• Restorative Dentistry and Endodontics
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• v.28 no.2
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• pp.127-133
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• 2003

The object of this study was to compare the microleakage between various composite resin systems of multistep, one-bottle, and self-etching systems using electrical conductivity. After making class V cavities ($4{\times}3{\times}1.5{\;}mm$ around CEJ), they were bulk filled with three kinds of resins of A3. Teeth were storaged in a saline solution for one day, after then, they were finished and polished using Sof-Lex system. Another stress of thermocycling was made for 500 times from $5^{\circ}{\;}to{\;}55^{\circ}C$ with each dwelling time of 10 seconds. Electrical conductivity (microamphere, $\mu\textrm{A}$) was checked four times: before and after cavity preparation, after filing, after thermocycling. One-way ANOVA and 95% Scheffe Post Hoc test was used for checking any statistical difference among groups. Another 95% Paired Samples T-test was also used for estimating any significant difference within group after cavity filling or thermocycling. The results were as follows: 1 Every specimen showed various range of microleakage after filing. There was, however, no difference between composite resin systems. 2. All composite resin systems showed marked increase in microleakage with a thermocycling (p<0.05), there was, however, no difference between composite resin systems. 3. Although there was no significant difference between groups (p=0.078), one-bottle and self-etching systems seemed to be unstable than multistep system. Within the limits of this study, it was concluded that much more consideration should be needed when using thermally unstable one-bottle and self-etching systems that have multi-advantages from simplified step. More studies will be needed to solve these kinds of problems.

• Journal of Korean Dental Science
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• v.7 no.2
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• pp.87-93
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• 2014

Purpose: The objective of this study was to evaluate the caries prevention effect of school-based fluoride mouth rinsing (FMR) program implemented in the Hanuul district of Mongolia, which has a very low socioeconomic status and extremely poor infrastructure for oral health. Materials and Methods: One hundred and seventy children aged from 6 to 8 years of the FMR school and 187 children aged from 6 to 8 years of the control school completed the baseline survey. Children from the FMR school rinsed with 0.05% sodium fluoride everyday under supervision, while those from the control school did not. Adjusted caries preventive fraction (CPF) for 2 years were calculated to evaluate the effect of the FMR program. Result: After 2 years, 288 schoolchildren remained in the study. Decayed, missing or filled permanent teeth (DMFT) and index of the FMR and the control schools at baseline were 0.11 and 0.12, respectively, and the average DMFT increment of the FMR and the control schools after 2 years were 0.35 and 0.65, respectively. The adjusted CPF of DMFT was 48.5%. Conclusion: These findings show that a school-based FMR is an effective caries preventive program in a socially deprived community with poor infrastructure for oral health.

• The Journal of Korean Academy of Prosthodontics
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• v.24 no.1
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• pp.125-138
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• 1986

It is considered that etching solution or material itself of phosphoric ester cement will induce not a little pulpal irritation, if applied directly onto unsealed dentinal tubules. This study was designed to confirm above consideration by comparing two different conditions between $Ca(OH)_2$-based and non-$Ca(OH)_2$-based group. Posterior teeth of 15 male dogs were selected for this experiment. One experimental group was filled with cement after $Ca(OH)_2$-basing and enamel-etching, the other experimental group after enamel etching without $Ca(OH)_2$-basing. And both of two experimental groups were observed at 2 hours, 15 hours, 3 days, 1 week, 2 weeks, 4 weeks, and 6 weeks after filling. The findings reached to the following conclusions histologically. 1. In both groups, the damaged odontoblasts were atrophied and eventually disappeared. 2. In non-based group at early stage, odontoblasts were severely atrophied and defective areas were appeared between odontoblast cell layers. However, in based group, the odontoblasts were arranged slight irregularly. 3. In non-based group, a small number of undifferentiated cells below the odontoblast cell layers started to appear at 1 week after filling. However, in based group, the undifferentiated cells were appeared at 15 hours after filling. 4. In non-based group, formation of reparative dentin was not begun until late stage of experiment. However, in based group, formation of reparative dentin matrix was begun at 2 weeks after filling and very thickened reparative dentin was formed at 6 weeks after filling. 5. In odontoblast cell layers of both groups, dilated capillaries were observed. 6. Argyrophilic fibers were reticularly condensed in zone of Weil, and they were connected to the pulp tissue and dentin.

• The korean journal of orthodontics
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• v.43 no.1
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• pp.35-41
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• 2013

Objective: To assess the prevalence of malocclusion and its relationship with dental caries among school children in southern India. Methods: This cross-sectional study included 1,800 students aged 11 - 15 years whose Dental Aesthetic Index (DAI) and dentition status were recorded and analyzed. The chi-square test, ANOVA, and Spearman's correlation tests were carried out. Results: The mean DAI score ${\pm}$ the standard deviation was $18.61{\pm}6.1$. Approximately 85% of the students (83.0% males, 86.8% females) had DAI scores of < 26 and were classified as not requiring orthodontic treatment. One tenth of the sample had mean DAI scores between 26 - 30 (indicating definite malocclusion and elective treatment), while about 3% had mean scores between 31 - 35 (indicating severe malocclusion and treatment desirability). Only 29 children (1.6%; 16 boys, 13 girls) had a DAI score of > 35, which suggested very severe or handicapping malocclusion requiring mandatory treatment. The mean decayed, missing, filled teeth (DMFT) was $2.28{\pm}1.47$. A DMFT of > 0 was observed in 91.8% of the study subjects. Children with a DAI score of > 35 were found to have significantly (p < 0.001) higher caries experience as compared to other children. Moreover, the DAI scores showed a significant correlation with the mean DMFT scores (r = 0.368, p < 0.05). Conclusions: A positive correlation was found between the severity of malocclusion and dental caries.

• Journal of dental hygiene science
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• v.14 no.3
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• pp.364-370
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• 2014

The purpose of this study was to examine association between oral health status and perceived general health symptom. We analyzed 14,231 subjects who participated in Korea National Health and Nutrition Examination Survey (2007~2009). All individuals were examined by a questionnaire about socioeconomic history, smoking and drinking habit, the frequency of daily tooth brushing, the presence of regular dental visit, and EuroQol-5D. Dental survey was conducted to find the decayed, missing, and filled teeth (DMFT) index and community periodontal index. Subjects with perceived problem with mobility had higher DMFT index (odds ratio, 1.18, p<0.001). Subjects with with perceived problem with pain/discomfort had higher DMFT index (odds ratio, 1.16, p<0.001). Self-rating general health symptom was not associated with periodontitis (p>0.05). Perceived general health was associated with DMFT index. It is recommendable that we can use the perceived general health to predict oral health status.

• Journal of Korean Dental Science
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• v.5 no.1
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• pp.21-28
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• 2012

Purpose: In this study the bone healing ability of autogenous tooth bone graft material as a substitute material was evaluated in a mini-pig cranial defect model through histologic examinations and osteonectin reverse transcription polymerase chain reaction (RT-PCR) quantitative analysis. Materials and Methods: A defect was generated in the cranium of mini-pigs and those without a defect were used as controls. In the experimental group, teeth extracted from the mini-pig were manufactured into autogenous tooth bone graft material and grafted to the defect. The mini-pigs were sacrificed at 4, 8, and 12 weeks to histologically evaluate bone healing ability and observe the osteonectin gene expression pattern with RT-PCR. Result: At 4 weeks, the inside of the bur hole showed fibrosis and there was no sign of bone formation in the control group. On the other hand, bone formation surrounding the tooth powder granule was observed at 4 weeks in the experimental group where the bur hole was filled with tooth powder. Osteonectin gene expression; there was nearly no osteonectin expression in the control group while active osteonectin expression was observed from 4 to 12 weeks in the experimental group. Conclusion: We believe this material will show better results when applied in a clinical setting.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.49-57
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• 2017

The purpose of this study was to investigate factors affecting perceived oral health status according to socioeconomic status and community periodontal index(CPI) and decayed, missing, and filled teeth(DMFT) using the 6th Korean national health and nutritional examination survey(KNHANES VI) and provide a basic data for plan of policy. The higher the age, the lower the household income and education level, the worse the subjective oral health had better oral health and there was a tendency that the respondents who had no oral exam within 1 year and experienced CPI or DMFT estimated their own health as worse. It is needed to make policy development to resolve the inequality of oral health.

• Restorative Dentistry and Endodontics
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• v.39 no.1
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• pp.24-31
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• 2014

Objectives: The purpose of present study was to evaluate the internal adaptation of composite restorations using different adhesive systems. Materials and Methods: Typical class I cavities were prepared in 32 human third molars. The teeth were divided into the following four groups: 3-step etch-and-rinse, 2-step etch-and-rinse, 2-step self-etch and 1-step self-etch system were used. After the dentin adhesives were applied, composite resins were filled and light-cured in two layers. Then, silver nitrate solution was infiltrated, and all of the samples were scanned by micro-CT before and after thermo-mechanical load cycling. For each image, the length to which silver nitrate infiltrated, as a percentage of the whole pulpal floor length, was calculated (%SP). To evaluate the internal adaptation using conventional method, the samples were cut into 3 pieces by two sectioning at an interval of 1 mm in the middle of the cavity and they were dyed with Rhodamine-B. The cross sections of the specimens were examined by stereomicroscope. The lengths of the parts where actual leakage was shown were measured and calculated as a percentage of real leakage (%RP). The values for %SP and %RP were compared. Results: After thermo-mechanical loading, all specimens showed significantly increased %SP compared to before thermo-mechanical loading and 1-step self-etch system had the highest %SP (p < 0.05). There was a tendency for %SP and %RP to show similar microleakage percentage depending on its sectioning. Conclusions: After thermo-mechanical load cycling, there were differences in internal adaptation among the groups using different adhesive systems.

• Restorative Dentistry and Endodontics
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• v.43 no.2
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• pp.23.1-23.9
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• 2018

Objectives: This study evaluated the effect of ultrasonic agitation of mineral trioxide aggregate (MTA), calcium silicate-based cement (CSC), and Sealer 26 (S26) on adaptation at the cement/dentin interface and push-out bond strength. Materials and Methods: Sixty maxillary canines were divided into 6 groups (n = 10): MTA, S26, and CSC, with or without ultrasonic activation (US). After obturation, the apical portions of the teeth were sectioned, and retrograde cavities were prepared and filled with cement by hand condensation. In the US groups, the cement was activated for 60 seconds: 30 seconds in the mesio-distal direction and 30 seconds in the buccal-lingual direction, using a mini Irrisonic insert coupled with the ultrasound transducer. After the materials set, 1.5-mm thick sections were obtained from the apexes. The presence of gaps and the bond between cement and dentin were analyzed using low-vacuum scanning electron microscopy. Push-out bond strength was measured using a universal testing machine. Results: Ultrasonic agitation increased the interfacial adaptation of the cements. The S26 US group showed a higher adaptation value than MTA (p < 0.05). US improved the push-out bond strength for all the cements (p < 0.05). Conclusions: The US of retrograde filling cements enhanced the bond to the dentin wall of the root-end filling materials tested.

• Restorative Dentistry and Endodontics
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• v.6 no.1
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• pp.7-16
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• 1980

The author observed the periodontal tissue reactions to the root canal sealers after root perforations were made intentionally in dogs. The perforations were made on 74 teeth from 7 dogs. The experiments were performed in two different modes of procedure: In Group I, the perforations were made through the root canal to the alveolar bone. In Group II, the perforations were made from site of alveolar bone to the root canals. The perforated canals in Group I were filled with gutta-percha and root canal cements; Calxyl (Calcium Hydroxide in Ringer's solution), Zinc Oxide -Eugenol cement (Z.O.E.), Kerr sealer (Rickert's paste) and AH 26 (Epoxy Resin preparations). The perforated canals in Group II were sealed with Calxyl, Z.O.E, Kerr sealer and AH26. Histologic examinations of periodontal tissue reactions were observed at various time intervals. The results were as follows; l. Cementum deposition on the perforated root surface in Group II cases showed slightly earlier than that of Group I. Healing tendency of injured alveolar bone in Group II was greater than that of Group I. 2. According to the time increase after experiment, the cementum deposition on the site of perforated dentin in Group II with intact pulp was notably thickened. Secondary dentin deposition on the root canal surface where the dentinal tubles were cut was also found in similar pattern. 3. In the cases of perforated canals sealed with Calxyl both in Group I and Group II, It revealed the earliest cementum-deposition among 4 different root canal cements. In the cases of perforated canals sealed with Kerr sealer and AH26, the cementum-deposition on the root surface was not found. 4. Proliferation of epithelium around the perforated area was first seen at 5-week cases in Group I, and at 3-week cases in Group II. 5. In all cases, dentin resorption on the site of perforated root surface was always occured.