• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.5
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• pp.360-364
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• 2021

Objectives: The purpose of this study was to evaluate the clinical and radiographic characteristics of idiopathic bone cavity (IBC) to determine the effect of surgical intervention on the process of healing. Materials and Methods: All cases diagnosed with IBC during the period of 2011 to 2020 at our Department of Oral and Maxillofacial Surgery were searched. Ninety cases were retrieved. The features evaluated were sex, age, contour of the lesion, number of teeth involved, site, history of trauma, and postoperative healing pattern. The significance of differences was assessed by Mann-Whitney U test and chi-square test. Results: The female:male ratio showed no predilection toward either sex (0.9:0.8). The mean age of the collected sample was 22.05±14.38 years, and the age ranged from 10 to 58 years. All cases presented in the mandible and showed well-circumscribed radiolucency. Margins were either scalloped or round in shape, and the size varied from one tooth to six teeth involvement. Seventy cases involved three or fewer roots. Three cases showed bilateral lesion. Four cases had a history of trauma at the area of the lesion. Fifty-one cases were followed for six months after surgery, and all showed increased bone density at the lesion. Conclusion: There is no definitive radiological or clinical feature of IBC. Considering the diversity of clinical and radiological features, such a diagnosis relies primarily on surgical findings of an empty bone cavity with no epithelial lining. Our data suggest that surgical intervention be the first choice of treatment as opposed to observation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.2
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• pp.112-119
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• 2021

Objectives: Myxomatous odontogenic tumors (MOTs) are the third most common odontogenic tumors in the oral and maxillofacial region. Due to its slow-growing, but locally invasive nature, the tumor is usually detected by accident or only when it becomes a large mass, which causes facial deformity. Materials and Methods: Current study reports three unusual cases of MOT including huge myxoma involve the mandible in middle-aged man, MOT with ossifying fibroma pattern in mandible, and MOT in maxilla of young female patient. The diagnosis and treatment strategy of MOTs was also summarized and updated. Results: In reported three cases of patients with large MOTs, surgical treatment was indicated with fibular free flap reconstruction in the mandible and plate reconstruction in the maxilla. The tumors were successfully treated with radical resection and did not show signs of recurrence during the follow-up period. Conclusion: Surgical treatment indication depends on size, the position of the lesion, patient systemic condition and surgeon individual experience. In the case of a large tumor, radical resection and reconstruction is the standard surgical strategy. The conservative surgical treatment including enucleation with wide curettage is still under controversy. The recurrence rate for MOTs is significantly high, up to 30%, therefore long-term follow-up is essential.

• Fashion & Textile Research Journal
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• v.25 no.2
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• pp.248-254
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• 2023

This study aims to measure the skin rigidity of different facial areas among Koreans and propose guidelines for each area's skin rigidity that can be applied with a facial robot for testing respiratory protective devices. The facial skin rigidity of 40 participants, which included 20 men and 20 women, aged 20 to 50, was analyzed. The rigidity measurement was conducted in 13 facial areas, including six areas in contact with the mask and seven non-contact areas, by referring to the facial measurement guidelines of Size Korea. The facial rigidity was measured using the Durometer RX-1600-OO while in a supine position. The measurement procedure involved contacting the durometer vertically with the reference point, repeating the measurement of the same area five times, and using the average of three values whose variability was between 0.4 and 4.2 Shore OO. The rigidity data analysis used precision analysis, descriptive statistics analysis, and mixed-effect ANOVA. The analysis confirmed the rigidity of the 13 measurement areas, with the highest rigidity of the face being at the nose and forehead points, with values of 51.2 and 50.8, respectively, and the lowest rigidity being at the chin and center of the cheek points, with values of 19.2 and 20.7, respectively. Significant differences between gender groups were observed in four areas: the tip of the nose, the point below the chin, the area below the lower jaw, and the inner concha.

• Journal of Periodontal and Implant Science
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• v.54 no.2
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• pp.122-135
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• 2024

Purpose: This retrospective study aimed to assess the long-term cumulative survival rate of titanium, sandblasted, large-grit, acid-etched implants over a 10-year follow-up period and investigate the factors affecting the survival rate and change in marginal bone loss (MBL). Methods: The study included 400 patients who underwent dental implant placement at the Department of Periodontology of Seoul National University Dental Hospital (SNUDH) between 2005 and 2015. Panoramic radiographic images and dental records of patients were collected and examined using Kaplan-Meier analysis, Cox proportional hazards regression analysis, and multiple regression analysis to determine the survival rates and identify any factors related to implant failure and MBL. Results: A total of 782 implants were placed with a follow-up period ranging from 0 to 16 years (mean: 8.21±3.75 years). Overall, 25 implants were lost, resulting in a cumulative survival rate of 96.8%. Comparisons of the research variables regarding cumulative survival rate mostly yielded insignificant results. The mean mesial and distal MBLs were 1.85±2.31 mm and 1.59±2.03 mm, respectively. Factors influencing these values included age, diabetes mellitus (DM), jaw location, implant diameter, bone augmentation surgery, and prosthetic unit. Conclusions: This study found that the implant survival rates at SNUDH fell within the acceptable published criteria. The patients' sex, age, DM status, implant location, implant design, implant size, surgical type, bone augmentation, and prosthetic unit had no discernible influence on long-term implant survival. Sandblasted, large-grit, acid-etched implants might offer advantages in terms of implant longevity and consistent clinical outcomes.

• Radiation Oncology Journal
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• v.17 no.1
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• pp.78-83
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• 1999

Purpose : We have compared the characteristics of Siemens virtual wedge device with physical wedges for clinical application. Materials and Methods : We investigated the characteristics of virtual and physical wedges for various wedge angles (15, 30, 45, and 60$^{\circ}$) using 6- and 15MV photon beams. Wedge factors were measured in water using an ion chamber for various field sizes and depths. In case of virtual wedge device, as upper jaw moves during irradiation, wedge angles were estimated by accumulated doses. These measurements were performed at off-axis points perpendicular to the beam central axis in water for a 15cm${\times}$20cm radiation field size at the depth of loom. Surface doses without and with virtual or physical wedges were measured using a parallel plate ion chamber at surface. Field size was 15cm H20cm and a polystyrene phantom was used. Results : For various field sizes, virtual and physical wedge factors were changed by maximum 2.1% and 3.9%) , respectively. For various depths, virtual and physical wedge factors were changed by maximum 1.9% and 2.9%, respectively. No major difference was found between the virtual and physical wedge angles and the difference was within 0.5$^{\circ}$ . Suface dose with physical wedge was reduced by maximum 20% (x-ray beam :6 MV, wedge angle:45$^{\circ}$, 550: 80 cm) relative to one with virtual wedge or without wedge. Conclusions : Comparison of the characteristics of Siemens virtual wedge device with physical wedges was performed. Depth dependence of virtual wedge factor was smaller than that of physical wedge factor. Virtual and physical wedge factors were nearly independent of field sizes. The accuracy of virtual and physical wedge angles was excellent. Surface dose was found to be reduced using physical wedge.

• The korean journal of orthodontics
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• v.32 no.1 s.90
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• pp.19-31
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• 2002

To investigate the association between the hypertrophy of adenoid and jaw morphology during growth, this paper was based on children patients with experimental adenoids (male-15 subjects at each bone age group, female-15 subjects at each bone group) and comparing them to data taken from a control group (male-15 subjects at each bone age group, female-15 subjects at each bone group) with normal respiratory function. The comparisons between the groups were done at each growth stage using cervical vertebrae maturation index(CVMI) of Hassel. The obtained results were as follows : 1. The differences in craniofacial morphology between experimental group and control group were appeared from CVMI 3 and CVMI 4 (aroud adolescent period) in males, and from CVMI 1 in females. 2. The mandibular position of experimental group was more inferior than control group. The difference appeared at adolescent period(male : at CVMI 4, female : at CVMI 5). 3. Experimental group had greater anterior facial height than control group. This difference seemed a relation with lower anterior facial height. The difference appears at CVMI 3(11.94 ${\pm}$ 1.38 years old, at adolescent period) in male and at CVMI 1 in female. 4. The adenoid size of control male group was increased until CVMI 2(10.58 ${\pm}$ 1.07 years old, just before adolescent growth peak) and then decreased, but in female the adenoid size was decreased from CVMI 1(6.92 ${\pm}$ 0.53 years old).

• Progress in Medical Physics
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• v.26 no.3
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• pp.160-167
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• 2015

Radiation exposure from medical diagnostic imaging procedures to patients is one of the most significant interests in diagnostic x-ray system. A miniature x-ray intraoral tube was developed for the first time in the world which can be inserted into the mouth for imaging. Dose evaluation should be carried out in order to utilize such an imaging device for clinical use. In this study, dose evaluation of the new x-ray unit was performed by 1) using a custom made in vivo Pig phantom, 2) determining exposure condition for the clinical use, and 3) measuring patient dose of the new system. On the basis of DRLs (Diagnostic Reference Level) recommended by KDFA (Korea Food & Drug Administration), the ESD (Entrance Skin Dose) and DAP (Dose Area Product) measurements for the new x-ray imaging device were designed and measured. The maximum voltage and current of the x-ray tubes used in this study were 55 kVp, and 300 mA. The active area of the detector was $72{\times}72mm$ with pixel size of $48{\mu}m$. To obtain the operating condition of the new system, pig jaw phantom images showing major tooth-associated tissues, such as clown, pulp cavity were acquired at 1 frame/sec. Changing the beam currents 20 to $80{\mu}A$, x-ray images of 50 frames were obtained for one beam current with optimum x-ray exposure setting. Pig jaw phantom images were acquired from two commercial x-ray imaging units and compared to the new x-ray device: CS 2100, Carestream Dental LLC and EXARO, HIOSSEN, Inc. Their exposure conditions were 60 kV, 7 mA, and 60 kV, 2 mA, respectively. Comparing the new x-ray device and conventional x-ray imaging units, images of the new x-ray device around teeth and their neighboring tissues turn out to be better in spite of its small x-ray field size. ESD of the new x-ray device was measured 1.369 mGy on the beam condition for the best image quality, 0.051 mAs, which is much less than DRLs recommended by IAEA (International Atomic Energy Agency) and KDFA, both. Its dose distribution in the x-ray field size was observed to be uniform with standard deviation of 5~10 %. DAP of the new x-ray device was $82.4mGy*cm^2$ less than DRL established by KDFA even though its x-ray field size was small. This study shows that the new x-ray imaging device offers better in image quality and lower radiation dose compared to the conventional intraoral units. In additions, methods and know-how for studies in x-ray features could be accumulated from this work.

• The korean journal of orthodontics
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• v.31 no.5 s.88
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• pp.505-515
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• 2001

The purpose of this study was to measure the average tooth size of Korean with normal occlusion. According to the study, the average tooth ratios between the upper and lower teeth which could assure the proper ovebite, overjet and good interdigitation were calculated. The normal occluson sample of this study consisted of 43 Korean male adults and 51 Korean female adults. Among them, 22 Korean male adults and 51 Korean female adults were from KAO(Korean Association of Orthodontists), 21 Korean male adults were from Department of Orthodontics, College of Dentistry, Yonsei University. The results from this study were as follows : 1 The average tooth size of Korean Norm classified by male and female was measured. 2. The average tooth size of Korean male adults with normal occlusion was significantly larger than that of Korean female adults except upper and lower first molars. (p<0.05) 3. The tooth ratio which could Predict the proper overbite and overjet in anterior teeth and proper occlusion in posterior teeth was calculated. 1) Sum of inciosrs = 4:2.97 2) Neff's anterior coefficient = 1.22 3) Bolton's anterior ratio = 78.29%, overall ratio = 91.14% 4. A positive correlation was observed between the sum of lower anterior incisors and the sum of unilateral canine and premolars In each jaw. Based this correlation, the regression equation was made which could Predict the sum of unerupted unilateral canine and premolars in mired dentition. 1) Sum of unilateral unerupted upper canine and premolars' width = 10.435018 + 0.513346 ${\times}$ (sum or lower 4 incisors' width) 2) Sum of unilateral unerupted lower canine and premolars' width = 9.654002 + 0.502565 ${\times}$ (sum of lower 4 incisors' width)

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.380-385
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• 2010

Introduction: The iliac crest has been the accepted place to obtain bone for reconstruction in oral and maxillofacial surgery. The iliac crest has many advantages because of its accessibility, large amount of cancellous bone, relative ease of bone harvest, possibility of two team approach and ability to close the wound primarily. This study evaluated retrospectively the morbidity of bone harvesting from the anterior iliac crest to provide a logical guide for recognizing the complications and morbidities of an iliac crest bone graft. Materials and Methods: Fifty healthy patients (mean age of 35.5 years; range 7 to 59) underwent iliac crest bone harvesting for a maxillofacial reconstruction from January 2007 to September 2009 at the Department of Oral and Maxillofacial Surgery in Kyungpook National University Hospital. Age, sex, size and kind of grafted bone, duration of pain on donor site, duration of gait disturbance, sensory deficit, scar, contour defect were measured in each patients by retrospective research. Results: The mean duration of pain is 6.7 days, and mean duration of gait disturbance is 7.2 days. Most patients were free from gait disturbances and pain within 2 weeks and there was no correlation between the size of the harvesting block bone and the duration of gait disturbance or pain. However, this study showed that the duration of pain is associated with gait disturbance. In addition, most patients had no complaints regarding their surgical scar and contour defect, and only one patient had permanent impairment of the sensory function. Moreover, an iliac bone graft did not extend the length of hospitalization. Conclusion: This study suggests that split thickness bone harvesting from the inner table of the anterior iliac crest is a well accepted procedure with relatively low morbidity.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.6
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• pp.515-519
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• 2010

Introduction: Bone defects in the jaw are frequently observed after odontogenic cyst enucleation. The success of bone healing appears to be related to the size of the bone defect, the anatomical location, the patient's age and other parameters. The use of bone grafting material is dependent on the operator's preference. No evidence-based definite treatment protocol has been established. This study evaluated the effect of a bone graft into the defect after odontogenic cyst enucleation. Materials and Methods: A total of 55 patients, who had been treated for an odontogenic cyst with cyst enucleation from 2000 to 2009 at the department of Oral and Maxillofacial Surgery, Samsung Medical Center, were included in this study. Patients who were followed-up for more than 1 year were included. Two groups were defined according to the bone graft (with or without a bone graft) after cyst enucleation. The differences in the healing periods and patterns of bone healing were compared clinically and radiologically. The postoperative 1 year radiographs were analyzed for bone healing and density. Statistical analysis was performed using a Pearson chi square test and Wilcoxon rank-sum test. Results: More infection signs were observed in the bone graft group than in the other group, but there was no statistically significant difference. Radiographically, there was also no significant difference in the size of the radiolucent lesions between the two groups. Conclusion: There was no significant difference in healing between the groups with a bone graft and without bone graft after cyst enucleation.