• The Journal of the Acoustical Society of Korea
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• v.29 no.3E
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• pp.140-145
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• 2010

In the present study, tubular polyvinyl chloride (PVC) cortical bone mimics that simulate the cortical shell of long bones were used to validate the axial transmission technique for assessing the cortical thickness by measuring the ultrasonic velocities along the cortical shell of long bones. The ultrasonic velocities in the 9 PVC cortical bone mimics with wall thicknesses from 4.0 to 16.1 mm and inner diameters from 40 to 300 mm were measured as a function of the thickness by using a pair of custom-made transducers with a diameter of 12.7 mm and a center frequency of 200 kHz. In order to clarify the measured behavior, they were also compared with the predictions from a theory of guided waves in thin plates. This phantom study using the PVC cortical bone mimics provides useful insight into the dependencies of ultrasonic velocities on the cortical thickness in human long bones.

• The korean journal of orthodontics
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• v.42 no.3
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• pp.110-117
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• 2012

Objective: In this study, we measured the cortical bone thickness in the mandibular buccal and lingual areas using computed tomography in order to evaluate the suitability of these areas for application of temporary anchorage devices (TADs) and to suggest a clinical guide for TADs. Methods: The buccal and lingual cortical bone thickness was measured in 15 men and 15 women. Bone thickness was measured 4 mm apical to the interdental cementoenamel junction between the mandibular canine and the 2nd molar using the transaxial slices in computed tomography images. Results: The cortical bone in the mandibular buccal and lingual areas was thicker in men than in women. In men, the mandibular lingual cortical bone was thicker than the buccal cortical bone, except between the 1st and 2nd molars on both sides. In women, the mandibular lingual cortical bone was thicker in all regions when compared to the buccal cortical bone. The mandibular buccal cortical bone thickness increased from the canine to the molars. The mandibular lingual cortical bone was thickest between the 1st and 2nd premolars, followed by the areas between the canine and 1st premolar, between the 2nd premolar and 1st molar, and between the 1st molar and 2nd molar. Conclusions: There is sufficient cortical bone for TAD applications in the mandibular buccal and lingual areas. This provides the basis and guidelines for the clinical use of TADs in the mandibular buccal and lingual areas.

• Investigative Magnetic Resonance Imaging
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• v.19 no.3
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• pp.168-177
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• 2015

Purpose: Brain surface intensity model (BSIM)-based cortical thickness analysis does not require complicated 3D segmentation of brain gray/white matters. Instead, this technique uses the local intensity profile to compute cortical thickness. The aim of the present study was to evaluate intra-rater and inter-rater reliability of BSIM-based cortical thickness analysis using images from elderly participants. Materials and Methods: Fifteen healthy elderly participants (ages, 55-84 years) were included in this study. High-resolution 3D T1-spoiled gradient recalled-echo (SPGR) images were obtained using 3T MRI. BSIM-based processing steps included an inhomogeneity correction, intensity normalization, skull stripping, atlas registration, extraction of intensity profiles, and calculation of cortical thickness. Processing steps were automatic, with the exception of semiautomatic skull stripping. Individual cortical thicknesses were compared to a database indicating mean cortical thickness of healthy adults, in order to produce Z-score thinning maps. Intra-class correlation coefficients (ICCs) were calculated in order to evaluate inter-rater and intra-rater reliabilities. Results: ICCs for intra-rater reliability were excellent, ranging from 0.751-0.940 in brain regions except the right occipital, left anterior cingulate, and left and right cerebellum (ICCs = 0.65-0.741). Although ICCs for inter-rater reliability were fair to excellent in most regions, poor inter-rater correlations were observed for the cingulate and occipital regions. Processing time, including manual skull stripping, was $17.07{\pm}3.43min$. Z-score maps for all participants indicated that cortical thicknesses were not significantly different from those in the comparison databases of healthy adults. Conclusion: BSIM-based cortical thickness measurements provide acceptable intra-rater and inter-rater reliability. We therefore suggest BSIM-based cortical thickness analysis as an adjunct clinical tool to detect cortical atrophy.

• Korean Journal of Biological Psychiatry
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• v.22 no.3
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• pp.118-127
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• 2015

Objectives Standardization of head size is essential for the volume study. Cortical thickness analyses are increasingly being used in many fields of neuroscience. However, it is not established whether head size correction should be done for thickness study. Methods Using the Open Access Series of Imaging Studies data, we determined cortical thickness of 316 cognitively normal participants aged 18-94 with FreeSurfer. The association between head size and cortical thickness of whole cortical mantle and in each lobe among age tertile groups was assessed. Estimated total intracranial volume (eTIV) was calculated for determining head size. Results Across all participants, cortical thickness in whole brain except some areas in cingulate and insula decreased with aging. eTIV had positive correlation with the thickness of frontal, parietal, occipital and whole brain areas. However, the age effect was not shown in whole brain of the first tertile group and in cingulate areas of the third tertile group. eTIV had negative correlation with the thickness of cingulate in the third tertile group. Gender effects were shown in some areas in third tertile group, but it would be due to difference of head size. Conclusions These findings suggest that head size standardization might be done especially in older population and in studies of paralimbic areas.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.2
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• pp.248-257
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• 2005

Statement of problem. Cortical bone plays an important role in the primary implant stability, which is essential to immediate/early loading. However, immediate load-bearing capacity and primary implant stability according to the change of the cortical bone thickness have not been reported. Purpose. The objectives of this study were (1) to measure the immediate load-bearing capacity of implant and primary implant stability according to the change of cortical bone thickness, and (2) to evaluate the correlation between them. Material and methods.48, screw-shaped implants (3.75 mm$\times$7 mm) were placed into bovine rib bone blocks with different upper cortical bone thickness (0-2.5 mm) and resonance frequency (RF) values were measured subsequently. After fastening of healing abutment. implants were subjected to a compressive load until tolerated micromotion threshold known for the osseointegration and load values at threshold were recorded. Thereafter, RF measurement after loading, CT taking and image analysis were performed serially to evaluate the cortical bone quality and quantity. Immediate load-bearing capacity and RF values were analyzed statistically with ANOVA and post-hoc method at 95% confidence level (P<0.05). Regression analysis and correlation test were also performed. Results. Existence and increase of cortical bone thickness increased the immediate load-bearing capacity and RF value (P<0.05) With the result of regression analysis, all parameter's of cortical bone thickness to immediate load-bearing capacity and resonance frequency showed significant positive values (P<0.0001). A significant high correlation was observed between the cortical bone thickness and immediate load-beating capacity (r=0.706, P<0.0001), between the cortical bone thickness and resonance frequency (r=0.753, P<0.0001) and between the immediate load-bearing capacity and resonance frequency (r=0.755, P<0.0001). Conclusion. In summary, cortical bone thickness change affected the immediate load-baring capacity and the RF value. Although RF analysis (RFA) is based on the measurement of implant/bone interfacial stiffness, when the implant is inserted stably, RFA is also considered to reflect implant/bone interfacial strength of immediately after placement from high correlation with the immediate load-baring capacity. RFA and measuring the cortical bone thickness with X-ray before and during surgery could be an effective diagnosis tool for the success of immediate loading of implant.

• Journal of Korean Dental Science
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• v.3 no.2
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• pp.4-11
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• 2010

Purpose: This study aimed at examining the thickness of lateral cortical bone in the mandibular posterior body and the location of the inferior alveolar nerve canal as well as investigating the clinically viable bone grafting site(s) and proper thickness of the bone grafts. Subjects and Methods: The study enrolled a total of 49 patients who visited the Department of Oral and Maxillofacial Surgery at Kyung Hee University Dental Hospital to have their lower third molar extracted and received cone beam computed tomography (CBCT) examinations. Their CBCT data were used for the study. The thickness of lateral cortical bone and the location of inferior alveolar nerve canal were each measured from the buccal midpoint of the patients' lower first molar to the mandibular ramus area in the occlusal plane of the molar area. Results: Except in the external oblique ridge and alveolar ridge, all measured areas exhibited the greatest cortical bone thickness near the lower second molar area and the smallest cortical bone thickness in the retromolar area. The inferior alveolar nerve canal was found to be located in the innermost site near the lower second molar area compared to other areas. In addition, the greatest thickness of the trabecular bone was found between the inferior alveolar nerve canal and the lateral cortical bone. Conclusions: In actual clinical settings involving bone harvesting in the posterior mandibular body, clinicians are advised to avoid locating the osteotomy line in the retromolar area to help protect the inferior alveolar nerve canal from damage. Harvesting the bone near the lower second molar area is judged to be the proper way of securing cortical bone with the greatest thickness.

• Imaging Science in Dentistry
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• v.41 no.4
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• pp.151-153
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• 2011

Purpose : The purpose of this study was to obtain the description of the mandibular bone quality of male and female patients between 40-60 years old and their differences based on mandibular cortical bone thickness measured using Mental Index (MI). Materials and Methods : Forty digital panoramic radiographs, which consisted of twenty male and twenty female patients, 40-60 years old, were observed. Mandibular cortical bone thickness was measured using MI on both sides of the mandible. The average MI score of two groups were then assessed using t-sample independent test. Results : There were significant differences of mandibular bone quality based on mandibular cortical bone thickness measurement using MI between male and female patients (p<0.05). Conclusion : Mandibular bone quality based on cortical bone thickness measurement using MI of male and female patients indicated a significant difference.

• The Journal of Advanced Prosthodontics
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• v.4 no.3
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• pp.146-152
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• 2012

PURPOSE. The cortical bone thickness on the anterior region is important for achieving implant stability. The purpose of this study was to examine the thickness of the cortical and cancellous bones on the anterior region of the maxilla and mandible. MATERIALS AND METHODS. Twenty-five cadaver heads were used (16 male and 9 female; mean death age, 56.7 years). After the long axis of alveolar process was set up, it was measured in 5 levels starting from 2 mm below the cementoenamel junction (L1) at intervals of 3 mm. All data was analysed statistically by one-way ANOVA at the .05 significance level. RESULTS. The cortical bone thickness according to measurement levels in both the labial and lingual sides increased from L1 to L5, and the lingual side below L3 was significantly thicker than the labial side on the maxilla and mandible. In particular, the labial cortical bone thickness in the maxilla was the thinnest compared to the other regions. The cancellous bone thickness according to measurement levels increased from L1 to L5 on the maxilla, and on the mandible it was the thinnest at the middle level of the root. CONCLUSION. For implant placement on the anterior region, a careful evaluation and full knowledge on the thickness of the cortical and cancellous bone are necessary, therefore, these results may provide an anatomic guideline to clinicians.

• Journal of Periodontal and Implant Science
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• v.46 no.3
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• pp.152-165
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• 2016

Purpose: This study investigated the effects of bone density and crestal cortical bone thickness at the implant-placement site on micromotion (relative displacement between the implant and bone) and the peri-implant bone strain distribution under immediate-loading conditions. Methods: A three-dimensional finite element model of the posterior mandible with an implant was constructed. Various bone parameters were simulated, including low or high cancellous bone density, low or high crestal cortical bone density, and crestal cortical bone thicknesses ranging from 0.5 to 2.5 mm. Delayed- and immediate-loading conditions were simulated. A buccolingual oblique load of 200 N was applied to the top of the abutment. Results: The maximum extent of micromotion was approximately $100{\mu}m$ in the low-density cancellous bone models, whereas it was under $30{\mu}m$ in the high-density cancellous bone models. Crestal cortical bone thickness significantly affected the maximum micromotion in the low-density cancellous bone models. The minimum principal strain in the peri-implant cortical bone was affected by the density of the crestal cortical bone and cancellous bone to the same degree for both delayed and immediate loading. In the low-density cancellous bone models under immediate loading, the minimum principal strain in the peri-implant cortical bone decreased with an increase in crestal cortical bone thickness. Conclusions: Cancellous bone density may be a critical factor for avoiding excessive micromotion in immediately loaded implants. Crestal cortical bone thickness significantly affected the maximum extent of micromotion and peri-implant bone strain in simulations of low-density cancellous bone under immediate loading.

• Korean Journal of Biological Psychiatry
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• v.25 no.3
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• pp.60-71
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• 2018

Objectives A growing body of evidence has suggested that morphologic changes in cerebellum may be implicated with pathophysiology of major depressive disorder (MDD). The aim of this study is to investigate a difference in the volume and cortical thickness of the specific region of cerebellum between patients with MDD and healthy controls (HC). Methods A total of 127 patients with MDD and 105 HC participated in this study and underwent T1-weighted structural magnetic resonance imaging. We analyzed volume and cortical thickness of each twelve cerebellum regions divided by left and right and the volume and cortical thickness of the whole cerebellum from T1-weigted image of participants. One-way analysis of covariance was used to investigate the volume and cortical thickness difference of total and specific regions between two groups adjusting for age, gender, medication, and total intracranial cavity volume. Results We found that the patients with MDD had significantly greater volume in the left cerebellum lobule III region [false discovery rate (FDR)-corrected p = 0.034] compared to HC. Also, our findings indicate that cortical thickness of left lobule VIIB (FDR-corrected p = 0.032) and lobule VIIIB (FDR-corrected p = 0.032) are significantly thinner in the patients with MDD compared with the HC. No significant volume and cortical thickness differences were observed in other sub-regions of the cerebellum. The volumes and cortical thickness of whole cerebellum between patients with MDD and HC did not differ significantly. Conclusions We observed the region-specific volume and cortical thickness difference in cerebellum between the patients with MDD and HC. The results of our study implicate that the information about structural alterations in cerebellum with further replicative studies might provide a stepping stone toward a specific marker to diagnose MDD.