• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.32-39
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• 2000

The purpose of this study was to assess the cariogenic potential of five infant formulas in vitro. as compared with 10% sucrose solution and whole bovine milk. Buffering capacities were determined by the amount of 0.1 N lactic acid consumed to titrate the 50ml specimen solutions to pH 4.0. The pH of the specimen solution inoculated by Streptococcus mutans was measured by pH meter and the surface microhardness of primary tooth enamel immersed in the specimen solution was measured by the microhardness tester, before and after 48 hours incubation. Also, the solubility of calcium from synthetic hydroxyapatite was evaluated by atomic absorption spectrophotometer The buffering capacity of infant formulas was higher than that of sucrose solution and lower than that of milk, and there were significant differences among infant formulas(P<0.01). The average pH of infant formulas after 48 hours incubation was lower than that of sucrose solution and milk, and there was significant difference between infant formulas and milk(P<0.05). There were no signifiant differences among oops in the microhardness change of primary tooth enamel and in the amount of dissolved calcium ion from synthetic hydroxyapatite after incubation with Streptococcus mutans. In conclusion, infant formulas seemed to fulfill the basic requirments to cause dental caries in primary teeth, and there were significant differences of cariogenic potential among infant formulas. Cooperative efforts of dentistry and manufacturers to reduce the cariogenic potential of infant formulas would be necessary to prevent the early childhood caries in children.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.662-670
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• 2008

The purpose of this in vitro study was to evaluate the effect of fluoride containing adhesive film on prevention of enamel demineralization. Eighty bovine enamel blocks were divided randomly into 4 groups of 25: (1) APF gel applied ; (2) CavityShield$^{TM}$ applied; (3) 3% fluoride film applied; (4) 5% fluoride film applied; Early caries lesions were produced by placing each specimen into demineralization solution at pH 4.0 for 72 hours. Then lesion of the surface microhardness were measured by the Vicke's hardness test and the lesions depth were measured by polarizing light microscope. The results of the present study are as follows: 1. Difference of microhardness value ($M{\pm}SD$) between control and experimental side was the highest in group II, followed by group IV, III, I but, no significant difference was between group II, III and IV. 2. Difference of mean lesion depth ($M{\pm}SD$) between control and experimental side was the highest in group II, followed by group III, IV and I but no significant difference was between group III and IV. The results of the present study indicate that the fluoride film application is more effective than APF gel and is similar to fluoride varnish application for prevention of dental caries.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.613-622
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• 2007

The purpose of this study was to evaluate the effect of fluoride varnish on prevention of enamel demineralization. Eighty bovine enamel blocks were divided randomly into 4 groups of 20 specimens: Group I served as the control with no topical application of fluoride. Group II was treated with APF gel for 4 minutes. Group III was treated with Fluor $Protector^{(R)}$. Group IVV was treated with $CavityShield^{TM}$. After 24 hours of treatment, samples were brushed with a soft bristled tooth brush to stimulate normal mechanical wear of varnish. Early caries lesions were produced by placing each specimen into demineralization solution at pH 4.0 for 48 hours. Then the optical density of the lesions was measured by light fluorescence induced by plasma light and the surface microhardness were measured by the vicker's hardness test. The results were as follows: 1. The optical densities of group III, IV were significantly higher than that of group II, but no significant difference was noted between group III and IV. 2. The surface microhardness of group IV was the highest, followed by group III, II, and I(p<0.05). 3. There were no significant differences between group III and IV in optical density. However, the surface microhardness of group IV was significantly higher than that of group III. The results of present study indicate that the fluoride varnish is more effective than APF gel for prevention of dental caries.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.3
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• pp.215-222
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• 2014

Purpose: The aim of this study was to investigate differences between the morphology of the mandibular symphysis and four facial skeletal types. Materials and Methods: 40 cone-beam computed tomographies were selected and classified in to 4 groups according to their vertical and anterior-posterior skeletal patterns. The bone volume ($mm^3$) of the symphysis, the cross sectional area corresponding to the 4 mandibular incisors' axis: the cross sectional area of total bone ($mm^2$), the area of the cancellous bone ($mm^2$) and the thickness (mm) of labial and lingual alveolar bone at 2 mm, 3 mm under the cemento-enamel junction (CEJ) were measured. General linear model (GLM), Kruskal-Wallis test and Tukey honestly significant difference (HSD) test were subsequently used for statistical analysis. Results: The lingual cortical bone thickness of the lateral incisors at 2, 3 mm under CEJ was greater in the Class I low angle group than the other 3 groups (P < 0.05). There were no statistically significant differences in the volume of the mandibular incisor bony support, cross-sectional area of total bone and cancellous bone at the mandibular incisor' axis. Conclusion: Patients in Class I, low angle group have a thicker lingual mandibular symphysis than Class I, high angle patients.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.83-91
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• 2008

Dental caries which is one of the most common chronic disease complexly developed by the action of oral bacteria, diet, and host factor. Various prevention program enhance resistance of demineralization and reduce the acidogenecity of oral bacteria have been introduced, representative material is fluoride and chlorhexidine. The purpose of the study was to evaluate and compare effectiveness of fluoride varnish and chlorhexidine varnish in vivo. Bovine tooth specimens were implanted in the lower space maintainers and applied with fluoride varnish and chlorhexidine varnish. After seven days in oral environment, metal mesh was covered to make similar condition of plaque accumulation and induce caries. All specimens were analysed by EPMA to evaluate quantitative change of Ca, P and by polarized microscope to identify histological changes. The results were as follows : After initial artificial caries induction in the mouth, there were remarkable enamel caries lesion in the control group under polarized light microscopy. The highest amount of mineral decrease were showed in control group. No statistically significant mineral decrease were showed in fluoride varnish group, while chlorhexidine varnish group showed only significant decrease of P(P<0.05). In conclusion both fluoride varnish and chlorhexidine varnish seemed to be effective for protecting enamel surface from caries activity, although fluoride varnish has more anticariogenic effect than chlorhexidine varnish.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.159-166
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• 2008

The dental caries can be recovered or worse depending on the velocity of de- and remineralization of tooth. It is possible to remineralize the lesions by fluoride agent, but the results can be distinguished according to one's salivary flow rate, quantity of ion contents, and pH of the saliva. This article presents good results after applying the CPP-ACP paste for the patients who have incipient enamel caries. We instructed the patients to apply the paste everyday in the customed tray. We observed the white spot lesions without getting worse and reducing the size of lesions. After applying the CPP-ACP paste for 6 weeks, we concluded that; 1. It was possible to remineralize the incipient caries without preparation of the teeth. 2. CPP-ACP paste was successful for recovery of the demineralized lesions, especially for mild and moderate caries lesions, not for the severe developemental defects or chronic lesions. 3. CPP-ACP paste was efficient for pediatric patients, and the custumed tray was very useful for patients to apply the paste. 4. The ability of the patients for caring their oral hygiene was improved by routine check up and instructions.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.562-570
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• 2008

Amelogenesis imperfecta is a group of hereditary defects of enamel, unassociated with any other generalized defects. It is classified into 14 subtypes according to different clinical and genetic features. According to its clinical features, it is classified into hypoplastic type, hypocalcified type and hypomaturation type. However, these features tend to co-exist often. Dental features associated with amelogenesis imperfecta include quantitative and qualitative enamel deficiencies, pulpal calcification, root malformations, abnormal eruption, impaction of permanent teeth, progressive resorption of root and crown, congenital missing teeth and anterior and posterior open bite occlusions. The first case patient is a 16 month-old child with discoloration of deciduous teeth. All of her deciduous and permanent dentition has shown amelogenesis imperfecta. The restorational, orthodontic and recent prosthodontic treatments have been completed. Another patient is a 9 year and 3 month-old child with amelogenesis imperfecta in both deciduous and permanent dentition. The restoration has been done and the prosthodontic treatment is planned after the completion of growth. Above cases indicate that amelogenesis imperfecta occurs both in deciduous and permanent dentition, and it requires the long term treatment and care.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.53-61
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• 2007

In case of missing tooth caused by dental caries or periodontal disease, it can be restored by various methods, and there has been much interest in implant and tooth transplantation. The success of tooth transplantation is going to be attained through the knowledge of growth, development and calcification of tooth. Tooth transplantation has been experimented in vivo and in vitro. Many animals such as rats, mice, cats and dogs are used for tooth transplantation experiment in vivo. In most experiments, tooth was transplanted into the extraoral site, but rare into the intraoral site In this study, to observe the capacity of formation and mineralization of tooth germ, first molar of a matured white rat was extracted and the cap stage tooth germ of a 13.5 Embryonic day embryo rat was transplanted into the extracted socket. The rats were killed 6 months later and the radiographical and histological results are as followings. 1. Tooth germ transplanted for 2 and 6 months are developing calcified tooth material such as dentin, cementum, pulp tissue, and epithelium around enamel space in the maxilla was seen. 2. The epithelium around enamel space was located beneath the oral epithelium and contained connective tissue and periodontal ligament. 3. Tooth formation was progressed as transplantation period but the size of newly formed tooth was small and the shape of tooth was incomplete.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.477-483
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• 2009

The purpose of this study was to compare the microleakage of low and high viscosity flowable resins in class V cavities applied with 1-step adhesives. Forty Class V cavities were prepared on the cervices of buccal and lingual surfaces of extracted molar teeth and divided into four groups (n=8). Cavities were restored with AQ Bond Plus /Metafil Flo $\alpha$, G-Bond/ UniFil LoFlo Plus (Low flow groups), AQ Bond Plus/Metafil Flo and G-Bond/UniFil Flow (High flow group), respectively. Specimens were immersed in a 2% methylene blue solution for 24 hours, and bisected longitudinally. They were observed microleakages at the enamel and dentinal margins. In conclusion, the low viscosity flowable resins showed lower marginal microleakage than do the high vis cosity flowable resins in class V cavities.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.4
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• pp.252-259
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• 2017

Purpose: The purpose of this study was to compare and analyze the wear of a prosthesis for 6 months after restoration with implant-supported fixed dental prosthesis made of either zirconia or gold. Materials and Methods: This study was conducted on patients requiring implant-supported fixed dental prostheses on first or second molar from January, 2015 to January, 2016. A total of 47 prostheses and antagonists were examined. Occlusal surface was recorded by impression of each prosthesis and antagonist 1 week and 6 months after prosthesis delivery. The digital files were created by impression scan. Occlusal shapes of 1 week and 6 months were compared and wear of prostheses and antagonists was analyzed. The Mann-Whitney test was used to analyzed the result data underwent normality test using SPSS (Version 23.0, IBM Corporation) Results: Mann-Whitney test revealed that there was no statistically significant difference in the median amount of mean vertical wear for 6 months in zirconia ($50.84{\mu}m$) and gold ($42.84{\mu}m$) prostheses (P > 0.05). When the opposing teeth were natural, the median amount of mean vertical wear of zirconia and gold prostheses was $47.72{\mu}m$ and $41.97{\mu}m$, respectively, and the median amount of mean vertical wear of enamel was $47.26{\mu}m$ and $44.59{\mu}m$, respectively. Statistical analysis showed no significant difference (P > 0.05). Conclusion: Despite the short study period and the small number of experimental groups, zirconia and gold showed no significant difference in wear during the first 6 months. Opposing natural enamel also showed no significant difference in the wear.