• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.109-116
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• 2010

Impaction is defined as a cessation of the eruption of a tooth caused by a clinically or radiographically detectable physical barrier in the eruption path or by an ectopic position of the tooth. The reasons for impaction of the maxillary central incisor are supernumerary tooth, odontoma, ectopic position of tooth germ, dilacerated tooth and so force. Impacted tooth cause space loss due to proximal movement of adjacent tooth, malocclusion, root resorption of adjacent tooth, cyst formation, so careful observation and early detection is important and exact treatment should be applied to prevent these results. The treatment options of impacted tooth include induction an eruption through extraction of deciduous tooth or surgical exposure, reposition of impacted tooth by surgical method or orthodontic treatment. Orthodontic traction is recommended when an eruption does not happen after removal of barrier or surgical exposure, when eruption path is too transpositioned to be corrected spontaneously so eruption does not expected. In these cases, traction of impacted maxillary central incisor was carried out using orthodontic method with closed eruption technique and it showed good clinical results so we report these cases.

• Restorative Dentistry and Endodontics
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• v.26 no.6
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• pp.451-463
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• 2001

목적 - Inflammatory cytokine으로 알려진 interleukin 1$\beta$, tumor necrosis factor $\alpha$는 치수 및 치근단질환에서 주요한 역할을 하며, 골흡수를 자극하고 골형성을 방해하는 것으로 알려져 왔다. 이들 cytokine은 주로 단핵세포/대식세포가 형성하는 것으로 알려져 왔으나 최근 연구에 의하면, PMN도 또한 이 런 cytokine들을 형성할 수 있다는 것이 보고되었다. 오랫동안 염증반응이나 면역반응에서 PMN의 역할이 주로 포식작용 을 통해 병원균을 제거하는 것이라고만 생각되어져 왔던 것을 생각하면, 새로운 발견이라 할 수 있다. 또, PMN은 IL-1ra도 생성하는 것으로 보고되었는데, IL-1ra란 IL-1의 생물학적 작용을 방해하는 인자이므로, IL-1과 밀접한 관련을 가지는 질환의 발전에 있어서 IL-1과 IL-1ra의 balance가 매우 중요한 역할을 할 것으로 생각된다 즉, IL-1ra는 IL-1$\beta$의 proinflammatory effect를 제한할 수 있는 negative feedback mechanism이라고 할 수 있다. 이 연구의 목적은 치수 및 치근단 조직의 감염에 있어서 주요 원인균인 Porphyromonas endodontalis의 LPS가 PMN의 IL-1$\beta$, TNF-$\alpha$, IL-1ra생성에 미치는 영향을 단백질과 mRNA 수준에서 관찰하는 것이다. 잘 알려진 non-oral bacterium인 E. coli의 LPS를 positive control로 사용하였으며, IL-1ra가 IL-1$\beta$의 생물학적 작용을 방해하는 작용을 관찰하기 위해, IL-1의 biological assay도 시행하였다. 방법 - P. endodontalis ATCC 35406을 혐기성 조건에서 배양하고, hot phenol-water extraction의 방법으로 LPS를 추출(crude LPS)한 후, 제조회사로부터 구입한 E. coli의 crude LPS와 함께 정제하였다. 건강한 자원자들을 대상으로 말초혈액을 채취한 후 dextran sedimentaion을 거쳐 Lymphoprep을 이용하여 PMN층을 분리하였다. 얻어진 세포들은 RPMI 1640 (supplemented with fetal bovine serum antibiotics)에 5$\times$$10^{6}$cells/ml이 되도록 resuspend시킨 후 각기 다른 농도 (0, 0.01, 0.1, 1 and 10$\mu$g/ml)의 LPS를 처리하여, 각기 다른 시간(Northern blot : 1, 2, 4시간 ELISA : 2, 6, 12, 18시간)동안 37$^{\circ}C$ in 5% $CO_2$ 의 조건으로 배양하였다. 상층액은 -7$0^{\circ}C$에 보관하였다가 추후에 ELISA를 이용한 단백질 농도 측정과 IL-1 biological assay에 사용되어졌으며, 배양된 세포로부터 RNA를 추출하여 Northern hybridization을 통해 mRNA expression을 관찰하였다. (중략)

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.3
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• pp.307-317
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• 2023

Due to increasing demand for aesthetics, zirconia crowns have become a popular choice for treating primary molars. However, there is limited literature available comparing the survival rates of zirconia crowns with those of other restorative materials. The objective of this study was to compare the 36-month survival rates of zirconia crowns and stainless steel crowns for proximal caries, as well as to analyze failure types associated with each crown type. Electronic medical records and radiographs of 1,061 primary molars from 498 patients treated with 2 types of prefabricated crowns at Chosun University Dental Hospital and 2 private dental clinics between 2017 and 2019 were collected and analyzed. The survival rate of zirconia crowns was found to be lower compared to that of stainless steel crowns. Regarding the groups without pulp treatment, the survival rate of stainless steel crowns was significantly higher than that of zirconia crowns. However, in the groups that received pulp therapy, no significant difference in the survival rates was observed between the two preformed crowns. Notably, abnormal root resorption or periapical lesions were identified as the primary cause of restorative failure in stainless steel crowns, whereas loss of restoration was the predominant cause in zirconia crowns. This study holds valuable implications for clinicians when selecting preformed crowns for primary molars.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.1
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• pp.25-39
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• 2011

In animal studies, Magnesium (Mg) - incorporated oxidized implants showed significant enhancement of the bone response. This prospective clinical trial was performed to investigate the success rate, implant stability and marginal bone loss of Mg oxidized clinical implant. The experimental protocol was approved by Institutional Review Board of the Gangneung-Wonju National University Dental Hospital. Fifty healthy patients had partial edentulism were included in this study. Mg oxidized clinical implants (Implant M, Shinhung, Korea) were installed and restored with conventional protocol. The patients were recalled at 1, 3, 6 months after functional loading. Implant stability quotient (ISQ) was measured and periapical radiographic images were obtained. Amount of marginal bone loss was calculated with calibrated images from periapical radiographs. Repeated measured analysis of variance and post hoc Tukey test were used to compare the mean ISQ and bone level. A total of 101 implants were analyzed. The mean ISQ values increased continuously with time lapse from 68.4 at fixture installation to 71.5 at 6 months after loading. Implant stability was correlated with gender, fixture diameter, bone quality and implant sites. The mean marginal bone loss during 6 months after loading was 0.26 mm. There was no failed implant and six-month success rate was 100%. Within the limitations of this study, the six-month success rate of Mg oxidized implant was satisfactory. The implant stability and marginal bone level were excellent. However, further longer clinical studies will be needed to confirm the success of Mg oxidized clinical implant.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.367-373
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• 1992

The author observed a 35-year-old male patient who came to the Dental Infirmary of Kyungpook National University Hospital who had complained of gradual swelling on both side of the mandible for 15 years. As a result of careful analysis of clinical, radiological and histopathological findings, the authors diagnosed it as cementifying fibroma and obtained the results as follows: 1. In clinical examination, main clinical symptom was facial deformity due to gradual swelling on both side of the mandible. 2. In radiographic examination, radiolucent lesions with central radiopaque foci were seen on both mandibular body areas bilaterally, and cortical thinning and expansion of the mandibular body were seen buccolingually. And loss of lamina dura and root resortption of adjacent teeth were also seen. In histopathological examination, this lesion was composed of delicate interlacing collagen fibers interspersed by the fibroblasts and cementoblasts. And round or oval shaped basophilic masses of cementum-like tissue were observed in the connective tissue.

• The Journal of the Korean dental association
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• v.50 no.7
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• pp.420-430
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• 2012

Purpose: The purpose of this study was to measure the absorbed dose and to calculate the effective dose for full-mouth periapical radiography using the portable dental x-ray machine and panoramic radiography Material and Method: Thermoluminescent chips were placed at 25sites throughout the layers of the head and neck of a tissue-equivalent human skull phantom. The man phantom was exposed with the portable dental x-ray machine and panoramic unit. During full-mouth periapical radiography the exposure setting was 60 kVp, 2 mA and 0.15 ~ 0.25 seconds, while during panoramic radiography the selected exposure setting was 72 kVp, 8 mA and 18 seconds. Absorbed dose measurements were obtained and equivalent doses to individual organs were summed using ICRP 103 to calculate of effective dose. Result: In the full-mouth periapical radiography, the highest absorbed dose was recorded at the mandible body follow with submandibular glands and cheek. Using panoramic unit, the highest absorbed dose was parotid glands and the following was back of neck and submandibular glands. The effective dose in full-mouth periapical radiography using portable dental x-ray machine was 46 ${\mu}Sv$. In panoramic radiography, the effective dose was 38 ${\mu}pSv$. Conclusion: It was recommended to panoramic radiography for general check in the head and neck area because that the effect dose in the panoramic radiography was lower than the dose in the full-mouth periapical radiography using portable dental x-ray machine.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.1
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• pp.51-59
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• 2016

The purpose of the present retrospective study was to analyze gender, age, awareness, etiology, and treatment choice in patients with failed eruption of the mandibular first molar. Radiographic material and dental records from 67 patients with 74 mandibular first molars with failed eruption treated during the years 2001-2014 were evaluated. As results, the prevalence of mandibular first molar with failed eruption was higher in males than females, and the average awareness age was 9.19 years old. The most common etiological cause was unknown, and the next most common causes were abnormal eruption pathway and odontogenic tumor in order. In this study, it is suggested that more dental education to children about the time of eruption of permanent tooth is required, and the importance of regular dental check-ups is emphasized during mixed dentition.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.631-648
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• 1994

The purpose of this study was to investigate the effects of different types of orthodontic force on the root resorption and repair in rat molar. 77 rats were divided into three groups; The control group was not equiped with orthodontic appliance between incisor and first molar. The experimental group was subdivided into closed coil spring subgroup and elastic chain subgroup by the application methods of orthodontic force. Initial orthodontic force between incisor and first molar was 100g. Experimental period was 8 weeks; for 4 weeks the appliance was acting and for another 4 weeks, removed. Root resorption and repair in the root of first molar was examined by light microscope for histologic changes and by inductively coupled plasma spectroscopy(ICP) for quantitative changes. The results were as follows: 1. In the closed coil spring subgroup odontoclasts and root resolution were appeared one week earlier. 2. One week after orthodontic force was eliminated the repair response in the resorptive lacuna was seen in both subgroups. Delayed resorption was seen on the periphery of resorptive lacunae whereas reparative response was seen in the center of lacunae. A new resorption was seen one week after orthodontic force was eliminated. Root contour was partially restored by repairing of resorbed root. 3. The weight ratios of calcium and phosphorous to the sample were decreased during resorptive process but increased during repair process in both the orthodontic groups, but not more than the control group. 4. By different types of orthodontic force (closed coil spring or elastic chain) resorption process was affected but repair process was not.

• Journal of Periodontal and Implant Science
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• v.38 no.4
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• pp.603-610
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• 2008

Purpose: The guided bone regeneration (GBR) technique is widely used in periradicular surgery. However, there is still some controversy regarding the effectiveness of GBR in promoting bone healing after periradicular surgery. The purpose of this study was to evaluate the resorbable membrane on the osteointegration of immediate implants in sites with periradicular lesion that had been removed by periradicular surgery. Materials and methods: Six roots of lower second premolars and 15 roots of lower third and fourth premolars of dogs were used as control and experimental teeth, respectively. Periradicular lesions were induced only in the experimental teeth. Twelve weeks later, the control and experimental teeth were extracted and implants were placed immediately. Periradicular lesions were removed with osteotomy, curettage and saline irrigation. Resorbable membranes were used in experimental group 1 but not in experimental group 2. After 12 week of healing period, the implants were clinically not mobile and showed no signs of infection. Data obtained by histomorphometric analysis were analyzed by Kruskal-Wallis test. Results: The control group showed a significantly higher bone to implant contact (BIC) ($74.14{\pm}16.18$) than experimental group 1 ($40.28{\pm}15.96$) and 2 ($48.70{\pm}17.75$)(p<0.05). However, there was no significant difference between experimental group 1 and 2. Conclusion: Although BIC in experimental groups were lower than in control group, immediate implant can be successfully placed at extraction socket with periradicular lesion and osseous defect. However, the use of resorbable membrane in bony defect created during periradicular surgery was questioned.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.1
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• pp.87-101
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• 2015

The premature loss of the mandibular primary canine is relatively frequent and a sign of the upcoming space problems in the transitional period. This situation is caused by the permanent lateral incisor resorbing the root of the primary canine during its eruption. Bilateral loss of primary canines in a crowded arch leads to the lingual tipping of the permanent incisors, with the consequent reduction in the arch perimeter and increase in overbite. When the loss of a primary canine is unilateral, tipping of the adjacent incisors occurs toward the space, resulting in midline deviation. In these situations, treatment possibilities, such as extraction of the antimeric tooth or placement of a passive lingual arch, can be applied; although there are some controversies concerning this. Most space problems with less than 4 mm can be resolved through preservation of the leeway space using sequential disking of the primary teeth and a passive lingual arch, regaining space or limited arch expansion in the late mixed dentition. In cases with 4~6 mm of space problems, arch expansion (A-P or transverse) can be applied. Space problems with more than 6 mm should be treated through diagnosis and treatment planning. Most of these cases will require extraction of permanent teeth including serial extraction (guidance of eruption).