• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.6
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• pp.466-472
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• 2012

The loss of mandibular continuity due to trauma, neoplasm, or infection results in major esthetic and biologic compromise. The reconstruction of the mandibular bone defect still poses a challenge to oral and maxillofacial surgeons. There have been a number of variety graft materials. Among them, free block bone graft with rigid fixation has been widely used. However, cases using free block bone grafts may lead to a marked invasion of the donor site, mal-union, and absorption of the block bone. In this respect, particulate cortical bone using a titanium mesh tray can be an effective alternative option in order to achieve a proper bone contour and good oral rehabilitation. We have developed an intraoral approach for the mandibular reconstruction method using a titanium mesh tray with autogenous particulate cortical bone graft.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.6
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• pp.467-473
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• 2009

Purpose: The aim of this study is to compare volume and revascularization of autogenous block bone grafts in simultaneously cortical perforation of recipient beds and grafts, and only cortical perforation of recipient beds. Materials and methods: Two block bone in 8mm diameter was harvested in both skull using trephine bur on 20 New Zealand white rabbits. Harvested block bone was grafted on both inferior border of mandible. On the left side(experimental side), cortical bone of recipient beds and graft were perforated, and on the right side(control side), the only recipient bed was perforated. The rabbits had been sacrificed and infused the India ink for the observation of revascularization at 20 day and 40 day after surgery. The specimens were processed for H-E staining and quantitative analysis(independent t-test, p<0.01) was made under an optical microscope. In additional, specimens were processed for the observation of revascularization. Results: After 20 days, more bone volume was observed in experimental group, but no significant difference between two groups(p=0.106). There were significantly more bone volume in the experimental group at 40 days after surgery(p<0.01). After 20 days, more discrete vascular sprouts were observed in experimental side, but no difference at 40 days after surgery. Conclusion: We conclude that the cortical perforation of both the recipient beds and grafts improve revascularization at early stage and overall graft persistence.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.1
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• pp.187-200
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• 1996

After loss of tooth, initial healing process is critical to preserve residual alveolar process. This study was conducted to compare the effect of hydroxylapatite particle synthetic graft and guided tissue regeneration procedure on healing of extraction wounds in 5 mongrel dogs. To investigate the maturity of bone and velocity of bone heating, bone-labeled tracers were used. After 16 weeks healing period, dogs were sacrificed. The specimens were treated with Villanueva bone stain. Fluorescence microscopy and polarized microscopy were performed to exam the pattern of bone formation in the extraction socket. The results were following ; 1. Pattern of bone regeneration in the group of hydroxylapatie graft and the group of membrane protection after hydroxylapatite graft was following ; bone regeneration was slow, regenerated bone was immature, and thickness of cortical layer was thin compare to that of untreated control group. 2. Cortical layers in membrane protected group were somewhat thicker but less condense to that of untreated control group. 3. Infiltration of inflammation cells were found in the groups using hydroxylapatite graft and membrane. We concluded that grafting of replamineform hydroxylapatite particles into the extraction socket delayed healing of the wound and disturbed the formation of cortical bone at the roof of extraction socket. The placement of expanded polytetrafluoroethylene membranes on the extraction socket promotes the bone regeneration. But newly formed bone in cortical layer consists of the cortico-cancellous bone in comparison with the cortical bone of the control group.

• Imaging Science in Dentistry
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• v.32 no.2
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• pp.81-87
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• 2002

Purpose : To investigate the diagnostic significance of cortical changes in the bone of diseased jaws utilizing computed tomography (CT). Materials and Methods: Computed tomographic images of 91 patients, consisting of 7 osteomyelitis, 46 cysts, 18 benign tumors, and 20 malignant tumors, were analyzed. The pattern of cortical expansion was classified into three types: no expansion (N), buccal or lingual expansion (B/L), and buccolingual expansion (B & L). The pattern of cortical destruction was classified into four types: no destruction (N), point destruction (PO), gross destruction (GR), and permeative destruction (PE). The pattern of periosteal reaction was classified into four types: parallel, irregular, spicule, and Codmans triangle. The relationship between the pattern of cortical bone changes and diseases of the jaws was assessed. Results: When the pattern of cortical expansion was compared to diseases of the jaw, N-type was most prevalent in cases of osteomyelitis and malignant tumors, B/L-type with cysts, and B&L-types with benign tumors. Comparison between the pattern of cortical bone destruction with diseases of the jaw showed strong correlations between PO and PE-types to osteomyelitis, N-type with cysts, N and GR-types with benign tumors, and GR-type with malignant tumors. Finally, the relationship between the pattern of periosteal reaction to diseases of the jaw showed a strong correlation between parallel-type to osteomyelitis and spicule-type to malignant tumors. Conclusion : The pattern of cortical expansion and cortical destruction is useful in differentiating diseases of the jaws.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.1
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• pp.69-78
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• 2007

This study was performed to compare the stress distribution pattern in the crestal cortical bone and cancellous bone using 3-dimensional finite element stress analysis when 2 different Young's modulus(high modulus, model 1; low modulus, model 2) of cancellous bone was assumed. For the analysis, a finite element model was designed to have two square-threaded implants fused together and located at first and second molar area. Stress distribution was observed when vertical load of 200N was applied at several points on the occlusal surfaces of the implants, including central fossa, points 1.5mm, 2mm, 3mm and 3.5mm buccally away from central fossa. The results were as follows; 1. In both model, the maximum Von-Mises stress in the crestal cortical bone was greater when the load was applied at the central point, points 1.5mm and 2mm buccally away from central fossa than other cases. 2. In the cortical bone around first and second molar, model 2 showed greater Von-Mises stress than model 1. It is concluded that when the occlusal contact is afforded, the distribution of stress varies depending on the density of cancellous bone and the location of loading. More favorable stress distribution is expected when the contact load is applied within the diameter of fixtures.

• Journal of Veterinary Clinics
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• v.20 no.4
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• pp.482-488
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• 2003

Transplanted cortical bone grafts of freeze-dried bones also function as sustaining for defected bones, however, it has less strength and is fragile without rehydration. In this study, strength and stiffness of freeze-dried bone from bovine cortical bones were evaluated by three point bending test according to different time frames such as rehydration times of 0.5, 3, 6, 12 and 24 hrs in electrolyte solution and was compared with those of frozen bones. The strength and stiffness of frozen bone were $264.4\pm36.7$ MPa, $17.0\pm1.5$ GPa, respectively. The strength and stiffness of freeze-dried bone which fat was removed by treatments of chloroform-methanol solutions for 6 days, then was freeze-dried at $-80^{\circ}C$ and sterilized with ethylene oxide gas, were $224.9\pm27.6$ MPa, $19.2\pm2.8$ GPa, respectively. The strength and stiffness of feeze-dried bone were decreased 15.0% and increased 13.2% than these of frozen bone, respectively. The strength and stiffness of freeze-dried bone rehydrated for 6 hrs were restored to 96.0% strength and 99.2% stiffness of frozen bone. The rehydration time of freeze-dried bone which had the highest strength and stiffness was six hours and three hours, respectively. The results of the mathematica program for the variation of the strength and stiffness showed 3 hours and 30 minutes of rehydration time in electrolyte solution for the best condition in the strength and stiffness which was adequate to treat freeze-dried cortical bone.

• Food Science and Biotechnology
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• v.17 no.3
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• pp.553-557
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• 2008

The effects of cheonggukjang and doenjang on bone mineral density, trabecular area and cortical thickness of the tibia, and serum osteocalcin level in ovariectomized rats were investigated. After 4 weeks, bone mineral density, bone trabecular area, the cortical thickness index, and serum osteocalcin level were analyzed. The cheonggukjang and doenjang diet groups showed significant prevention of ovariectomized (OVX)-related body weight gain. Whole body bone mineral density of the OVX group was significantly lower than that of the sham group, whereas the cheonggulgang and doenjang diets resulted in complete restoration of bone mineral density. Trabecular area in the proximal diaphysis and cortical thickness in the distal diaphysis of the tibia were increased significantly in the cheonggukjang and doenjang diet fed groups. The cheonggukjang and doenjang diets significantly reduced serum osteocalcin level in the OVX rats. These results suggest that cheonggukjang and doenjang might have inhibitory effects on osteoporosis, by showing accelerated bone formation in OVX rats.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.892-895
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• 2005

This study investigated changes of mechanical characteristics in the trabecular and cortical bone of the lumbar vertebrae of the ovariectomised(OVX) rat. In previous researches, there were many studies for morphology of osteoporotic bones based on Micro-CT (Micro - Computed Tomography). However, there were few studies for detecting and tracking changes of mechanical characteristics in the trabecular bone and cortical bone of the lumbar vertebrae for the OVX rat. For this study, one female Sprague-Dawley rat was used: an OVX rat. The 4th lumbar of the OVX rat was utilized as a specimen. Detecting and tracking changes of mechanical characteristics could be investigated in the trabecular and cortical bone of the lumbar vertebrae for an OVX rat using In-vivo Micro-CT. An OVX rat was scanned at week 0 (just before surgery), at week 4, and week 8 after surgery. Micro finite element(${\mu}\;FE$) analysis was used to investigate mechanical characteristics in the trabecular and cortical bone of the lumbar vertebrae for an OVX rat.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.109-123
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• 2009

The aim of the study was to assess the influence of insertion torque of bone quality and to compare axial force, moment and von Mises stress using finite element analysis of plastoelastic property for bone stress and strain by dividing bone quality to its thickness of cortical bone, density of trabecular bone and existence of lower cortical bone when implant inserted to mandibular premolar region. The $Br{\aa}nemark$ MKIII. RP implant and cylindrical bone finite model were designed as cortical bone at upper border and trabecular bone below the cortical bone. 7 models were made according to thickness of cortical bone, density of trabecular bone and bicortical anchorage and von Mises stress, axial force and moment were compared by running time. Dividing the insertion time, it seemed 300msec that inferior border of implant flange impinged the upper border of bone, 550msec that implant flange placed in middle of upper border and 800msec that superior border of implant flange was at the same level as bone surface. The maximum axial force peak was at about 500msec, and maximum moment peak was at about 800msec. The correlation of von Mises stress distribution was seen at both peak level. The following findings were appeared by the study which compared the axial force by its each area. The axial force was measured highest when $Br{\aa}nemark$ MKIII implant flange inserts the cortical bone. And maximal moment was measured highest after axial force suddenly decreased when the flange impinged at upper border and the concentration of von Mises stress distribution was at the same site. When implant was placed, the axial force and moment was measured high as the cortical bone got thicker and the force concentrated at the cortical bone site. The influence of density in trabecular bone to axial force was less when cortical bone was 1.5 mm thick but it might be more affected when the thickness was 0.5 mm. The total axial force with bicortical anchorage, was similar when upper border thickness was the same. But at the lower border the axial force of bicortical model was higher than that of monocortical model. Within the limitation of this FEA study, the insertion torque was most affected by the thickness of cortical bone when it was placed the $Br{\aa}nemark$ MKIII implant in premolar region of mandible.

• Imaging Science in Dentistry
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• v.40 no.2
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• pp.83-87
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• 2010

Purpose : This study was to determine the relationship between age and the mandibular cortical bone thickness on panoramic radiograph. Materials and Methods : Panoramic radiographs of 360 patients (180 men and 180 women) over 20 years old, who visited the Chonbuk National University Hospital from January to December in 2007, were assessed. The subjects were divided into 5 age groups. Five indices such as cortical bone thickness at the gonion (GI), antegonion (AI), and below the mental foramen (MI), the panoramic mandibular index (PMI), the mandibular cortical index (MCI) were measured on panoramic radiographs. Results : All five indices including GI, AI, MI, PMI, and MCI showed significant differences between third decade and over 8 decade groups (p<0.05). PMI, MI and GI showed significant differences with gender statistically (p<0.05). Conclusion : The mandibular cortical bone thickness showed negative correlation with age, and the value of the thickness (PMI, MI, and GI) was greater in men than in women.