• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.233-239
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• 2010

Space loss of dental arch can appear when the proper position of teeth within the dental arch changes by a certain cause, because the balance of force makes changes about tooth position as well as alignment. The causes of space loss include proximal caries, early extraction, congenital missing of a tooth and hypodontia, etc. Among those causes of space loss, congenital missing of a tooth is more rarely observed in the primary dentition than in the permanent dentition. Congenital missing in the primary dentition is associated with that in the permanent dentition. Furthermore, it can cause space problem, such as mesial tilting or drift of adjacent teeth, space loss for permanent successors and dental arch constriction, etc. Primary lateral incisors is the most commonly involved, in the maxilla rather than in the mandible, but primary canine is rarely reported. In this patient, who visited the department of pediatric dentistry at Yonsei university dental hospital, it was observed that the maxillary right primary canine was congenitally missing and an odontoma was found insteadly. However, neither the space loss for the congenitally missing primary canine nor midline deviation is remarkable during the 2-year-10-month observation period. In addition, any clinical or radiographical symptom did not occur in spite of odontoma. Therefore, surgical enucleation of odontoma is planned according to the eruption of permanent lateral incisor or canine, unless eruption failure of permanent lateral incisor or canine nor cystic change around the odontoma is occurred. Through further evaluation, space maintainer or orthodontic treatment may be necessary.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.1
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• pp.81-93
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• 2013

The objectives were to evaluate the accuracy of shade selection by human visual system(VS) and 2 different colorimeters ($ShadeEye^{(R)}$(SE) and Shadepilot (SP)). Maxillary anterior teeth of 30 volunteers which had no caries or restorations were included in the study. Firstly, the accordance in shade selection by 3 dentists and 2 colorimeters was investigated. Secondly, the color of the teeth were measured by 1 observer's naked eye and 2 colorimeters under different illumination conditions (Sunny versus cloudy day). Additionally testing of inter-observer variability selected colors by 2 novice and 2 experienced dentists were compared. For comparing visual and 2 different colorimeters, SP(60%) showed significantly highest rate of accordance than the visual (23.3%) or SE (16.7%) and lowest mean ${\Delta}E$ ($2.62{\pm}0.74$ versus $3.83{\pm}1.38$;SE or $4.04{\pm}1.61$;VS)(p<0.001). If accuracy of shade selection were measured using VS, the mean ${\Delta}E$ value of cloudy day was higher than that of sunny day ($4.35{\pm}1.70$ versus $3.53{\pm}1.31$; p<0.001). There were no significant difference of the mean ${\Delta}E$ value between sunny and cloudy day in both SE and SP. Inter- observer repeatability was higher in 2 experienced group (73.3%) than novice group (36.7%). The mean ${\Delta}E$ of experienced group was lower than that of novice group ($3.60{\pm}1.47$ versus $4.70{\pm}1.67$; p<0.001). Colorimeters (SE or SP) is more accurate and more reproducible compared with human shade assessment. Using visual system may be limited by cloudy and inexperience of tester, then more experience and using colorimeters may be helpful of raising the accurate repeatability of shade selection.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.699-716
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• 1998

This study was designed to evaluate the expression of non-collagenous protein in periodontal tissue during the experimental movement of rat incisors, by LSAB(labelled streptavidine biotin) immunohistochemical staining for osteonectin and osteocalcin. Twenty seven Sprague-Dawley rats were divided into a control group(3 rats) and 6 experimental groups(24 rats) where 75g of force was applied from helical springs across the maxillary incisors. Rats of experimental groups were sacrificed at 12 hours, 1, 4, 7, 14 and 28 days after force application, respectively. And the tissues of a control group and experimental groups were studied immunohistochemically and histologically. The results were as follows : 1. Until 28 days after force application, periodontal fibers had been strectched on tension side and compressed in pressure side of all the experimental groups, and the arrangement of periodontal fibers had not been recovered yet. 2. The expression of osteonectin in control group was rare in dentin, cementum and osteocyte, and was mild in odontoblasts and matrix of alveolar bone. 3. The expression of osteocalcin in control group was negative in gingiva, osteoblasts, osteocyte and cementum, and was rare in predentin, capillaries in pulp and periodontal ligament and the matrix of alveolar bone. 4. There was no difference in the expression of osteocalcin or osteonectin in dentin, cementum, pulp, odontoblasts, between of control and of experimental groups. 5. The expression of osteonectin in intermaxillary suture got the peak in 7-day and was declined after 14-day. The expression of osteocalcin remained in a same degree since it became mild in 14-day. 6. The expression of osteonectin in pressure side of periodontal ligament of experimental group was rare, which was similar to control group. But in tension side, it was increased until 14-day aftrer which it was declined. 7. The expression of osteocalcin in periodntal ligament was rare in 12-hour to 14-day, but became severe in 28-day, which was greater in tension side than in pressure side, and in the periodontal fiber next to alveolar bone than to tooth surface. 8. The expression of osteocalcin in alveolar bone was rare until 14-day in pressure side, but became moderate in 28-day. The expression of osteonectin was increased from 7-day by time dependency, which was greater in tension side than in pressure side.

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.963-978
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• 1997

Orthodontic patients are individuals that grow and develop ;therefore selection of the proper time for orthodontic treatment Is considered to be one of the most difficult and yet difficult factor.Since the development of cephalometric X-ray, amount and pattern of craniofacial growth change with aging could be predicted and became useful in the process of orthodontic treatment. The relationship between the mean values of cephalometric measurements and body height and weight was studied among the groups(boys and girls) of Korean children from the ages of 3-years to 12-years. 126 boys and 90 girls with no abnormality in growth and development and no history of orthodontic treatment from the ages of 3 years to 12 years were chosen as subjects: Cephalometric X-ray were taken for 2 years and hard tissue analysis based on Burstone's COGS, which was divided into measurements of 6 parts (Cranial base, Maxillar and Mandible, Vertical measurements, Horizontal measurements, Basal bone relationship, Dental measurements). The relationship between craniofacial growth and body height & weight was studied. The following conclusions were obtained : 1. The maximum growth in the measurements of cranial base, N-Ar(FH), N-Ba(FH) corresponded with the age with the maximum increasein body height & weight in both boys and girls. 2. Genial angle gradually decreased with aging in both boys and girls. 3. N-ANS(L) showed greater amount of growth than ANS-Me(L), and this had greater influence on facial profile. 4. $N-A-Pog^{\circ}$ decreased with aging, and mandibular growth exceeded maxillary growth in amount and rate. 5. Length of Y-axis increased, but Y-axis to FH plane remained constant. This show that mandible grows at a constant angulation to cranial base. 6. As Permanent teeth erupt, interincisal angle deceased.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.3
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• pp.214-221
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• 2011

Purpose: To date most of finite element analysis assumed the presence of 100% contact between bone and implant, which is inconsistent with clinical reality. In human retrieval study bone-implant contact (BIC) ratio ranged from 20 to 80%. The objective of this study was to explore the influence of bone-implant contact pattern on bone of the interface using nonlinear 3-dimensional finite element analysis. Materials and methods: A computer tomography-based finite element models with two types of implant (Mark III Br${\aa}$nemark$^{(R)}$, Inplant$^{(R)}$) which placed in the maxillary 2nd premolar area were constructed. Two different degrees of bone-implant contact ratio (40, 70%) each implant design were simulated. 5 finite element models were constructed each bone-implant contact ratio and implant design, and sum of models was 40. The position of bone-implant contact was determined according to random shuffle method. Elements of bone-implant contact in group W (wholly randomized osseointegration) was randomly selected in terms of total implant length including cortical and cancellous bone, while ones in group S (segmentally randomized osseointegration) was randomly selected each 0.75 mm vertically and horizontally. Results: Maximum von Mises strain between group W and group S was not significantly different regardless of bone-implant contact ratio and implant design (P=.939). Peak von Mises strain of 40% BIC was significantly lower than one of 70% BIC (P=.007). There was no significant difference between Mark III Br${\aa}$nemark$^{(R)}$ and Inplant$^{(R)}$ in 40% BIC, while average of peak von Mises strain for Inplant$^{(R)}$ was significantly lower ($4886{\pm}1034\;{\mu}m/m$) compared with MK III Br${\aa}$nemark$^{(R)}$ ($7134{\pm}1232\;{\mu}m/m$) in BIC 70% (P<.0001). Conclusion: Assuming bone-implant contact in finite element method, whether the contact elements in bone were wholly randomly or segmentally randomly selected using random shuffle method, both methods could be effective to be no significant difference regardless of sample size.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.179-188
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• 1981

The authors made an investigation concerning the geographical distribution and some major differentiations in morphological characteristics associated with the each habitat, of the pond smelt, Hypomesus olidus, which was introduced into Korea more than 50 years ago. Major characteristics utilized for the comparison study were upper jaw (maxillary), number of fin rays, scale structure, vertebral count, number of pyloric caeca, number of gill rakers, and the relative measurements of these and other internal characters. 1. The main areas of natural distribution are Paro Lake, Soyang Lake, Han River, Euirim Lake, and Ogjeong Lake (or Unam Lake) and the tributaries of these waters. 2. Morphological variations varied when the mean values of measurements from each area were compared with the standard measurement value by mosaic comparison, and in some instances a significant variation was found. 3. The most significant variations were found in the number of fin rays of pectoral and anal fins; the lengths from the tip of snout to the origin of pectoral fin, from snout to ventral fin, and from snout to anal fin, relative to standard body length; eye depth relative to head length; upper jaw: the number of pyloric caeca and the scale structure. Variations, on the other hand, by each habitat were not clear in the numbers of ventral and dorsal fin rays, gill rakers, vertebrae and lateral line scale : and the depth of caudal peduncle and distance from the tip of snout to the origin of dorsal fin relative to standard body length. 4. The scales of pond smelt showed some differences in the shape of scales, the shape and position of the focus and the number of ridges according to the scale positions on the body. No radii were present. The relations between longitudinal and transverse diameters of the scale suggest that the pond smelts of Soyang Lake and Un-am Lake are closely related, and those of Han River and Euirim Lake are also closely related. 5. The geographical variations in morphology of the pond smelt seem to have resulted from the variations in turbidity, water temperature, salinity (rather conductivity) and currents. 6. From the results obtained, it may be concluded that such factors as supramaxillary, relation between scale length and its breadth, number of caudal vertebrae and eye depth relative to head length may be used as the key characters for the classification of geographical varieties of Pond smelt.

• The korean journal of orthodontics
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• v.31 no.4 s.87
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• pp.467-477
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• 2001

This investigation was designed to determine the effects of wire size, bracket width and the number of bracket on bracket-wire dynamic frictional resistance during simulating arch wire-guided tooth movement in vitro. For simulation of an arch wire-guided tooth movement, we simulated tooth, periodontal ligament and cancellous bone. Maxillary premolar and 1st molar were simulated as real sized resin teeth, the simulated resin teeth which its root was coated by polyether impression material which its elastic modulus is similar to periodontal ligament were embedded in steel housing with inlay wax which its elastic modulus is similar to cancellous bone. Stainless steel wires in four wire size (0.016, 0.018, $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$ inch) were examined with respect to three (stainless steel) bracket widths (2.4, 3.0, 4.3mm) and the number of medium bracket(one, two, three) included in the experimental assembly under dry condition. The wires were ligated into the brackets with elastomeric module. The results were as follows : 1. In all the brackets, frictional resistance increased with increase in wire size. But, statistically similar levels of frictional resistance were observed between 0.018 inch and $0.016\;{\times}\;0.022$ inch wires in narrow bracket and also between 0.016 inch and 0.018 inch wire in wide backet. 2. The frictional forces produced by 0.016 inch wire were statistically similar levels in all the brackets. In 0.018 inch round wire, wide bracket was associated with lower amounts of friction than both narrow and medium brackets. In $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$ inch rectangular wire, wide bracket produced target friction than both narrow and medium brackets. In all the wirer, narrow and medium bracket demonstrated no statistical difference in levels of frictional resistance. 3. Frictional resistance increased with increase In number of medium bracket. 0.016 inch round wire demonstrated the greatest increment in frictional resistance, followed by $0.019\;{\times}\;0.025,\;0.016\;{\times}\;0.022$ inch rectangular wire which were similar level in increment of frictional resistance, 0.018 inch wire demonstrated the least increment. The increments of frictional resistance were not constantly direct proportion to number of bracket.

• The korean journal of orthodontics
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• v.32 no.3 s.92
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• pp.195-207
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• 2002

Numerous studies have revealed the similarities and discrepancies in two divisions of class II malocclusion, since these malocclusion groups have been postulated to be disparate criterion, much as classified under one diagnostic umbrella. This study was undertaken to describe the craniofacial configurations of class II division 1 and 2, and consequently to discriminate the morphologic differences between the two malocclusion groups in Korean sample. Lateral headfilms of 34 class H division 1 and 29 division 2 were employed, while those of 142 adults of normal occlusion served as a control. The landmarks were digitized and 26 variables were statistically analyzed for one way ANOVA. 1. There manifested no statistically significant difference in maxillary position anteroposteriorly. Normal occlusion group exhibited most anteriorly positioned mandible, whereas class II division 1 showed the most retroposition. Class II division 1 disclosed clockwise rotation tendency of mandible, which resulted in position of the chin Posteriorly. 2. Class II division 1 showed greater in SN to MP, SN to PP significantly than other groups. 3. Class II division 2 showed smaller genial angle and larger mandibular body length than other groups. 4. Class II division 1 revealed greater anterior lower face height than other groups, whereas division 2 dictated significantly greater posterior face height. 5. Class II division 2 expressed the most retroclined lower incisor, while division 1 manifested the most proclination. The largest interincisal angle resided in Class II division 2 group. There were no significant differences in upper molar position anteroposteriorly.

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.593-604
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• 1995

Mandibular incisor crowding is one of the most common features of malocclusion and is interesting characteristic in view of relapse and stability after orthodontic treatment. There are many potential factors in the etiology of lower anterior crowding. The tooth size variation is one of them, but biologic significance for the faciolingual width of the teeth has been overlooked. Peck and Peck reported that persons with ideal mandibular incisor alignment were shown to have incisor with smaller mesiodistal and larger faciolingual dimensions than persons with incisor crowding. On the basis of these findings they suggested MD/FL index as a clinical guideline for the assessment for lower incisor crowding. The present study was undertaken to examine the relationship between mandibular incisor crowding and mandibular incisor dimension, and determine their correlation with arch length discrepancy. 154 dental casts of people from 11 to 17 years of age were made, and were divided into normal group with irregularity index less than of 1, and crowding group with irregularity index greater than 1.The casts were measured and analyzed statistically. The results were as follows. 1. The mean mesiodistal width for mandibular incisor was larger in crowding group, and has significant difference in central inciosr measurement. There are no significant differences in the faciolingul width and MD/FL index. 2. Irregularity index has significant correlation coefficients with mesiodistal width and MD/FL index for mandibular incisor in crowding group, but no correlation with faciolingual width. It also has correlation with maxillary and mandibular arch length discrepancy, total tooth material, mandibular intercanine width, and mandibular inter first premolar width. 3. Upper and lower arch length discrepancy have significant correlation with mesiodistal width of mandibular incisor and overbite, but have no correlation with faciolingual width. Lower arch lenth discrepancy has significant correlation with MD/FL index for mandibular incisor and upper arch length discrepancy has correlation with MD/FL index for mandibular lateral incisor. 4. Significant differences were observed between normal and crowding group for the mandibular arch length discrepancy and overbite.

• The korean journal of orthodontics
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• v.29 no.1 s.72
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• pp.73-81
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• 1999

Midpalatal suture expansion is often used for patients haying narrow maxillary arch, cleft palate, respiratory handicap with narrow nasal cavity. CGRP has been known as a modulator of pain transmission in central nervous system and a local effector to peripheral tissue causing vasodilation, increase of blood flow, modulation of immune system, regulation of macrophagic function and stimulation of bone formation. To investigate changes of CGRP-immunoreactive nerve fibers in midpalatal suture during the expansion, immunohistochemical study was performed by using rats. Experimental rats (10 weeks, 250 gm) were divided into five groups (control, 1, 4, 7, 14 days group (each n=4) and applied orthodontic force (approximately 200gm) to upper anterior incisors. Frozen sections of midpalatal suture area were immunostained by using rabbit antisera. The results were as follows. ${\cdot}$ The CGRP-immunoreactive nerve fibers were hardly observed in control group. ${\cdot}$ In 1 day group, the CGRP-immunoreactive nerve fibers were more increased around the vessels than control group. ${\cdot}$ In 4 days group, the CGRP-immunoreactive nerve fibers were more increased than control group, but not more increased than 1 day group. Vascular diameter was more enlarged. ${\cdot}$ In 7 days group, especially, hematoxilin affinity of cells was remarkable and cells were arranged along the bone margin. The CGRP-immunoreactive nerve fibers were more reduced than 4 days group and vascular diameter was also reduced. ${\cdot}$ In 14 days group, the CGRP-immunoreactive nerve fibers were similar to those of 7 days group and the irregularity of bone margin was almost recoverd. In Conclusion, the CGRP-immunoreactive nerve fibers nay be related to initial neurogenic inflammatory reaction in expanding mid-palatal suture.