• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.430-437
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• 2007

The probability table of Moyers and prediction equation of Tanaka and Johnston that have been the most frequently used, cannot produce accurate prediction when used in Korean because they are based on the Caucasian popularity of the Northern European race. The method of Moyers or Tanaka and Johnston predicts sizes of the unerupted canine and premolars on the basis of the sizes of mandibular incisors. However, some of the recent papers raise a question as to whether the mandibular incisors are the best combination to predict the sizes of the unerupted canine and premolars. The purpose of this study is to determine which sum or combination of sums of permanent tooth widths present the best prediction for the unerupted canine and premolars in a Korean sample, to calculate a specific linear regression equation for this population, and to evaluate the clinical significance. A new linear regression equation was calculated based on the data of 178 Korean young adults(70 women, 108 men, mean age 21.63 years) with complete permanent dentitions. Fifty three more children(28 girls, 25 boys, mean age 14.22 years) were used as a validation sample for the application of the multiple linear regression equation. The conclusions were as follows: 1. The combination of the sums of permanent upper central incisors, lower lateral incisors and upper first molars was the best predictor for the unerupted canine and premolars in this sample($r=0.65{\sim}0.80$). 2. The multiple linear regression equation was calculated including sex and arch as additional predictor variables. male, upper: $Y\;=\;0.332{\times}X_0\;+\;6.195$ male, lower: $Y\;=\;0.332{\times}X_0\;+\;5.269$ female, upper: $Y\;=\;0.332{\times}X_0\;+\;5.929$ female, lower: $Y\;=\;0.332{\times}X_0\;+\;5.003$. The determination coefficient of the equation was 64% and a standard error of the estimate was 0.71mm. 3. In about 97% of the validation sample, the estimation of the tooth width sums of unerupted canine and premolars using the new multiple linear regression equation was smaller than 1mm compaired with the actual values.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.4
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• pp.540-548
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• 2000

The aim of this study was to evaluate the timing of sequence of tooth calcification in current Korean growing children. The Calcification stage of permanent teeth of Korean children was investigated by classifying them into 10 stages by the criteria of Nolla, using the panoramic radiographs of 258 healthy Korean children, 149 males and 109 females, between the ages of 4 years and 13 years, with normal growing tendency and no orthodontic treatment experience. The obtained results were as follows: 1. Timing of calcification of permanent teeth by Nolla stage was established with mean values. Among the mean value, results of Nolla stage 7 were as follows: Calcification timing of male in the maxilla was 6 year 9 month on central incisor, 7 year 4 month on lateral incisor,7 year 9 month on canine, 8 year 8 month on the first premolar, 9 year 4 month on the second premolar, 6 years 3 month on the first molar and 10 year 8 month on the second molar, calcification timing of male in the mandible was 5 year 11 month on central incisor, 6 year 4 month on lateral incisor, 7 year 5 month on canine, 8 year 1 month on the first premolar, 8 year 6 month on the second premolar 5 years 6 month on the first molar and 10 year 3 month on the second molar. Calcification timing of female in the maxilla was 6 year 2 month on central incisor, 6 year 7 month on lateral incisor, 6 year 11 month on canine, 8 year 1 month on the first premolar, 8 year 5 month on the second premolar, 5 years 10 month on the first molar and 9 year 10 month on the second molar, calcification timing of male in the mandible was 5 year 6 month on central incisor, 5 year 9 month on lateral incisor, 6 year 8 month on canine, 7 year 6 month on the first premolar, 8 year 4 month on the second premolar, 5 years 3 month on the first molar and 9 year 7 month on the second molar. 2. The sequence of calcification at Nolla stage 7 was in consequence to the first molar, central incisor, lateral incisor, canine, the first premolar, the second premolar and second molar. 3. While the sequence of root completion of maxilla was in consequence to the first molar, central incisor, lateral incisor, that of mandible was in order of central incisor, first molar and lateral incisor. 4 the calcification timing of permanent teeth was earlier in female than in male (p<0.05). According to above data, the result of this study is applicable for diagnosis and routine clinical practice for children.

• The korean journal of orthodontics
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• v.29 no.5 s.76
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• pp.521-534
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• 1999

The purpose of this study was to find the difference of stress distribution on canine altered by the application point of preangulated T-loop spring. For this study, the finite element models of upper left canine, upper left second premolar and upper left first molar were made. Also, the finite element models of $0.017{\times}0.025$ inch preangulated, preactivated T-loop spring and $0.018{\times}0.025$ inch stainless steel wire were made. Three types of T-loop spring were made . the middle of activated T-loop is positioned in accordance with the middle position of distance of bracket position of both the canine and first molar, 2mm anterior, 2mm posterior. We compared the forces and the distribution of stress that were generated by the difference of position of T-loop spring. The results were as follows. 1. All of the 3 types of T-loop spring showed the similar retraction forces. 2. All showed the similar amount & pattern of stress distribution. 3. The centers of rotation of canine in 3 types of T-loop spring were same and were positioned between C and D plane. 4. The canine showed the intrusive force by 2mm anterior positioned T-loop spring, but the extrusive force by 2mm posterior positioned T-loop suing. Neverthless, because of the small amount of the forces, the effect of vertical force was not significant.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.772-781
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• 2016

This study is to set the objective criteria on maxillary incisors shade selection by using the colorimetric Shade-Eye NCC as measuring in CIE $L^*$, $a^*$, $b^*$ values, and look into the meaning by analyzing its values. We explain the purpose of this study and gotten their agreement from patients visiting the dentist, 111 people's (men 50, women 61) three teeth, the maxillary central incisor, maxillary lateral incisor, maxillary canines, total of 333 teeth colorimetry. As a result of comparing the differences in colors between cervical margin and incisal edge, ${\Delta}E^*$ of canine is shown as low as $5.81({\pm}2.98)$, followed by lateral incisor of maxilla as $6.51({\pm}3.23)$ and central incisor of maxilla $7.51({\pm}3.04)$. Females show higher luminosity(L*) than males do in all teeth- central incisor, lateral incisor and canine; in yello chroma(b*) males' central incisor is slightly higher than that of females (p<0.05). Age significantly influences the luminosity and red (a*) and yellow chroma (b*) of central incisor(L*); the luminosity(L*), and yellow chroma(b*) of lateral incisor and canine (p<0.05). Smoking doesn't significantly influence the color of natural teeth. Drinking reduces the luminosity of central incisor as well as red chroma of lateral incisor(p<0.05). A chronic illness is likely to reduce the luminosity of central incisor and lateral incisor(p<0.05).

• The korean journal of orthodontics
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• v.39 no.2
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• pp.112-119
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• 2009

Objective: To develop a mixed dentition analysis method in consideration of the normal variation of tooth sizes. Methods: According to the tooth-size of the maxillary central incisor, maxillary 1st molar, mandibular central incisor, mandibular lateral incisor, and mandibular 1st molar, 307 normal occlusion subjects were clustered into the smaller and larger tooth-size groups. Multiple regression analyses were then performed to predict the sizes of the canine and premolars for the 2 groups and both genders separately. For a cross validation dataset, 504 malocclusion patients were assigned into the 2 groups. Then multiple regression equations were applied. Results: Our results show that the maximum errors of the predicted space for the canine, 1st and 2nd premolars were 0.71 and 0.82 mm residual standard deviation for the normal occlusion and malocclusion groups, respectively. For malocclusion patients, the prediction errors did not imply a statistically significant difference depending on the types of malocclusion nor the types of tooth-size groups. The frequency of prediction error more than 1 mm and 2 mm were 17.3% and 1.8%, respectively. The overall prediction accuracy was dramatically improved in this study compared to that of previous studies. Conclusions: The computer aided calculation method used in this study appeared to be more efficient.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.4
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• pp.306-313
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• 2014

Impacted teeth are teeth with a delayed eruption time or that are expected to erupt incompletely. Those teeth can cause a series of potential problems such as root displacement and resorption, periodontal problems in adjacent teeth, referred pain and the formation of cysts and odontogenic tumors. The purpose of this study was to investigate characteristics and treatment of child and adolescent patients younger than 15 years of age that were diagnosed with an impacted tooth who visited the Chosun University Dental Hospital. The impacted tooth, its etiology, treatment and traction period were surveyed through electric medical records, radiographs in 335 patients. We excluded the impacted third molar, supernumerary and deciduous teeth from this study. The most frequently impacted teeth are upper canine, followed by the upper incisor. The most common etiologies of impaction were an abnormal eruption pathway and localized pathologic lesions. The treatment of an impacted tooth was mostly orthodontic traction. The traction period was relatively short in cases with distinct obstacles, with an impacted upper incisor and if patients were younger. An orthodontic traction is considered to be more unfavorable if the patient gets older. Therefore, an early diagnosis and a precise treatment plan through a regular check-ups are mandatory.

• The korean journal of orthodontics
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• v.41 no.6
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• pp.384-398
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• 2011

Objective: The purpose of this study was to analyze the stress distribution and the displacement pattern of mandibular anterior teeth under various intrusive force vectors according to the position of orthodontic miniscrews and hooks, using three-dimensional finite element analysis. Methods: A three-dimensional finite element model was constructed to simulate mandibular teeth, periodontal ligament, and alveolar bone. The displacement of individual tooth on three-dimensional planes and the von Mises stress distribution were compared when various intrusion force vectors were applied. Results: Intrusive forces applied to 4 mandibular anterior teeth largely resulted in remarkable labial tipping of the segment according to the miniscrew position. All 6 mandibular anterior teeth were labially tipped and the stress concentrated on the labiogingival area by intrusive force from miniscrews placed mesial to the canine. The distointrusive force vector led to pure intrusion and the stress was evenly distributed in the whole periodontal ligament when the hook was placed between the central and lateral incisors and the miniscrew was placed distal to the canine. Conclusions: Within the limits of this study, it can be concluded that predictable pure intrusion of the 6 anterior teeth segment may be accomplished using miniscrews placed distal to the canine and hooks located between the central and lateral incisors.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.2
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• pp.253-261
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• 2006

Estimating the size of unerupted teeth is an essential aspect of orthodontic diagnosis and treatment planning in the mixed dentition. Several methods were introduced and used for the prediction. The most common methods among these would be Moyers probability chart and Tanaka and Johnston equations. These are currently used widely, but they were developed for Caucasians. Because there are clear racial differences in teeth size, the objectives of this study were to produce correlation coefficients between the combined mesiodistal widths of the permanent mandibular incisors and those of the canines and premolars for each quadrant, and prediction tables with regression equations, specifically for Korean. 178 young adults (70 women, 108 men, mean age 21.63 years) were selected from the College of Dentistry, Yonsei University, Seoul, Korea. The mesiodistal crown diameters of the permanent teeth were measured with calipers. Significant sexual dimorphism was found in tooth sizes. The correlation coefficients between the total mesiodistal width of the mandibular permanent incisors and those of the maxillary and mandibular canines and premolars were found to be between 0.52 and 0.64. The standard error of the estimatation was better (0.60) for women and the ${\gamma}^2$ values ranged from 0.27 to 0.41 for both sexes Prediction tables were prepared for Korean. This study showed larger canine and premolar diameters than Tanaka and Johnston's and Moyers' studies which might be due to the racial differences. Further investigations with a larger sample size will be needed for more representative data on the Korean population.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.109-115
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• 2006

The calcifying odontogenic cyst (COC) predominantly affected Maxillary anterior segment and it is developmental cyst. But COC showed diverse terminology or classification, clinicopathologic features as well as its biologic behavior COC usually presents as slowly enlarging but otherwise symptomless swelling. Association with impacted teeth and odontoma is described in $24{\sim}30%$. The epithelial lining of COC(ghost cell) appears to have ability to induce the formation of dental tissues in the asjcents connective tissue wall. This case is a COC associated with a odontoma involving an impacted left maxillary canine in 14-year-old female child. Radiographic examination revealed a well-demarcated radiolucent lesion partially occupied by a radiopaque mass, involving the left canine. The histologic sections showed cystic cavity lined with ameloblastic epithelium containing ghost cell masses with regular and irregular shape odontoma. The final pathologic diagnosis was calcifying odontogenic cyst with odontoma(Type IB by Preatorius). Enucleation and elimination of the included tooth were performed. Now endodontic treatment was preformed on the 1st premolar of the upper left jaw, which had a lesion. And the patient and their parents want to have the orthodontic treatment performed and would like to keep the space maintainer.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.101-105
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• 2011

The purpose of this study was to assess the marginal fit of three-unit bridges produced using LAVA CAD/CAM (computer-aided design/computer-aided manufacturing) system and conventional PFG in vitro. Materials and methods: #11, 13 resin teeth were prepared on dentiform, then duplicated. Twenty resin models were fabricated, ten for PFG 3-unit bridges and ten for LAVA 3-unit bridges. Each bridge was cemented on the resin model. Marginal discrepancy was measured with stereoscopic microscope (Nikon DS-Fi 1, Nikon, Japan) at a magnification of ${\times}75$. Independent t-test was done for the statistical analysis. Results: The mean marginal discrepancy values and standard deviations of the PFG bridges was $97.1{\pm}18.7\;{\mu}m$ for incisors, $76.6{\pm}21.8\;{\mu}m$ for canines; that of the LAVA bridges was $90.4{\pm}26.7\;{\mu}m$ for incisor, $110.2{\pm}30.2\;{\mu}m$ for canines. The mean marginal discrepancy between PFG and LAVA for incisor did not show significant difference (P<.05). But for canine, the mean marginal discrepancy of PFG bridges was smaller than that of LAVA bridges (P<.05). Conclusion: The LAVA CAD/CAM 3-unit bridges and the PFG 3-unit bridges showed clinically acceptable marginal discrepancy.