• The korean journal of orthodontics
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• v.28 no.6 s.71
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• pp.915-926
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• 1998

The cytoskeleton has been shown to form a network, connecting the extracelluar matrix via integrin with the nucleus and the cytoplasmic constituents of the cell. It is therefore assumed that the cytoskeleton may mediate signals generated by perturbations originating in the matrix. The purpose of this study is to examine the effect of cytoskeletal change on osteoblastic cell activities. The author cultured osteoblastic cells obtained from neonatal mouse calvaria. The cells were teated with cytochalasin B(CB) or colchicine (COL) at four concentrations for 3 hours and after another 24 hours the conditioned media was collected and assayed for prostaglandin $E_2\;(PGE_2)$, interleukin-6(IL-6), tumor necrosis factor-$\alpha$ (TNF-$\alpha$) and matrix metalloproteinase-1(MMP-1). In addition, the cytoskeletal protein actin were observed by immuno-fluorescence. The results were as follows: 1. The production of $PGE_2$ showed the tendency to be increased in CB-treated group. $PGE_2$ was increased in COL-treated group dose-dependantly, 2. IL-6 production, in CB-treated group, was increased, except at 1.0 ${\mu}g/ml$. IL-6 was induced in COL-treated group. 3. TNF-$\alpha$ production was increased in CB-treated group, except at 1.0 ${\mu}g/ml$, and in COL-treated group, that was increased. 4. The MMP-1 production was decreased in CB-treated soup and was not changed in COL-treated group, which could be selectively visualized by immunoblotting with monospecific antibody. 5. The cytoskeletal actin stress fibers were disappeared and the cells showed to be rounded in CB-treated group. These results indicated that there are a relationship between the cytoskeletal rearrangements and osteoblastic cell activities, especially in release of paracrine/autocrine factors, such as $PGE_2$, IL-6, and TNF-$\alpha$.

• The korean journal of orthodontics
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• v.28 no.6 s.71
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• pp.927-935
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• 1998

The purpose of this study is to investigate the changes of mechanical properties and surface topography of various nickel titanium wires after heat sterilization for recycling with quantitative method. The materials used were four kinds of nickel titanium orthodontic wires including a Korean product. Experimental specimens were treated with two kinds of heat sterilization methods ; dry heat ($180^{\circ}C$, 60min) and autoclave ($121^{\circ}C$, 15-20psi, 30min). Mechanical properties were evaluated by tensile test with Instron 4466 (load cell capacity:.1000 kg, cross head speed:5mm/min, grip distince:40mm in room temperature). Surface topography of various wires was compared with each other qualitatively by using scanning electron microscopy and quantitatively by using profilometer. The findings were analyzed statistically with student t-tests. The results were as follows; 1. Neither method of heat sterilization had any effects on tensile properties of the nickel-titanium wires used in this experiment. 2. Before heat sterilization, the surface smoothness was highest in Optimalloy, followed by Align and Sentalloy, with NiTi showing the lowest smoothness value. 3. In surface topography, Align and Optimalloy were not influenced by heat sterilization. NiTi, on the other hand, had increased roughness after dry heat sterilization and Sentalloy showed the same tendency after each of the two heat sterilization procedures.

• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.687-698
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• 2000

The purpose of this study was to evaluate the changes of skeletodental patterns during Class II treatment and its retention period. Forty two patients of Class II malocclusion, which was treated with nonextraction or first premolar-extraction were selected and their lateral cephalograms were examined in this study. Various skeletodental changes in lateral cephalograms of pre-treatment, post-treatment and retention were measured by superimposition in reference to the cranial base for jaws, the palatal plane for maxillary teeth, and mandibular plane for mandibular teeth. The data were analyzed by paired t-test. In this study, occlusal plane showed the significant anterior downward steepening after active treatment, and remained during retention period. In the nonextraction group, maxillary incisors were retracted and extruded during treatment. Maxillary molars were extended, and mandibular molar were uprighted, with no mesial movement. In the extraction group, both maxillary and mandibular incisors were retracted and extruded. Maxillary molars were extruded and moved mesially, and mandibular molars were extruded and moved mesially with no mesial tilting. During retention period in both groups, there were tendencies of labial tipping of maxillary incisor, and mesial tipping of maxillary and mandibular molar. But the changes were not significant and most of teeth showed no change in vortical and horizontal direction.

• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.713-721
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• 2000

Bone cells produce multiple growth factors and cytokines that have effects on bone metabolism and can be incorporated into the bone matrix. The present study was designed to extend these observations by examining the interactions between transforming growth factor-$\beta$(TGF-$\beta$) or interleukin-$1\beta$(rhIL-$1\beta$) and bone cells in a rat long bone culture model. IL-$1\beta$ regulates several activities of the osteoblast cells derived from rat long bone explants in vitro. IL-$1\beta$ stimulated cellular proliferation as well as the synthesis of prostaglandin $E_2$ and Plasminogen activator activity in the cultured cells in a dose-dependent manner. TGF-$\beta$ is present in the bone matrix and potentially released during bone resorption. TGF-$\beta$ reduced basal bone resorption and inhibited vitamin $D_3[1,25(OH)_2D_3]$-induced bone resorption in rat long bone cells. These results support the role of IL-$1\beta$ in the pathological modulation of bone cell metabolism, with regard to implication in the Pathogenesis of osteoporosis by IL-$1\beta$, and that TGF-$\beta$ positively inhibits the bone resorption.

• The korean journal of orthodontics
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• v.33 no.4 s.99
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• pp.223-233
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• 2003

The Purpose of this study was to Investigate the relationship between the space discrepancy of the mandibular dentition and craiofacial morphology in adults with good Angle class I occlusion. Dental casts of normal group, crowded group and spaced group were selected on the basis of dental crowding and spacing. Subjects with excessive space to accomodate the lower teeth were classified as spaced group(39). Subjects with a space discrepancy of more than 4mm were classified as crowded group(45). Normal subjects had little or no dental crowding and spacing(40). Various skeletodental measurements in lateral cephalograms were evaluated and compared by ANOVA, Pearson correlation analysis and multiple stepwise regression analysis. The results were as follows; 1. ANB angle was larger in crowded group than in spaced group. 2. Maxilla and mandible in crowded group were inclined more downward and forward than in spaced group, so crowded group was found to have vortical tendency. 3. Anterior cranial base length and mandibular body length were longer in spaced group than in crowded group. 4. According to the multiple stepwise regression analysis with space discrepancy as dependent variable, 40% of variance of space discrepancy could be explained by ANB angle, anterior facial height and ramus height. Multiple regression equation was as follows Space discrepancy=46.51-2.51ANB-0.58AFH+0.65RH

• The korean journal of orthodontics
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• v.34 no.6 s.107
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• pp.473-480
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• 2004

The aim of this study was to establish normative data on the tooth size and arch parameters of Koreans with normal occlusion, This study employed the dental casts of 296 (male: 179; female 117) normal occlusion samples, who were selected from 15,836 adults through a community dental health survey. The mesiodistal diameters of teeth, arch width, and arch length were measured by digital electronic calipers(accurate to 0.01 mm) and Bolton's indices as well as intermaxillary arch width ratios were calculated. In order to ensure reliability, intra- and inter-examiner error were evaluated. Although our dimensional data showed overt differences between genders, the indices and intermaxillary ratios evaluated were the same. The resultant data obtained were compared with the previous data to reveal whether any changes have occurred over the time. The clinical implication of the present findings was also discussed. This biometric study seemed to provide a clinically applicable diagnostic criteria for an individual malocclusion patient.

• The korean journal of orthodontics
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• v.34 no.6 s.107
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• pp.481-487
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• 2004

The purpose of this study was to clarify morphologic characteristics between mandibular clinical arch forms in Koreans with normal occlusions. The study included data from 102 Koreans. The most facial portion of 13 proximal contact areas was digitized from photocopied images of the mandibular dental arches. Clinical bracket points were calculated for each tooth based on mandibular tooth thickness data. Four linear and two proportional measurements were taken. The dental arches were classified into ovoid, square and tapered forms. The frequency distributions of the three mandibular arch form classifications were determined and compared between male and female subjects. No significant differences in arch form size were found between the sexes. However, there were a few differences in molar width. It was useful to classify mandibular clinical arch forms present in normal occlusion samples into ovoid, square and tapered categories. The frequency of the ovoid form was the highest, and that of the square form was the second highest. The tapered arch form was found in less than 10 percent of subjects. No significant differences in their frequency distributions and dimensions were shown between males and females.

• The korean journal of orthodontics
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• v.34 no.6 s.107
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• pp.506-513
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• 2004

Osteoclast action is necessary for alveolar bone remodeling in orthodontic tooth movement. The nervous system has also been reported to be associated with bone remodeling. This study was aimed to investigate the changes of osteoclasts in the periodontal ligament (PDL) space after surgical resection of the inferior alveolar nerve (IAN). Experimental rats were divided into young and adult groups. A surgical resection procedure of the IAN was carried out in the left side of the mandible and a sham operation in the right side of the mandible. The number of osteoclasts on the bundle bone surface and the resorption activity of the osteoclasts were histomorphometrically measured. The changes in distribution of substance P (SP) immunoreactive (IR) nerve fiber were evaluated in the PDL and pulp. SP-IR nerve fiber was depleted in both the PDL and pulp of the IAN resection side in both groups, which confirmed the resection of IAN to be successfully conducted. The number of osteoclasts in the IAN resection side was significantly reduced in both the young and adult groups (p<0.01 and p<0.05), whereas the resorption activity of osteoclasts did not show any significant difference between the IAN resection side and the sham operation side in both groups (p>0.05 and p<0.05). The adult group showed that the number of osteoclasts reduced significantly (p<0.01) and the resorption activity didn't change in comparison with the young group (p>0.05). These results suggest that surgical resection of the IAN and aging reduce the population of the recruited osteoclasts within the PDL, but don't affect on the osteoclastic resorption activity.

• The korean journal of orthodontics
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• v.34 no.6 s.107
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• pp.514-525
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• 2004

The purpose of this study was to evaluate the correlation between nicotine and the activity of bone forming cell. MG63 osteoblast-like cells were used for this study. Several factors were examined including the proliferation of cell, alkaline phosphatase activity, the formation of osteocalcin and osteoprotegerin. and the synthesis of its mRNA. MG63 osteoblast-like cells were incubated for 1, 2, 3 and 6 days with nicotine added to the culture medium in 1.0 ${\mu}M$, 1.0mM, 2.5mM, 5.0mM, 7.5mM, and 10.0mM concentrations. The proliferation of MG63 osteoblast-like cells was temporarily activated at the low nicotine concentrations. At high concentrations (>5.0 mM), however. it was suppressed. Alkaline phosphatase activity was suppressed in a dose-dependent manner as the concentration of nicotine increased. Osteocalcin decreased in a dose-dependent manner at high nicotine concentrations of more than 7.5mM and the same result was show when the osteoblasts were treated with low concentrations for longer than 3 days. There was a difference in the influence of nicotine on the synthesis of osteocalcin mRNA and formation of osteocalcin itself at 1 and 3 days. Generally, osteoprotegrin notably declined in all experimental groups. However, the level of its mRNA increased at high nicotine concentrations of more than 7.5mM after 3 days and more than 5.0mM after 6days.

• The korean journal of orthodontics
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• v.34 no.6 s.107
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• pp.526-536
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• 2004

This study was undertaken to determine the effect of a 2.2mg/Kg/day intraoral administration of NaF on the amount of root resorption and osteoclastic activity during or after a rapid maxillary expansion procedure. Ten puerile female dogs were divided into two groups: a control group and a NaF-treated group. A fixed type maxillary expansion device was delivered to all dogs. The appliance was activated twice daily throughout a 20-day period, causing a 5-mm expansion of maxillary bone. After the expansion procedure, the animals were sacrificed at days 0, 15, 30, 45, and 60 of the retention period. The buccal surface of the root of each maxillary canine was examined by means of a surface electron microscope (SEM). Using SEM, web-like resorption lacunae were observed on the bone or the tooth surface at the site of osteoclastic activity; these observations were verified by histological methods. No peculiar resorption lacunae were found in the apical tip of the roots of either the control group or the NaF-treated group animals. The NaF-treated retention group was found to have less resorption lacunae formation on day 45 and day 60. The preventative effect of NaF on resorption lacunae formation on the surface of the bone covering the anchor tooth was confirmed. Larger areas of resorption lacunae were found on the surface of the bone covering the canines in the control group animals, as compared to those of the NaF-treated group, especially on day 30 and day 60. Using SEM, the present study revealed a difference between the control group and the NaF-treated group in the prevalence and the size of the resorption lacunae formation on the cemental root surface. The preventative effect of NaF on bone resorption was confirmed. Further studies concerned with the optimum concentration of NaF that has an effect in vivo are necessary.