• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.3
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• pp.223-230
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• 2014

Purpose: The purpose of this study was to evaluate the improvement and posttreatment stability of patients treated with extraction of lower incisors. Materials and Methods: The total of 20 patients with extracted lower incisors were analyzed by means of diagnostic models and panoramic x-rays at the time of initial, final and after 2 years of retention period of the treatment. Irregularity index, overjet, overbite, tooth size-arch length discrepancy (TSALD), intercanine width, intermolar width and American Board of Orthodontics cast/radiographic evaluation (ABO-CRE) were analyzed. Statistical analysis was performed using Wilcoxon signed-rank test. Results: After treatment, irregularity index showed significant decrease (P = 0.000). TSALD showed significant increase (P = 0.028). During retention period, irregularity index showed significant increase (P = 0.001). For ABO-CRE, total score showed significant decrease after treatment (P = 0.000) and showed average decreased which was not significant result (P = 0.053). Conclusion: Through evaluation of stability of extraction of lower incisors by means of diagnostic models and panoramic x-rays, it can be concluded that lower incisor extraction treatment had been stable for 2 years after treatment.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.3
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• pp.215-221
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• 2015

Treating patients with severely worn dentition often requires comprehensive prosthetic treatments. Oral rehabilitation and long-term stability could be achieved by analyzing the cause of the wear and changing vertical dimension. The temporary restoration procedure is executed and patient's adaptation is evaluated by long-term observation when treatment is accompanied with increasing vertical dimension. In this case, 54 year-old male presented with worn dentition and esthetic dissatisfaction. In oral manifestations, severely worn dentition with attrition and erosion is diagnosed. To evaluate change of vertical dimension, interocclusal rest space, facial appearance, pronunciation, clinical crown length, distance from incisor edge to labial vestibule are evaluated. Consequently, 2.5 mm increase of vertical dimension that based on articulator incisal pin is determined. After 8 weeks stabilization period with temporary prostheses, definitive prostheses are fabricated. After 6 months follow up period, satisfactory outcomes were achieved both in functional and esthetic aspects through this procedure.

• The korean journal of orthodontics
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• v.25 no.1 s.48
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• pp.19-29
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• 1995

This study was performed to compare the size of soft palate, tongue and airway according to the types of the malocclusion and evaluate the correlation between the size of soft palate, tongue, airway and dentofacial skeleton respectively. The sample of this study was 98 malocclusion female patients between the ages 12 and 17 years. The lateral cephalometric radiographs were taken and the distance, angle, ratio and area of the dentofacial skeleton, soft palate, tongue and airway were measured and evaluated statistically. The results obtained were as follows: 1. There was significant difference in SNB, ANB, facial angle, facial convexity, A-B plane angel, Y axis to FH, SN-MP, Wits appraisal, ODI and APDI according to the types of malocclusion. 2. The hyoid bone was more posteriorly positioned in Class II malocclusion group than other two groups and superio-inferior position of the hyoid bone was not different according to the malocclusion types. 3. The nasopharyngeal area of Class II and Class III malocclusion group was smaller than that of Class I malocclusion group, and the pharyngeal area of Class II malocclusion group was smaller than that of Class I and Class III maocclusion group. There was no difference of the area of the soft palate, tongue, oropharynx and hypopharynx according to malocclusion types. 4. The ramal height and mandibular body length(Go-Me) showed positive correlation with the area of tongue, nasopharynx, oropharynx, and pharynx. SNA did not correlated with the area of tongue and airway but SNB showed positive correlation with the area of hypopharynx and pharynx. The anterior, posterior facial height, upper and lower central incisor position to facial plane showed positive correlation with tongue area.

• The korean journal of orthodontics
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• v.39 no.1
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• pp.6-17
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• 2009

Objective: The purpose of this study was to evaluate the possibility of using a digital model and cone beam computed tomograph(CBCT) image for model analysis. Methods: Model analyses of CBCT images, plaster models, and digital models of 20 orthodontic patients with a permanent dentition with no proximal metal restorations, were compared. Results: The average differences of tooth size measurements were 0.01 to 0.20 mm, and the average difference of arch length discrepancy measurements were 0.41 mm in the maxilla and 0.82 mm in the mandible. The difference in Bolton discrepancy measurements was 0.17 mm for the anterior region and 0.44 mm overall but with no statistically significant difference. When comparing CBCT images with plaster models, the average differences in tooth size measurements were -0.22 to 0.01 mm, and the average differences in arch length discrepancy measurements were 0.43 mm in the maxilla and 0.32 mm in the mandible. Difference in Bolton discrepancy measurements were 0.35 mm in the anterior region and 1.25 mm overall. CBCT images showed significantly smaller overall Bolton discrepancy measurements. Conclusions: Although there were statistically significant differences in some model analysis measurements, the ranges of measurement errors of the digital model and CBCT images were clinically acceptable. Therefore, a digital model and CBCT image can be used for model analysis.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.599-612
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• 2007

The present study was designed to compare the morphological and structural differences of craniofacial structures among 146 children with Class I and Class III malocclusions. The results below were obtained from the study. 1. Sphenoethmoidal synchondrosis continues to grow later in Class III. 2. Anteroposterior length of the nasomaxillary complex was significantly shorter in Class III, but the height of the nasomaxillary complex was similar. 3. Mandibular length and mandibular body length were longer in Class III, but had no statistical significance. Lower anterior facial height was shorter in Class III, but had no statistical significance. 4. Dentoalveolar height was similar between Class I and Class III. 5. In Class I, anterior cranial base took part in the anteroposterior length of the nasomaxillary complex and the mandible. 6. In Class III, anterior cranial base and middle cranial base had higher correlation with the mandible with aging. These results suggest that there exist a little differences between Class I and Class III malocclusions at age $7{\sim}11$, but growth patterns are mostly similar. Therefore it is necessary to correct Class III malocclusions at an early age before skeletal differences appear.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.372-380
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• 2008

Purpose: The purpose of this study was to evaluate the effect of various methods of dentin bonding agent application on microtensile bond strength between dentin and resin, using a 2-step etch-and-rinse dentin bonding agent. Material and methods: Twenty freshly extracted human molars were obtained and divided into 4 groups of 5 teeth. 2-step etch-and-rinse dentin bonding agent was used for all groups. The control specimens were prepared using a direct immediate bonding technique. The delayed dentin sealing (A, C) specimens were prepared using an indirect approach with delayed dentin sealing. For group A, resin was built-up on uncured dentin bonding agent, and for group C, resin was built-up on pre-cured dentin bonding agent. Preparation of the immediate dentin sealing (B) specimens also used an indirect approach with immediate dentin sealing immediately following preparation. All teeth were prepared for a microtensile bond strength test. Specimens were stored in water for 24 hours. Ten beams (1.0 ${\times}$ 1.0 ${\times}$ 11 mm) from each tooth were selected for testing. Bond strength data (MPa) were analyzed with a one-way ANOVA test, and post hoc comparison was done using the Scheffe's test. Results: The mean microtensile bond strengths of control group, B and C (DDS with pre-cure) were not statisticaaly different from each other at 32.7, 33.3, 34.2 MPa. the bond strength for group A (DDS without pre-cure), 19.5 MPa, was statistically different (P < .01) from the other 3 groups. Conclusion: When preparing teeth for indirect bonded restorations, DDS with pre-curing dentin bonding agent and IDS results in the same bond strength between dentin and resin. On the contrast, the bond strength was decreased when DDS without pre-curing dentin bonding agent was used.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.342-347
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• 2009

Statement of problem: when using resin for class II restoration, micoleakage by instrumentation can be regarded as the primary negative characteristic. A review of the available literature suggests that using flowable resin as liner to decreased microleakage. Purpose: The aim of this study was to determine the influence of the nanofilled flowable resin lining on marginal microleakage after load cycling in class II composite restoration fillings using nanofiller resin. Material and methods: 24 extracted premolars were prepared with class II cavity. F group was restored the nanofilled resin with the nanofilled flowable resin as liner. NF group was restored the nanofilled resin only. After restoration, an experiment was performed on 2 groups using a 300N load at 104, 105 and 106 cycles. Prior to and before each load cycling, it was gauged length on total marginal microleakage, axial marginal microleakage and buccal, gingival, lingual marginal microleakage. Data were analyzed with the Mann-Whitney test & Kruskal-Wallis test. Results: There were statistically significant differences between 2 groups and between individual groups. (P <.05) The result showed less microleakage in teeth restored by the nanofilled resin, which was lined by the nanofilled flowable resin. Conclusion: There was significant reduction in microleakage when the nanofilled flowable resin lining was placed underneath the nanofilled resin in class II composite restoration fillings.

• The korean journal of orthodontics
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• v.34 no.3 s.104
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• pp.241-251
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• 2004

Previous studies have focused on the causes of root resorption after orthodontic treatment and treatment methods to reduce this phenomenon, and have been mainly associated with developed, mature roots. As parents become increasingly interested in their children's' dentition, orthodontists are performing fixed orthodontic treatment on patients of less than 10 years and before the completion of the immature root. Thus, the author evaluated the changes of root length and root form of maxillary immature incisors after orthodontic treatment, compared with those of mature teeth, and investigated the correlation according to gender, treatment duration, and displacement of incisors. The sample consisted of an immature root group of twenty-eight persons (between 8 and 10 years old) and a mature root group of thirty-one persons (between 11 and 15 years old). The crown and root length of the maxillary four incisors were measured with a periapical radiograph, changes in root length and crown-root ratio were calculated, and root form was classified according to a scoring system. The results were as follows. 1. The development of immature roots was not affected by orthodontic treatment and mostly showed normal root length and apical form. 2. Root length of immature teeth was sustained or became shorter, partially in long treatment duration or with open bite patients. Even though the teeth reached their normal root length, they demonstrated a blunt form. 3. Most of the mature roots showed mild resorption, and the form of mature roots was more blunt than the developed form of the immature roots (p<0.05). 4. The developed form of the immature roots was statistically related to treatment duration, while the form of the mature roots was significantly related to the displacement of incisors (p<0.05). 5. In contrast, other variables such as gender, classification of malocclusion, changes in overbite, and changes of U1 to SN showed no correlation with the root resorption of both groups.

• Applied Microscopy
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• v.40 no.3
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• pp.147-154
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• 2010

The aim of this study is to determine microstructure, chemical composition and crystal structure of hydroxyapatite for mouth teeth using optical microscopy and electron microscopy as well as electron probe micro-analysis (EPMA). Enamel, a protective cover to the teeth, consisted of rods oriented in regular and had relatively higher crystallinity and Ca component. In contrast, dentin showed a sponge-like microstructure with circular holes which were passages of dentinal tubules, and had higher Mg component than the enamel region due to its higher organic content. Hydroxyapatite crystals appeared as large rods in enamel, but as small needles in dentin. Their electron diffraction patterns were different by their crystallinity as well as by the organic content of the matrix.

• Journal of Periodontal and Implant Science
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• v.28 no.1
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• pp.1-16
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• 1998

자연치의 경우에는 치주지수간의 상관관계가 정립되어 병적인 상태에 대한 진단과 그에 따른 치료방법을 결정하는데 많은 정보를 제공하나, 인공매식치에서는 아직 논란의 여지가 많다. 이에 임상적으로 안정화되어 기능하고 있는 인공매식치에서 치주지수간의 상관관계에 관하여 연구하고자 하였다. 총 43명의 환자(평균 44.7세)에 식립된 178개의 인공매식치를 연구에 이용하였다. 인공치아매식술을 시행한 후 1년에서 6년이 경과한 인공매식치에서 상부보철물을 제거한 후 치태지수, 치은열구출혈지수, 각화점막지수, 치주낭깊이, Periotest Values(PTVs) 등을 측정하여 각각의 분포상황과 상관관계를 분석하였다. 이 연구의 결과는 다음과 같다. 1. 치태지수의 평균값은 $0.83{\pm}0.82$이었다. 2. 치은열구출혈지수의 평균값은 $1.04{\pm}0.86$이었다. 3. 각화점막지수의 평균값은 $2.47{\pm}0.95$이었다. 4. 치주낭깊이의 평균값은 $3.12{\pm}1.14\;mm$이었다. 5. Periotest Values(PTVs)의 평균값은 $-0.66{\pm}4.28$이었다. 6. 치태지수, 치주낭깊이가 증가함에 따라 치은열구출혈지수는 유의성있게 증가하였다(P<0.01). 7. 각화점막지수가 증가함에 따라 치은열구출혈지수는 유의성있게 감소하였다(P<0.01). 8. 치은열구출혈지수와 매식치동요도 사이에서는 유의성있는 상관관계를 발견할 수 없었다(P>0.05). 9. 치주낭깊이와 매식치동요도 사이에서도 유의성있는 상관관계를 발견할 수 없었다(P>0.05). 10. 인공매식치의 직경과 길이가 증가함에 따라 매식치동요도는 유의성있게 감소하였다(P<0.01). 11. 하악에서의 매식치동요도가 상악의 경우와 비교하여 유의성있게 작았다(P<0.01). 결론적으로, 인공매식치에서도 자연치에서와 동일한 양상으로 치태가 많을수록, 그리고 치주낭 깊이가 깊을수록 염증의 심도와 관련이 깊은 것으로 생각된다. 특히, 인공매식치의 경우에는 같은 양의 치태가 존재시에 각화치은이 충분히 있는 쪽이 염증발생이 적은 것으로 나타났다. 치주조직에 염증이 존재하는 경우, 자연치아에서는 치아의 동요도가 증가하는 것으로 알려져있으나, 이 실험의 인공매식치에서는 유의성있는 상관관계를 발견할 수 없었다. 임상적으로 안정화된 인공매식치의 동요도는 염증정도에는 큰 영향을 받지 않고 인공매식치의 직경과 길이가 증가함에 따라 감소함을 보여주고 있다. 또한, 인공매식치의 동요도는 상하악골의 골질에 따라 차이가 있음을 명확히 보여주고 있다.