMOS) compatible processes is presented, and the circuit performances are numerically and experimentally discussed from the viewpoint of operating speed and energy loss. The transmission speed of plasmonic signals, which is governed by the dispersion of circuits, is calculated to be about two orders of magnitude higher than that of electric signals. The energy loss per single transmitted-bit is estimated using shot-noise limits, and it is clarified that plasmonic signals are superior to electric ones if the transmitted distance is set to an area within a few hundred micrometers. Based on these results and the experimental results of each plasmonic components, the feasibility of plasmonic circuits are demonstrated. In addition, the feasibility of the functional expansion of plasmonic circuits, such as wavelength-division-multiplexing networks, is discussed using experimental values of plasmonic components fabricated by CMOS-compatible processes. These plasmonic circuits and networks can be merged into silicon integrated circuits on a silicon substrate using CMOS compatible processes.

Periodontal disease is a chronic inflammatory disease of the periodontal tissue. The periodontal inflamed surface area (PISA) is a proposed index for quantifying the inflammatory burden resulting from periodontitis lesions. This study aimed to investigate longitudinal changes in the periodontal status as evaluated by the PISA following the active periodontal treatment. To elucidate the prognostic factors of PISA, mixed-effect modeling was performed for clinical parameters, tooth-type, and levels of periodontal pathogens as independent variables. One-hundred-twenty-five patients with chronic periodontitis who completed the active periodontal treatment were followed-up for 24 months, with evaluations conducted at 6-month intervals. Five-times repeated measures of mean PISA values were 130+/−173, 161+/−276, 184+/−320, 175+/−417, and 209+/−469 mm2. Changes in clinical parameters and salivary and subgingival periodontal pathogens were analyzed by mixed-effect modeling. Plaque index, clinical attachment level, and salivary levels of Porphyromonas gingivalis were associated with changes in PISA at the patient- and tooth-level. Subgingival levels of P. gingivalis and Prevotella intermedia were associated with changes in PISA at the sample site. For most patients, changes in PISA were within 10% of baseline during the 24-month follow-up. However, an increase in the number of bleeding sites in a tooth with a deep periodontal pocket increased the PISA value exponentially.

Laser diodes are the main optical source in various optical fiber communication systems and indispensable for our daily lives. The wavelength of the laser diodes are set at 1300 nm or 1550 nm for most communication systems, including submarine systems corresponding to the low loss window of silica fiber. Laser diodes used in such wavelength bands are usually InGaAsP/InP lasers. Wavelength in 850-nm band is also used for short-range communication, such as intraoffice systems. The laser diodes used for the wavelengths are AlGaAs/GaAs laser diodes. In these systems, high reliability is required for those laser diodes since the communication systems are serious lifelines, and the operating conditions have been severe year by year. In those applications for communication systems, high-speed operation for trunk systems and long-term stable wavelength operation for wavelength division multiplexing (WDM) systems are required. For subscriber systems, high and wide operating temperature are required, corresponding to the environmental conditions of applications. In addition to those applications, some laser diodes have begun to be used in space for satellite communications and sensing systems. The environmental conditions of space applications are quite different from those of terrestrial applications such as land and submarine communication systems. Compared with the operating conditions in terrestrial systems, there are large variations in the ambient temperature in space, and laser diodes are possibly exposed to severe irradiation by high-energy particles and ultraviolet rays. These environmental factors are inherent features in space applications and have been added to the reliability issues of terrestrial applications. The basic reliability of laser diodes used in the communication systems is usually determined by optical output characteristics. The stability of lasing wavelength and spectral linewidth are also important in these applications.

Periodontal examination data have a complex structure. For epidemiological studies, mass screenings, and public health use, a simple index that represents the periodontal condition is necessary. Periodontal indices for partial examination of selected teeth have been developed. However, the selected teeth vary between indices, and a justification for the selection of examination teeth has not been presented. We applied a graded response model based on the item response theory to select optimal examination teeth and sites that represent periodontal conditions. Data were obtained from 254 patients who participated in a multicenter follow-up study. Baseline data were obtained from initial follow-up. Optimal examination sites were selected using item information calculated by graded response modeling. Twelve sites&mdash, maxillary 2nd premolar (palatal-medial), 1st premolar (palatal-distal), canine (palatal-medial), lateral incisor (palatal-central), central incisor (palatal-distal) and mandibular 1st premolar (lingual, medial)&mdash, were selected. Mean values for clinical attachment level, probing pocket depth, and bleeding on probing by full mouth examinations were used for objective variables. Measuring the clinical parameters of these sites can predict the results of full mouth examination. For calculating the periodontal index by partial oral examination, a justification for the selection of examination sites is essential. This study presents an evidence-based partial examination methodology and its modeling.

This paper presents and discusses the modeling and evaluation of plasmonic circuits including plasmonic devices such as a multimode interferometer, mode converter, multiplexer, logic circuits, and signal transmission networks.

Plasmonic signal transmission via nanoscale plasmonic waveguides is a new technique with the potential to increase the information transfer capacity in silicon integrated circuits (ICs). During propagation, surface plasmon polaritons (SPPs) exhibit characteristics of a lightwave whose transmission loss is mainly determined by the collective oscillation of electrons. Using this lightwave aspect of SPPs, information can be transmitted using plasmonic signals and optical transmission circuits and networks can be built at the micro/nanoscale. This size scale correlates well with that of electronic circuits comprising metal-oxide-semiconductor field-effect transistors (MOSFETs). In this article, the feasibility of on-chip interconnects and other circuits were discussed and confirmed on the basis of previously developed plasmonic components. The first example examined herein was a wavelength-division-multiplexing circuit comprising a multiplexer and demultiplexer (in 1310 and 1550 nm-wavelength bands), discussed based on the experimental results for each component. Multiplexed signals at the multiplexer were guided into a single-mode waveguide, divided at the demultiplexer and then passed to the electronic circuits. The transmitted plasmonic signals were converted to electric signals at the slits etched on the gate electrode, thereby driving the MOSFET without photodetectors, whereupon the MOSFET-amplified signals were outputted to the electronic circuits. The second example was coherent signal transmission via plasmonic circuits. The signal transmission was performed using micro/nanoscale plasmonic circuits in a manner similar to those of optical fiber transmission systems. These coherent signal transmissions via plasmonic signals were experimentally confirmed, being detected and converted to electric signals at the slits etched on the gate electrode of the MOSFET and then outputted therefrom. These experimental examples confirmed the feasibility of plasmonic circuits integrated with MOSFETs. In plasmonic circuits, signal transmission loss is generally high compared to that of electric and lightwave signals. Herein, it was numerically confirmed again that the plasmonic signal transmission losses were lower than those of electric signals transmitted in electric circuits for plasmonic circuits not exceeding an area of a few hundred square micrometers. The loss of lightwave signals (e.g., transmitted in silicon waveguides) was much lower than those of plasmonic signals. However, as the waveguide width approached the cut-off wavelength, the loss quickly increased to be greater than that of plasmonic signals. This work indicates that plasmonic circuits have an advantage in nanoscale circuits. The circuits presented herein are currently too primitive for actual silicon IC applications, but are adequate to indicate the feasibility of merging plasmonic circuits with silicon ICs.

Wet-electrospun (WES) polymer micron and submicron fibers are promising building blocks for small, flexible optical fiber devices, such as waveguides, sensors, and lasers. WES polymer fibers have an inherent cylindrical geometry similar to that of optical fibers and a relatively large aspect ratio. Furthermore, WES fibers can be produced using low-cost and low-energy manufacturing techniques with large-area fabrication and a large variety of materials. However, the high propagation loss in the fibers, which is normally on the order of tens or thousands of decibels per centimeter in the visible light region, has impeded the use of these fibers in optical fiber devices. Here, the origin of propagation losses is examined to develop a comprehensive and versatile approach to reduce these losses. The excess light scattering that occurs in fibers due to their inhomogeneous density is one of the primary factors in the propagation loss. To reduce this loss, the light transmission characteristics were investigated for single WES polymer fibers heated at different temperatures. The propagation loss was significantly reduced from 17.0 to 8.1 dB cm–1 at 533 nm wavelength, by heating the fibers above their glass transition temperature, 49.8 °C. In addition, systematic verification of the possible loss factors in the fibers confirmed that the propagation loss reduction could be attributed to the reduction of extrinsic excess scattering loss. Heating WES polymer fibers above their glass transition temperature is a versatile approach for reducing the propagation loss and should be applicable to a variety of WES fibers. This finding paves the way for low-loss WES fiber waveguides and their subsequent application in small, flexible optical fiber devices, including waveguides, sensors, and lasers.

Two passive plasmonic demultiplexers with multimode interferometer (MMI) based rectangular and bow-tie designs are demonstrated for 1.31- and 1.55-μm-band wavelength division multiplexing system operation in plasmonic circuits. These demultiplexers are designed using the finite-difference time-domain (FDTD) method and fabricated using complementary metal–oxide–semiconductor compatible processes. SiO2 films deposited on metal films are etched to form mesa structures by focused ion beam milling, and single-mode waveguides, MMIs, and bow-tie structures are then formed on the metal films. In the plasmonic circuits, 1.31- or 1.55-μm-wavelength surface plasmon polariton (SPP) signals can be distributed to each of the different demultiplexer outputs without any change in signal propagation speed. The SPP intensity distributions that are measured using a scanning near-field optical microscope agree well with the distributions that were calculated using the FDTD method. The insertion loss and crosstalk are then calculated for each demultiplexer. In the rectangular-type demultiplexer, the calculated values were less than 9.5 dB and –2.4 dB, and in the bow-tie-type demultiplexer, the corresponding values were 8.9 dB and less than –2.3 dB, respectively. These results demonstrate the applicability of the developed plasmonic demultiplexers to plasmonic circuits when monolithically integrated on a silicon substrate.

研究ノート

Apical periodontitis, an inflammatory lesion causing bone resorption around the apex of teeth, is treated by eradicating infectious bacteria from the root canal. However, it has a high recurrence rate and often requires retreatment. We investigated the bactericidal effect of antimicrobial photodynamic therapy (aPDT)/photodynamic antimicrobial chemotherapy (PACT) using indocyanine green (ICG)-loaded nanospheres coated with chitosan and a diode laser on a biofilm of Enterococcus faecalis, a pathogen of refractory apical periodontitis. Biofilm of E. faecalis was cultured in a porcine infected root canal model. ICG solution was injected into the root canal, which was then irradiated with a laser (810 nm wavelength) from outside the root canal. The bactericidal effect was evaluated by colony counts and scanning electron microscopy. The result of the colony counts showed a maximum 1.89 log reduction after irradiation at 2.1 W for 5 min. The temperature rise during aPDT/PACT was confirmed to be within a safe range. Furthermore, the light energy transmittance through the root was at a peak approximately 1 min after the start of irradiation, indicating that most of the ICG in the root canal was consumed. This study shows that aPDT/PACT can suppress E. faecalis in infected root canals with high efficiency.

We have analyzed the propagation behavior of 1.31-and 1.55-μm-wavelength-band surface plasmon polaritons (SPPs) for three simple Si-based plasmonic waveguides: the Au stripe waveguide, the SiO2 stripe waveguide, and the Au/SiO2 stripe waveguide on a Si substrate. The SPP propagation length in the waveguide varied depending on the waveguide structure and propagation lengths for waveguides with different structural parameters are summarized. The energy that was required for SPP detection after propagation along the waveguides for the 1.31- and 1.55-μm-wavelength bands was calculated for intensity-modulation direct-detection and heterodyne frequency-shift keying systems. The results demonstrate that SPPs can propagate with lower energy consumption than conventional electric wiring below a specific interconnect length. A wavelength-selective structure for SPPs that comprised nano-slits in an Au film on an Si substrate was fabricated. The device can selectively detect 1.31-μm-wavelength SPPs as electrical signals and transmit 1.55-μm-wavelength SPPs. Experimental photoresponses and transmittances were measured and compared with calculated results. Magnitude correlation of the measured and calculated photoresponses and transmittances showed good agreement. Evaluation of the SPP propagation behavior and the wavelength-selective structure are important considerations for the development of optoelectronic integrated circuits that use SPPs and electrons as signal carriers.

Dye-doped, submicron fiber waveguides composed of hole- and electron-transport materials, with a mean diameter of 480–660 nm were fabricated and their waveguiding properties studied. Dye emitted photoluminescence was guided in the fibers and the loss coefficient was calculated to be 1.2 × 10−3–3.9 × 10−3 μm−1 at a wavelength of 540 nm, which is lower than previously reported for optically active polymer submicron fibers. Finally, a feasible method to couple the fibers with counter electrodes is presented using phase segregation of an insulating polymer. These submicron fiber waveguides, composed of optically and electrically active materials, can be used to produce OLED-waveguides, which are applicable in the fields of textile optoelectronics, lab-on-a-chip, and optogenetics.

We demonstrate a novel wavelength-division multiplexing 1.31- and 1.55-μm-wavelength-band plasmonic multiplexer that employs the multimode interference effect. The multiplexer comprises SiO 2 stripes on a Au film and was fabricated using a process compatible with standard complementary metal-oxide-semiconductor processing techniques. To suppress the return loss, tapered structures were introduced to the multiplexer. Finite-difference time-domain simulations indicate that losses were reduced by 12 dB. The multiplexing operation was confirmed with a scanning near-field optical microscopy. The reflection effect (return loss) appeared as an interference fringe of incident and reflecting surface plasmons in the multimode waveguide. The interference fringe disappeared in the multiplexer employing the taper structure.

This paper presents a plasmonic circuit that has been monolithically integrated with electronic devices on a silicon substrate and then discusses the concept behind this circuit. To form the proposed circuit, two plasmonic waveguides and a detector are integrated with metal–oxide–semiconductor field-effect transistors (MOSFETs) on the substrate. In the circuit, intensity signals or coherent plasmonic signals are generated by coherent light at an operating wavelength at which silicon is transparent, and these signals propagate along the waveguides before they are converted into electrical signals by the detector. These electrical intensity and coherent signals then drive the MOSFETs during both DC and AC operation. The measured performances of the devices indicate that surface plasmon polaritons propagate on the metal surface at the speed of light and drive the electronic devices without any absorption in the silicon.

The periodontal inflamed surface area (PISA) is a useful index for clinical and epidemiological assessments, since it can represent the inflammation status of patients in one contentious variable. However, calculation of the PISA is difficult, requiring six point probing depth measurements with or without bleeding on probing on 28 teeth, followed by data input in a calculation program. More simple methods are essential for screening periodontal disease or in epidemiological studies. In this study, we tried to establish a convenient partial examination method to estimate PISA. Cross-sectional data of 254 subjects who completed active periodontal therapy were analyzed. Teeth that represent the PISA value were selected by an item response theory approach. The maxillary second molar, first premolar, and lateral incisor and the mandibular second molar and lateral incisor were selected. The sum of the PISAs of these teeth was significantly correlated with the patient’s PISA (R2 = 0.938). More simply, the sum of the maximum values of probing pocket depth with bleeding for these teeth were also significantly correlated with the patient’s PISA (R2 = 0.6457). The simple model presented in this study may be useful to estimate PISA.

Dye-doped submicron poly(N-vinylcarbazole) fibers having mean diameters of 290–430 nm were fabricated via electrospinning and their waveguiding properties were investigated. The middle of each fiber's length was excited with UV light and guided photoluminescence (PL) was measured at the end of each of the fibers for different propagation lengths. The spectral shapes of the guided PL differed depending on the fiber diameter because of leakage of light into the substrate. We propose a model that reproduces the PL attenuation with increasing propagation lengths and includes the temporal PL decay due to photobleaching and the size of the excitation area. The calculated propagation loss coefficient in the fibers was 6.3 × 10−3−1.4 × 10−1 µm−1 with λ = 430–500 nm. The propagation loss was inherent in the fiber itself because the re-absorption loss coefficient of the doped dye was

We investigated the efficacy, safety, and clinical significance of trafermin, a recombinant human fibroblast growth factor (rhFGF)-2, for periodontal regeneration in intrabony defects in Phase III trials. Study A, a multicenter, randomized, double-blind, placebo-controlled study, was conducted at 24 centers. Patients with periodontitis with 4-mm and 3-mm or deeper probing pocket depth and intrabony defects, respectively, were included. A total of 328 patients were randomly assigned (2:1) to receive 0.3% rhFGF-2 or placebo, and 323 patients received the assigned investigational drug during flap surgery. One of the co-primary endpoints, the percentage of bone fill at 36 weeks after drug administration, was significantly greater in the rhFGF-2 group at 37.131% (95% confidence interval [CI], 32.7502 to 41.5123; n = 208) than it was in the placebo group at 21.579% (95% CI, 16.3571 to 26.8011; n = 100; p < 0.001). The other endpoint, the clinical attachment level regained at 36 weeks, was not significantly different between groups. Study B, a multicenter, randomized, blinded (patients and evaluators of radiographs), and active-controlled study was conducted at 15 centers to clarify the clinical significance of rhFGF-2. Patients with 6-mm and 4-mm or deeper probing pocket depth and intrabony defects, respectively, were included. A total of 274 patients were randomly assigned (5:5:2) to receive rhFGF-2, enamel matrix derivative (EMD), or flap surgery alone. A total of 267 patients received the assigned treatment during flap surgery. The primary endpoint, the linear alveolar bone growth at 36 weeks, was 1.927 mm (95% CI, 1.6615 to 2.1920; n = 108) in the rhFGF-2 group and 1.359 mm (95% CI, 1.0683 to 1.6495; n = 109) in the EMD group, showing non-inferiority (a prespecified margin of 0.3 mm) and superiority of rhFGF-2 to EMD. Safety problems were not identified in either study. Therefore, trafermin is an effective and safe treatment for periodontal regeneration in intrabony defect, and its efficacy was superior in rhFGF-2 compared to EMD treatments.

We demonstrate a plasmonic slow light device using super focusing on a bow-tied metallic waveguide that can be fabricated using complementary metal-oxide semiconductor compatible processes. By solving the characteristic equation of a bow-tied metallic waveguide, we confirmed that the group indices increased as the waveguide width decreased and that they could attain over 11.0 in the telecommunication wavelength band. Additionally, we experimentally confirmed using an autocorrelation measurement system in which the pulse width of the bow-tied metallic waveguide was 8.0 fs longer than that of a ridged metallic waveguide. Therefore, the proposed device will contribute to the realization of all-plasmonic memories and amplifiers.

This paper presents a feasibility study of optical interconnections using surface plasmon polaritons (SPPs) as coherent carrier waves in a silicon-based electrical circuit. A gold film plasmonic waveguide and a gold/silicon Schottky-type plasmonic detector were monolithically integrated with an electrical circuit based on metal–oxide–semiconductor field-effect transistors on a silicon substrate. A 1550-nm-band laser source was used for SPP excitation, and the photocurrent generated by the plasmonic detector was amplified 16 000 times by the monolithically integrated electrical circuit after SPPs carrying the optical intensity signal propagated over the gold film surface for a distance of 100 μm. The integrated circuit detected an optical beat signal by using a delayed self-homodyne technique, thus demonstrating that SPPs can be used as coherent carrier waves in the circuit. Additionally, optical amplitude- and frequency-modulated signal transmission in a gold film plasmonic waveguide and optical heterodyne detection by amplification of the signal intensity in a gold/silicon Schottky-type plasmonic detector were also demonstrated.

Using metal plasmonic waveguides as transmission lines for optical signals and an electrical bias is shown to be feasible in Si-based devices with a separation gap formed between the waveguide and Au/Si Schottky-barrier diode (SBD). Optical signal transmission is confirmed by calculating the radiation pattern from the waveguide edge and measuring the photocurrent detected at the SBD. From a finite-difference time-domain simulation, the radiation pattern from the waveguide edge is represented as an interference fringe. The simulation result for the separation-length dependence of the detected photocurrent at the SBD corresponds well with experiment. Moreover, the intensity-modulated optical signal at 10 MHz is also observed across the 3-μm-length separation gap. The electrical bias separation is confirmed by applying a bias voltage between the waveguide and the Si substrate and generating a bias current through the waveguide. The detected photocurrent at the SBD barely increased with changing bias voltage and was clearly smaller than that under changes in optical intensity. In addition, electrical current produced no influence on the surface-plasmon signal on the waveguide.

A plasmonic integrated circuit configuration comprising plasmonic and electronic components is presented and the feasibility for high-speed signal processing applications is discussed. In integrated circuits, plasmonic signals transmit data at high transfer rates with light velocity. Plasmonic and electronic components such as wavelength-divisionmultiplexing (WDM) networks comprising metal wires, plasmonic multiplexers/demultiplexers, and crossing metal wires are connected via plasmonic waveguides on the nanometer or micrometer scales. To merge plasmonic and electronic components, several types of plasmonic components were developed. To ensure that the plasmonic components could be easily fabricated and monolithically integrated onto a silicon substrate using silicon complementary metal-oxide-semiconductor (CMOS)-compatible processes, the components were fabricated on a Si substrate and made from silicon, silicon oxides, and metal; no other materials were used in the fabrication. The plasmonic components operated in the 1300- and 1550-nm-wavelength bands, which are typically employed in optical fiber communication systems. The plasmonic logic circuits were formed by patterning a silicon oxide film on a metal film, and the operation as a half adder was confirmed. The computed plasmonic signals can propagate through the plasmonic WDM networks and be connected to electronic integrated circuits at high data-transfer rates.

論文, From the viewpoint of Christian education, especially early childhood education and child-rearing, the promotion of a childʼs self-worth and self-direction is very significant. This is achieved through quality teaching practices. In order to improve the quality of child rearing and teaching practices, self-reflection and evaluation are necessary. Certain theories, principles and methods (supported by studies and research) are available as reference tools for the self-evaluation of teachers and those involved with child-rearing. Two theories are introduced in this paper which promote quality teaching practices: “Effective Teacher Training” and “The Boundaries” Also included are concrete examples from “Arigato child rearing workshop” and “Hokurikugakuin-Daiichi Kindergarten.

Antimicrobial photodynamic therapy (aPDT) has been proposed as an adjunctive strategy for periodontitis treatments. However, use of aPDT for periodontal treatment is complicated by the difficulty in accessing morphologically complex lesions such as furcation involvement, which the irradiation beam (which is targeted parallel to the tooth axis into the periodontal pocket) cannot access directly. The aim of this study was to validate a modified aPDT method that photosensitizes indocyanine green-loaded nanospheres through the gingivae from outside the pocket using a diode laser. To establish this trans-gingival irradiation method, we built an in vitro aPDT model using a substitution for gingivae. Irradiation conditions and the cooling method were optimized before the bactericidal effects on Porphyromonas gingivalis were investigated. The permeable energy through the gingival model at irradiation conditions of 2 W output power in a 50% duty cycle was comparable with the transmitted energy of conventional irradiation. Intermittent irradiation with air cooling limited the temperature increase in the gingival model to 2.75 °C. The aPDT group showed significant bactericidal effects, with reductions in colony-forming units of 99.99% after 5 min of irradiation. This effect of aPDT against a periodontal pathogen demonstrates the validity of trans-gingival irradiation for periodontal treatment.

Objective: The aim of this study was to investigate the effect of laser irradiation on root surface demineralization caused by local drug delivery systems (DDS), and to evaluate the effect of sealing on drug retention. Background data: The duration of supportive periodontal treatment (SPT) has increased with increasing life expectancy. Repeated root planing and DDS application during SPT should be reconsidered with regard to their effects on the root surface. Methods: Extracted human teeth were collected, cut into 3×3×2 mm root dentin specimens, and divided randomly into eight groups with various combinations of Nd:YAG laser power (0, 0.5, 1, and 2 W), with and without DDS (minocycline HCl). Specimen microhardness and calcium (Ca) solubility were measured after treatment. The specimens (control and laser and DDS groups) were examined by scanning electron microscopy. Forty SPT patients were recruited, to assess the effect of periodontal pocket sealing on drug retention. Results: Laser irradiation increased the microhardness of root specimens in an energy-dependent manner. Calcium solubilities decreased from the 0 W+DDS group to the 2.0 W+DDS group. The mean Ca solubilities in the 1.0 W+DDS and 2.0 W+DDS groups were significantly lower than in the 0 W+DDS group (p

We demonstrated previously that low-level diode laser irradiation with an indocyanine green-loaded nanosphere coated with chitosan (ICG-Nano/c) had an antimicrobial effect, and thus could be used for periodontal antimicrobial photodynamic therapy (aPDT). Since little is known about the effects of aPDT on periodontal tissue, we here investigated the effect of low-level laser irradiation, with and without ICG-Nano/c, on cultured epithelial cells. Human oral epithelial cells were irradiated in a repeated pulse mode (duty cycle, 10 %; pulse width, 100 ms; peak power output, 5 W). The expression of the developmental endothelial locus 1 (Del-1), interleukin-6 (IL-6), IL-8, and the intercellular adhesion molecule-1 (ICAM-1) were evaluated in Ca9-22 cells stimulated by laser irradiation and Escherichia coli-derived lipopolysaccharide (LPS). A wound healing assay was carried out on SCC-25 cells irradiated by diode laser with or without ICG-Nano/c. The mRNA expression of Del-1, which is known to have anti-inflammatory activity, was significantly upregulated by laser irradiation (p < 0.01). Concurrently, LPS-induced IL-6 and IL-8 expression was significantly suppressed in the LPS + laser group (p < 0.01). ICAM-1 expression was significantly higher in the LPS + laser group than in the LPS only or control groups. Finally, compared with the control, the migration of epithelial cells was significantly increased by diode laser irradiation with or without ICG-Nano/c. These results suggest that, in addition to its antimicrobial effect, low-level diode laser irradiation, with or without ICG-Nano/c, can suppress excessive inflammatory responses via a mechanism involving Del-1, and assists in wound healing.