• Imaging Science in Dentistry
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• v.30 no.4
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• pp.259-263
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• 2000

Purpose: Upper cervical vertebrae are commonly imaged together with the jaw bones in panoramic radiography. There have been many studies investigating the possible role of mandible as an indicator of osteoporosis. But the result doesn't show unanimity. This study measured bone densities of mandible and second and third cervical vertebrae to find out any relationship between these two areas. These results may contribute in panorama being used as a screening method in detecting possible osteoporotic patient. Materials and Methods: Randomly selected 226 digitized panoramic images with cervical vertebrae shadows from 156 dental patients between 5 to 80 years of age were used. And the bone densities of second and third cervical vertebrae, apical areas of first and second mandibular molars and interdental areas were measured. The bone density measurements were restricted to the cancellous bone and the average and standard deviations and paired t-tests were done to each measurements. Results: All the measurements were statistically significantly related. The best relationship was found between the third cervical vertebrae and first and second mandibular apical areas. The average and standard deviations of the measured bone density ratios of these areas were 1.20±0.45 and 1.34±0.48 each. Conclusion: Patients whose panoramic bone density of the third cervical vertebrae are much below those of mandibular first or second molar apical areas may have osteoporosis.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.265-276
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• 1990

The purpose of this experiment was to evaluate radiographic interpretation, of various sized 60 periapical and 60 cancellous lesions in 10 mandibular sections of 5 dogs according to kVp (65, 70, 75, 80 and 85 kVp). The results were as follows; The change of kilovoltage within 65kVp-85kVp range did not have influence on the radiographic interpretation of the same-sized bony defects at the constant radiographic density (p> 0.05). When the bony defects were less than the size of No.2 round bur, radiographic interpretation of bony defects prepared with No.2 round bur was easier than those prepared with No. 1 round bur at 80-85kVp in periapical region (p<0.05). However, in cancellous bone, this radiographic interpretation was easier at 65-75kVp (p<0.05). There were significant differences in the radiographic interpretation between the defects confined only to the cancellous, bone and the defects involved in the compact bone (p<0.05). However there were no significant differences between the defects confined only to the cancellous bone and the defects involved in junctional area of cancellous and compact bone (p>0.05). From the results of densitometric analysis, there was a difference in densitometric measurements at the same radiographic interpretation scores, and aluminum equivalent differences of 0.15-1.66㎜ thickness were needed for radiographic interpretation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1336-1340
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• 2003

The compressed fracture of spine caused by osteoporosis is one of the most frequent diseases in bone fracture. Recently the vertebroplasty has drawn much attention as a medical treatment for the compressed fracture of spine, which strengthens the vertebral body and corrects deformity, and relieves pain in patients by injecting bone cement. The purpose of this research is to provide the theoretical background for the vertebroplasty by employing scientific methods and thus to find out the improvements of the conventional surgical method. By applying the engineering analysis tools to clinical study, new application fields can also be obtained

• Imaging Science in Dentistry
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• v.38 no.1
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• pp.49-56
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• 2008

Purpose: Diagnostic estimation of destruction and formation of bone has the typical limit according to capacity of x-ray generator and image detector. So the aim of this study was to find out how much it can reproduce the shape and the density of bone in the case of using recently developed dental type of cone beam computed tomography, and which image is applied by new detector and mathematic calculation. Materials and Methods: Cone beam computed tomography (PSR 9000N, Asahi Roentgen Ind. Co., Ltd., Japan) and soft x-ray radiography were executed on dry mandible that was already decalcified during 5 hours, 10 hours, 15 hours, 20 hours, and 25 hours. Estimating and comparing of those came to the following results. Results: The change of inferior border of mandible and anterior border of ramus in the region of cortical bone was observed between first 5 and 10 hours of decalcification. The reproduction of shape and density in the region of cortical bone and cancellous bone can be hardly observed at cone beam computed tomography compared with soft x-ray radiography. The difference of decrease of bone density according to hours of decalcification increase wasn't reproduced at cone beam computed tomography compared with soft x-ray radiography. Conclusion: CBCT images revealed higher spatial resolution. However, contrast resolution in region of low contrast sensitivity is the inferiority of images' property.

• Journal of Korean Neurosurgical Society
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• v.64 no.5
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• pp.763-775
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• 2021

Objective : Hemorrhagic transformation (HT) can be occurred after acute cerebral infarction. HT can worse symptoms in severe cases and adversely affect long-term prognosis. As bone and vascular smooth muscle are composed of type 1 collagen, we aimed to identify a potential relationship between bone mineral density (BMD) and HT after acute cardioembolic stroke. Methods : As an indicator of BMD, we used mean frontal skull Hounsfield unit (HU) values on brain computed tomography (CT). Multivariative hazard ratios were calculated using Cox regression analysis to identify whether the osteoporotic condition was an independent predictor of HT after acute cardioembolic stroke. Results : This 11-year analysis enrolled 506 patients who diagnosed as acute cardioembolic infarction. The first tertile of skull HU value was an independent predictor of HT development compared to the third tertile (hazard ratio, 2.12; 95% confidence interval, 1.13-3.98; p=0.020). We observed no interactions between age and skull HU with respect to HT statistically. Conclusion : The results of this study revealed an association between osteoporotic conditions and HT development after acute cardioembolic stroke. A convenient method to measure the cancellous bone HU value of the frontal skull using brain CT images may be useful for predicting HT in patients with acute cerebral infarction.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.155-156
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• 1998

Screw loosening and subsequent pullout can be attributed to the reduction in bone mineral density in the vertebrae manifested by osteoporosis in which the decrease in fixation strength between the cancellous bone and screw threads are accelerated by repeated loads exerted by patients own weight and activities following the surgery. In this study, the change in pullout strength of the pedicle screws was investigated before and after repeated loads were imparted. For this purpose. Diapason pedicle screws $(6.7\times40mm)$ were inserted onto fresh porcine spine specimens (T1-L5) after bone mineral density was measured using a DEXA. With an MTS, an axial load was applied at a loading rate of 0.33mm/sec until failure to measure the maximum pullout strength. Flexion moment of 7.5N-m was then imparted at 0.5Hz for 2000 cycles. It was found that the maximum pullout strength was exponentially related to BMD regardless of load types ($107.71\;\times\;\exp^{(1.43{\times}BMD)}r^2=0.93$, P<0.0001 without repeated load; ($107.71\;\times\;\exp^{(2.19{\times}BMD)}r^2=0.78$, P<0.0001 with repeated load). The results suggest that the reduction in pullout strength for pedicle screws is far more prominent in osteoporotic spine than in normal spine especially as number of repeated load was increased. More importantly, it was demonstrated that the level of bone mineral density and the activity level of the patient should be evaluated in more detail for successful implementation of pedicle screw systems in spinal surgery.

• Journal of Biomedical Engineering Research
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• v.19 no.2
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• pp.177-182
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• 1998

This study investigated the effects of a titanium prosthesis, malalignment, field of view, and distal flare of titanium prosthesis on computed tomography( CT) measurements of home mineral density. Eight femora and eight tibiae from fresh male cadavers were used. Fifteen pieces of cancellous bone from the proximal tibiae were milled into rectangular parallelepipeds. Parallelepipeds and femors were scanned with and without titanium prosthesis when centered in the gantry of the CT scanner and malaligned, respectively. Image data were then reconstructed with field of view of 10 and 30 cm. Bone mineral density(BMD) values were obtained from CT images using C-MED software. The effects of titanium prosthesis, malalignmetn, and field of view were investigated. When bone was centered in the gantry of the CT scanner, the mean relative difference of BMD measurements caused by a titanium prosthesis was less than 1% for both cortical and cancellous bone. Field of view had negligible effect on BMD measurements as well. Malalignment and distal flare of prosthesis, however, caused a significant difference in BMD measurements(p<0.0001). The titanium prosthesis did not interfere with malalignment combining the existence of a titnium prosthesis on BMD measurements was significant.

• Journal of Oral Medicine and Pain
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• v.32 no.1
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• pp.35-43
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• 2007

This study was conducted to investigate the preventing effects of OPB (water extracts of Rehmannia glutinosa Libosch and Eleutherococcus senticosus Max) on bone loss in ovariectomized rats. Twenty Sprague Dawley rats of 13 week-old were divided into two groups: control group (ovariectomized, OVX)) and experimental group (OVX + OPB). The preventing effects of OPB on bone loss, OPB were fed with 100 mg OPB/kg body weight from 3 days after ovariectomization. The duration of the treatment period was 8 weeks. All bone mineral density, bone mineral content indices and bone strength indices measured by peripheral quantitative computerized tomography (pQCT) and serum bone marker assessment were carried out at end of experiment. pQCT scanning showed that OVX induced a significant decrease in cancellous bone mineral density in the proximal tibia ($-29.8{\pm}3.0%$). These decreases were significantly prevented by the administration of OPB 100 mg/kg ($-21.4{\pm}2.3%$. p<0.05). Bone strength indices showed significant difference between OVX and OPB treated rats (anti-fracture, anti-twisting, p<0.05). These data suggested that administration of OPB inhibited the loss of bone in OVX rats. CTx level were lower than in the OPB-treated animals compared with OVX. However there was no significant difference between OVX and OPB treated OVX rat. Our results suggest that OPB is effective in preventing the development of bone loss induced by ovariectomy in rats.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.4
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• pp.627-646
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• 1997

In order to find the degree of osseointegration at bone-implant interface of clinically successful implants, models including the 3.75mm wide, 10mm long screw type $Br{\aa}nemark$ implant as a standard and cylinder, 15mm long, 5.0mm wide, two splinted implants, and implants installed in various cancellous bone density were designed. Also, the amount of load and material of prostheses were changed. The stress and minimum contact fraction were analyzed on each model using three-dimensional finite element method(I-DEAS and ABAQUS version 5.5). The results of this study were as follows. 1. 10mm long, 3.75mm diameter-screw type implant had $36.5{\sim}43.7%$ of minimum contact fraction. 2. Cylinder type implant showed inferior stress distribution and higher minimum contact fraction than screw type. 3. As implant length was increased, minimum contact fraction was increased a little, however, maximum principal stress was decreased. 4. Implants with a large diameter had lower stress value with slightly higher minimum contact fraction than standard screw type. 5. Two splinted implants showed no change of minimum contact fraction. 6. The higher bone density, the lower stress value. 7. The material of occlusal surface had no effect on the stress of the bone-implant interface.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.5
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• pp.470-478
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• 2007

The purpose of this study was to investigate the clinical, biomechanical, and histologic changes in new distraction osteogenesis(DO) technique combined with a compression stimulation in accordance to different compression-distraction force ratio. 23 adult male rabbits underwent open-osteotomy at the mandibular body area and a external distraction device was applied. In the control group of 8 rabbits, only a 8 mm of distraction was performed by conventional DO technique. In an experimental group of 15 rabbits, a distraction followed by a compression force was performed according to the ratio of compression-distraction suggested by authors. The rate of experimental group I was set up as a 2 mm compression versus 10 mm distraction and the rate of experimental group II was set up as a 3 mm compression versus 11 mm distraction. All the rabbits were sacrificed for a gross finding, biomechanical, histomorphometric and histologic findings at the time of 55 days from the operation day. The results were as follows: 1. On the gross findings, because all rabbits had a sufficient healing time, every distracted new bone had good bone quality and we could not find any difference among all three groups. 2. In the histologic findings, rapid bone maturation(wide lamellar bone formation in the cancellous and cortical bone areas) was observed in two experimental groups compared to the control group. 3. On the bone density tests, the experimental group II showed higher bone density than the other experimental group and control group(control group-$0,2906g/cm^2$, experimental group I-$0.2961g/cm^2$, experimental group II-$0.3328g/cm^2$). 4. On the biomechanical tests, the experimental group II had significantly higher bone microhardness than the other experimental group and control group(control group-252.7 MPa, experimental group I-263.5 MPa, experimental group II-426.0 MPa). 5. On the microhardness tests, when we compared the hardness ratio of distracted bone versus normal bone, we could find experimental group II had significantly higher hardness ratio than the other experimental group and control group(control group-0.47, experimental group I-0.575, experimental group II-0.80). From this study, we could deduce that the modified distraction osteogenesis method with a compression stimulation might improve the quality of bone regeneration and shorten the consolidation period in comparison with conventional distraction osteogenesis techniques.