To observe the change in the status of stresses according to three different postural angulation of an intervertebral disc with or without nucleus pulposus, 6 specimens of a 3-dimensional photoelastic model of the spine were made of epoxy. The nucleus pulposus portion was replaced with silicon in three models, and the three were made without silicon. Through axial application of a vertical compressive load of 8 kg, the peculiar patterns of the isochromatic fringes were observed. Stresses on the intervertebral disc were analyzed according to three different postural angulations of the intervertebral disc with the nucleus pulposus and without the nucleus pulposus. The results of these study are as follow: 1. In an erect neutral posture with the nucleus pulposus, the stress concentration was much increased at the posterior portion rather than at the anterior portion. Also, the high stress was concentrated at the medial and central portion. In an erect neutral posture without the nucleus pulposus, the stress concentration was much increased at the anterior portion rather than at the posterior portion and the stress distribution seemed to be locally concentrated. 2. In a maximal flexed posture, the stress concentration was much increased at the posterior portion rather than at the anterior portion. Comparing the presence of the nucleus pulposus with the absence of the nucleus pulposus, the stress concentration was lower at the anterior portion in the presence of the nucleus pulposus than in the absence of the nucleus pulposus. However, the stress distribution at the posterior portion was nearly same in the two groups. According to the analysis of the stress distribution diagram, as a whole, the stress pattern around the disc was evenly distributed. 3. In a maximal extended posture, the higher concentration of the stress distribution at the anterior and medial portion rather than in the posterior and lateral portion was observed. The stress concentration was higher in the presence of the nucleus pulposus than in the absence of the nucleus pulposus. 4. Comparing the maximal flexed posture with the erect neutral posture, the stress concentration in the flexed posture was much decreased in the posterior portion rather than in the erect neutral posture, and an even distribution of the stress pattern in the flexed posture was observed. 5. In the presence of the nucleus pulposus, at the anterior and posterior portion, the stress concentration in the flexed posture was much decreased compared with the extended posture. In the absence of the nucleus pulposus, at the anterior and posterior portion, the stress concentration in the extended posture was much decreased compared with the flexed posture.
Intervertebral Disc* ; Posture ; Silicon ; Spine

No abstract available.
Arthroplasty, Replacement, Hip*

The purpose of this study was to compare the soft tissue movements in facial profile predicted by a computer package with those that had actually accured following a sagittal split ramal osteotomy. The reliability of predicting the results of orthodontic surgical treatment was analysed. The study was based on the serial records of 30 consecutive patients who had been treated by means of a sagittal split ramal osteotomy. The serial lateral cephalometric radiographs used for the study were taken at the following stages: immediate preoperative : immediate postoperative : 6 months postoperative. A superimposition T1, T2-3 was generated to allow visual comparision. The results can be considered in relation to four important parts of the facial profile :the nose, upper lip, lower lip, and chin. The nose & Upper lip:The amount of movement of the upper lipwas not badly predicted for the average case. The lower lip: There was a significant trend over the whole sample for vertical positionof the lower lip to be less well predicted. The chin: The soft tissue movements of the chin were well predicted.
Chin ; Humans ; Lip ; Nose ; Orthognathic Surgery ; Osteotomy, Sagittal Split Ramus ; Prognathism*

In postmenopausal osteoporosis, estrogen deficiency leads to unbalance of bone metabolism, decreased bone formation and increased bone resorption, and the result is reduced bone mineral density (BMD) and bone stiffness. The processes of bone formation and resorption involves the expression of integrins in anchoragedependent cells, such as osteoblast and osteoclast. The osteoporosis-induced rats frequently demonstrated the loss of trabecular bone volume in the tibia, vertebra and mandible due to estrogen depletion. However, in maxilla, study has been rare because of its anatomical limits. So the objective of this study was to investigate bony change and property of integrin expression in maxilla of osteoporosis-induced rats. 12-week-old female Sprague-Dawley rats were bilaterally ovariectomized (OVX). At 1, 2, 3, 4, 8 and 12 weeks, control and OVX group rats were sacrificed respectively. BMD of maxilla of the rats was measured using dual-energy X-ray absorptiometry (DEXA). And then the histopathologic observation, histomorphometric analysis and immunohistochemistry with CD44, alpha2 integrin, alpha5 integrin, alpha6 integrin, alphav integrin and beta3 integrin were done. BMD of alveolar bone in maxilla was decreased with significance statistically after OVX 4 weeks and was decreased 18.15% at OVX 12 weeks group compared to control group. From OVX 4 to 12 weeks, the thickness of periodontal ligament space was decreased, the number of osteoclast and the size of marrow stroma were increased than control group. By histomorphometric analysis, the size of marrow stroma of alveolar bone in maxilla was increased 86.42% at OVX 12 weeks group compared to control group. CD44 was widely expressed throughout the odontoblast, cementoblast, dental pulp, preiodontal ligament, osteocyte, osteoclast and perivascular tissue at control group, and CD44 immunoreactivity was increased the odontoblast, osteoblast and osteoclast at OVX groups. alpha2 integrin was expressed the odontoblast and osteoblast at control group, but alpha2 integrin immunoreactivity was decreased the osteoblast at OVX 12 weeks group. alpha5 integrin was expressed the cementoblast, osteoblast and osteoclast at control group, and alpha5 integrin immunoreactivity was decreased the osteoblast and was increased the osteoclast from OVX 4 weeks group. alpha6 integrin was weakly expressed the odontoblast, cementoblast, osteoblast and osteoclast at control group, and alpha6 integrin immunoreactivity was weakly increased the osteoclast from OVX 4 weeks. alphav integrin was expressed the odontoblast and osteoclast at control group, and alphav integrin immunoreactivity was strongly increased the osteoclast from OVX 4 weeks. beta3 integrin was expressed the osteocyte and osteoclast at control group, and beta3 integrin immunoreactivity was strongly increased the osteoclast from OVX 4 weeks. From these results, alveolar bone in maxilla of OVX rats was decreased BMD gradually. Moreover, alpha2 and alpha5 integrin expression of osteoblast was decreased, and alpha5, alphav and beta3 integrin expression of osteoclast was increased in OVX rats. Thus, this study indicates that consideration of reduced BMD is necessary in dental procedure of postmenopausal women.
Absorptiometry, Photon ; Animals ; Bone Density* ; Bone Marrow ; Bone Resorption ; Dental Cementum ; Dental Pulp ; Estrogens ; Female ; Humans ; Immunohistochemistry ; Integrin alpha2 ; Integrin alpha5 ; Integrin alpha6 ; Integrin alphaV ; Integrin beta3 ; Integrins ; Ligaments ; Mandible ; Maxilla* ; Metabolism ; Odontoblasts ; Osteoblasts ; Osteoclasts ; Osteocytes ; Osteogenesis ; Osteoporosis, Postmenopausal ; Ovariectomy* ; Periodontal Ligament ; Rats* ; Rats, Sprague-Dawley ; Spine ; Tibia

PURPOSE: To assess the histological response and the reinforcing effects of bone ingrowth within porous hydroxyapatite implants depending on pore geometry. MATERIALS AND METHODS: Three types of porous hydroxyapatite (cylindrical, sponge and cross type) were prepared. Forty-two white rabbits were divided into 3 groups and 5x5x7 mm-sized porous hydroxyapatite block was inserted through the medial cortical window of a proximal tibia. Histomorphological changes were examined using light and scanning electron microscopy. Biomechanical compression test was performed using material test machine. RESULTS: At four weeks after implantation, the implants showed different histological changes depending on pore geometry. In cylindrical type porous hydroxyapatite, new bone was arranged in a concentric pattern around vessel similar to osteon. In sponge and cross type, irregular lamellar bone pattern was found. At 8 weeks, evidence of remodelling of new bone and bone marrow formation within porous hydroxyapatite was found. In biomechanical study, ultimate compressive strength significantly increased in all three implants after 8 weeks of implantation compared to preimplantation. CONCLUSIONS: In cylindrical type porous hydroxyapatite, new bone was arranged in a concentric pattern around vessel, and compressive strength was highest. Sponge type porous hydroxyapatite showed irregular lamellar bone pattern and was rather flexible and ductile. Cross type porous hydroxyapatite showed borderline pattern of both cylindrical and sponge type porous hydroxyapatite.
Bone Marrow ; Bone Regeneration* ; Compressive Strength ; Durapatite* ; Haversian System ; Microscopy, Electron, Scanning ; Porifera ; Rabbits ; Tibia

OBJECTIVE: The authors evaluate the usefulness, results, and technical problem of endovascular treatment of cerebral aneurysms with Guglielmi detachable coil(GDC). METHODS: Forty patients with 31 ruptured and 11 unruptured aneurysms were treated with GDC embolization. Twenty-four aneurysms were located in the anterior circulation and 18 in the posterior circulation. Aneurysms size was categorized small(n=31) or large(n=11) and neck size was categorized narrow(n=30) or wide(n=12). We statistically analyzed occlusion rate according to the location, rupture, size, and neck size of aneurysms, and investigated the procedure-related complications and clinical outcomes. RESULTS: GDC treatment of aneursyms was successful in 40 aneurysms of 39 patients(95.2%). Total occlusion was achieved in 24(60.0%) cases, subtotal occlusion in 12(30%), and incomplete occlusion in 4(10.0%). Each total occlusion rate was 69.0% in small-sized, 36.4% in large-sized, 69.0% in narrow-necked, and 36.4% in wide-necked aneurysms. Location and rupture of aneurysms did not influence occlusion rate. The technical complications included 4 thromboembolisms, 3 parent artery occlusions, and 1 perforation of aneurysm. Procedure-related morbidity and mortality were 10.3% and 2.6%. 3 subtotally or incompletely embolized aneurysms in posterior circulation rebled during the follow-up period. CONCLUSION: The results of this study indicate that endovascular GDC treatment is an appropriate therapeutic alternative in cerebral aneurysms. However, the rebleeding by aneurysmal recanalization or regrowth is a major limitation of GDC treatment. Follow-up angiography and further technical improvement are mandatory to overcome rebleeding.
Aneurysm ; Angiography ; Arteries ; Follow-Up Studies ; Humans ; Intracranial Aneurysm* ; Mortality ; Neck ; Parents ; Retrospective Studies* ; Rupture ; Thromboembolism

PURPOSE: The purpose of this study was to report the reproducibility of intra-observer and inter-observer consistency of cephalometric measurements using three-dimensional (3D) computed tomography (CT), and the degree of difference of the cephalometric measurements. MATERIALS AND METHODS: CT images of 16 adult patients with normal class I occlusion were sent to personal computer and reconstructed into 3D images using V-Works 3.5 TM (Cybermed Inc., Seoul, Korea). With the internal program of V-Works 3.5 TM, 12 landmarks on regular cephalograms were transformed into 21 analytic categories and measured by 2 observers and in addition, one of the observers repeated their measurements. Intra-observer difference was calculated using paired t-test, and inter-observer by two sample test. RESULTS: There were significant differences in the intra-observer measurements (p< 0.05) in four of the categories which included ANS-Me, ANS-PNS, Cdl-Go (Lt), GoL-GoR, but with the exception of Cdl-Go (Lt), ZmL-ZmR, Zyo-Zyo, the average differences were within 2 mm of each other. The inter-observer observations also showed significant differences in the measurements of the ZmL-ZmR and Zyo-Zyo categories (p< 0.05). With the exception of the Cdl-Me (Rt), ZmL-ZmR, Zyo-Zyo categories, the average differences between the two observers were within 2 mm, but the ZmL-ZmR and Zyo-Zyo values differed greatly with values of 8.10 and 19.8 mm respectively. CONCLUSION: In general, 3D CT images showed greater accuracy and reproducibility, with the exception of suture areas such as Zm and Zyo, than regular cephalograms in orthodontic measurements, showing differences of less than 2 mm, therefore 3D CT images can be useful in cephalometric measurements and treatment planning.
Adult ; Cephalometry ; Humans ; Microcomputers* ; Reproducibility of Results ; Seoul ; Sutures ; Tomography, X-Ray Computed

PURPOSE: To evaluate the CT features of abdominal tuberculosis by the pattern anaylsis. MATERIALS AND METHODS: We retrosepctively reviewed the CT findings of confirmed abdominal tuberculosis in 16 patients. Of the 16 patients, 1 was man and the remaining 15 were women with an average age of 34.1 years and the highest incidence in the twenties of age. Intravenous and oral contrast agents were used in all patients. The amount and location of ascites and the changes in the omenturn, mesentery, bowel wall, and peritoneum were analyzed. The morphologic feature, size and main compartment of involvement were also evaluated in the cases with lymphadenopathy as well as other changes in intraabdominal organs. RESULTS: The abdominal tuberculosis was more common in the female(15/16, 93.8%) and could be classified into 3 patterns on their CT findings;Complex ascitic, lymphadenopathy, or abscess forms. The complex ascitic form(10/16, 62.5%) was most commonly seen and characterized by uneven distribution and Ioculation of intraperitoneal fluid collection and marked changes of the omenturn and mesentery. The lymphadenopathy form(3/16, 18.8%) was characterized by central low density and peripheral rim enhancement on postcontrast CT with common involvements of porta hepatis and upper abdominal and paraaortic lymph nodes. The abscess form(3/16, 18.8%) was mainly related to the pelvic abscesses. CONCLUSION: CT was valuable in analyzing the patterns of the lesions and making a diagnosis of abdominal tuberculosis.
Abscess ; Ascites ; Contrast Media ; Diagnosis ; Female ; Humans ; Incidence ; Lymph Nodes ; Lymphatic Diseases ; Mesentery ; Peritoneum ; Tuberculosis*

PURPOSE: Porous hydroxyapatite is resorbable and osteoconductive, so it is slowly replaced by ingrowing new bone. Optimal pore geometry for osteoconduction, however, has not been determined yet. The objective of this investigation was to assess both the histological response and the reinforcing effects of bone ingrowth within the porous hydroxyapatite implants depending on pore size. MATERIALS AND METHODS: Four kinds of cylindrical types (50, 100, 300, 500 micrometer) of porous hydrox-yapatite were prepared. Fifty-six white rabbits were divided into 4 groups and porous hydroxyapatite block was inserted through the medial cortical window of a proximal tibia. Histomorphological changes were examined using light microscopy and scanning electron microscopy. Biomechanical compression test was performed using a material test machine. RESULTS: Hydroxyapatite implants appeared to have no early adverse effects, such as inflammation and foreign body reaction. Osteoconduction through the pores was found in all four implants and new bone was found on the surface of pores with no histologically demonstrable intervening nonosseous tissue. At four weeks after implantation, new bone was arranged in a concentric pattern around the vessel, similar to osteon. New bone formation through pores was most evident at 300 micrometer-sized type. At 8 weeks, active osteoconduction was also found at 50 micrometer-sized type. Evidence of bone marrow formation within porous hydroxyapatite was found. In a biomechanical study, ultimate compression strength significantly increased in the 300 micrometer-sized type, after 8 weeks implantation compared to preimplantation. CONCLUSIONS: Porous hydroxyapatite implanted into rabbit tibia showed biological fixation and osteointegration. A pore size of 300 micrometer was most effective for bone ingrowth. Osteoconduction also took place in 50 micrometer-sized cylindrical pores.
Bone Marrow ; Bone Regeneration* ; Durapatite* ; Foreign-Body Reaction ; Haversian System ; Inflammation ; Microscopy ; Microscopy, Electron, Scanning ; Osteogenesis ; Rabbits ; Tibia

The change of conditions of hydroxyapatite synthesis can affect not oniy the material properties, but also the body reaction to the hydroxyapatite implants. To find out conditions for preparing more biocompatible hydroxyapatite implants as bone graft substitute. we evaluated the biologic response to the dense synthetic hydroxyapatite implants, made with various synthetic conditions, placed in corticocancellous defects of rabbits' long bone. The hydroxyapatites were synthesized with coprecipitation technique using Ca(NO3) 4H2O and (NH4)2HPO4, made with various Ca/P ratio and aging temperatures. Four kinds of hydroxyapatites were selected to use as implants(HA I: Ca/P ratio 1.5, aging temperature 90degrees C; HA V :1.5 , 30degrees C; HA VI: 1.83, 30degrees C; and HA lX: 1.67, 30degrees C). These hydroxyapatites were pressed and sintered at l300degrees C to fabricate dense plates. Biomechanical test and rnorphological examination were performed using Instron, light microscope and electron microscope. The characteristics of hydroxyapatite powder and sintered body were more significantly affected by siarting Ca/P ratios. The bonding strength of HA IX(1.67, 30degrees C) with bone was grcatest at 4 or 8 weeks after implantation with statistically significant difference(p<0.05). Bonding behavior betweeb HA IX and bone was most excellent in terms of new bone formation and new bone ingrowth into resorbed surface of hydroxyapatite plate.
Aging ; Durapatite* ; Hydroxyapatites ; Osteogenesis ; Transplants