• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.2
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• pp.119-128
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• 2011

In the process of assessing the children with anterior crossbite in early mixed dentition, it has frequently been detected that the stronger the skeletal pattern of the malocclusion is, the more markedly delayed the development and eruption of maxillary teeth are. If the anteroposterior characteristics of craniofacial skeleton has any relationship with dental maturation, the evaluation of dental development and eruption was thought to be able to contribute to early diagnosis of crossbite in children. This study was performed for the purpose of elucidating the relationship between dental maturation of maxillary teeth and some cephalometric values in children with anterior crossbite of maxillary undergrowth type in early mixed dentition. Among the children in Hellman dental age IIA and IIC who attended the Pediatric Dental Clinic of Pusan National University Hospital with orthodontic problems, cases with Class III malocclusion were classified and 50 cases of maxillary undergrowth type and type with normal maxilla respectively were randomly selected and studied as subjects. From their lateral cephalographs and panoramic radiographs, their anteroposterior skeletal features, the dental maturity and eruption rate were obtained of each group and data were analyzed to yield the results as follows: 1. Comparing the maturity of maxillary teeth of both groups, only the first molars of maxillary undergrowth group showed significantly slower development and eruption (p<0.05). 2. There was high correlation between maturation of maxillary 1st molar and chronological age(p<0.05). 3. Among the parameters of anteroposterior relationship of skeletal pattern in maxilla and mandible. Wits was revealed as a useful index to predict both the calcification and eruption rate of the 1st molars whereas SNA was to eruption rate(p<0.05).

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.855-864
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• 1998

The purposes of this study were to evaluate the cephalometric characteristics of Korean female patients with Class II division 2 malocclusion and to compare Korean females with Caucasian females who had same type of malocclusion. All of the samples had Class II division 2 malocclusion with deep overbite (more than 4mm) and full permanent dentition. These samples were divided into two groups according to the races: Group 1(N=16; Korean females; average age=18Y 2M) and Group 2 (N:20; Caucasian females; average age=14Y 2M). The pretreatment lateral cephalograms were measured, analyzed and compared by using 38 variables and independent t-test. And the results were as follows: 1. Although there were no differences in Overbite, SN to mandibular plane angle, Palatomandibular plane angle, and FMA between Group 1 and 2, the other vertical relation variables of maxilla and mandible (SN to palatal plane angle, SN to occlusal plane angle, ODI) of Group 1 showed more clockwise rotation tendency of occlusal plane and less hypodivergency tendency than those of Group 2. 2. There were no differences in mandibular body length and ramus height between Group 1 and 2 except small upper genial angle of Group 1. There was less counterclockwise rotation tendency of mandible in Group 1. 3. There were no statistical significant differences in UAFH/LAFH and PFH/AFH between Group 1 and 2. 4. Although there were no differences of overjet and anteroposterior position of mandible between Group 1 and 2, the position of maxilla of Group 1 was more retropositioned than that of Group 2. 5. Except the more protrusion of lower incisor to A-Pog of Group 1, there were no differences of inclination and distance of upper and lower incisors to basal plane between Group 1 and 2. 6. The distance from upper- first molar to palatal plane showed no difference between Group 1 and 2. But the distance from lower first molar to mandibular plane of Group 1 was greater than that of Group 2. So it may be partially related to the clockwise rotation of occlusal plane and the less counterclockwise rotation tendency of mandible of Group 1. 7. Group 1 had more protrusive upper and lower lips than Group 2.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.537-549
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• 1998

The purpose of this study was to evaluate the influence of root resection and retrograde cavity preparation methods on the apical leakage in endodontic surgery. To investigate the effect of various root resection and retrograde cavity preparation methods on the apical leakage, 71 roots of extracted human maxillary anterior teeth and 44 mesiobuccal roots of extracted human maxillary first molars were used. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. Three millimeters of each root was resected at a 45 degree angle or perpendicular to the long axis of the tooth according to the groups. Retrograde cavities were prepared with ultrasonic instruments or a slow-speed round bur, and occlusal access cavities were filled with zinc oxide eugenol cement. Three coats of clear nail polish were placed on the lateral and coronal surfaces of the specimens except the apical cut one millimeter. All the specimens were immerged in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using two-way ANOVA and Duncans Multiple Range Test. The results were as follows: 1. No statistically significant difference was observed between ultrasonic retrograde cavity preparation method and slow-speed round bur technique, without apical bevel (p>0.05). 2. Ultrasonic retrograde preparation method showed significantly less apical leakage than slow-speed round bur technique, with bevel (p<0.0001). 3. No statistically significant difference was found between beveled resected root surface and non-beveled resected root surface, with ultrasonic technique (p>0.05). 4. Non-beveled resected root surface showed significantly less apical leakage than beveled resected root surface, with slow-speed round bur technique (p<0.0001). 5. No statistically significant difference in apical leakage was found between the group of retrograde cavity prepared parallel to the long axis of the tooth and the group of one prepared perpendicular to the long axis of the tooth (p>0.05). 6. Regarding isthmus preparation, ultrasonic retrograde preparation method showed significantly less apical leakage than slow-speed round bur technique, in the mesiobuccal root of maxillary molar, without bevel (p<0.0001).

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.1
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• pp.32-44
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• 2023

Purpose: The purpose of this study was to investigate the effect of implant connection type on marginal bone loss (MBL) and to analyze the factors that affect MBL. This study focuses on single implants planted in the upper and lower first molar area. Materials and Methods: A total of 87 implants from 68 patients were tracked for a period over 5 years. There were 57 external connection type (EC) implants and 30 internal connection type (IC) implants in 38 males and 30 females. The MBL and EA were measured from intraoral radiograph images taken after 5 years at most. Results: Significant difference in MBL between EC and IC type was observed in patients without GBR or diabetes. Patients without GBR exhibited an MBL of -0.065 ± 0.859 mm in EC type and -0.627 ± 0.639 mm in IC type (P = 0.025). Using multiple regression analysis, a statistically significant negative correlation was observed between MBL and conditions including implant-abutment connection type (β = -0.303), diabetes (β = -0.113), emergence angle > 30° (β = -0.234), and age (β = -0.776). Conclusion: Within this results, IC type implants had less MBL than EC type, and implant prosthesis with emergence angle over 30° showed greater MBL. To minimize the MBL of the implant and ensure implant stability, careful consideration should be given to the EA of implant prosthesis and its connection type.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.4
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• pp.373-384
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• 2023

This study aims to confirm the average chronologic age according to the developmental stages of the mandibular canine (L3), first and second premolars (L4, L5), and second and third molars (L7, L8) in children and adolescents, and to confirm the developmental stage of L3, L4, L5, and L7, which can estimate the development of L8. A total of 1,956 digital panoramic radiographs of healthy individuals aged between 6 and 15 years who visited Seoul National University Dental Hospital from January 2019 to December 2020 were selected. The developmental stages of L3, L4, L5, L7, and L8 on both sides were evaluated using the dental maturity scoring system proposed by Demirjian and Goldstein. The average age at which the follicle of L8 was first observed was around 9.34 ± 1.35 years and varied from 6 to 12 years. The possibility of agenesis of L8 was high when no traces of L8 were observed after the following stages: L3, L4, and L5 at the developmental stage F and L7 at the developmental stage E; the age was about 10 years. In estimating the development of L8, when only one tooth was considered, estimation accuracy with L5 was the highest, and there was no significant difference when all four teeth were included. This study showed the age distribution according to the developmental stages of L3, L4, L5, L7, and L8 in children and adolescents and confirmed the developmental stages of L3, L4, L5, and L7, which can be used to estimate the development of L8.

• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.785-797
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• 1998

This study has been done to prove that keratinized gingiva is required for the periodontal health and to analyse the adequate width that is necessary. Until now, the study on frenum has been documented on changing its location. But the location or the formation of the frenum has not been reported. This experiment has used 173 patients from the department of periodontology of Dankook University to investigate the width of keratinized gingiva, the formation of the frenum and its location for the frequency. This study also looks into the relationship between the gingival recession and the structure of the frenum, and affects they have on periodontal health. The width of the keratinized gingiva in the mandible has been found to be highest in the lateral incisor than in the central incisor. The width decreased from the canine to the first premolar until it reached the molar. The interproximal area of the mandibular frenum was 77.9%, which was greater than the frequency (22.1%) from the midline of the teeth. The highest frequency of frenum was at 30.6% in between the both central incisor then second greatest at 20.6% in between the right canine and the right first premolar. Frenum was not found in between the second premolar and the distal area. In the morphology of the frenum, it was found that 43.4% out of 551 parts were found to be a single narrow frenum, and the double or triple ligamented form of the complex frenum were found in similar frequency of 237 parts, but the broad frenum was rarely frequent. The incisal area was popular mostly with the single narrow frenum, the left premolar area frequented 57.4%, and the right premolar frequented 64.7%. Because the distance between the frenum apex and the gingival margin measured to be about 5mm or greater, the frenum apex started in the mucogingival junction and not just below the keratinized gingiva. In the 551 area investigated, 48.3% of gingiva showed recession, incisal area had recession the least at 44.9%, right buccal side at 47.4%, and right buccal side frequented the highest at 52.1%. The teeth that showed recession recessed at the average of 2.151.0.mm and the left canine showed the greatest amount of gingival recession. In the investigation to find out if the keratinized gingiva and the gingiva recession had mutually related somehow, the width of keratinized gingiva showed no affect on the probing depth, but had affected in the gingiva recession. This investigation showed that the gingival recession and the morphology of the frenum related in that, the single narrow frenum had recessed the least and the broad frenum recessed the most. With this analysis, a conclusion was drawn that the morphology of the frenum had affected in the gingical recession.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.135-143
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• 2017

Purpose: This research was conducted to compare the marginal and internal fit of zirconia prostheses fabricated with the model scan method and the intraoral scan method. Materials and methods: In this study, 20 extracted human mandibular first molar was used in the preparation of abutment tooth for the fabrication of zirconia prostheses. In the first group, the model scan method was applied on 10 prepared teeth. In the other group, the intraoral scan method was used on other 10 prepared teeth. Datum of both groups were transmitted to the software system. Afterwards, 20 zirconia prostheses were fabricated using the Ceramill system. Weight technique was used to evaluate the internal gap of the zirconia prostheses. In the Replica technique, marginal gap of the zirconia prostheses were analyzed by optical microscopy. Statistical analysis was based on one-way ANOVA. Results: Model scan group showed lower average weight than intraoral scan group when weight technique was applied, which has significance (P < .05). Also, model scan group showed significantly lower figures in all 5 measurements of replica technique than intraoral scan group (P < .05). Conclusion: Zirconia prostheses of both groups demonstrated clinically acceptable margin and internal fit. However, model scanned zirconia prostheses showed higher marginal and internal fit than intraoral scanned crowns.

• The korean journal of orthodontics
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• v.34 no.4 s.105
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• pp.289-301
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• 2004

It is the purpose of this study to characterize oral symptoms and to comprehend the cause and the relapse possibility of patients with open bite. This case study examines the orthodontic treatment of a group of female patients with open bite and Angle's Class I malocclusion. A cephalograph of the patient was taken and tracing of the radiograph was completed. In addition to Bjork and Ricketts analysis, additional measurements of specific areas were taken. The occlusal plane was determined by drawing a line connecting the mesiobuccal cusp tip of the maxillary first molar and the incisal edge of the maxillary central incisors. Patients were divided into two groups depending on the relationship between the marginal ridge of the maxillayy first premolar and the drawn line. Those patients with marginal ridges above the occlusal plane were placed into Group 1, while Group 2 subjects exhibited marginal ridges lower than the occlusal plane. The common characteristics within each group and the characteristic differences between each group both prior to and after orthodontic treatment were examined, and finally, the functional oral volume of each patient was analyzed. The results of the case study were as follows: 1. An examination of the skeletal relationship and anatomical form for both Group 1 and 2 showed that all subjects exhibited hyperdivergent skeletal forms, but Group 2 subjects generally demonstrated underdevelopment of the mandible and a smaller articular angle, resulting in an anterior positioning tendency of the mandible. 2. An analysis of the maxillary arches of Group 1 subjects prior to and after orthodontic treatment showed that the antero-inferior direction had changed to an antero-superior directional tendency, while the maxillary arches of the Group 2 patients showed a trend from an antero-superior direction to an antero-inferior relationship. The mandibular arches in both groups showed a change to an antero-superior direction. 3. Functional space analysis showed that Group 2 patients exhibited a greater tendency of haying palatal planes that drop in a postero-inferior direction, resulting in a more severe open bite than their Group 1 counterparts. The results of this case study show that although patients belonging to either Group 1 or 2 exhibited few external differences in the appearance of open bite, an examination of the dental and skeletal relationships by analyzing patient cephalographs showed that patients presenting with flat maxillary occlusal planes exhibited more severe open bite relationships than patients with curved occlusal planes.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.4
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• pp.394-402
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• 2017

Purpose: The purpose of this study is to evaluate the displacement of artificial tooth of monolithic complete denture manufactured by milling and 3D printing method in which the denture base and the artificial teeth are simultaneously made. Materials and methods: Twelve upper and lower complete dentures for each were made by milling and 3D printing method. Group Up and Group Lp are a group of upper and lower dentures made by printing, and Group Um and Group Lm are denture groups made by milling. Group Uc and Group Lc are is a group of finally designed upper and lower dentures respectively. Measurements were performed between both central incisors (AB, ab), both canines (CD, cd), both first molars (EF, ef), between an incisor and a first molar (AE, ae), and between incisor and lingual point (AG, ag) for each upper and lower denture. Results: AG and ag value between printed dentures and original ones as well as between milled dentures and original ones showed a statistically significant difference (One-way ANOVA, P<.05) in both lower and upper monolithic dentures. In the lower monolithic ones, ab, cd and ef value revealed a significant difference between Group Lp and Group Lm (One-way ANOVA, P<.05). Conclusion: Dentures made using milling or 3D printers revealed statistically significant difference compared with those of original data. However, it showed clinically very accurate reproducibility.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.6
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• pp.643-647
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• 2007

Purpose: The purpose of study was to investigate the correlationship between lip canting change and occlusal canting change after bimaxillary orthognathic surgery, and the ratio of lip canting change and occlusal canting change after the surgery. Patients and methods: The subjects for this study was obtained from a group of 25 patients who took bimaxillary orthognathic surgery for occlusal canting correction at the Department of the Oral and Maxillofacial Surgery, Samsung Medical Center in Seoul, Korea between January 2000 and December 2005 and a patient's chart had to contain a resting frontal facial photograph in natural head position and a corresponding PA cephalogram in occlusion on the same day before the surgery and post-op 6 months later. The lip canting change was assessed with the angle each labial commissure and the bipupilary reference line. And, the occlusal caning change in the frontal plane was assessed with the angle between the each maxillary first molar occulasal surface and the bi-frontozygomatic suture reference line. Results: In angular measurement, average occlusal canting change was $3.09^{\circ}$ and standard deviation was $1.05^{\circ}$, average lip canting change was $1.56^{\circ}$ and standard deviation was $1.05^{\circ}$. In linear measurement, average occlusal canting change was 2.41mm and standard deviation was 2.75mm, average lip canting change was 1.18mm and standard deviation was 0.43mm. Lip canting correction ration to occlusal canting correction was 51.5(${\pm}8.4$)% in angular measurement and 48.8(${\pm}9.1$)% in linear measurement. Under Pearson's correlation analysis, Pearson's correlation coefficient was 0.869 in angular measurement and 0.887 in linear measurement(p-value < 0.01). High correlationship was shown between occlusal canting change and lip canting change. Conclusion: First, Bimaxillary orthognathic surgery can correct lip canting as well as occlusal canting. Second, The average amount of lip canting correction is $51.5{\pm}8.4%,\;48.8{\pm}9.1%$ of occlusal canting correction in the study.