• Current Optics and Photonics
• /
• v.3 no.1
• /
• pp.1-7
• /
• 2019

Optical stimulation provides a promising alternative to electrical stimulation to selectively modulate tissue. However, developing noninvasive techniques to directly stimulate excitable tissue without introducing genetic modifications and minimizing cellular stress remains an ongoing challenge. Infrared (IR) light has been used to achieve optical pacing for electrophysiological studies in embryonic quail and mammalian hearts. Here, we demonstrate optical stimulation and pacing of the embryonic chicken heart using a pulsed infrared thulium laser with a wavelength of 1927 nm. By recording stereomicroscope outputs and quantifying heart rates and movements through video processing, we found that heart rate increases instantly following irradiation with a large spot size and high radiant exposure. Targeting the atrium using a smaller spot size and lower radiant exposure achieved pacing, as the heart rate synchronized with the laser to 2 Hz. This study demonstrates the viability of using the 1927 nm thulium laser for cardiac stimulation and optical pacing, expanding the optical parameters and IR lasers that can be used to modulate cardiac dynamics.

• Journal of dental hygiene science
• /
• v.13 no.2
• /
• pp.191-196
• /
• 2013

The purpose of this study was to evaluate the tooth brightening of whitening dentifrice and to determine the tooth stain level over 20 days depending on beverages that have various pH values after using whitening dentifrice. Thirty teeth were randomly divided into two groups. Group 1 was provided with a whitening dentifrice for 3 minutes and group 2 was treated with a control dentifrice for 3 minutes thrice a day for four weeks. All teeth were photographed using a digital imaging system under a stereomicroscope (magnification, ${\times}10$). After four weeks, the ten teeth were immersed in the tea solution, another of ten teeth were immersed in the orange juice and the other of the teeth were immersed in the coffee solution. Three solutions were renewed each day for the appropriate groups. Stain development was monitored under a stereomicroscope daily over 20 days period by immersion of teeth in a tea, juice, coffee solution at room temperature ($25^{\circ}C$) in individual container. Whitening dentifrice gave a statistically higher value of overall color change as compared to control dentifrice after 21 days (p<0.05). Stain level of whiten tooth immersed in orange juice was the grestest overall color change, but there was not statistically significant difference (p>0.05). On the other hand, stain level of whiten tooth immersed in coffee and green tea showed a statistically significant difference after 15 days and 5 days, respectively (p<0.05). Tooth immersed in green tea was higher negative value than control dentifrice. The tooth using whitening dentifrice was shown to be effectively whiter color than control dentifrice. However, stain level by orange juice, coffee and green tea has a strong staining effect.

• Restorative Dentistry and Endodontics
• /
• v.27 no.4
• /
• pp.432-440
• /
• 2002

The purpose of this study is to identificate root canal system including ideal access placement, root curvature, canal configuration, incidence of isthmus in mandibular incisors for success of endodontic treatment. 200 mandibular incisors were selected. The ideal access placement was determimed as follows. The teeth there radiographed from mesiodistal and buccolingual views using intraoral dental film. The image was divided into coronal, middle and apical third using the proximal film. Straight line access was determined by measuring the faciolingual canal width and placing points at midway point between the buccal and lingual wall at the junction of the middle and apical third and at the juntion of coronal and middle third of the root canal. A line was drawn connecting these two points extending through the crown of the tooth. The point at which the line crossed the external crown surface was recorded as facial, incisal, lingual. Degree of root curvature was determined by Schneider Protractor Method. Both section method and clearing method were used in this study. By section method, 100 mandibular incisors were embedded in clear resin and transeverse serial sectioned at 0.5, 1.0, 2.0, 3.0, 4.0, 5.0mm level from root apex. The resected surfaces were stained by methylene blue and examined under $\times$40 magnification with a stereomicroscope. By clearing method, 100 mandibular incisors were cleared in methysalicylate after decalcification with 10% nitric acid and evaluated under $\times$18 magnification with a stereomicroscope. The results were as follows ; 1. 29% had the center of the plotted straight-line access facial to incisal edge, whereas 71% had straight-line access at the incisal edge. When incisal wear classified as extensive, the straight-line access was plotted on the incisal edge 95.5%. When incisal wear classified as slight/none, the straight-line access was plotted on the facial 65.9%. 2. Degree of curvature of main canal was straight or almost straight, and only 10% in buccolingual direction had a degree of curvature greater than 20 degrees and 5.5% in mesiodistal direction had. 3. In section method, canal configuration analysis showed that 51% of the specimen classified as type I, 27% as type II, 12% as type III, 10% as type IV. For theses setions with two canals, the incidence of an isthmus was 36.7%, 64.3%, 79.2%, 96.3%, 97.4%, 97.6% at each level and highest in 3~5mm sections. 4. In clearing method, canal configuration analysis showed that 74% of the specimen classified as type I, 11% as type II, 6% as type III, 9% as type IV. These results suggested that traditional access from lingual should be moved as far toward the incisal as possible to locate and debride the lingual canal and root canal system should be cleaned, shaped completely and obturated three dimensionally for successful endodontic treatment.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.27 no.2
• /
• pp.229-236
• /
• 2000

For the purpose of evaluating the microleakage of compomer restorations in cervical cavities of primary molars according to the length of etching time, an experiment was performed through next procedures. 48 extracted human primary molars were divided into 6 groups according to applied compomers and the etching time of 0, 15, 30 seconds. All the restorations were filled under the manufacturer's direction, and the degree of dye penetration was evaluated with stereomicroscope. The microleakage of etch group was measured and statistically analyzed and obtained the results as follows: 1. Compared with groups without etching, the degree of microleakage was reduced by acid etching the cavities (p<0.05). 2. There revealed similar preventive effects of microleakage when the teeth were etched for 15 seconds and 30 seconds respectively(p>0.05). 3. No significant difference was observed between two compomers examined in this study(p>0.05). It was, therefore, thought acid etching is effective to minimize the microleakage of compomer restorations in primary teeth, and in cases of performing, 15 seconds is adequate for etching.

• Journal of Periodontal and Implant Science
• /
• v.32 no.4
• /
• pp.857-864
• /
• 2002

The aim of this study is to investigate the end of filaments of the different toothbrushes in the market through the stereomicroscope and to evaluate the % of rounded-end filaments considered to be acceptable. 9 brands, total 11 type toothbrushes were tested. 2 toothbrushes of each type which is marked as rounded-end filaments were tested. The toothbrushes which are not marked as rounded-end filaments were excluded. The domestic as well as foreign toothbrushes which are familiar to consumers were tested. 2 tufts of each toothbrushes were cut and examined by stereomicroscope using $40{\times}$ magnification. The procedure was carried out with blind-technique, and the digital photographs were taken. Besides the % of rounded-end filaments, total tufts number, material of the tuft, stiffness, and other special characteristics were recorded. By the classification of Silverstone and Featherstone, rounded-end filaments were examined and counted. The results shows that there are different range of rounded-end filaments according to the toothbrush types(17.7%-91.2%). Atman toothbrush has the most rounded-end filaments(91.2%) among the observed toothbrushes, and the Advantage Plus(Ora1-B) has the next(86.75%). E-Clean #411 has the least(17.70%) and E-Clean #410 of the same brand has also low % rounded-end filaments(20.60%). While G.U.M #409(Butler) has 67.90% rounded-end filaments, G.U.M #471 of the Same brand has comparative low 41.83% rounded-end filaments. 4 types of total 11 have the rounded-end filaments over 80%, however other 4 types have under even 50%. Considering that the correct brushing habit with a toothbrush which has rounded-end filaments can protect the gingival injury and tooth abrasion, it is thought that we dentists need to give the correct information about toothbrush to the patients

• Restorative Dentistry and Endodontics
• /
• v.30 no.4
• /
• pp.327-334
• /
• 2005

This study investigated the effect of anticurvature filing method on preparation of the curved root canal using ProFile. Thirty six resin blocks were divided equally into three groups by instrumentation motions: anticurvature filing motion. circumferential filing motion and straight up-and-down motion. Each resin block was sectioned at 8mm level from the apex and at the greatest curvature of the canal and reassembled in metal mold by a modified Bramante technique. All groups were instrumented with the ProFile system. At each levels. image of sectioned surface were taken using CCD camera under a stereomicroscope at $\times40$ magnification and stored. Distances of transportation at the inner and outer area of curvature and the centering ratio were determined and compared by statistical analysis. along with the assessment of the increase of root canal cross-sectional area. The results were as follows; 1. In all groups. there was no statistical difference in the mean increase of root canal cross-sectional area. the centering ratio. and the mean distances of transportation at the inner area of curvature at each level. 2. At 8mm level from the apex. the mean distances of transportation at the outer area of curvature decreases in following order anticurvature filing motion. circumferential filing motion. straight up-and­down motion but. no significant difference at the greatest curvature of the canal among three groups. Effect of anticurvature filing motion using ProFile does not seem to be different from other instrumentation motions at the inner area of curvature in curved root canal.

• Imaging Science in Dentistry
• /
• v.44 no.3
• /
• pp.199-205
• /
• 2014

Purpose: This study aimed to investigate the effect of changing the kilovoltage peak (kVp) on the radiographic assessment of dental caries. Materials and Methods: Seventy-five extracted posterior teeth with proximal caries or apparently sound proximal surfaces were radiographed with conventional E-speed films and a photostimulable phosphor system using 60 kVp and 70 kVp for the caries assessment. The images were evaluated by three oral radiologists and compared with the results of the stereomicroscope analysis. Results: No statistically significant difference was found between 60 kVp and 70 kVp for the caries detection, determination of caries extension into dentin, and caries severity in either the conventional or the digital images. Good to very good inter-observer and intra-observer agreements were found for both kilovoltage values on the conventional and digital images. Conclusion: Changing the kilovoltage between 60 kVp and 70 kVp had no obvious effect on the detection of proximal caries or determination of its extension or severity.

• Parasites, Hosts and Diseases
• /
• v.54 no.2
• /
• pp.221-224
• /
• 2016

A visceral helminth of the squid, Todarodes pacificus, is reported from the East Sea, the Republic of Korea. Total 39 squid samples were purchased from a fish market in Jumunjin-eup, Gangneung-si (City) from August 2014 to July 2015 and were examined for helminth parasites with naked eyes and under a stereomicroscope after opening the abdominal cavity with a pair of scissors. Whitish larval worms were mainly found in the stomach and abdominal cavity of the squid. They were detected in 25 (64.1%) out of 39 squids examined, and the infection density was 7 larvae per infected squid. Spatula-shaped larvae were $8.2{\times}2.0mm$ in average size, round to slightly flattened anteriorly, with round hatching posteriorly, and had characteristic 4 tentacles with numerous hooklets in the scolex. The larvae were identified as the plerocercoid stage of Nybelinia surmenicola by their morphological features. This finding represents a new host record and the first report of N. surmenicola infection in T. pacificus squids from the east coast of Korea.

• The Journal of the Korean dental association
• /
• v.41 no.1 s.404
• /
• pp.35-41
• /
• 2003

Wettability of addition silicone impression material is very important property for making an accurate restoration. This study examined theimpression quality in clinical condition and the wettability of impression material. Three commercially available addition silicone impression material (Imprint; 3M, USA, Examix; GC, Japan, Perfect; Handae, Korea) were studied. A total of 90 putty/wash impressions of semi-dried premolars and wet molar teeth were examined for void production in impression body. The percentae of the sulcus reproduction ability of each material was calculated from the sulcus depths of cross-sectioned casts from the impressions with stereomicroscope. Three impression materials were used to produce die stone casts from vcid entrapment die. Voids in the stone casts were counted with the stereomicroscpe. From the experiment, the following results were obtained: 1. In direct observation, Imprint showed greatest numbers of void in impression body (P<.001).However, correlations were not found between sulcus reproduction and void production. 2. Sulcus reproduction ability of additional silicone impression material was diminished in order of Imprint, Examix, Perfect. The significant difference was found between Imprint and other material (P<.001). 3. In void entrapment laboratory test, void productions was diminished in order of Examix, Imprint, Perfect. All voids in casts were less in delayed poured cast than immediately poured cast. 4. Especially, the stone pouring time of Perfect impression material should be delayed.

• Journal of Species Research
• /
• v.5 no.1
• /
• pp.157-165
• /
• 2016

The hyporheic zone is an ecologically important area for investigating habitat biodiversity. However, only few studies have been conducted on this aspect in Korea. This study aimed to investigate the distribution of arthropod communities in the hyporheic zone of Nakdonggang River between 2012 and 2013. The meiobenthic arthropod communities found in the hyporheic zone were identified using a stereomicroscope and classified into 9 taxanomic groups. The abundance of arthropod communities was higher in the hyporheic zones of streams having well-formed sandbanks and gravelly areas. The arthropod communities found along the Nakdonggang River differed depending on the conditions of levees and the regions of the river from where they were collected. The frequency of species of the order Harpacticoida was high in the Nakdonggang main stream and western downstream region. The abundance of species belonging to Cyclopidae was high in the upstream region, midstream region, and eastern downstream region of the river. The frequency of species of the order Bathynellacea was high in the riverside parks or cement levees, but that of species belonging to Cyclopidae was high in the natural levees and gabion levees. Our findings suggested that arthropod communities preferred natural levees.