• Journal of Korean Association for Spatial Structures
• /
• v.5 no.4 s.18
• /
• pp.91-100
• /
• 2005

Composite slab structures consisted with steel deck plate and concrete material show generally anisotropic structural behavior because of different stiffness between the major direction and sub-direction of deck plate, and also the structures can be regarded as the laminated slab structures. It is necessary for the composite deck slab structures to carry out the exact vibration analysis to evaluate the serviceability. Also, it is needed to evaluate the exact structural behavior of composite deck slab with a layered orthotropic materials. In this paper, the thickness of topping concrete and deck plate are used to calculate the material coefficient stiffness of a sub-direction, and an equivalent depth calculated from sectional stiffness of concrete and deck plate is applied to get the stiffness of a major direction. The stiffness of two layered composite plates with different depth is determined by laminated theory. It is concluded that the presented method can efficiently analyze the structural behavior of composite deck slab consisted with steel deck plate and concrete material in the practical engineering field.

• Journal of Periodontal and Implant Science
• /
• v.32 no.2
• /
• pp.379-388
• /
• 2002

For the success of dental implant, accurate radiographic evaluation is prerequisite for planning the location of the osseointegrated implants and avoiding injury to vital structures. CT/MPR(computed tomography/multiplanar reformation) shows improved visualization of inferior alveolar canal. In order to obtain cross-sectional images parallel to the teeth, the occlusal plane is used to orientate for the axial plane. If the direction of axial plane is not parallel to the occlusal plane, the reformatted cross-sectional scans will be oblique to the planned fixture direction and will not show the actual dimension of the planned fixture's location. If the available bone height which measured in the cross-sectional view is much greater than the actual available bone height, penetration of canal may occur. The aim of this study is to assess the effect of the axial plane to measurement of available bone height for dental implant in computed tomography of the mandible. 40 patients who had made radiographic stents and had taken CT were selected. The sites that were included in the study were 45 molar regions. In the central panoramic scan, the length from alveolar crest to superior border of inferior alveolar canal(available bone height, ABH) was measured in direction of reformatted cross-sectional plane(uncorrected ABH). Then, length from alveolar crest to superior border of canal was measured in direction of stent(corrected ABH). The angle between uncorrected ABH and corrected ABH was measured. From each ABH, available fixture length was decided by $Br{{\aa}}nemark$ system. The results were following ; the difference between two ABHs was statistically significant in both first and second molar(p< 0.01). The percentage of difference more than 1 mm was 8.7% in first molar and 15.5% in second molar. The percentage of difference more than 2 mm was 2.0% in first molar and 6.6% in second molar. The maximum value of difference was 2.5 mm in first molar and 2.2 mm in second molar. The correlations between difference of 2 ABHs and angle was positive correlations in both first and second molar. The correlation coefficient was 0.534 in first molar and 0.728 in second molar. The second molar has a stronger positive correlation. The percentage of disagreement between 2 fixture lengths from two ABHs was 24.4% in first molar and 28.9% in second molar.

• Clinical and Experimental Pediatrics
• /
• v.50 no.2
• /
• pp.198-204
• /
• 2007

Purpose : The hope that arresting pubertal developement might increase final adult height has led to an attempt to use GnRH agonist (GnRHa) in children with early puberty and poor growth prognosis. We investigated the growth-promoting effect of GnRH agonists with or without growth hormone (GH) in girls with early puberty and decreased predicted adult height (PAH). Methods : Thirty five girls with advanced bone age and early pubertal signs were randomized for treatment for about 1 year with monthly GnRHa in group 1 (n=18), or with a combination of GH and GnRHa in group 2 (n=17). The following growth parameters were compared between groups, and the difference ($\Delta$) before and after treatment : chronological age (CA), bone age (BA), $\Delta$(BA-CA), height (HT), target height (TH), predicted adult height (PAH), $\Delta$ (TH-PAH), serum insulin-like growth factor (IGF-1) and insulin-like growth factor binding protein (IGFBP-3). Results : Before treatment, BA, TH, PAH Standard deviation scores (SDS), $\Delta$(TH-PAH) were not different between the two groups, but CA was higher in group 2 and $\Delta$(BA-CA) were higher in group 1 (P<0.05). After $1.06{\pm}0.93$ year of treatment, $\Delta$ (BA-CA) decreased and there were significant changes in PAH and $\Delta$ (TH-PAH), especially in group 2 (P<0.05 in group 1, and P<0.001 in group 2). In both groups, IGF-1 and IGFBP-3 were not different before and after treatment, but after treatment, IGF-1 level in group 2 was marginally higher than IGF-1 in group 1 (P<0.1). Conclusion : Compromised predicted adult height in girls with early puberty and advanced bone age was significantly improved with GnRH with/without GH treatment in the short-term period. The addition of GH to GnRHa results in a significant increase in PAH compared to GnRHa alone because GnRHa suppressed growth hormone-IGF-1 axis. For comparison of final adult height, further longitudinal follow-up will be needed.

• The Journal of Korean Academy of Prosthodontics
• /
• v.58 no.4
• /
• pp.306-312
• /
• 2020

Purpose: The aim of this study was to compare radiographic outcomes around narrow-diameter implants placed using guided flapless surgery at longer than 6 month post-placement. Materials and methods: A total of 12 implants were assessed in 12 patients for the sites where 0.5 - 1.5 mm labial bone was covering the implants, using CBCT. Results: A statistically significant preservation of crestal bone was observed in the narrow-diameter implants. Conclusion: Guided flapless implant surgery may be important in preventing bone loss around the narrow-diameter implants that are placed in narrow alveolar ridges.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.30 no.2
• /
• pp.184-191
• /
• 2014

In the mandibular posterior molar area, ridge deficiency is an unfortunate obstacle in the field of implant dentistry. Many techniques are available to rebuild the deficient ridge. Selection and necessity of these techniques are associated with significant morbidity and often require a second surgical site. With the advent of guided bone regeneration (GBR), one may now graft the deficient ridge with decreased morbidity and without a second surgical site. In this case, guided bone regeneration procedures were performed with a combination of allograft, xenograft, and alloplast, excepting autogerous bone at severe defected mandibular alveolar ridge and then placed to the implant successfully. We report that implant placement were good in two cases.

• The Journal of the Korean dental association
• /
• v.34 no.10 s.329
• /
• pp.742-751
• /
• 1996

본 연구의 목적은 관통된 뼈의 결손부위를 각기 다른 membrane(Gore-tex, Vicryl, Guidor)을 사용하여 보다 나은 골 재생을 얻을 수 있는 가를 평가하는 데 있다. 여섯 마리 흰 족제비의 12개 하악 소구치를 근관치료한 후, 치근단 절제술을 실시하여 $3mm\times5mm$ 크기의 관통된 뼈의 결손을 소구치의 근첨부에 형성하였다. 전부 12개의 결손부위가 형성되었고, 이를 3개의 군으로 나누었다. 대조군으로 결손부위를 membrane barrier없이 점막골막피판으로 덮었다. 다른 각 군은 결손부위를 각 Gore-Tex, Vicryl, Guidor membrane을 사용하여 설측과 협측 모두 덮었다. 각 군을 치유기간 6주와 12주로 두 아군으로 분리하였다. 방사선학적 소견으로 6주군에서 대조군은 $65\%$, Gore-Tex군은 $90\%$, Vicryl군은 $95\%$, Guidor군은 $65\%$의 결손부위의 치유를 보였다. 12주 군에서 대조군은 $80\%$, Gore-Tex군은 $95\%$, Vicryl군은 $95\%$, Guidor군은 $90\%$의 치유를 보였다. 조직학적 소견으로 대조군에서는 완전한 골 재생이 일어나지 않았으며, 결손부위로 결합조직이 자라들어온 것이 관찰되었다. Gore-Tex 6 주군에서는 대부분 fibrillar bone이 관찰되었고, 12 주군에서는 부분적으로 lamellar bone이 형성되었다. Vicryl군에서는 거의 완전한 골의 재생이 관찰되었다. 6주군에서는 재생된 뼈는 fibrillar bone이고 부분적으로 lamellar bone을 관찰되었고, 12주 군에서는 주로 lamellar bone으로 구성되었다. Guidor군에서는 제한적인 골 재생과 함께 심한 염증이 관찰되었다. 본 연구의 결과에서 조직재생유도술은 일반적으로 골 재생을 증진시킴을 볼 수 있었고, Vicryl membrane이 가장 뛰어난 골 재생유도 가능성을 보였다.

• Journal of Chest Surgery
• /
• v.41 no.2
• /
• pp.292-294
• /
• 2008

Diffuse pulmonary ossification is a rare entity which was reported just a case in Korea, defined as "wide spread heterotropic bone formation within the lung parenchyme", and it's pathogenesis remains unclear. Generally, diffuse pulmonary ossification is diagnosed by autopsy because most of case is asymptomatic, and classified as either nodular and dendriform diagnosed pathologic examination. We reviewed a case of diffuse dendriform pulmonary ossification with spontaneous pneumothorax.

• The Journal of the Korean bone and joint tumor society
• /
• v.9 no.2
• /
• pp.139-147
• /
• 2003

Purpose: The purpose of this study was to determine if bony union can be obtained when a bone graft substitute is transplanted in order to treat a benign bone tumor and if there is a difference between calcium sulfate and hydroxyapatite in the healing procedure when the degree of the bony union after the bone graft are compared. Materials and Methods: This study selected 20 cases, in which a curettage on the benign bone tumors was conducted and a bone graft substitute was transplanted. The area of the focus, the new bone formation, the recurrence of the focus in the plain radiographs and histological findings were observed. Results: Twenty cases (13 males, 7 females) were evaluated. Their mean age at surgery was 15.8 years (2~45), and the mean follow-up period was 3 years. The mean area of focus was 30.7 $cm^3$ in the radiographs, and 19 cases showed successful results in the ultimate visit, while 1 case has a recurrence of the focus. Conclusion: Calcium sulfate has osteoconduction and superior bioavailability, and is absorbed in vivo in proportion to the new bone formation. On the other hand, hydroxyapatite has good osteoconduction. It can result in better bone formation when it is combined with an autologous bone graft, autologous bone marrow, and an allogenic bone graft, but is absorbed in vivo more slowly than the former.

• Journal of Periodontal and Implant Science
• /
• v.28 no.4
• /
• pp.577-604
• /
• 1998

chitosan은 골치유증진 및 골세포의 분화를 촉진하는 것으로 알려진 천연의 생분해성 고분자이다. 이연구에서는 chitosan 및 chitosan/tricalcium phosphate(TCP) 다공성 기질을 제조하여 골이식재 및 조직공학적 골형성을 위한 3차원적 세포배양 지지체로서의 가능성을 평가하고자 하였다. chitosan 용액 및 TCP가 포함된 chitosan 용액을 동결건조함으로써 소공의 크기가 $100-200{\mu}m$인 스폰지형태의 chitosan 및 chitosan/TCP 다공성 기질을 제작하였다. 골이식재로서의 효과를 평가하기 위하여 백서의 두개골 결손부에 제작된 chiosan 및 chitosan/TCP 다공성 기질을 각각 이식하고 2주 및 4주 후에 동물을 희생하여 조직학적으로 치유양상을 관찰하였다. 조직공학적 골형성을 위한 세포배양 지지체로서의 가능성을 평가하기 위하여 백서 태자의 두개골에서 분리된 골아세포를 chitosan 및 chitosan/TCP 다공성 기질에 각각 접종하고 56일간 배양하면서 각 기간 별로 세포수, 염기성 인산효소 활성, 축적된 calcium의 양을 측정하였고 배양된 세포-기질 혼합체를 광학현미경 및 주사전자현 미경하에서 조직학적 관찰을 시행하였다. 백서 두개골결손부에 이식된 chitosan 및 chiosan/TCP 다공성 기질은 별다른 이물반응 없이 자연 분해되면서 신생골조직 내에 매립되었으며 이식하지 않은 대조군에 비해 유의하게 높은 신생골형성 효과를 나타내어 우수한 골전도성이 있음이 확인되었다. 신생골형성 양상이나 형성된 양에 있어서 두 가지 기질간의 유의한 차이는 없었다. 골아세포-기질 혼합체의 배양결과, 접종후 배양 28일 경과 시까지 골아세포수는 지속적으로 증가하다가 이후에는 5 8일까지 성장정도가 둔화되었다. 염기성 인산효소의 활성 및 calcium 축적량은 접종후 배양시간경과에 따라 56일까지 지속적으로 증가하였다. 세포수 및 염기성 인산효소의 활성에서 두 기질간의 유의한 차이는 없었고, calcium 축적량에 있어서는 chitosan/TCP 기질에서 유의하게 높았고 증가속도도 컸다. 배양된 골아세포가 접종된 다공성 기질의 조직학적 관찰결과, 골아세포는 다공성 기질에 잘 부착하여 중층의 형태로 성장하면서 광화된 골기질을 형성함이 관찰되었다. 배양 14일부터 작은 골편형태의 골형성이 기질 표면에 부착되어 관찰되었고, 배양기간이 길어짐에 따라 성장하여 배양 56일째에는 상당한 양의 광화된 골질이 형성됨이 관찰되었다. 배양 56일 경과후의 광화된 골질의 양은 chitosan/TCP 기질에서 더 많았다. 이 연구의 결과, chitosan 및 chitosan/TCP 다공성 기질이 골이식재로서 뿐만 아니라, 조직공학적 골형성에 적용되는 골아세포의 배양을 위한 3차원구조의 세포지지체로 이용되어 골재생술식에 유용한 생체재료로 활용될 수 있음이 확인되었다.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.35 no.2
• /
• pp.103-111
• /
• 2015

The present study investigated the influence of thick cortical endplates on the ultrasonic properties of trabecular bone in a femur with a high fracture risk. Twelve trabecular bone samples were prepared from bovine femurs, and acrylic plates with thicknesses of 1.25, 1.80, and 2.75 mm were manufactured to simulate the cortical endplates using acrylic with a density and a sound speed similar to cortical bone. Although the thickness of the acrylic plates attached to the two sides of the trabecular bone increased, high correlations were observed between the speed of sound and the apparent bone density of the trabecular bone, with Pearson's correlation coefficients of 0.80-0.86. High correlations were also observed between the attenuation coefficient at 0.5 MHz and the apparent bone density of the trabecular bone, with Pearson's correlation coefficients of 0.84-0.91. These results suggest that the speed of sound and attenuation coefficient at a specific frequency measured in a femur with relatively thick cortical endplates compared to the calcaneus could be used as indices for predicting the bone mineral density of the femur.