• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.33-45
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• 2004

The purpose of this experimental study was to determine appropriate magnitude of the Gable bends to produce maximum retraction of the anterior teeth. The Calorific Machine was used to illustrate the tooth movement in three dimension. The experimental teeth except the first premolar were embedded in the artificial alveolar bone part. In a series of experiments, the extraction space was closed using arch wires with bull loops into which the gable bends of $10^{\circ},\;20^{\circ},\;30^{\circ}$ degrees were incorporated. The experiments were repeated three times for each degree of the gable bend. Before and after the space closure, radiographs were taken in the sagittal and occlusal directions using occlusal films. Analysis of variance and Scheffe post hoc test were used to determine significant differences among the three groups. The following results were obtained. 1. As magnitudes of the gable bends increased, more bodily anterior tooth movement was seen and the distance of retraction also increased. 2. As magnitudes of the gable bends increase, the amount of posterior tooth protraction decreased while intrusive and buccal movement increased. 3. The arch was coordinated by distal-in rotation of the canine and mesial-in rotation of the second premolar adjacent to the extraction space.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.273-285
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• 2000

The aim of this investigation was to evaluate the differences of two canti-leyer springs by using a new simulation system. This was done using a Calorific machine that compared iron uprighting spring and root uprighting spring. The Calorific machine was designed to allow observation of the whole process of tooth moving, and is composed of three parts(a temperature regulating system, electro-thermodynamic teeth, and an artificial alveolar bone component). The experiment of both mechanics were repeated five times and measured two times. The intra-examiner agreement and inlet-examiner agreement were $96.54\%\;and\;95.73\%$ and these data were statistically tested by paired t-test. The obtained results were as follows. 1. Distal and buccal movement of the anchor teeth were observed greater in the root uprighting spring than the crown uprighting spring. 2. Crown uprighting spring showed distal movement of the crown of lower second molar for 3.29mm but root uprighting spring showed only 1.68mm. 3. Crown uprighting spring exhibited forward movement of mesial and distal root of the lower second molar for 3.91mm, 3.60mm but the root uprighting spring showed 6.76mm, 6.26mm.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.183-191
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• 2007

Through out the world dental caries seems to be decreased as it is difficult to make an accurate diagnosis for dental caries. The traditional diagnostic method which is probing and x-ray taking has many limitations to diagnose the early caries, so there were recommendations for the needs of new equipments such as laser fluorescence(LF), digital imaging fiber-optic trans-illumination(DIFOTI), and quantitative light fluorescence (QLF) which were developed from various study results. Also confocal laser scanning microscopy(CLSM) and ultrasonics are used for research progression. This study is to evaluate whether it is possible to monitor accurately for remineralization amount of enamel surface early caries using DIFOTI or LF After inducing artificial caries to bovine teeth to 10 participants remineralization was enhanced by 0 ppm and 500 ppm fluoride mouth rinse solution for 3 weeks. Then they were cross sectioned and analyzed using gold standard of the lesion depth measured by CLSM. The following results were obtained: 1. The measured percentage of light intensity(luminosity ratio) by DIFOTI increased with remineralization period, and showed significant reverse correlation with lesion depth measured by CLSM (p<0.01). 2. The measurement of laser fluorescence increased with remineralization period, and showed significant correlation with lesion depth measured by CLSM (p<0.01). 3. To the result for CLSM, 500 ppm fluoride mouth rinse group showed rapid rate for decreased tendency of lesion depth than 0 ppm fluoride mouth rinse group. In conclusion DIFOTI system was used to measure accurately for the remineralization amount of early surface caries, it is a very useful equipment to detect precisely the changes for early enamel caries remineralization during treatments.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.4
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• pp.247-252
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• 2013

Pit and fissure sealant prevents biofilm accumulation, plays a role in forming a barrier to acidic substance made by the bacteria. The Surface reaction-type pre-reacted glass ionomerI(S-PRG) filler was developed in 1999. S-PRG filler releases fluoride continuously and does not decompose under wet conditions. The aim of this study was to test the microleakage and anticariogenic effect to adjacent enamel of S-PRG filler-containing pit and fissure sealant. Sound premolars and molars were used in this study. A S-PRG filler-containing pit and fissure sealant, Beautisealant$^{(R)}$(Shofu, Japan) was used for this experiment, the composite resin sealant Concise$^{(R)}$(3M ESPE, USA) was used as control. For the microleakage test, all teeth surface were double coated with finger nail varnish, with the exception of a 1.0 mm window around the restoration margins. The teeth were immersed in 2% methylene blue solution for 24 hours and then rinsed in tap water. For the anticariogenic effect evaluation, all tooth were immersed in artificial carious solution for 9 days and rinsed with tap water. Each tooth was embedded in orthodontic acrylic rein and subsequently sectioned longitudinally in a bucco-lingual direction with a low-speed diamond saw. The cut sections were examined using a stereomicroscope. Differences in microleakage between the two groups were not different significantly. But the S-PRG filler-containing pit and fissure sealant showed higher anticariogenic effect than that of flowable resin sealant.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.257-267
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• 2020

The goal of suction denture is to enhance retention of dentures by the formation of negative pressure between the denture base and the underlying tissue and sealing around the denture by the mucosa. This patient has been converted to a completely edentulous state after the extraction of residual teeth. Fabrication of suction denture was planned because it was estimated that the conventional compete would be hard to achieve retention due to the absorption of residual ridge and lack of sublingual fold. Through appropriate clinical and laboratory technique such as preliminary impression on the mandibular rest position, provisional vertical dimension determination with Centric Tray^® (Ivoclar Vivadent AG, Schaan, Liechtenstein), closed mouth definitive impression and jaw relation record using individual tray with Gnathometer M^® (Ivoclar Vivadent AG, Schaan, Liechtenstein), artificial teeth arrangement considering stability of the denture, and proper polymerization technique that minimizes polymerization shrinkage, restoring the patient with suction denture resulted in satisfaction throughout the function and asesthetics.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.700-708
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• 2001

Traumatic injuries in young patients can result in the interruption of the development of the incompletely formed roots. In teeth with incomplete root-end formation and necrotic pulps, the root canals must be completely debrided. Because of a lack of an apical stop and the presence of thin and fragile walls in these teeth, it is imperative to perform apexification to obtain an adequate apical seal. Calcium hydroxide has become the material of choice for apexification. Despite its popularity for the apexification procedure, calcium hydroxide therapy has some inherent disadvantages that include variablility of treatment time, unpredictability of apical closure, difficulty in patient follow-up, and delayed treatment. An alternative treatment to long-term apexification procedure is the use of an artificial apical barrier that allows immediate obturation of the canal. MTA(Mineral Trioxide Aggregate) is a powder consisting of fine hydrophilic particles of tricalcium silicate, tricalcium aluminate, tricalcium oxide and silicate oxide. MTA has a pH of 12.5 after setting, similar to calcium hydroxide. This may impart some antimicrobial properties. MTA has low solubility and a radiopacity slightly eater than that of dentin. Also, MTA leaked significantly less than other materials and induced hard-tissue formation more than other materials.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.1
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• pp.18-25
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• 2023

We present the case of a 65-year-old man with maxillary and mandibular complete dentures prepared using neutral zone technique after undergoing mandibulotomy due to tonsil cancer 10 years ago. The patient had a short edentulous period; hence, there was minimal absorption of the alveolar ridge and no abnormality in the motor function of the tongue. However, the retromolar pad was located inside the hamular notch, and the posterior alveolar ridge was relatively turned inward. If the artificial teeth would have been aligned conventionally, the functional space of the tongue would have been invaded, which would have moved the tongue posteriorly thereby reducing the stability of the denture. Therefore, applying the concept of the neutral zone can be a good reference point in such cases. The neutral zone was registered using tissue conditioner, and tooth alignment was performed by making a silicone putty index. The biggest advantage of using neutral zone concept is denture stability. In this case, the neutral zone technique was applied to obtain the lingual alignment limit of the posterior teeth to avoid invasion of the tongue space by the left posterior part of the mandible. Particularly, in case of a patient in which denture stability is difficult to obtain due to absorption of the alveolar ridge, it is believed that better results can be obtained using neutral zone technique.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.2
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• pp.146-154
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• 2011

An in vitro study on cariogenic potential of 8 over-the-counter syrups for children was performed. The experimental groups were 8 over-the-counter syrups. The positive control group was 10% sucrose solution, and the negative control group was artificial saliva. The pH of each group was determined. The buffering capacity was measured by the volume of 2 N NaOH adding to equalize the pH of 20 ml of experimental solution to pH 7. The consistency was measured by the time to pass Ostwald pipette for 2 ml of the experimental solution. The experimental solutions were inoculated with S. mutans and cultured in $37^{\circ}C$ anaerobic condition for 48 hours. To estimate acid production, pH of the experimental solutions were measured before and after the culture. The primary teeth specimens were soaked in the experimental solutions for 20 minutes three times a day. Except on those hours the specimens were stored in artificial saliva. After 5 days, the microhardness changes of the specimens were measured. These results show that most of syrup-form medicines for children tend to have cariogenic potential partially in endogenous pH, buffering capacity, consistency, acid production and erosive ability of enamel. For the oral health of children, the alternative sweeteners (ex. xylitol) may be substituted for the cariogenic sweeteners of syrups. Additionally, It may be helpful that the chewable tablet replace liquid or syrup in term of dose form.

• Journal of Life Science
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• v.23 no.10
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• pp.1288-1294
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• 2013

Knowledge of morphological changes in eel larvae is very important for artificial rearing of eel larvae. In this study, we investigated the morphological structure of the head region and histological changes of the eye retina in artificially reared larvae at various stages and in glass eel just after metamorphosis. Structural changes were observed in the upper jaw (maxilla) and the lower jaw (mandible) after 100 dah (day after hatchery) and after metamorphosis. Teeth had degenerated by the time of completion of metamorphosis. Major histological changes observed in the eye retina were the formation of the outer plexiform layer and the outer nuclear layer from 100 dah larva and a change in the rod cell layer after metamorphosis. The cornea was not observed at 10 dah in the eel larva. More information is needed on the early developmental stages of eel larvae to enable mass production of glass eels. The results obtained in the present research will be useful when developing novel rearing programs for eel larvae.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.3
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• pp.186-194
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• 2015

Purpose: To evaluate the effects of implant location and length on stress distribution and displacement in osseointegrated-implants that were associated with mandibular distal extension removable partial dentures (DERPD). Materials and Methods: A sagittally cut model with the #33, #34 teeth and a removable partial denture of the left mandible was used. Seven models were designed with NX 9.0. Models A, B, C had implants with lengths of 11, 6, 4 mm, respectively, under the denture base of the #37 artificial tooth. Models D, E, F had implants with lengths of 11, 6, 4 mm, respectively, under the denture base of the #36 artificial tooth. Model G did not have any implants. Axial force (250 N) was loaded on #36 central fossa. The finite element analysis was performed with MSC Nastran. Von Mises stress maps were plotted to visualize the results. Results: The models of #37 implant placement showed much lower stress concentration on the surrounding bone of the implant compared with #36. The #36 implant position tended to reduce displacement more than #37. Conclusion: When an IARPD is designed, the distal positioning of implant placement has more advantages in the edentulous bone of DERPD on the prognosis of short implants and the stress distribution of edentulous alveolar bone. Using implants with longer lengths are important for stress distribution. However, Additional studies are necessary of the effects of length on implant survival.