• Journal of Periodontal and Implant Science
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• v.34 no.2
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• pp.303-315
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• 2004

The success and failure of dental implants depends on various factors such as patient's systemic status, quantity and quality of surrounding bone, presence or absence of marginal infection and mechanical loading condition. The measurement of crestal bone changes around the implants is implemental to evaluate the success and long-term prognosis of the implant. This study was to evaluate the cumulative survival rate of the implants which had been placed in the Department of Periodontics, Chonnam National University Hospital between 1992 and 2003, and to observe the crestal bone loss around the implants which had at least 2 consecutive periapical radiographs after connecting the transmucosal abutment. The radiographs were scanned and digitalized, and the crestal bone levels on the mesial and distal surface of implants were measured using Image analyzer (Image Pro Plus, Media Cybernetics, USA), immediately after implant placement, at 2nd surgery, and 3 months, 6 months, 1 year, and every year thereafter. Any bone loss was not observed during the period between the 1stand 2nd surgery, and the bone loss was 0.86 ${\pm}$ 0.92 mm for the first year of loading after connecting the transmucosal abutment. After 1 year of loading, annual bone loss was 0.1 ${\pm}$ 0.27 mm, and total bone loss was 0.90 ${\pm}$ 0.80 mm (during the average follow-up periods of 22.5 ${\pm}$ 25.6 Mos), The implant, with smooth surface, in the mandible, and with the fixed bridge prosthesis showed greater bone loss, compared to those, with the rough surface, in the maxilla and with single crown. In systemically diseased patients (including DM or osteoporosis), the greater bone loss was observed. The cumulative survival rate among 432 implants was 94.10% for 7 years. Among 15 failed implants, 9 implants were removed due to mobility from disintegration of bone-implant interface. From this results, crestal bone loss around the implants were greatest during 1 year after transmucosal abutment connection, and various factors could affect peri-implant bone loss. To prevent and predict the bone loss around the implants and improve the prognosis, further comprehensive maintenance and follow-up schedules are required.

• The korean journal of orthodontics
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• v.44 no.2
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• pp.96-102
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• 2014

Objective: A recent study suggested that rs6504340, a polymorphism within the homeobox B (HOXB) gene cluster, is associated with the susceptibility for malocclusions in Europeans. The resulting malocclusions require orthodontic treatment. The aim of this study was to investigate the association of rs6504340 and other dentition-implicated polymorphisms with dental and occlusal traits in Korean and Japanese populations. Methods: The study participants included 223 unrelated Koreans from the Busan area and 256 unrelated Japanese individuals from the Tokyo metropolitan area. DNA samples were extracted from saliva specimens. Genotyping for rs6504340 and four single nucleotide polymorphisms (SNPs) that have been shown to be associated with the timing of first tooth eruption and the number of teeth at 1 year of age (rs10506525, rs1956529, rs9674544, and rs8079702) was performed using TaqMan assays. The Index of Orthodontic Treatment Need (IOTN), overjet, overbite, arch length discrepancy, crown sizes, and length and width of the dental arches were measured. Spearman's correlation coefficients were calculated to evaluate relationships between rs6504340 and these dental/occlusal traits. Results: We evaluated the aesthetic components and dental health components of the IOTN in the Korean and Japanese populations and found that neither rs6504340 nor the other four SNPs showed any association with dental and occlusal traits in these East Asian populations. Conclusions: These negative results suggest that further research is needed to identify the genetic determinants of malocclusions in order to reach a consensus.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.6
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• pp.717-729
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• 1999

Although many studies on the cytotoxicity of the dental cast base metal alloys and their components have been carried out, the results are rather conflicting because of the different type of cells used and the various experimental procedures taken. Recently a number of scientists have claimed that it would be preferable to focus on the use of cells from relevant specific location of the human bodies. Consequently, the primary cultured oral keratinocyte derived from oral mucous along with nickel chloride and several of widely used dental cast base metal alloys(two Ni-Cr alloys and one Co-Cr alloy)in domestic were selected for this study, from which 1) The amounts of released metal ions were determined using atomic absorption spectrometry, 2) The cytotoxicity of nickel chloride and dental cast base metal alloys was evaluated via MTT assay, and finally, 3) The amounts of released metal ions and the cytotoxicity of nickel chloride were correlated with the cytotoxicity of dental cast base metal alloys And, the results were summarized as follows; 1. Nickel ion from Ni-Cr alloys and Cobalt ion from Co-Cr alloys resulted in maximum releasing rate during first 2h hours, followed by a decrease in releasing rate with time. Chromium ion were found to be minimal in all alloys. 2. In cytotoxic test. with $40{\mu}M,\;80{\mu}M$ of nickel chloride, there were observed an increase in the relative cell number compared to control samples after 24 hours. With $160{\mu}M$, there was found to be no difference in the relative cell number with control, except that 48 hour showed a increase in relative cell number. With $320{\mu}M$, the relative cell number remained constant and decreased after 48 hours, and with $640{\mu}M$, a continuing decrease in relative cell number was observed throughout test period. 3 The sensitivity of primary cultured oral epithelium to nickel was lower compared to the cells used in other studies. 4. CB-80 Soft and Regalloy showed no cytotoxicity to primary cultured oral epithelium and New crown resulted in a slight cytotoxicity. In conclusion, it was shown that the primary cultured oral keratinocytes could be applied successfully as testing cells in cytotoxicity test. Futhermore, the dental cast base metal alloys used in this study were found to be biocompatible.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.12 no.2
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• pp.96-100
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• 2016

Metachromatic leukodystrophy (MLD) is a progressive and degenerative neurological disease caused by a deficiency of the catabolic enzyme arylsulfatase A. Deficiency of arylsulfatase A results in accumulation of sulfatide in the white matter of the peripheral and central nervous system and it occurs demyelination as a result. The patient gradually goes through mental and motor failure. General symptoms of MLD include gait disturbance, mental deterioration, muscle rigidity and impaired swallowing. Inheritance of the disease is autosomal recessive. We report a dental caries treatment of a 3-year old boy with MLD. The patient underwent hematopoietic stem cell transplantation (HSCT) to slow the progression of the disease. He was suffered from difficulties of mastication and swallowing from the degenerative neurological symptom. He was ingesting food by both oral feeding and tubal feeding after he took percutaneous endoscopic gastrostomy (PEG). The cause of multiple caries was mainly presumed as patient's prolonged time of meal. The treatment was performed under general anesthesia considering patient's incompliance. Severely affected lower primary molars were treated with pulp treatment and restored with stainless steel crown. Others were restored with composite resin. There were no postoperative complications. MLD is life threatening progressive disease and also has an impact on unfavorable condition for oral health. Routine home oral care and periodic professional dental care should be emphasized to the caregiver of patient considering the susceptibility of dental caries. Not only the medical care, but periodic dental office visit would benefit the quality of life of the patient.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.645-650
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• 2004

Calcifying odontogenic cyst(COC) is a rare developmental odontogenic cyst, which shows diverse classification and terminology. Cystic epithelial lining of COC is composed of basal cell layer of columnar cells and overlying layer of stellate reticulum. In the epithelium, ghost cells that might induce adjacent mesenchymal tissue to develop dental organ are shown characteristically. In spite of low rate of recurrence, we have to get a histopathological examination so that odontogenic lesions may recur without fully curettage of lining epithelium. 7-year-old male child came pediatric dentistry in wonkwang university dental hospital in order to check the delayed eruption of left maxillary central incisor. Radiographic examination revealed a well-defined radiopaque mass, overlapping impacted left central and lateral incisor crown. Enucleated mass was tooth-like features and also had epithelium lining. Results of histopathologic procedure, we saw the lots of ghost cell and proliferating hard dental tissues. Also we saw the cystic epithelium cells. It revealed diagnosis of the COC associated complex odontoma. For this reason one should consider of COC when patients present odontoma-like lesion with impacted tooth.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.15 no.1
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• pp.60-64
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• 2019

Swyer-James syndrome (SJS), also known as Swyer-James-MacLeod syndrome and unilateral hyperlucent lung syndrome, is rare acquired pulmonary disorder develops secondary to infectious etiologies in early childhood. Viral respiratory infection such as adenoviruses or Mycoplasma pneumoniae in infancy or early childhood rarely cause Swyer-James syndrome. It is generally characterized on radiographs by a unilateral small lung with hyperlucency and air trapping on expiration. In many cases unaffected lung tissue functions normally, compensating for affected lung portion. Preoperative assessment is needed to determinate individual's pulmonary function. A 4-year-old boy with Swyer-James syndrome visited Seoul National University Dental Hospital Department of pediatric dentistry for caries treatment. Clinical and radiographic examinations revealed multiple carious lesions on deciduous teeth. Considering patient's underling disease, age, and level of cooperation, dental treatment under general anesthesia was scheduled. Dental treatment was done with composite resin and stainless-steel crown. Since ventilation of Swyer-James syndrome patients was diminished because of airway obstruction, close monitoring of ventilation is necessary during dental treatment. Considering pulmonary pathology, general anesthesia rather than sedation is recommended when special behavior management is required for dental treatment. Swyer-James syndrome patients can tolerate general anesthesia and surgery well, according to several reports.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.243-254
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• 2002

For the purpose of evaluating the biocompatability of 3 kinds of metallic materials frequently used in pediatric dentistry (stainless steel crown, orthodontic band, orthodontic wire), cellular and molecular studies, including cell growth and proliferation, screening of cell death with determination of types whether necrosis or apoptosis and changes in expressions of related signaling molecules were examined, using cultured human gingival fibroblasts (HGF-1), HGF-1 was cultured in Dulbecco's modified Eagle's medium. among which the 3rd to 6th generations of HGF-1 were used. The specimen were divided into stainless steel crown (R), band (B) and wire (W). The immunocytochemical study was done for the detection of anti-PCNA (proliferating cell nuclear antigen) labeling. With extracted protein, western blot was done for the detection of ERK1/2, JNK, and p38, using individual antibodies. Cultured cells proliferated, remarkably till 7 day and slightly at 11 day. There was no statistical significance in the counts of proliferating HGF-1 between control and experimental groups (p>0.05). Relative growth rates were no statistically significant difference between control and experimental groups (p>0.05). PCNA labeling indexes showing similar patterns in control and experimental groups. The expressions of ERK1 and ERK2, p38 were similar in control and experimental groups. The expression of JNK increased at 1st day, slightly decreased at 4th day and markedly increased at 7th and 11 day. Although the patterns of control and experimental groups were similar, the increased expressions of JNK at late period suggest a possible stress due to inhibited cell growth and proliferation, and worse culture condition. Conclusively, the 3 kinds of metal specimens used in this study did not induce cellular and molecular hazards during short term culture of HGF-1. But, for the better clinical stability, the establishment of long period culture and animal experiment was thought necessary.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.1
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• pp.1-17
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• 2008

The purpose of this study were to report the reasons for removal of fixed prostheses and survival rate of abutment teeth. A total 192 fixed prostheses removed at Chosun university Dental Hospital and 308 abutment were investigated. The most frequent reason of removal was periodontal problem(30.7%), followed by caries(29.7%), then periapical problem(18.8%) and defective margins(14%). In metal ceramic crown, periodontal problem was the most frequent reason of removal. In complete cast crown, caries was the most frequent reason of removal. Periapical and periodontal problem was the most frequent reason people under forties and over fifties, respectively. Of the 308 abutment teeth, vital and non-vital teeth were 135(43.8%) and 173(56.2%), respectively. Of 135 vital abutment teeth, 39(28.9%) were extracted and of 173 non-vital abutment teeth, 85(49.1%) were extracted. Each risk factor for removal of fixed prostheses and extraction of abutment should be evaluated more clearly for prediction of prognosis of final prostheses and abutment teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.210-217
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• 2016

Purpose: The aim of this study was to evaluate the marginal and internal adaptation of monolithic zirconia restoration made without physical model by digital intraoral scanner. Materials and methods: A prospective clinical trial was performed on 11 restorations as a pilot study. The monolithic zirconia restorations were fabricated after digital intraoral impression taking by intraoral scanner (TRIOS, 3shape, Copenhagen, Denmark), computer-aided designing, and milling manufacturing process. Completed zirconia crowns were tried in the patients' mouth and a replica technique was used to acquire the crown-abutment replica. The absolute marginal discrepancy, marginal gap, and internal gap of axial, line angle, and occlusal part were measured after sectioning the replica in the mesiodistal and buccolingual direction. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U test (${\alpha}=.05$). Results: From the adaptation analysis by replica, the statistically significant difference was not found between mesiodistal and buccolingual sections (P>.05), but there was significant difference among the measurement location (P<.01). The amount of absolute marginal discrepancy was larger than those of marginal gap and internal gap (P<.01). Conclusion: Within the limitations of this study, the adaptation accuracy of model-free monolithic zirconia restoration fabricated by intraoral scanner exhibited clinically acceptable result. However, the margin of zirconia crown showed tendency of overcontour and cautious clinical application and follow up is necessary.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.4
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• pp.257-274
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• 2001

To properly prepare teeth, dentists require a direct view of the working area and are often placed in a difficult position, moreover, a high proportion of dentists suffer from headache and back pain. Dentists who make use of the dental mirror and position their patients carefully to gain a proper view report less headache, pain and discomfort in the shoulders. It is recommended that dentists learn the "Home Position(H.P.)" which among the various "Random Position(R.P.)" methods, enables dentists to approach their patients in a stable posture. The purpose of this study was to compare tooth preparation in the H.P. and the R.P., and evaluate the clinical efficacy of the H.P.. Tooth preparation for a full cast crown was performed on the maxillary left 1st molar using the H.P. and the R.P., and the shapes of the prepared tooth surfaces at the two different operating positions were compared. The amount of occlusal reduction, marginal width, height, and axial taper were measured and analyzed. A T-test was performed separately to compare the results of the H.P. and the R.P. with respect to the accuracy of the corresponding tooth reduction. The results were as follows. ; 1. The amount of occlusal reduction was excessive on the mesiobuccal cusp(P<0.05), and deficient on the lingual cusp in the H.P.(P<0.01). In the R.P., this was excessive on the buccal cusp and deficient on the fossa and distolingual cusp(P<0.01). 2. The amounts of marginal width were excessive in all areas except on the lingual and mesial surfaces in the H.P. and lingual surface in the R.P.(P<0.01). 3. The marginal heights were achieved more accurately in the R.P. than the H.P.(P<0.01). 4. Axial surface taper was excessive in all areas in the H.P.(P<0.01). But the axial taper of measured areas was even, and tooth is more like to retain its original axis after reduction. In the R.P., axial surface taper was excessive on the mesial and buccal area, and deficient on the distolingual area(P<0.01), and therefore, the axis of the prepared teeth was tipped in the distolingual direction. 5. The times needed for preparation were 12 minutes and 49 seconds in the H.P., and 11 minutes and 35 seconds in the R.P., and the R.P. was statistically faster(P<0.01). The tooth preparation in the H.P. achieved its goal, in that it enabled the operator to make even tooth reduction. In conclusion, the H.P. system offers an improved method that can be used in clinic after specific training.