• Imaging Science in Dentistry
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• v.50 no.2
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• pp.161-168
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• 2020

Purpose: The aim of this study was to evaluate the influence of voxel size and different post-processing algorithms on the analysis of dental materials using micro-computed tomography (micro-CT). Materials and Methods: Root-end cavities were prepared in extracted maxillary premolars, filled with mineral trioxide aggregate (MTA), Biodentine, and Intermediate Restorative Material (IRM), and scanned using micro-CT. The volume and porosity of materials were evaluated and compared using voxel sizes of 5, 10, and 20 ㎛, as well as different software tools(post-processing algorithms). The CTAn or MeVisLab/Materialise 3-matic software package was used to perform volume and morphological analyses, and the CTAn or MeVisLab/Amira software was used to evaluate porosity. Data were analyzed using 1-way ANOVA and the Tukey test(P<0.05). Results: Using MeVisLab/Materialise 3-matic, a consistent tendency was observed for volume to increase at larger voxel sizes. CTAn showed higher volumes for MTA and IRM at 20 ㎛. Using CTAn, porosity values decreased as voxel size increased, with statistically significant differences for all materials. MeVisLab/Amira showed a difference for MTA and IRM at 5 ㎛, and for Biodentine at 20 ㎛. Significant differences in volume and porosity were observed in all software packages for Biodentine across all voxel sizes. Conclusion: Some differences in volume and porosity were found according to voxel size, image-processing software, and the radiopacity of the material. Consistent protocols are needed for research evaluating dental materials.

• Journal of Periodontal and Implant Science
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• v.50 no.1
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• pp.14-27
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• 2020

Purpose: To overcome several drawbacks of chemically-crosslinked collagen membranes, modification processes such as ultraviolet (UV) crosslinking and the addition of biphasic calcium phosphate (BCP) to collagen membranes have been introduced. This study evaluated the efficacy and biocompatibility of BCP-supplemented UV-crosslinked collagen membrane for guided bone regeneration (GBR) in a rabbit calvarial model. Methods: Four circular bone defects (diameter, 8 mm) were created in the calvarium of 10 rabbits. Each defect was randomly allocated to one of the following groups: 1) the sham control group (spontaneous healing); 2) the M group (defect coverage with a BCP-supplemented UV-crosslinked collagen membrane and no graft material); 3) the BG (defects filled with BCP particles without membrane coverage); and 4) the BG+M group (defects filled with BCP particles and covered with a BCP-supplemented UV-crosslinked collagen membrane in a conventional GBR procedure). At 2 and 8 weeks, rabbits were sacrificed, and experimental defects were investigated histologically and by micro-computed tomography (micro-CT). Results: In both micro-CT and histometric analyses, the BG and BG+M groups at both 2 and 8 weeks showed significantly higher new bone formation than the control group. On micro-CT, the new bone volume of the BG+M group (48.39±5.47 ㎣) was larger than that of the BG group (38.71±2.24 ㎣, P=0.032) at 8 weeks. Histologically, greater new bone area was observed in the BG+M group than in the BG or M groups. BCP-supplemented UV-crosslinked collagen membrane did not cause an abnormal cellular reaction and was stable until 8 weeks. Conclusions: Enhanced new bone formation in GBR can be achieved by simultaneously using bone graft material and a BCP-supplemented UV-crosslinked collagen membrane, which showed high biocompatibility and resistance to degradation, making it a biocompatible alternative to chemically-crosslinked collagen membranes.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.4
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• pp.392-401
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• 2022

This study investigated the effects of silver diamine fluoride (SDF) and potassium iodide (KI) treatments on the acid resistance of dentin exposed to secondary caries. Sixteen bovine dentin specimens with artificially induced caries were assigned to the following four groups: untreated negative control, untreated positive control, SDF-treated (SDF), and SDF and KI-treated (SDFKI). Multispecies cariogenic biofilms containing Streptococcus mutans, Lactobacillus casei, and Candida albicans were cultured on the specimens for 28 days, except for the negative control group. Specimens from the negative control group were stored in phosphate-buffered saline for that period. After a cariogenic biofilm challenge, the degree of demineralization was evaluated using micro-computed tomography (micro-CT). As a result of data analysis using micro-CT, the demineralization depths of the negative control, positive control, SDF, and SDFKI groups were 149.0 ± 7 ㎛, 392.0 ± 11 ㎛, 206.0 ± 20 ㎛, and 230.0 ± 31 ㎛, respectively. The degree of demineralization was significantly reduced in the SDF and SDFKI groups compared with that in the untreated positive control group. There were no significant differences between the SDF and SDFKI groups. This study confirmed that SDF and SDFKI treatments increase the acid resistance of dentin to secondary caries. KI did not significantly affect the caries-arresting effect of the SDF.

• The Journal of Korean Medicine
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• v.34 no.3
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• pp.69-85
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• 2013

Objectives: This study investigated the anti-osteoarthritic effects of Kyejiinsam-tang (hereinafter referred to KIT) on the monosodium iodoacetate (MIA)-induced osteoarthritis rats. Methods: Anti-oxidative effects of KIT were measured by scavenging activities of DPPH, reactive oxygen species (ROS) and nitric oxide (NO). Scavenging activities of anti-oxidation in lipopolysaccharide (LPS)-treated RAW 264.7 cells were also measured for inhibitory effects against the production of inflammatory mediators (tumor necrosis factor-${\alpha}$, interleukin-$1{\beta}$, interleukin-6). Osteoarthritis was induced in rats by injecting MIA in the knee joint. Rats were divided into a total of 4 groups (n=6). The normal group were not treated at all without inducing osteoarthritis whereas the control group were induced for osteoarthritis by MIA and oral medicated physiological saline per day. The positive comparison group was injected with MIA and after 7 days, 2 mg/kg of Indomethacin. The experimental group was injected with MIA and after 7 days was medicated with 34 mg/kg of KIT. Indomethacin and KIT were orally-medicated for each substance a total of 4 weeks, once per day. Weight-bearing on hind legs was measured every week after MIA injection. At the end of the experiment (5 weeks after MIA injection), micro CT (computed tomography)-arthrography and histopathological examinations on the articular structures of knee joint were performed. The effect on inflammatory cytokines and immunological cells in synovial fluid was measured. Volume of cartilage was measured by micro CT-arthrography. Injury to synovial tissue was measured by H & E (hematoxylin and eosin), Safranin-O immunofluorescence. Results: 1. Cytotoxicity against hFCs was insignificant. 2. KIT showed the potent full term for DPPH. 1. NO was significantly reduced by KIT (at 100, $200{\mu}g/m{\ell}$) and ROS was also reduced, but not significantly, by KIT (at $200{\mu}g/m{\ell}$). 2. IL-6 and IL-$1{\beta}$ were significantly reduced by KIT (at 100, $200{\mu}g/m{\ell}$) and TNF-${\alpha}$ was also reduced, but not significantly, by KIT (at $200{\mu}g/m{\ell}$). 1. In hind legs weight-bearing measurement, level of weight increased. 2. Functions of liver and kidney were not affected. 3. IL-$1{\beta}$ was significantly reduced and TNF-${\alpha}$, IL-6 were also reduced but not significantly. 4. PGE2 (prostaglandin E2), LTB4 (leukotriene B4) were significantly reduced in the KIT group. 5. MMP-9 (matrix metalloproteinase-9), TIMP-1 (tissue inhibitor of metalloproteinases-1) and Osteocalcin were significantly reduced in the KIT group. 6. Destruction of cartilage on micro CT arthrography was reduced but had no significant differences. 7. Histopathologically, injury to synovial membrane of the KIT group was decreased and proteoglycan content of KIT group was increased. Conclusions: According to this study, Kyejiinsam-tang has inhibiting effect on the progression of arthritis in MIA-induced osteoarthritis rat. Kyejiinsam-tang has anti-oxidants and anti-inflammation effects, and is related to inhibiting the activity of inflammatory cytokine and injury of volume in cartilage.

• Journal of Periodontal and Implant Science
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• v.47 no.2
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• pp.77-85
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• 2017

Purpose: Guided bone regeneration (GBR) is the most widely used technique to regenerate and augment bones. Even though augmented bones (ABs) have been examined histologically in many studies, few studies have been conducted to examine the biological potential of these bones and the healing dynamics following their use. Moreover, whether the bone obtained from the GBR procedure possesses the same functions as the existing autogenous bone is uncertain. In particular, little attention has been paid to the regenerative ability of GBR bone. Therefore, the present study histologically evaluated the regenerative capacity of AB in the occlusive space of a rat guided bone augmentation (GBA) model. Methods: The calvaria of 30 rats were exposed, and plastic caps were placed on the right of the calvaria in 10 of the 30 rats. After a 12-week healing phase, critical-sized calvarial bone defects (diameter: 5.0 mm) were trephined into the dorsal parietal bone on the left of the calvaria. Bone particles were harvested from the AB or the cortical bone (CB) using a bone scraper and transplanted into the critical defects. Results: The newly generated bone at the defects' edge was evaluated using micro-computed tomography (micro-CT) and histological sections. In the micro-CT analysis, the radiopacity in both the augmented and the CB groups remained high throughout the observational period. In the histological analysis, the closure rate of the CB was significantly higher than in the AB group. The numbers of cells positive for runt-related transcription factor 2 (Runx2) and tartrate-resistant acid phosphatase (TRAP) in the AB group were larger than in the CB group. Conclusions: The regenerative capacity of AB in the occlusive space of the rat GBA model was confirmed. Within the limitations of this study, the regenerative ability of the AB particulate transplant was inferior to that of the CB particulate transplant.

• Journal of Biomedical Engineering Research
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• v.30 no.1
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• pp.49-55
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• 2009

Purpose : The aim of this study is to evaluate a possibility of clinical application for the effects of low intensity ultrasound stimulation (LIUS) in morphological characteristics (i.e., structure, bone mineral density) of bone on osteoporotic fracturesprevention. Materials and Methods : Eight virgin 14-week-old ICR mice (approximate weight 25g) were used and ovariectomized (OVX) to induce osteoporosis. Right tibia (US) for each mouse served as the LIUS (1.5MHz frequency, 1.0 kHz pulse repetition on frequency, $30mW/cm^2$ intensity, $200{\mu}s$ pulse length, and stimulation for 20 minutes a day and 5 days a week over a 6-week period). Left tibia (CON) for each mouse served as the non-stimulated controls. Structural parameters and bone mineral density ($g/cm^3$) on trabecular bone of tibiae were calculated and measured from images derived in-vivo micro computed tomography (micro-CT) at 0 week and after 6weeks. Results : The BV/TV and Tb.N in US group were significantly bigger than those in CON group. The Tb.Pf in US group, moreover, was significantly smaller than that in CON group (p<0.05).For the others structural parameters and BMD, however, there were no significant difference between US group and CON group (p>0.05). Conclusion : The LIUS might prevent bone loss and keep bone connectivity in osteoporotic bones. Therefore, the LIUS might prevent effectively the osteoporotic fractures in clinics.

• Journal of Periodontal and Implant Science
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• v.40 no.3
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• pp.132-138
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• 2010

Purpose: The purpose of this study was to compare the bone regeneration effects of cortical, cancellous, and cortico-cancellous human bone substitutes on calvarial defects of rabbits. Methods: Four 8-mm diameter calvarial defects were created in each of nine New Zealand white rabbits. Freeze-dried cortical bone, freeze-dried cortico-cancellous bone, and demineralized bone matrix with freeze-dried cancellous bone were inserted into the defects, while the non-grafted defect was regarded as the control. After 4, 8, and 12 weeks of healing, the experimental animals were euthanized for specimen preparation. Micro-computed tomography (micro-CT) was performed to calculate the percent bone volume. After histological evaluation, histomorphometric analysis was performed to quantify new bone formation. Results: In micro-CT evaluation, freeze-dried cortico-cancellous human bone showed the highest percent bone volume value among the experimental groups at week 4. At week 8 and week 12, freeze-dried cortical human bone showed the highest percent bone volume value among the experimental groups. In histologic evaluation, at week 4, freeze-dried cortico-cancellous human bone showed more prominent osteoid tissue than any other group. New bone formation was increased in all of the experimental groups at week 8 and 12. Histomorphometric data showed that freeze-dried cortico-cancellous human bone showed a significantly higher new bone formation percentile value than any other experimental group at week 4. At week 8, freeze-dried cortical human bone showed the highest value, of which a significant difference existed between freeze-dried cortical human bone and demineralized bone matrix with freeze-dried cancellous human bone. At week 12, there were no significant differences among the experimental groups. Conclusions: Freeze-dried cortico-cancellous human bone showed swift new bone formation at the 4-week healing phase, whereas there was less difference in new bone formation among the experimental groups in the following healing phases.

• Journal of Biomedical Engineering Research
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• v.38 no.4
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• pp.175-182
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• 2017

Microcurrent electrical stimulation(MES) has been used to accelerate recovery of atrophied skeletal muscle. However, convincing stimulation parameters for suppressing muscle atrophy due to injured sciatic nerve remains unclear. The objective of this study was to investigate the effective intensity of MES on restraining muscle atrophy with rat model underwent sciatic nerve injury(SNI). Twenty-5-week-old Sprague Dawley male rats were equally assigned to five groups : Control group(Control, CON, n = 4), Denervation group(Denervation, D, n = 4), Denervation with MES of $22{\mu}A$ group(Denervation + $22{\mu}A$, D+22, n = 4), Denervation with MES of $100{\mu}A$ group (Denervation + $100{\mu}A$, D+100 n = 4), Denervation with MES of $400{\mu}A$ group(Denervation + $400{\mu}A$, D+400, n = 4). To induce muscle atrophy, all rats in the D, D+22, D+100, and D+400 groups, were subjected to sciatic nerve injury on their right hindlimb and allowed to have 1 week of resting period. Following this period, rats underwent daily MES(60 min/ a day, 5times/1week) for 4 weeks. After that, we investigate morphological changes in muscle volume by using in vivo micro-computed tomography at week 0, 1, 3 and 5. After 5 weeks, the muscle volume had the highest value in D+400 group, and also noticeably increased in D+100 group compared to it in D group. The results of this study imply that MES with current intensities between $100-400{\mu}A$ can suppress muscle atrophy effectively.

• Journal of Periodontal and Implant Science
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• v.46 no.5
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• pp.303-319
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• 2016

Purpose: The purpose of this animal study was to perform a 3-dimensional micro-computed tomography (micro-CT) analysis in order to investigate the influence of root surface distance to the alveolar bone and the periodontal ligament on periodontal wound healing after a guided tissue regeneration (GTR) procedure. Methods: Three adult Sus scrofa domesticus specimens were used. The study sample included 6 teeth, corresponding to 2 third mandibular incisors from each animal. After coronectomy, a circumferential bone defect was created in each tooth by means of calibrated piezoelectric inserts. The experimental defects had depths of 3 mm, 5 mm, 7 mm, 9 mm, and 11 mm, with a constant width of 2 mm. One tooth with no defect was used as a control. The defects were covered with a bioresorbable membrane and protected with a flap. After 6 months, the animals were euthanised and tissue blocks were harvested and preserved for micro-CT analysis. Results: New alveolar bone was consistently present in all experimental defects. Signs of root resorption were observed in all samples, with the extent of resorption directly correlated to the vertical extent of the defect; the medial third of the root was the most commonly affected area. Signs of ankylosis were recorded in the defects that were 3 mm and 7 mm in depth. Density and other indicators of bone quality decreased with increasing defect depth. Conclusions: After a GTR procedure, the periodontal ligament and the alveolar bone appeared to compete in periodontal wound healing. Moreover, the observed decrease in bone quality indicators suggests that intrabony defects beyond a critical size cannot be regenerated. This finding may be relevant for the clinical application of periodontal regeneration, since it implies that GTR has a dimensional limit.

• Journal of Life Science
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• v.20 no.8
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• pp.1207-1213
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• 2010

The purpose of this study was to evaluate the effect of porcine cancellous bone as a scaffold in a rat calvarial defect model. Critical-sized defects were created in 30 male Sprague-Dawley rats. The animals were divided into critical defect (CD, n=10), $\beta$-tricalcium phosphate (TCP) graft (BT, n=10) and porcine cancellous bone graft (PCB, n=10) groups. Each defect was filled with $\beta$-TCP mixed with fibrin glue or porcine cancellous bone powder mixed with fibrin glue. In the CD group, the defect was left empty. All rats were sacrificed at 8 weeks after bone graft surgery, and bone formation was evaluated by gross observation, plain radiography, micro-computed tomography scanning and histological evaluation. Repair of bone defect was the least in the CD group, and significant new bone formation was observed in the PCB group. Grafting of porcine cancellous bone was more efficient for regenerating new bone than grafting $\beta$-TCP.