• The korean journal of orthodontics
• /
• v.41 no.6
• /
• pp.384-398
• /
• 2011

Objective: The purpose of this study was to analyze the stress distribution and the displacement pattern of mandibular anterior teeth under various intrusive force vectors according to the position of orthodontic miniscrews and hooks, using three-dimensional finite element analysis. Methods: A three-dimensional finite element model was constructed to simulate mandibular teeth, periodontal ligament, and alveolar bone. The displacement of individual tooth on three-dimensional planes and the von Mises stress distribution were compared when various intrusion force vectors were applied. Results: Intrusive forces applied to 4 mandibular anterior teeth largely resulted in remarkable labial tipping of the segment according to the miniscrew position. All 6 mandibular anterior teeth were labially tipped and the stress concentrated on the labiogingival area by intrusive force from miniscrews placed mesial to the canine. The distointrusive force vector led to pure intrusion and the stress was evenly distributed in the whole periodontal ligament when the hook was placed between the central and lateral incisors and the miniscrew was placed distal to the canine. Conclusions: Within the limits of this study, it can be concluded that predictable pure intrusion of the 6 anterior teeth segment may be accomplished using miniscrews placed distal to the canine and hooks located between the central and lateral incisors.

• Restorative Dentistry and Endodontics
• /
• v.23 no.1
• /
• pp.366-378
• /
• 1998

Thermocondensation root canal filling technique have been used to fill accessary canals or to obtain homogeneous root caral fillings. But these thermocondensation technique inevitably produce heat in the canal which can be transmitted through the dentin and cementum and consequently damage periodontal ligamental cells and osteoblasts. In this study, System $B^{TM}$(Analytic technology, WA.D.S.A.) was used to evaluate the reaction of periodontal ligament tissue to "Continous Wave condensation technique" introduced by Buchanan, and the transmitted root surface temperature was measured according to measured root thicknesses. 12 Mandibular incisors of two adult dogs were used for the experiment. 6 controls were filled by lateral condensation technique with sealer.3 specimens were apically filled by Continuous Wave technique at $200^{\circ}C$ for 5 seconds and remaining 3 specimens were additionally backfilled using System $B^{TM}$(Analytic technology, WA.D.S.A.) was used to evaluate the reaction of periodontal ligament tissue to "Continous Wave condensation technique" introduced by Buchanan, and the transmitted root surface temperature was measured according to measured root thicknesses. 12 Mandibular incisors of two adult dogs were used for the experiment. 6 controls were filled by lateral condensation technique with sealer.3 specimens were apically filled by Continuous Wave technique at $200^{\circ}C$ for 5 seconds and remaining 3 specimens were additionally backfilled using System $B^{TM}$ at $100^{\circ}C$ for 20 seconds. Six weeks later, the dogs were sacrificed and the teeth stained with Hematoxylin and Eosin for histologic examination. 6 extracted human teeth were used to measure the transmitted temperature. After cutting off the crown, the canals were prepared and divided into 3 groups with root thickness of 1.5mm, 1.0mm, 0.5mm, 2 teeth in each group. Inside each root canal, System $B^{TM}$ was heated as with the temperature for the apically condensed and the back filled group, and the transmitted heat was measured on the external surface of the root. The temperature of System $B^{TM}$ heat spreader at $200^{\circ}C$ and $100^{\circ}C$ was also measured at root temperature. It can be concluded as follows: 1. In the thin area (200-$250{\mu}m$) of the root, root resorption could be seen even with heating at $200^{\circ}C$ for 5 seconds. 2. When the spreader was heated at $200^{\circ}C$ for 5 seconds and additionally at $100^{\circ}C$ for 20 seconds for backfill, all teeth showed root resorption regardless of their root thickness. 3. The transmitted external root surface temperature was higher as the root thickness decreased and as the heating time increased. In the thermocompaction technique using System $B^{TM}$, the spreader should be heated for the minimal time and used only in the apical area. The heated spreader shouldn't inserted to the binding point of the canal and backfilling should be done with other means of minimally heated gutta percha technique.

• Journal of the Korean Arthroscopy Society
• /
• v.10 no.1
• /
• pp.53-60
• /
• 2006

Purpose: This study is to analyze the clinical and radiological results after arthroscopic reduction and internal fixation of intra-articular fractures of lateral tibial plateau. Materials and Methods: The subject of the study are the 13 cases of the patients visited orthopedics surgery during March year 2000 to August year 2004 because of intra-articular fractures of lateral tibial plateau and were treated with arthroscopic reduction and internal fixation. X-rays and CT or MRI were both carried out to identify the precise pattern of fracture and the degree of depression which showed out to be all type 2 by Schatzker fracture classification. And in 9 of the cases, autogenous and allogenous bone grafts were given as bone loss were severe. The average age was 48, age group between 31 and 66, and average follow up period of about 38 months ($13{\sim}65months$). Radiological ratings were given by comparing the X-rays of degree of joint congruency before and after the operation, functional ratings by analyzing IKDC score and Lysholm score. Combined injuries observed after arthroscopy were posterior cruciate ligament injury in 1 case, meniscus injury in 4 cases and medial collateral ligament in 2 cases. Results: During follow up, X-rays showed well-maintained reduction of articular surface in all cases and no complications such as joint depression, fracture reduction loss, angular deformity or malunion were found. Average Lysholm score at last follow up was 87 points ranging from 65 to 97, in 8 of the cases excellent, 3 good, 1 fair and 1 poor according to Lynsholm classification. Average IKDC score was 92 (from 82 to 99). Conclusion: Not only does arthroscopic reduction of lateral tibial plateau fracture bring exact reduction of articular surface, but also, is considered to be a good way of operation to diagnose and treat combined injuries of knee joint using arthroscopy.

• Journal of Biomedical Engineering Research
• /
• v.28 no.3
• /
• pp.397-409
• /
• 2007

Owing to needs of biomechanical comprehension and analysis to obtain various medical treatment designs which are related with the spine in order to cure and diagnose LBP patients, the FE modeling and nonlinear analysis of lumbosacrum including a partial ilium and iliolumbar ligaments, were carried out. First, we investigated whether the geometrical configuration of vertebrae displayed by DICOM slice files is regular and normal condition. After constructing spinal vertebrae including a partial ilium, a sacrum and five lumbars (from L1 to L5)with anatomical shape reconstructed using softwares such as image modeler and CAD modeler, we added iliolumbar ligaments, lumbar ligaments, discs and facet joints, etc.. And also, we assigned material property and discretized the model using proper finite element types, thus it was completely modeled through the above procedure. For the verification of each segment, average sagittal ROM, average coronal ROM and average transversal ROM under various loading conditions(${\pm}10Nm$), average vertical displacement under compression(400N), ALL(Anterior Longitudinal Ligament) and PLL(Posterior Longitudinal Ligament) force at L12 level, strains of seven ligaments on sagittal plane at L45 level and maximal strain of disc fibers according to various loading conditions at L45 level, etc., they were compared with experimental results. For the verification of multilevel-lumbosacrum spine including partial ilium and iliolumbar ligaments, the cases with and without iliolumbar ligaments were compared with ROM of experiment. The results were obtained from analysis of the verified FE model as follows: I) Iliolumbar ligaments played a stabilizing role as mainly posterior iliolumbar ligaments under flexion and as both posterior and anterior iliolumbar ligaments of one side under lateral bending. 2) The iliolumbar ligaments decreased total ROM of 1-8% in total model according to various motion conditions, which changed facet contact forces of L5S level by approximately 0.8-1.4 times and disc forces of L5S level by approximately 0.8-1.5 times more than casewithout ilioligaments, under various loading conditions. 3) The force of lower discs such as L45 and L5S was bigger than upper discs under flexion, left and right bending and left and right twisting, except extension. 4) It was predicted that strains of posterior ligaments among iliolumbar ligaments would produce the maximum 16% under flexion and the maximum 10% under twisting. 5) It's expected that this present model applies to the development and design of artificial disc, since it was comparatively in agreement with the experimental datum.

• Journal of the Korean Arthroscopy Society
• /
• v.12 no.1
• /
• pp.40-44
• /
• 2008

Purpose: The purpose of this study was to report the real geometry of Resident's ridge doing in anterior cruciate ligament reconstruction Materials and Methods: From Jan 2007 to Aug 2007, 48 cases which had normal distal femoral condyle analyzed with Multidetector-Row Computed Tomography. Resident's ridge was defined as change of height above 1 mm in lateral wall of intercondylar notch. Anterior-posterior length of intercondylar notch, length and height of Resident's ridge, distance of Resident's ridge from posterior cortex were estimated with 3-D reconstruction using $Lucion^{(R)}$ program. Results: Cases were $59{\pm}16$ years olds and male was 16 cases, female was 32 cases. 9 cases had no Resident's ridge, anterior-posterior length of intercondylar notch was $25.4{\pm}3.5$ mm, average of length and height of the Resident's ridge was $8.2{\pm}2.6,\;3.5{\pm}1.5$ mm. Distance of the Resident's ridge from posterior cortex was $7.6{\pm}2.6$ mm. Conclusion: Resident's ridge was used as landmark in anterior cruciate ligament reconstruction, which presented in many cases and which had distinct length and height.

• Journal of Korean Orthopaedic Sports Medicine
• /
• v.3 no.1
• /
• pp.66-72
• /
• 2004

Purpose: To evaluate the compensatory mechanism in vivo and develop the treatment guide by performing the comprehensive functional tests of the posterior cruciate ligament (PCL) deficient subjects. Material and Methods: 10 PCL deficient subjects and 10 healthy control group were evaluated. Performed functional tests were range of motion, posterior drawer test, Telos, 30$^{\circ}$ flexion wt-bearing view, KT-1000 arthrometer, gait analysis, EMG test and isokinetic tests. Results: Physical, KT-1000, Telos posterior tests showed significant differences, but 300 full weight bearing lateral view, muscle strength test revealed no difference between two groups. Less knee flexion at initial contact and reduced maximum valgus moment were observed in PCL deficient group. In vertical drop landing, PCL group had increased plantar flexion angle at initial contact. Conclusion: Compensatory mechanisms such as reduced unstable components and absorbing the maximal load of the joint were occurred after PCL insufficiency, which result in good clinical and functional outcomes. Further investigations would be needed to understand the functional adaptations of PCL deficient subjects.

• Journal of Korean Neurosurgical Society
• /
• v.60 no.5
• /
• pp.597-603
• /
• 2017

Objective : Several surgical methods have been reported for treatment of ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine. Despite rapid innovation of instruments and techniques for spinal surgery, the postoperative outcomes are not always favorable. This article reports a minimally invasive anterior decompression technique without instrumented fusion, which was modified from the conventional procedure. The authors present 2 cases of huge beak-type OPLL. Patients underwent minimally invasive anterior decompression without fusion. This method created a space on the ventral side of the OPLL without violating global thoracic spinal stability. Via this space, the OPLL and anterior lateral side of the dural sac can be seen and manipulated directly. Then, total removal of the OPLL was accomplished. No orthosis was needed. In this article, we share our key technique and concepts for treatment of huge thoracic OPLL. Methods : Case 1. 51-year-old female was referred to our hospital with right lower limb radiating pain and paresis. Thoracic OPLL at T6-7 had been identified at our hospital, and conservative treatment had been tried without success. Case 2. This 54-year-old female with a 6-month history of progressive gait disturbance and bilateral lower extremity radiating pain (right>left) was admitted to our institute. She also had hypoesthesia in both lower legs. Her symptoms had been gradually progressing. Computed tomography scans showed massive OPLL at the T9-10 level. Magnetic resonance imaging of the thoracolumbar spine demonstrated ventral bony masses with severe anterior compression of the spinal cord at the same level. Results : We used this surgical method in 2 patients with a huge beaked-type OPLL in the thoracic level. Complete removal of the OPLL via anterior decompression without instrumented fusion was accomplished. The 1st case had no intraoperative or postoperative complications, and the 2nd case had 1 intraoperative complication (dural tear) and no postoperative complications. There were no residual symptoms of the lower extremities. Conclusion : This surgical technique allows the surgeon to safely and effectively perform minimally invasive anterior decompression without instrumented fusion via a transthoracic approach for thoracic OPLL. It can be applied at the mid and lower level of the thoracic spine and could become a standard procedure for treatment of huge beak-type thoracic OPLL.

• IMMUNE NETWORK
• /
• v.24 no.2
• /
• pp.17.1-17.16
• /
• 2024

We have reported that anterior cruciate ligament (ACL) injury leads to the differential dysregulation of the complement system in the synovium as compared to meniscus tear (MT) and proposed this as a mechanism for a greater post-injury prevalence of post traumatic osteoarthritis (PTOA). To explore additional roles of complement proteins and regulators, we determined the presence of decay-accelerating factor (DAF), C5b, and membrane attack complexes (MACs, C5b-9) in discarded surgical synovial tissue (DSST) collected during arthroscopic ACL reconstructive surgery, MT-related meniscectomy, osteoarthritis (OA)-related knee replacement surgery and normal controls. Multiplexed immunohistochemistry was used to detect and quantify complement proteins. To explore the involvement of body mass index (BMI), after these 2 injuries, we examined correlations among DAF, C5b, MAC and BMI. Using these approaches, we found that synovial cells after ACL injury expressed a significantly lower level of DAF as compared to MT (p<0.049). In contrast, C5b staining synovial cells were significantly higher after ACL injury (p<0.0009) and in OA DSST (p<0.039) compared to MT. Interestingly, there were significantly positive correlations between DAF & C5b (r=0.75, p<0.018) and DAF & C5b (r=0.64 p<0.022) after ACL injury and MT, respectively. The data support that DAF, which should normally dampen C5b deposition due to its regulatory activities on C3/C5 convertases, does not appear to exhibit that function in inflamed synovia following either ACL injury or MT. Ineffective DAF regulation may be an additional mechanism by which relatively uncontrolled complement activation damages tissue in these injury states.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.1
• /
• pp.93-103
• /
• 1997

Charpy V-notch impact tests were performed on the full-, half-and third-size specimens from two ferritic SA 508 Cl. 3 steels for nuclear pressure vessel. New normalization factors were proposed to predict the upper shelf energy(USE) and the ductile-brittle transition temperature(DBTT) of full-size specimens from the measured data on sub-size specimens. The factors for the USE and the DBTT are $(Bb^2/Kt); and; (Bb/R)^1/2/, $ respectively, where B the width, b the ligament size, $K_{t}$ the elastic stress concentration factor, and R the notch root radius. These correlations successfully estimated the USE and DBTT of the full-size specimens based on sub-size specimen data. In addition, the size effects were studied to develop the correlations among absorbed energy, lateral expansion(LE) and displacement. It was also found that the LE was able to be estimated from the displacement obtained by the instrumented impact test, and that the displacement would be used as a criterion for the toughness of the steels corresponding to change in their yield strength.h.

• Journal of the Korean Arthroscopy Society
• /
• v.2 no.1
• /
• pp.25-32
• /
• 1998

The distinction between isolated and combined injuries is crucial both for treatment and prognosis. For most combined injuries, surgical treatment continues to be favored over nonoperative treatment. It is generally agreed that isolatel PCL injuries do well without surgery. There has been an interest by many authors to fix the graft directly to the posterior aspect of the tibia(tibial inlay). With this procedure, tibial graft fixation will be more direct and theoretically reduce the bending effects of the graft with a fixation site far away from the tibial insertion. Modified tibial inlay technique, which is the posterior approach does not require the patient to be in the prone or lateral decubitus position during the operation. Use of a double-bundle reconstructive technique is attractive and has been performed by some surgeons. At this time, this procedure is still being investigated and should not be routinely used in the clinical setting until studies have indicated an advantage over current single-bundle techniques. However theologically, double-bundle reconstructive technique is more useful in severe posterior unstable knee. Recent advances have increased our knowledge of the anatomy and mechanical characteristics of the PCL. Basic science research has further increased our awareness of the interaction of the posterolateral structures with the PCL. To achieve restoration of normal posterior laxity, it is critical to address the posterior as well as the postero-lateral structures. Surgical treatment is often complex and requires a wide range of surgical techniques and skills to treat associated injuries. When the PCL is reconstructed, most surgeons choose to reconstruct the anterolateral component using a graft of sufficient size and strength. The initial postoperative rehabilitation should be addressed cautiously in an effort to avoid excessive forces on delicate repairs and reconstructions in these complex injuries. Further research is necessary to evaluate new surgical approaches such as double-bundle reconstructions and tibial inlay techniques as well as improved techniques for capsular and collateral ligament injuries.