• The korean journal of orthodontics
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• v.37 no.1 s.120
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• pp.65-72
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• 2007

Objective: This study was performed to investigate the influences of extraction and nonextraction treatment on smile esthetics by measuring dental arch width changes. Methods: Pretreatment and posttreatment study models of 30 first premolar extraction cases and 30 nonextraction cases were randomly selected to determine whether extraction treatment results in narrow dental arches, and a consequent unaesthetic smile. Arch widths were measured from the cusp tips of the canines and the first molars. Posterior arch widths were also measured at a constant arch depth derived by averaging randomly chosen nonextraction models. Results: The intercanine widths increased significantly in the extraction sample, whereas the intermolar widths decreased significantly. The arch width at a standardized arch depth was significantly wider in the extraction subjects. Conclusion: These results elucidate that constriction in arch width is not a materialized consequence of extraction treatment. It leads to postulate that an esthetically compromising effect from narrow dental arches on smile is hardly anticipated with extraction treatment.

• Journal of Korean society of Dental Hygiene
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• v.12 no.2
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• pp.345-353
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• 2012

Objectives : The author has studied about correlation of gingival exposure upon smiling and oral facial status that reduce facial aesthetic. Methods : The subjects in this study are 91 female vulunteers who were in aged $21.4{\pm}1.89$ in Suwon. Objectives should be normal oral and facial status without the prosthodontic, orthodontic appliance or conqenital missing tooth, and agree to be examined the oral status and impression taking. 1.Measure the length of gingival exposure upon smiling. 2.Measure of the size on central incisor. 3.Measure of Facial. SPSS(SPSS 10.0 for windows, SPSS Inc, Chicago, USA) was utilized for calculating the correlation coefficient between gingival exposure upon smiling and facial status. Regression analysis was calculated in order to predict the R square for gingival exposure upon smiling. Results : 1.Correlation coefficient between the gingival exposure and length of maxillary central incisor was calculated as reversed correlation(r=-.302, p<0.01), and between the gingival exposure and the ratio of the length of central incisor/width of central incisor was revealed as reversed correlation(r=-.250, p<0.05) on smiling. 2.There was correlation between the gingival exposure and the facial height(r=.351, p<0.01), the lower facial height(r=.454, p<0.01) and the upper lip height(r=.274, p<0.01) upon smiling. 3.There was correlation between the gingival exposure and the ratio of the facial height/facial width(r=.358, p<0.05), the ratio of the upper facial height/facial width(r=.214, p<0.05), and the ratio of the lower facial height/facial height(r=.383, p<0.01) upon smiling. 4.The equation of the regression analysis for gingival exposure upon smiling could be estimated as gingival exposure upon smiling=-5.139+.279${\times}$lower facial height-.615${\times}$maxillary central incisal length-.05${\times}$nasolabial angle. Conclusions : Considering these results, it recommended that treatment planning should be designed in consideration of such factors as the length of maxillary central incisor, facial height, upper lip height and lower facial height, in order to promote the easthetic problems of face on smiling.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.3
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• pp.262-275
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• 2015

The treatment of areas demanding esthetic requirements, such as maxillary anterior teeth, should take into account the achievement of a healthy, harmonious to the surrounding tissue, and an attractive smile line. In this case report, smile line, soft tissue and hard tissue morphology, and the anatomy and proportion of the tooth, must be considered. In patients with unesthetic maxillary anterior ratio due to inadequate gingival contour and diastema caused by peg lateralis, it would be challenging to achieve an esthetic restoration by orthodontic treatment alone. In such case, after orthodontic treatment, dento-gingivo-facial compositional diagnosis and analysis, followed by gingivectomy and prosthodontic restoration is needed to improve the interdental mesial/distal, width/length ratio to achieve a satisfactory esthetic result. In addition, when improving the tooth proportion of peg lateralis by prosthodontic treatment, Porcelain laminate veneer (PLV), which results in less tooth structure loss, reproduction of similar shade to that of the proximal tooth and high transparency, is recommended. This case report demonstrates esthetic improvements by prosthodontic restoration through systematic diagnosis and treatment procedure in patients with unesthetic maxillary anterior proportion after orthodontic treatment due to peg lateralis by means of two female patients aged twenty years old.

• Science of Emotion and Sensibility
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• v.16 no.1
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• pp.95-106
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• 2013

The study compares accuracies between humans and computer algorithms in the discrimination of spontaneous smiles from posed smiles. For this purpose, subjects performed two tasks, one was judgment with single pictures and the other was judgment with pair comparison. At the task of judgment with single pictures, in which pictures of smiling facial expression were presented one by one, subjects were required to judge whether smiles in the pictures were spontaneous or posed. In the task for judgment with pair comparison, in which two kinds of smiles from one person were presented simultaneously, subjects were to select spontaneous smile. To calculate the discrimination algorithm accuracy, 8 kinds of facial features were used. To calculate the discriminant function, stepwise linear discriminant analysis (SLDA) was performed by using approximately 50 % of pictures, and the rest of pictures were classified by using the calculated discriminant function. In the task of single pictures, the accuracy rate of SLDA was higher than that of humans. In the analysis of accuracy on pair comparison, the accuracy rate of SLDA was also higher than that of humans. Among the 20 subjects, none of them showed the above accuracy rate of SLDA. The facial feature contributed to SLDA effectively was angle of inner eye corner, which was the degree of the openness of the eyes. According to Ekman's FACS system, this feature corresponds to AU 6. The reason why the humans had low accuracy while classifying two kinds of smiles, it appears that they didn't use the information coming from the eyes enough.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.3
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• pp.318-327
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• 2019

The purpose of this study was to identify which combination of zirconia crowns and cements is most similar in color to the maxillary primary incisors by varying the color of zirconia crowns, crown thickness, and shade of cements. Prefabricated zirconia crowns in 3 shades and crowns fabricated using 6 types of zirconia blocks were used in this study. These were filled with A2-shade or translucent-shade resin cement and the $L^*$, $a^*$, and $b^*$ values were calculated using a spectrophotometer. The color differences between the natural teeth and the zirconia crowns were assessed. The shade of the final restoration was more similar to that of the natural teeth using A2-shade than translucent-shade resin cement. Application of A2-shade cement to a 0.5-mm-thick crown fabricated from a smile series 2 zirconia block resulted in the color most similar to that of the natural teeth. A2-shade resin cement is recommended for zirconia crown restoration in anterior primary teeth compared to TR-shade resin cement for more esthetic restoration. Since restorations with Nu-smile zirconia crowns were not esthetically favorable in terms of shade, improvement of the shade characteristics of the product or development of a new kind of zirconia crown is required.

• KDI Journal of Economic Policy
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• v.37 no.3
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• pp.55-74
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• 2015

This study examines the effect of a one-on-one outsourced pre-lending consulting service on the repayment behavior of microcredit borrowers in Korea with administrative data from the Smile Microcredit Bank. A random change in the cut-off loan amount for mandatory consulting is utilized as an identification strategy. This three-day pre-lending business consulting service is effective in encouraging repayment behavior of existing businesses but it has no significant effect on start-up loans. The effectiveness of the consulting service in deterring delinquency with regard to existing loans is greater among male borrowers than among females.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.57-75
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• 2005

Quasigroups are algebraic structures closely related to Latin squares which have many different applications. There are several classifications of quasigroups based on their algebraic properties. In this paper we propose another classification based on the properties of strings obtained by specific quasigroup transformations. More precisely, in our research we identified some quasigroup transformations which can be applied to arbitrary strings to produce pseudo random sequences. We performed tests for randomness of the obtained pseudo-random sequences by random walks on torus. The randomness tests provided an empirical classification of quasigroups.

• Bulletin of the Korean Mathematical Society
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• v.53 no.5
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• pp.1411-1425
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• 2016

We provide a partial differential equation for European options on a stock whose price process follows a general geometric Riemannian Brownian motion. The existence and the uniqueness of solutions to the partial differential equation are investigated, and then an expression of the value for European options is obtained using the fundamental solution technique. Proper Riemannian metrics on the real number field can make the distribution of return rates of the stock induced by our model have the character of leptokurtosis and fat-tail; in addition, they can also explain option pricing bias and implied volatility smile (skew).

• The korean journal of orthodontics
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• v.47 no.2
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• pp.100-107
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• 2017

Objective: To analyze the long-term changes in maxillary arch widths and buccal corridor ratios in orthodontic patients treated with and without premolar extractions. Methods: The study included 53 patients who were divided into the extraction (n = 28) and nonextraction (n = 25) groups. These patients had complete orthodontic records from the pretreatment (T1), posttreatment (T2), and postretention (T3) periods. Their mean retention and postretention times were 4 years 2 months and 17 years 8 months, respectively. Dental models and smiling photographs from all three periods were digitized to compare the changes in three dental arch width measurements and three buccal corridor ratios over time between the extraction and nonextraction groups. Data were analyzed using analysis of variance tests. Post-hoc multiple comparisons were made using Bonferroni correction. Results: Soft-tissue extension during smiling increased with age in both groups. The maximum dental width to smile width ratio (MDW/SW) also showed a favorable increase with treatment in both groups (p < 0.05), and remained virtually stable at T3 (p > 0.05). According to the MDW/SW ratio, the mean difference in the buccal corridor space of the two groups was $2.4{\pm}0.2%$ at T3. Additionally, no significant group ${\times}$ time interaction was found for any of the buccal corridor ratios studied. Conclusions: Premolar extractions did not negatively affect transverse maxillary arch widths and buccal corridor ratios. The long-term outcome of orthodontic treatment was comparable between the study groups.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.1 no.1
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• pp.18-24
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• 2005

The purposes of this study were 1) to investigate the oral health problem of the disabled according to the handicapped types, 2) to collect the empirical data for developing and establishing the oral health policies for the handicapped, and 3) to find out the major obstacles against the dental services and oral health promotion. The handicapped subjects were collected by designed cluster sampling and interviewed with structured questionnaire in order to measure the oral health knowledge and behaviors. The subjects were attending the special schools and private or public welfare institutions for crippled disorder, encephalopathy disorder, mental retardation, visual disturbance, hearing defect, and developmental disorder. Oral examination was conducted by 13 trained dentists. 1,476 of handicapped people were finally surveyed. The results were as follows; The experiences of visiting dental office during the last one year in 18~64 year-old disabled people were 48.86% in crippled disorder, 52.50% in mental retardation, 58.24% in visual disturbance, 39.29% in hearing defect, respectively. To improve this challenging situation, we should find out the obstacles against the dental service and oral hygiene maintenance by the types of handicap, and develop the oral health policies which could support and advocate the Korean disabled.