• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.292-299
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• 2000

The purpose of this study was to investigate parental knowledge and attitude and practices relating to infant oral health care and to promote their motivations to their children's oral health care. Authors interviewed 350 persons in Ilwon-Dong and whose children were between 0 to 36 months old and acquired questionnaire from them. The questionnaire constituted of questions about general knowledge of tooth eruption, methods of oral hygiene care, and opinions about preventive dental visit. The collected data were analysed and compared with other researches. The important results obtained from this study were : 1. Females and highly educated persons had more dental knowledge than males and poorly educated persons. But age and economic status did not affect their level of dental knowledge. 2. Fifty nine percents of respondents thought that tooth began to be formed before birth. 3. Seventy six percents of respondents thought that infant oral health care should begin before tooth eruption, but actually only 63% started oral hygiene care before age one. 4. Seventy percents of respondents used gauze for infant oral care. 5. Fifty seven percents of respondents still gave bottles to their children after they reached age one or more and 55% of respondents never heard of nursing caries. 6. Ninety percents of respondents agreed that carious deciduous teeth need restorations, and 31% of respondents thought that age two is the appropriate time for the first dental visit. 7. Forty seven percents of parents did not think that dental caries is an infectious disease. 8. Only Thirty three percents of parents visited dental clinics for examination and prevention during pregnancy and only 11% of expecting parents were offered dental health care education in pediatric or obstetrician clincs. 9. Information about oral health care was mostly given from baby megazines. 10. Overall parental knowledge about infant oral health care was not sufficient to maintain appropriate dental care for infants.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.351-360
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• 2000

The purpose of this study was to evaluate the microleakage of class V compomers according to acid etching treatment and treatment times. Extracted 180 sound human molar teeth were selected then prepared physiologic pulpal pressure far this experiment. In this study class V cavities were prepared on buccal surface with gingival margin located in 1mm superior to CEJ under simulate physiological conditions. These specimens were randomly divided into 6 groups of 30 each and restored following methods : A: Dyract AP + Prime&Bond 2.1 Group 1 : No acid etching, according to manufacturer's instruction. Group 2 : 15 seconds acid etching and same method with Group 1. Group 3 : 30 seconds acid etching and same method with Group 1. B: F2000 groups + Single Bond adhesive Group 1 : No acid etching, according to manufacturer's instruction. Group 2 : 15 seconds acid etching and same method with Group 1 Group 3 : 30 seconds acid etching and same method with Group 1. After 500 thermocycling between $5^{\circ}C\;and\;55^{\circ}C$, the specimens were sealed with glass ionomer and nail varnish then placed in 5% methylene blue dye for 5 hours and rinsed with tab water. The specimens were embedded in orthodontic clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimens were then observed with a stereomicroscope at $\times20$ magnification. The results of this study were statistically analyzed using the indepedent sample t-test and analysis of variance. Results were as follows, 1. In occlusal walls, microleakage were significantly reduced in acid etched group restored with Dyract AP but no statistically significance in F2000 groups. 2. In gingival walls, microleakage were significantly reduced in group 2 restored with Dyract AP, and group 2 and group 3 in F2000 groups. 3. All groups, except group 3 in Dyract AP, showed significantly less microleakage in occlusal wall than gingival wall. 4. No statistical significance were showed between group 2 and group 3 in both materials.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.318-332
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• 2000

The purpose of this study was to investigate the effects of demineralized freeze-dried bone (DFDB) on mechanically exposed pulp of dog by evaluating the pulpal inflammation and healing process, formation of dental hard tissue, and structural changes of fibroblasts of the remaining pulp tissue. Teeth of 4 dogs, weighing 10kg, were used in this study. Class V cavities were prepared followed by exposed the pulp tissue mechanically by sterilized round bur. In control group, exposed pulps were capped with calcium hydroxide paste followed by sealed with IRM. In experimental groups, the exposed pulps of one group were capped with the collagen and those of the other group were capped with DFDB. All cavities were sealed with same manor as control group. The animals were sacrificed at the intervals of 3, 7, 14, and 28 days for histopathlogic evaluation. The specimens were observed by the light microscope and trans-electron microscope. The results were as follows: 1. Pulp necrosis was not observed in all groups. Inflammatory response was disappeared from 1 week in control group and group 2. But it was not disappeared until 2 weeks and also irregular arrangement of odontoblasts was showed at the lateral walls of root canal just beneath the amputated site of the pulp in group 1. 2. Dentinal bridge was formed incompletely at 2 weeks but it was formed completely at 4 weeks in control group. Odontoid tissue was also found in control group at 4 weeks from treatment. Amputated site of pulp was encapsulated with fibrous tissue and odontoblast and dentinal bridge was not found in group 1. Preodontoid tissue and reparative dentin which were formed by odontoblast differentiated around DFDB were found, but dentinal bridge was not found in group 2. 3. Cell with large basophillic-stained nuclei infiltrated to amputated site and DFDB at 1 week from treatment in control group and group 2. They were found more in group 2 than in control group. Odontoblasts arranged more regularly and reparative dentin was found more as time elapsed. 4. Dentin-formative odontoblasts which showed ultramicrostructure of cytoplasm with polarized nucleus, rEM, Golgi complex, secretory granules, secretion of organic matrix in control of group and group 2. In regards to above results, the demineralized freeze-dried bone(DFDB) induce odontoblastic differentiation and further come up to the dentin formation in amputated pulp.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.278-286
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• 2008

Many studies regarding Casein phosphopeptides-amorphous calcium phosphate(CPP-ACP) have demonstrated the remineralization ability on the demineralized enamel surface. A question is still remained that how deep can the calcium (Ca) and phosphorus (P) ions supplied by the CPP-ACP paste penetrate into the enamel subsurface. The aims of this study were to measure the penetrating depth of Ca and P ions in the demineralized human enamel in vitro, and were to determine the amount and depth of Ca and P ions according to the duration. The amount and depth of Ca and P ions were measured by microscopic observation with Field Emission Scanning Electron Microscopy (FE-SEM; LEO SUPRA 55, Carl Zeiss, Germany) and Energy Dispersive X-ray Spectrometer (EDS; GENESIS 2000, EDAX, USA: Linescan of Calcium and Phosphorus). Freshly extracted four human 1st premolars were obtained from the Dept. of Pediatric Dent., Kyung Hee Univ. Buccal surfaces of the 1st premolars were covered with nail varnish to form a window on the middle third of buccal surface. All of the teeth with enamel windows were immersed in a solution of 0.1 M lactic acid, Carbopol C907 (carboxypolymethylene BF Goodrich, Cleveland, OH, USA) at pH 4.8, and then incubated for 7 days. Each tooth crown was sawn in half through the midline of buccal window along the long axis of premolar. The four blocks of premolars were immersed in a 10-times diluted solution of CPP-ACP paste (Tooth Mousse, GC Corp., Tokyo, Japan) for 1, 2, 3 and 5 weeks while the rests were immersed in a placebo solution (distilled water) for the same duration. Each specimen was embedded in epoxy resin, and was sectioned perpendicular to the window, using a water-cooled diamond blade saw. The spectrum density indices of Ca and P were measured in the sound, de- and remineralized enamels by FE-SEM and EDS. The Student's t test was performed to compare the Spectrum Density Indices (SDI) of sound, re-and demineralized enamels, and to compare the differences among the durations. Followings are the conclusion : 1. The penetration depth of the remineralizing ions (Ca & P) of CPP-ACP paste is related to the depth of demineralized enamel (approximately $1050{\sim}1350{\mu}m$). It is revealed that the penetration depth of both ions reaches full thickness of decalcification and even slightly into the sound enamel. 2. The Ca & P levels of remineralized enamels in 1, 2 weeks were significantly higher than those of the sound enamels (p<0.05). 3. No statistically significant difference of Ca & P levels was found in relation with the increasing duration of remineralization (p>0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.235-242
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• 2008

The purpose of this study was to investigate the relationship of the skeletal maturity of hand-wrist and the development of mandibular third molar in subjects with class I and class III malocclusion. The subjects used in this study were 304 children(149 boys, 155 girls) with class I malocclusions and 308 children( 153 boys, 155 girls) with class III malocclusions, ranged from 8 to 15 years of age. Hand-wrist radiographs and panoramic radiographs were used to evaluate the stage of skeletal maturity and teeth development. Fishman's method for the skeletal maturity stages of the hand-wrist and new six-developmental-stage method for the calcification stages of mandibular third molars were analyzed. The results were as follows : 1. In subjects with class I and class III malocclusion, skeletal maturity of the hand-wrist occured earlier in females than in males(p<0.05), while the calcification stages of mandibular third molars were no significant gender differences. 2. There were no significant differences between the groups, when comparing the skeletal maturity stages of the hand-wrist and the calcification stages of mandibular third molars between subjects with the class I and the class III malocclusion. 3. The correlation coefficients between the calcification stages of mandibular third molars and the skeletal maturity stages of the hand-wrist in subjects with class I and class III malocclusion showed a high interrelationship(p<0.01). 4. The correlation coefficients between the calcification stages of mandibular third molars and chronological age in subjects with class I and class III malocclusion showed a high interrelationship (p<0.01). As a result, there were no significant differences between class I and class III malocclusion group for skeletal maturity of the hand-wrist and third molar development.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.4
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• pp.422-429
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• 2006

The study aims to examine that regular leisure activity of the elderly has a beneficial effect to enhance their health condition. The elderly subjects of 164 (82 of elderly who do leisure and 82 of elderly who do not leisure) aged over 60 years in Suwon area were employed. Survey questionnaires were administered to investigate general characteristics, life style, mental status, dietary life and nutritional status. From the findings, the elderly who do leisure were highly educated, better in living status and higher employment rate. The mental status of the elderly without leisure activity was very much inferior to that of the elderly with leisure activity, representing higher prevalence rate of depression. Furthermore, the elderly who do not leisure showed higher drinking and smoking rates, irregular eating habits, poor teeth condition and chewing style as well as having eating obstacles. Mean caloric intake of both the elderly was also lower than that of RDA. The elderly who do not leisure have shown lower intakes in most of essential nutrients in contrast to the elderly who do leisure. In conclusion, the elderly with regular leisure activity seemed to have better life style and mental status, dietary life and nutritional status. Therefore, it is critically important to establish the health program combined with various leisure activity for the seniors to promote and energize the later years of life.

• The korean journal of orthodontics
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• v.28 no.6 s.71
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• pp.955-974
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• 1998

The purpose of the present study was to seek bracket-adhesive combinations which have adequate bond strength with no enamel and bracket fracture. The shear bond strengths were measured, the sites of failure and the enamel damage were investigated and the peripheral sealing and adaptation between enamel surface, bonding adhesive and bracket were evaluated. 240 noncarious human premolars were divided into twenty four groups of ten teeth. Shear bond strengths of each group were determined in an universal testing machine after two days passed and the debonded specimens were inspected to determine the predominant bond failure sites. To evaluate peripheral sealing and adaption between enamel surface, adhesive and bracket, each specimen was cut longitudinally into two halves which included the midsection of the bracket, adhesive and enamel and exmined in scanning electron microscope. Six different types of brackets were bonded to the tooth with four different type of adhesives. Six different types of brackets were Image, Plastic, Crystaline, Fascination, Transcend 2000 and metal bracket and four different adhesives were No-mix, Light-Bond, OrthoLC and Superbond C&B. From this study, it may be concluded that (1) The mean shear bond strength varied from a high of 36.58 Kg (410.07 Kg/$cm^2$) with the Fascination-Light Bond combination group to a low of 8.93 Kg (75.51 Kg/$cm^2$) with theImage-OrthoLC combination group. When using OrthoLC as adhesive, the mean shear bond strength was significantly lower than that of other combination groups, (2) Regardless of adhesives, the mean shear bond strength of Fascination brackets was relatively high whereas Plastic and Image brackets had low shear bonding strength. The shear bond strength of Crystaline bracket and Transcend 2m was relatively equal to or lower than that of metal bracket, (3) There was a correlation between bond strength, enamel damage and bracket fracture. As the shear bond strength was increased, the rate of enamel damage and bracket fracture were increased, (4) The combination groups that use OrthoLC as adhesive were debonded in shear stress without enamel fracture and bracket fracture, whereas the combination groups that use Superbond C&B as adhesive experienced a relative high enamel fracture rate and bracket fracture rate, (5) Peripheral sealing and adaptation between enamel-adhesive-bracket were relatively good when using Light-Bond or No-mix as adhesive. Regardless of adhesives, adaptation between bracket-adhesive were relatively good in Ceramic brackets, (6) The combination groups which had adequate bonding strength with no enamel and bracket fracture were Crystaline-No mix, Crystaline-Light Bond, Crystaline-OrthoLC, metal-No mix, metal-Light Bond and metal-OrthoLC combination groups.

• The korean journal of orthodontics
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• v.36 no.3 s.116
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• pp.188-197
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• 2006

Fiber reinforced composite (FRC) is usually used as a connector joining a few teeth into one unit in orthodontics. However, fracture often occurs during the two to three years of the orthodontic treatment period due to repeated occlusal loading or water sorption in the oral environment. We simulated the repair by overlapping and attaching portions of two FRC strips in the middle and performed a three-point bending test to investigate the changes of the repair strength among the different FRC groups. The specimens were grouped according to the overlapping lengths of the two FRC strips, which were 1, 2, 3 and 4 mm (group E1, E2, E3 and E4, respectively) and the control group consisted of unrepaired, intact FRC strips. Each group consisted of 6 specimens and were cured with a light emitting diode curing unit. Group E4 showed the highest maximum loads of 2.67 N, then the control group (2.39 N), group E3 (2.35 N), E2 (2.10 N), and E1 (1.75 N) in decreasing order. Group E4 also showed the highest stiffness, which was 2.32 N/mm, however, the stiffness of group E3 (2.06N/mm) was higher than that of the control group (1.88 N/mm). According to the visual examination, the specimens tended to be bent rather than being fractured into two pieces with an increased length of overlapping portions. The above results suggest that a minimum overlapping length of 3 mm was necessary to obtain an adequate repair of a 10 mm length of FRC connector. In addition, the critical section adjacent to the joint area, where the thickness decreased abruptly, should be reinforced with flowable resin to minimize the bending tendency.

• The korean journal of orthodontics
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• v.26 no.3
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• pp.255-265
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• 1996

The purpose of this study was to investigate if there were a significant difference between cephalometric measurements of mandibular position derived from a centric occlusion tracing compared to those of a converted centric relation tracing in the Class III malocclusion. The sample consisted of 25 Class III malocclusion and 25 normal occlusion persons who had no orthodontic treatment. The records included an lateral cephalometrics in centric occlusion, centric relation and centric occlusion bite registration and diagnostic casts mounted on the SAM II articulator in CR. The amount of CR-CO discrepancy of condyle was recorded using a MPI(Mandibular Position Indicator, MPI $200^{(R)}$, Great Lakes Orthodontics, USA). The conversion of the CO cephalogram to CR using the MPI readings was performed on the Conversion work sheet. Measures of mandibular position were chosen for the purpose of this study. The comparison of the difference between CO and CR cephalometric measurements in the normal occlusion and Class III malocclusion group were studied. The results were as follows: 1. In the features of CR-CO discrepancy of the condyle, the condyle was displaced posterior and inferior when the teeth were in centric occlusion. The horizontal component(${\Delta}X$) in Class HI malocclusion group was greater than the vertical component(${\Delta}Z$) and also greater than the horizontal component(${\Delta}X$) in normal occlusion group. There was no statistically significant correlation between MPI measurements and the groups of normal occlusion and Class III malocclusion group. 2. In the comparison of the cephalometric measurements in each group, Normal occlusion group showed significant difference in measurements such as ANB, Facial angle, Facial convexity and ODI. Class HI malocclusion group showed significant difference in measurements such as ANB, Facial angle, Facial convexity, ODI, SNB, APDI, L1-FP and it had more significance than the normal occlusion group. 3. The Value of cephalometric measurements was significantly different between CO and CR but there were no differences between the groups of normal occlusion and Class III malocclusion. The results of this study suggest that if the discrepancies are greater than the amount of normal displacement from clinically captured centric relation, centric relation should be considered as the starting point for proper diagnosis and treatment planning.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.4
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• pp.731-752
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• 1995

This study was performed to research the changes of masticatory system subsequent to randomly increasing the vertical dimension. The subjects were twenty seven persons, twenty two men and five women, with a mean age of 24.3(age ranged from 22 to 26). The subjects had a complete or almost complete set of natural teeth and reported no subjected symptoms of pain or dysfunction in the masticatory system. The occlusal splint increased vertical dimension was made on semiadjustable articulator. The subjects were randomly divided to three groups according to the vertical dimension, at which the occlusal splint was made. Group I occlusal splints were made at 2mm form the occlusal vertical dimension, group II occlusal splints at 5mm, group III occlusal splints at 8mm. The occlusal splints were almost weared for 2 weeks except meal-time. Clinical examination, muscle activity, changes of free-way space, movement of mandible and articular condyle were recorded and analyzed by means of biopak system(Bioresearch Inc, Millwakee Wisconsin.) and radiograph. 1. In clinical examination, various symptoms were reported by all subjects immediately after the placement of occlusal splint. At the end of experiment, symptoms were lasted by 1 subject in Group I, 2 subjects in Group II, 6 subjects in Group III. At the other subjects, the most of symptoms were disappered within 2-4 days after the placement of occlusal splints. 2. The average free-way space before the startof experiment was 1.77mm in all twenty seven subjects. Immediately after the placement of occlusal splints, 0.67mm at Group I, 0.49mm at Group II, 0.41mm at Group III, At 2 weeks after the placement of occlusal splint 0.93mm, 0.79mm, 0.78mm each other, 1.94mm, 1.77mm, 2.3 mm at immediately after the removal of occlual splint. At 1 week after the removal of occlusal splint, free-way space was recovered to the pre-experimental state 3. In cephalometric radiograph, following either the placement or the removal of the occlusal splints, the movements of mandible in an antero-posterior direction were not statistically significant(p>0.05). 4. In transcranial radiograghs of TMJ, 1 week after the placement of occlusal splint the movement of most superior position on condyle in all group shoed antero-inferior position than before the experiment(p<0.001) and also showed antero-inferior position in mandibular postural rest position than in certric occlusion(p<0.001). Following either the placement or the removal of the splints, the amount of movement of most superior position on condyle was group III. group II and group I in order(p<0.001). 5. In anterior temporal and superficial masseter muscle, muscle activity at postural rest position decreased at 2 weeks after the placement of occlusal splint in group I and group II (p>0.05), but significantly increased in group III(p<0.001). At 1 week after the removal of the occdusal splint, muscle activity at postural rest position was recovered preconditional state 6. In anterior temporal and superficail masseter muscle, muscle activity at clenching in all group was significantly decreased after placement of the occlusal splint, slightly increased during experimental period and recovered to the original state at 1 week after removal of the occlusal splint. But was not statistically significat(p>0.05)s.