• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.2
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• pp.176-187
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• 2020

The purpose of this study is to evaluate validity, reliability and reproducibility of tooth width (TW), arch length (AL) and arch length discrepancy (ALD) measured on a digital model taken via 3-dimensional model scanner and intraoral scanner compared to a plaster model. A total of 30 patients aged 12 to 18 were eligible for the study. 3 types of models were acquired from each patient: a conventional plaster model (P), a model scanned digital model (MSD) taken via Freedom UHD^® and an intraoral scanned digital model (ISD) taken via CS3600^® in-vivo. The reliability of TW and AL in each group was evaluated using Pearson's correlation coefficient, while the reproducibility was evaluated with intraclass correlation coefficient. The validity of space analysis was assessed by paired t-test. As a result, all measurements of P, MSD and ISD groups showed favorable reliability and reproducibility. Most of measurements for space analysis in MSD group and TW in ISD group also presented high validity. AL and ALD presented statistically significant difference between P and ISD group. The validity of measurements of space analysis in ISD group was short in doubt to valid, but clinically acceptable. Both MSD and ISD are clinically acceptable to use for space analysis but clinician should be aware that errors can be found using a digital model.

• Korean Journal of Cognitive Science
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• v.16 no.1
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• pp.1-15
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• 2005

Since human visual system has limited capacity for visual information processing, it should select goal-relevant information for further processing. There have been several studies that emphasized the possible involvement of memory in spatial shift of selective attention (Chun & Jiang, 1998, 1999; Klein, 1988; Klein & MacInnes, 1999). However, other studies suggested the inferiority of human visual memory in change detection(Rensink, O'Regan, & Clark, 1997; Simons & Levin, 1997) and in visual search(Hotowitz & Wolfe, 1998). The present study examined the involvement of memory in visual search; whether memory for the previously searched items guides selective attentional shift or not. We investigated how search works by comparing visual search performances in three different conditions; full exposure condition, partial exposure condition, and partial-to-full exposure condition. Revisiting searched items was allowed only in full exposure condition and not in either partial or partial-to-full exposure condition. The results showed that the efficiencies of attentional shift were nearly identical for all conditions. This finding implies that even in full exposure condition the participants scarcely re-examined the previously searched items. The results suggest that instant memory can be formed and used in visual search process. These results disagree with the earlier studies claiming thar visual search has no memory. We discussed the problems of the previous research paradigms and suggested some alternative accounts.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.341-349
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• 2017

Blood decontamination is an important factor in success of the orthodontic bracket. The purpose of this study is to evaluate the shear bond strength affected by blood decontamination. The shear bond strength was measured on blood decontamination before and after primer photopolymerization. And the adhesive remnants type and surface patterns was evaluated under scanning electron microscopy. A total of 50 human premolars were prepared. Group I was attached using conventional resin-acid etching method as control group. Group II and III were blood contaminated before curing primer and groups IV and V were blood contaminated after curing primer. Group II and IV were treated only with cotton pellet and Groups III and V were treated with cotton pellet after water washing. The mean shear bond strengths were in the order of groups I, V, III, II, and IV. In scanning electron micrographs group III and V showed more uniform surface than group II and IV. The ARI was significantly different between the control group and the experimental groups (p <0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.352-358
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• 2020

Glanzmann's thrombasthenia (GT) is a rare, autosomal recessive inherited congenital disorder, characterized by impaired blood coagulation due to platelet dysfunction. It was first reported by the pediatrician Glanzmann in 1918. GT affects both males and females, and it is more common in regions of the Middle East, India, and France, where intermarriage is common. It has an incidence of about 1 in 1,000,000 people. In South Korea, according to the Division of Rare Diseases, Korea Centers for Disease Control and Prevention, around 200 cases have been reported in 2018. Clinical symptoms include petechia, ecchymosis, epistaxis, and gingival bleeding. The spontaneous loss of deciduous teeth can result in excessive bleeding with that blood transfusion should be considered. Preventing hemorrhages and hemostasis are most important factors in dental treatment. Local bleeding can be controlled by compression, but platelet transfusion can be required by prolonged bleeding. Pediatric dentists can minimize the gingival bleeding by control of the oral hygiene to prevent gingivitis and dental caries. The importance of oral hygiene and periodic recall check-up should be emphasized. During dental treatment, the examination and the treatment plan of patient should be modified to prevention of hemorrhages carefully. A 6-year-old girl with GT was referred for the treatment of dental caries, and resin restoration was performed under nitrous oxide inhalation sedation. After treatment, compression was required for the bleeding control.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.320-326
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• 2020

The aim of this study was to compare compressive strength and microhardness of recently introduced alkasite restorative materials with glass ionomer cement and flowable composite resin. For each material, 20 samples were prepared respectively for compressive strength and Vickers microhardness test. The compressive strength was measured with universal testing machine at crosshead speed of 1 mm/min. And microhardness was measured using Vickers Micro hardness testing machine under 500 g load and 10 seconds dwelling time at 1 hour, 1 day, 7 days, 14 days, 21 days and 35 days. The compressive strength was highest in composite resin, followed by alkasite, and glass ionomer cement. In microhardness test, composite resin, which had no change throughout experimental periods, showed highest microhardness in 1 hour, 1 day, and 7 days measurement. The glass ionomer cement showed increase in microhardness for 7 days and no difference was found with composite resin after 14 days measurement. For alkasite, maximum microhardness was measured on 14 days, but showed gradual decrease.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.4
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• pp.397-405
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• 2020

The aim of this study is to compare cariogenic characteristics of fluoride-sensitive Streptococcus mutans [fluoride-sensitive (FS) S. mutans ] and fluoride-resistant Streptococcus mutans [fluoride-resistant (FR) S. mutans] in the presence of sucrose, and to evaluate its effect on cariogenic biofilm formation. S. mutans ATCC 25175 was continuously cultured in trypticase soy broth (TSB) containing NaF (70 ppm) for 40 days to generate FR S. mutans. FS and FR S. mutans were inoculated in TSB with or without 2% sucrose, and optical density and pH were measured every hour. An oral biofilm was formed using saliva bacteria and analyzed through confocal laser scanning microscopy and CFU count. Finally, the expression of glucosyltransferases genes of both S. mutans was investigated through RT-PCR. FR S. mutans exhibited slower growth and lower acidogenicity in the presence of sucrose compared to FS S. mutans . Both cariogenic and single species biofilm formation was lower in the presence of FR S. mutans, along with reduced number of bacteria. FR S. mutans showed significantly low levels of gtfB, gtfC, and gtfD expression compared to FS S. mutans . On the basis of results, FR S. mutans may be less virulent in the induction of dental caries.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.4
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• pp.283-291
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• 2014

Patients with extreme anxiety who are unable to cope with dental treatment under non-pharmacological behavioral management method may require sedation, or other forms pharmacological behavioral management method. The aim of this retrospective study was to investigate the effect of concomitant administration of 0.1 mg/kg intramuscular midazolam with or without sevoflurane insufflation sedation on sedation depth and cardiopulmonary function in pediatric patients. We analysed the records of anesthesia on patients who received dental treatment under deep sedation using sevoflurane insufflation from January 2013 to March 2014. Thirty-six children, aged 3 to 6 years, undergoing dental treatment were sedated using either sevoflurane insufflation alone (Group S, n = 18) or a combination of intramuscular injection of 0.1 mg/kg midazolam plus sevoflurane insufflation (Group SM, n = 18). Upon comparison, the average entropy value of group SM was lower than that of group S, but there were no statistically significant difference between the two groups (p > 0.05). The average heart rate and mean arterial pressure of group SM were higher than those of group S (p < 0.05). Concomitant intramuscular injection of 0.1 mg/kg midazolam with sevoflurane insufflation sedation is not sufficient to enhance the quality of sedation.

• 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.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.2
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• pp.119-125
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• 2015

Dental stress is suggested as a main reason for behavioral problems in dentistry, especially in children. Heart rate is a useful measure of dental stress. The purpose of the present study is to examine the effect of dental stress on children receiving restorative treatment under local anesthesia by using recently introduced a wrist-watch type heart rate monitoring device. Eighteen children with no previous dental experience, who needed dental treatment involving local anesthesia, were included in this study. In each session, heart rate was recorded. The largest increase was observed during local anesthesia and the highest values were recorded during preparation. However, no significant relationship was found between the measurements(p > 0.05). Regarding the number of visits, heart rate on the second session is significantly higher than the first session and the third session(p < 0.05). There was no significant different correlation between the first session and third session(p > 0.05). Based on the present study, children who have no previous dental treatment appeared to be more stressed at the second session and need at least 3 sessions to feel less stressed during dental treatment including dental injection.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.4
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• pp.418-425
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• 2018

This study was to measure and compare the amount of fluoride, microhardness and solubility of high viscosity glass ionomer and resin-reinforced glass ionomer during 84 days. Fuji IX GP EXTRA, Fuji IX GP, Fuji II LC and Filtek$^{TM}$ Z350XT stored in deionized water for 84 days to measure fluoride release, microhardness and solubility. As a result of measurement of fluoride release, all the glass ionomers showed the highest amount of fluoride release on day 1 and gradually decreased. Fuji IX GP EXTRA showed the highest amount of fluoride release and cumulative release. And Fuji IX GP and Fuji II LC showed no significant difference. Microhardness measurements showed that all experimental groups decreased 1 day after exposure to water. After 84 days, microhardness showed no significant difference between Fuji IX GP EXTRA and Fuji IX GP, and Fuji II LC was the lowest. In the solubility measurement, Fuji IX GP EXTRA, Fuji IX GP, and Fuji II LC increased rapidly to 21 days. After 21 days, there was no significant difference in the three groups. As a result, short term fluoride release affects solubility and microhardness, but long term fluoride release has no correlation. Through this study, the amount of fluoride, microhardness, and solubility of various glass ionomers were evaluated, and these properties could be applied clinically.