• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.175-180
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• 2008

Traumatic injuries to the primary dentition are commonly encountered problems in dental practice. It is found that 30% of the children had injuries to the primary dentition and 22% to the permanent dentition. The greatest incidence of trauma to the primary dentition occurs at the ages of 2 and 3 as children start to learn motor coordination. Because teeth and alveolar bone are traumatized simultaneously, alveolar bone fractures are likely to occur when multiple teeth are involved in injuries. Dental splints are indicated for the management of maxillofacial fractures. They enable anatomic reduction of fractured segments and help immobilization and maintenance of the fragments after reduction. They also act as a stabilizer during rehabilitation. Various types of dental splints are available. In this case, routine resin-wire splint technique could not be applied because of the child's uncooperative behavior. Oral sedation was not indicated because N.P.O. had not been preceded. Therefore, we decided to use open-cap acrylic splint instead. Stabilization using open cap acrylic splint requires minimum chair time with reduced discomfort to both patient and dentist. It is an effective means of splint for uncooperative children and especially useful when other means of fixation have been failed. Because trauma on the primary dentition can affect the underlying permanent tooth germ, it is important to monitor eruption process of the permanent dentition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.5
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• pp.208-215
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• 2005

The 10mm diameter aggregates made of clay, carbon and $Fe_2O_3$ were prepared to investigate the mechanism of black core formation. The specific gravity, absorption rate, percent of black core area, fracture strength, total Fe analysis, and XRF were measured at various compositions, sintering temperatures, sintering times, sintering atmospheres, and sintering methods. Small addition of $Fe_2O_3$ did not affect physical properties of the aggregates; however, the percent of black core area increased with increasing carbon contents and increasing sintering temperature. Specific gravity of the aggregates decreased and the water absorption ratio increased with increasing percent of black core area. The aggregates sintered at oxidation atmosphere showed clear border between shell and black core area. Hence, the aggregates sintered at reduction atmosphere showed only black core area in the cross-section of the aggregates. The specific gravity of the aggregates sintered at reduction atmosphere increased with increasing carbon contents and that was the lowest of all comparing other aggregates sintered at different atmospheres. Adsorption rate increased with increasing carbon contents at all atmospheres. The fast sintered aggregates showed lower specific gravity, higher absorption rate, and more black core area than the normally sintered aggregates. It was turned out that the aggregates having more black core area showed higher fracture strength than that of aggregates with no black core area. From the total Fe analysis, the concentration of Fe and FeO was higher at black core area than at shell. Because the concentration of $Fe_2O_3$ in the shell was higher than other area, the color of the shell appeared red. It was also turned out from the XRF analysis that carbon was exist only at black core area.

• Journal of the Korean Orthopaedic Association
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• v.56 no.3
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• pp.245-252
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• 2021

Purpose: This study examined the radiological and clinical outcomes of internal fixation using a reconstruction plate and 21G circumferential wire in comminuted midshaft clavicular fractures. Materials and Methods: A retrospective cohort study was performed on 51 patients between 2005 and 2019. Thirty-two patients underwent internal fixation with a reconstruction plate and a 21G circumferential wire with minimal soft tissue detachment, and 19 patients underwent surgery without a wire. The patients were assessed with the radiographic parameters, the University of California at Los Angeles (UCLA) score, and the visual analogue scale (VAS) pain score. Based on this, patients who operated without a circumferential wire were set as the control group, and the differences in bone union between the two groups were compared. Results: Thirty-two patients were followed-up for an average of 65 weeks, and 19 patients in the control group were followed-up for an average of 56 weeks. The radiological evaluation confirmed the anatomical reduction and bone union in all 32 patients. No case of nonunion was present. The UCLA score was 32.38 on average and 33.11 in the control group (p=0.395). The VAS score was 1.00 on average and 0.84 in the control group (p=0.668). A significant difference in the bony union time was observed between the group who underwent internal fixation with a reconstruction plate and a 21G circumferential wire with minimal soft tissue detachment, and the control group (p=0.015). On the other hand, there was no statistical significance when other variables were controlled (p=0.107). Conclusion: For displaced midshaft clavicular fractures, internal fixation using a reconstruction plate and 21G circumferential wire maintained accurate anatomical reduction. The satisfactory clinical and radiological results mean that internal fixation using a reconstruction plate and 21G circumferential wire may be a good option for surgical treatment.

• Journal of the Korean Arthroscopy Society
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• v.11 no.1
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• pp.39-44
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• 2007

Purpose: To evaluate the results of subtalar arthroscopy and to define the indications for the procedure. Materials and Methods: Fifty-four patients were followed up for more than 1 year after subtalar arthroscopy. The mean age was 40 years, and the mean follow-up period was 18 months. Preoperative diagnoses included sinus tarsi syndrome in 19 cases, degenerative arthritis in 13 cases, calcaneal fracture in 10 cases, arthrofibrosis in 5 cases, os trigonum syndrome in 3 cases, talar fracture in 3 cases, talocalcaneal coalition in 3 cases and calcaneal tumor in 1 case. Clinically AOFAS ankle-hindfoot scale and satisfaction of the patients were evaluated. Results: There were 23 synovectomies, 13 subtalar fusions, 11 diagnostic arthroscopies, 5 adhesiolyses, 4 loose body removals, 3 excisions of os trigonum and 1 arthroscopic reduction of fracture. Twenty-five ankle arthroscopies and 11 modified Brostrom's operations were performed for the accompaning 17 ankle impingment syndromes, 11 chronic ankle instabilities and 7 osteochondral lesions of talus. AOFAS ankle-hindfoot scale was increased from 33 points preoperatively to 77 points postoperatively in subtalar fusion group, and was increased from 69 points preoperatively to 89 points postoperatively in other-than-fusion group. Ninety one percent of patients were satisfied with the procedures. There were no serious complications related to the subtalar arthroscopy. Conclusion: Subtalar arthroscopy appears to be safe and highly accurate procedure for subtalar pathology, although it requires technical expertise.

• Journal of the Korean Orthopaedic Association
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• v.56 no.3
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• pp.208-214
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• 2021

Purpose: Verifying a reliable predictor of the progression of vertebral deformity in patients with acute osteoporotic fractures of the lumbar spine may be useful. A qualitative analysis of the muscle near the spine was performed using magnetic resonance imaging (MRI), and its correlation with a spinal deformity was determined under the hypothesis that the causes of the kyphotic deformity are associated with muscle reduction in the multifidus and erector spinae. Materials and Methods: The study was performed in a retrospective manner using the electronic medical records of patients who presented to the author's institution between January 2007 and March 2018, and were diagnosed with an acute lumbar fracture. The fat infiltration rates of the multifidus and erector spinae were measured using MRI taken at the time of injury, and the mean value was defined as the total fat infiltration rate (TFI). Based on lateral radiographs of the lumbar spine at the one-year follow-up, the loss of height of the vertebral body, the kyphotic angle and the wedge angle were measured. The statistical significance was confirmed by calculating the Pearson correlation coefficient. Results: One hundred twenty-nine patients, of which 30 were male and 99 were female, were examined. The mean age was 71.28 years. The mean T-score was -3.53±0.79 g/cm², and the mean fat infiltration was 15.20%±11.99%. TFI was positively correlated with age (R=0.373, p<0.001), compression rate (R=0.369, p<0.001), and Cobb's angle (R=0.386, p<0.001) after a one year follow-up, but negatively correlated with the BMD score (R=-0.252, p=0.004). As the fracture progressed to the lower lumbar level, the compression rate (R=-0191, p=0.030) and wedge angle (R=-0.428, p<0.001) at the time of injury tended to decrease. Conclusion: In patients with osteoporotic vertebral fractures, the fat infiltration rate may be an important predictor of conservative treatment. The prognosis of patients with a high-fat infiltration rate should be explained during patient education, and the patients must be monitored closely through short-term outpatient follow-up.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.737-760
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• 2022

For the geological disposal of high-level radioactive wastes (HLW), an understanding of deep subsurface environment is essential through geological, hydrogeological, geochemical, and geotechnical investigations. Although South Korea plans the geological disposal of HLW, only a few studies have been conducted for characterizing the geochemistry of deep subsurface environment. To guide the hydrogeochemical research for selecting suitable repository sites, this study overviewed the status and trends in hydrogeochemical characterization of deep groundwater for the deep geological disposal of HLW in developed countries. As a result of examining the selection process of geological disposal sites in 8 countries including USA, Canada, Finland, Sweden, France, Japan, Germany, and Switzerland, the following geochemical parameters were needed for the geochemical characterization of deep subsurface environment: major and minor elements and isotopes (e.g., ³⁴S and ¹⁸O of SO₄^2-, ¹³C and ¹⁴C of DIC, ²H and ¹⁸O of water) of both groundwater and pore water (in aquitard), fracture-filling minerals, organic materials, colloids, and oxidation-reduction indicators (e.g., Eh, Fe²⁺/Fe³⁺, H₂S/SO₄^2-, NH₄⁺/NO₃^-). A suitable repository was selected based on the integrated interpretation of these geochemical data from deep subsurface. In South Korea, hydrochemical types and evolutionary patterns of deep groundwater were identified using artificial neural networks (e.g., Self-Organizing Map), and the impact of shallow groundwater mixing was evaluated based on multivariate statistics (e.g., M3 modeling). The relationship between fracture-filling minerals and groundwater chemistry also has been investigated through a reaction-path modeling. However, these previous studies in South Korea had been conducted without some important geochemical data including isotopes, oxidationreduction indicators and DOC, mainly due to the lack of available data. Therefore, a detailed geochemical investigation is required over the country to collect these hydrochemical data to select a geological disposal site based on scientific evidence.

• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.555-565
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• 2006

The purpose of the present study is to evaluate the biological stability of the zirconia/alumina composite abutment by histologic and radiographic examination in clinical cases. 17 partially edentulous patients (5 men and 12 women, mean age 47) were treated with 37 implants. The implants were placed following the standard two-stage protocol. After a healing period of 3 to 6 months, zirconia/alumina composite abutments were connected. All radiographs were taken using paralleling technique with individually fabricated impression bite block, following insertion of the prosthesis and at the 3-, 6-, 12 month re-examinations. After processing the obtained images, the osseous level was calculated using the digital image in the mesial and distal aspect in each implant. An ANOVA and t-test were used to test for difference between the baseline and 3-, 6-, 12 months re-examinations, and for difference between maxilla and mandible. Differences at P <0.05 were considered statistically significant. For histologic examination, sample was obtained from the palatal gingiva which implant functioned for 12 months. Sections were examined under a light microscope under various magnifications. Clinically, no abutment fracture or crack as well as periimplantitis was observed during the period of study. The mean bone level reduction(${\pm}standard$ deviation) was 0.34 rom(${\pm}\;0.26$) at 3-months, 0.4 2mm(${\pm}\;0.30$) at 6-months, 0.62 mm(${\pm}\;0.28$) at 12-months respectively. No statistically significant difference was found between baseline and 3-, 6-, 12-months re-examinations (p > 0.05). The mean bone level reduction in maxilla was 0.33(${\pm}0.25$) at 3-months, 0.36(${\pm}0.33$) at 6-months, 0.56(${\pm}0.26$) at 12-months. And the mean bone level reduction in mandible was 0.35(${\pm}0.27$) at 3-months, 0,49(${\pm}0.27$) at 6-months, 0.68(${\pm}0.30$) at 12-months. No statistical difference in bone level reduction between implants placed in the maxilla and mandible. Histologically, the height of the junctional epithelium was about 2.09 mm. And the width was about 0.51 mm. Scattered fibroblasts and inflammatory cells, and dense collagen network with few vascular structures characterized the portion of connective tissue. The inflammatory cell infiltration was observed just beneath the apical end of junctional epithelium and the area of direct in contact with zirconia/alumina abutment. These results suggest the zirconia/alumina composite abutment can be used in variable intraoral condition, in posterior segment as well as anterior segment without adverse effects.

• Journal of the Korean Orthopaedic Association
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• v.52 no.1
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• pp.49-58
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• 2017

Purpose: To compare clinical outcome of Sanders type IV intra-articular calcaneal fracture treated with open reduction and internal fixation (ORIF) versus ORIF and primary subtalar arthrodesis (PSTA). Materials and Methods: Between March 2003 and November 2013, 22 patients with 22 Sanders type 4 intra-articular calcaneal fractures were included in this study. Of these, 11 were treated with ORIF (ORIF group), and 11 were treated with ORIF and PSTA (PSTA group). The mean follow-up period was 34.6 months (range, 18-72 months). Clinical outcomes were assessed along with the American Orthopedic Foot and Ankle Society's ankle-hindfoot scale (AOFAS score), and the visual analogue scale pain score (VAS score) at 6-month, 12-month, and last follow-up. Patient satisfaction, return to previous occupation and postoperative complications were also investigated. Results: The results for ORIF did not differ from those for PSTA based on the last follow-up AOFAS scores or the VAS scores (p>0.05). However, patient satisfaction was significantly higher in the PSTA group (p=0.008). Secondary subtalar arthrodesis was conducted in five patients (45.5%) of the ORIF group within 2 years postoperatively. Conclusion: We were unable to demonstrate a significant difference in clinical outcomes between ORIF and PSTA; however, the patient satisfaction was higher in the PSTA group. PSTA may be a suitable choice for patients who need fast recovery to daily activity and to prevent the need for secondary subtalar arthrodesis.

• Clinics in Shoulder and Elbow
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• v.16 no.1
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• pp.17-26
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• 2013

Purpose: A comparison of the radiographic and the clinical outcomes between two different surgical approaches-Deltoid splitting and Delto-pectoral interval-on the proximal humerus fractures treated by locking compressive plate (LCP), is done. Materials and Methods: Medical records and pre- and postoperative radiographs were reviewed retrospectively for 75 adult patients who underwent surgical fixations with locking compressive plates from May 2005 to December 2011. Patients were divided into two groups according to the surgical methods. Differences in the neck-shaft angle between immediate postoperative period and final follow-up were compared between the two groups. Differences in constant score and Korean shoulder score (KSS) between affected arms and contralateral arms at final follow-up were also compared. Results: The differences in the neck-shaft angle between immediate postoperative period and at final follow-up was 12.04 degrees on average in Deltoid splitting approach and 10.20 degrees in Delto-pectoral interval approach, which was not statistically significant. Differences in constant score/KSS between the affected arm and the contralateral arm were 13.78/22.74 points in deltoid-splitting approach on average and 19.41/31.13 points in Delto-pectoral interval approach, showing that deltoid-splitting approach is significantly superior. Conclusion: Deltoid-splitting approach showed better functional outcomes in the fracture reduction and internal fixation using LCP for the treatment of unstable proximal humerus fractures.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.583-594
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• 2000

Dislodgement of a crown or extension bridge and the loosening of a retainer of a bridge is a serious clinical problem in fixed restoration. Generally these problems are considered to be associated with deformation of the restoration. During biting, the restoration is subjected to complex forces and deforms considerably within the limit of its elasticity. Deformation of the restoration under the occlusal force induces excessive stress in the cement film, which then leads to the cement fracture. Such a fracture may eventually cause loss of the restoration. Because most of the past retention tests for full veneer crown were done without fatigue loading, they were not exactly simulating intraoral environment. And the purpose of this study was to evaluate the effect of cyclic cantilever loading on the retentive strength of full veneer crowns depending on different type of cements and taper of prepared abutment. Steel dies with $8^{\circ}\;or\;16^{\circ}$ convergence angle were fabricated through milling and crowns with the same method. These dies and crowns were divided into 8 groups. Group 1 : $16^{\circ}$ taper die, cementation with zinc phosphate cement, without loading Group 2 : $16^{\circ}$ taper die, cementation with zinc phosphate cement, with loading Group 3 : $8^{\circ}$ taper die, cementation with zinc phosphate cement, without loading Group 4 : $8^{\circ}$ taper die, cementation with zinc phosphate cement, with loading Group 5 : $16^{\circ}$ taper die, cementation with Panavia 21, without loading Group 6 : $16^{\circ}$ taper die, cementation with Panavia 21, with loading Group 7 : $8^{\circ}$ taper die, cementation with Panavia 21 without loading Group 8 : $8^{\circ}$ taper die, cementation with Panavia 21, with loading After checking the fit of die and crown, the luting surface of dies and inner surface of crowns were air-abraded for 10 seconds. The crowns were cemented to the dies, with cements mixed according to the manufacturer's recommendations. A static load of 5kg was then applied for 10 minutes with static loading device. Twenty-four hours later, group 1, 3, 5, 7 were only thermocycled, group 2, 4, 6, 8 were subjected to cyclic loading after thermocycling. Retentive tests were performed on the Instron machine. From the finding of this study, the following conclusions were obtained 1. Panavia 21 showed significantly higher retentive strength than zinc phosphate cement for all groups (p<0.05). 2. There was a significant difference in the retentive strength between $8^{\circ}\;and\;16^{\circ}$ taper for zinc phosphate cement(p<0.05), but no significant difference for Panavia 21 (p>0.05). 3. Cyclic loading significantly decreased the retentive strength for all groups(p<0.05). 4. For zinc phosphate cement, there was 35% reduction of the retentive strength after loading in the $16^{\circ}$ taper die, 25% in the $8^{\circ}$ taper die, and for Panavia 21, 21% in the $16^{\circ}$ taper die, 18% in the $8^{\circ}$ taper die.