• The Journal of Korean Academy of Prosthodontics
• /
• v.36 no.1
• /
• pp.150-165
• /
• 1998

For the purpose of evaluating the effect of both direct retainer design and bony absorption degree around abutment of indirect retainer on the supporting tissue of abutment of indirect retainer, dislodging force was transmitted to unilateral distal extension RPD bases. Analysis of stress distributed within the supporting tissue around abutment of indirect retainer was carried out. Using three-dimensional photoelastic stress analysis method and the conclusion is a follows. 1. According to the extent of force which the direct retainer of the most distal abutment tooth, the amount of force transmitted to the abutment tooth of indirect retainer was small. 2. Of all the cases, Mandibular first premolar which was used abutment tooth of indirect retainer, buccal, mesial and distal sides represented compression stress and lingual side represented tensile stress. 3. The more bone resorption of abutment tooth of indirect retainer, the more distortion of buccal and distal side of abutment tooth was existed and the extent of compression stress which was existed and distal side to abutment tooth was large. 4. When the alveolar bone around the abutment with indircet retainer is normal. The amount of force transmitted on abutment with indirect retainer was small in the order of Akers clasp, RPA clasp, RPI clasp. 5. When the alveolar bone around the abutment with indirect retainer has been absorbed 20% and 30%, the amount of force transmitted on abutment with indirect retainer was small in the order of RPA calsp, RPI clasp, Akers clasp. 6. When denture is displaced, shape of the direct retainer reciprocating abutment affect much the function of indirect retainer.

• The korean journal of orthodontics
• /
• v.22 no.1
• /
• pp.241-251
• /
• 1992

The purpose of this study was to investigate the root resorption pattern in incisors in dog under intrusive orthodontic loadings of various magnitude and duration. Intrusive forces were generated by closed coil springs. Force magnitudes were 15-30gm, 50-60gm and 80-110gm. Durations were continuous and intermittent. Intermittent duration was applied at intervals of 12 hours. The readjustment of the force was done every 4 days. The forces were maintained for 30 days. All specimens were decalfied, embedded in paraffin and stained with hematoxylin-eosin stain. Observations were made with light microscope. The following results were obtained; 1. The continuity of root surface was ceased in all, except intermittent forced teeth with 25gm. 2. The root resorptions, cementoclasts and cemental lacunae, were increased around periapical regions and the destructive scope of bone was deeply extended as the exerted orthodontic forces increased. 3. It was inspected that, under the same forces, root resorption and bone destruction were more deeply appeared in the continuously forced teeth than the intermittently forced ones. 4. All of the alveolar bone, showed direct and undermining bone resorptions.

• Proceedings of the KACD Conference
• /
• 2001.11a
• /
• pp.552-552
• /
• 2001

Bacterial lipopolysaccharide (LPS) plays a major role in the development of periapical bone resorption. IL-1 and $TNF-{\alpha}$ are known to stimulate bone resorption and inhibit bone formation. Recent evidence has indicated that polymorphonuclear leukocytes (PMNs) have the ability to release IL-1 and $TNF-{\alpha}$ Calcium hydroxide is an effective medicament in root canal infections, reducing the microbial titre within the canal. It has been proposed that the therapeutic effect of $Ca(OH)_2$ may also be the result of direct inactivation of LPS.(omitted)

• Proceedings of the KACD Conference
• /
• 2001.11a
• /
• pp.562.1-562
• /
• 2001

Bacterial lipopolysaccharide (LPS) plays a major role in the development of periapical bone resorption. IL-1 and $TNF-{\alpha}$ are known to stimulate bone resorption and inhibit bone formation. Recent evidence has indicated that polymophonuclear leukocytes(PMNs) have the ability to release IL-1 and $TNF-{\alpha}$ Calcium hydroxide is an effective medicament in root canal infections, reducing the microbial titre within the canal. It has been proposed that the therapeutic effect of $CA(OH)_2$ may also be the result of direct inactivation of LPS.(omitted)

• The Journal of Korean Academy of Prosthodontics
• /
• v.30 no.4
• /
• pp.541-564
• /
• 1992

The purpose of this experiment was to study the effect of implantation of the dense hydroxyapatite (HA) granules$(Apaceram^{(R)})$ in the fresh extraction sockets on the residual ridge resorption in normal and induced diabetic rabbits. Sixty-four white rabbits, weighing 3.0kg, were utilized in this study and they were divided into four group : group 1-sixteen normal rabbits without filling HA granules, group 2-sixteen normal rabbits with filling HA granules, group 3-sixteen diabetic rabbits without filling HA granules, group 4-sixteen diabetic rabbits with filling HA granules. HA granules were filled immediately after extraction in the extraction sockets of the mandibular left 1st, 2nd, and 3rd molar in group 2 and 4, and no HA granules were filled in group 1 and 3. The calculation of residual ridge resoption was done at 4th week, 8th week, 12th week, and 16th week after surgery, and histologic examination was performed to study healing process at 2nd week, 4th week, 8th week, and 16th week after surgery. The results were as follows : 1. The amount of residual ridge resorption was largest in group 3, and smallest in group 2 in every interval. There was no statistically significant difference between group 1 and 4. 2. In all groups, the amount of residual ridge resorption was high until 4th week after surgery, but the rate of residual ridge resolution slowly decreased after 4th week 3. There was more active healing process in group 1 and 2 than in group 2 and 4. 4. According to filling of HA granules, there was no difference in the amount of new bone formation, but direct contact could be observed between newly formed bone and HA granules in group 2 and 4. 5. Group 1 and 3 showed marked bone resorption and adipose marrow from 8th-16th week after surgery, but group 2 and 4 did not show maeked bone resolution, and showed fibrous tissue and a little adipose tissue among trabeculae from 8th week.

• YAKHAK HOEJI
• /
• v.53 no.4
• /
• pp.206-216
• /
• 2009

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (Statins) are potent inhibitors of cholesterol biosynthesis. Cholesterol-lowering therapy using statins significantly reduces the risk of coronary heart disease. Various discovery of statins as bone anabolic agents has spurred a great deal of interest among both basic and clinical bone researchers. In-vitro and some animal studies suggest that statins increase the bone mass by enhancing bone morphogenetic protein-2 (BMP-2)-mediated osteoblast expression. Clinical and animal test results of statins focusing on the prevention and treatment of bone fractures was collected. Three independent literature searches were performed by using from January 1, 2002 to September 2008 for clinical and animal test results. Search term included statins, HMG-CoA reductase inhibitors, pleiotropic effects, fracture, osteoporosis and clinical and animal test. No consensus has been reached whether clinical use of statins has beneficial effects on bone health, partly due to lower statin concentrations because of first-pass metabolism by the liver. Experimental use of statins as stimulators of bone formation suggests that they may have widespread applicability in the field of orthopaedics. With their combined effects on osteoblasts and osteoclasts, statins have the potential to enhance resorption of synthetic materials and improve bone ingrowth. In conclusion, The use of statins in the prevention and treatment of bone fractures requires further study. But observational studies suggest that statins for decreasing bone fractures including osteoporosis have to be considered local direct administration like transdermal or subcutaneous type over oral adminstration.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.47 no.3
• /
• pp.153-174
• /
• 2021

Dental implants are popular for dental rehabilitation after tooth loss. The goal of this systematic review was to assess bone changes around bone-level and tissue-level implants and the possible causes. Electronic searches of PubMed, Google Scholar, Scopus, and Web of Science, and a hand search limited to English language clinical trials were performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines up to September 2020. Studies that stated the type of implants used, and that reported bone-level changes after insertion met the inclusion criteria. The risk of bias was also evaluated. A total of 38 studies were included. Eighteen studies only used bone-level implants, 10 utilized tissue-level designs and 10 observed bone-level changes in both types of implants. Based on bias assessments, evaluating the risk of bias was not applicable in most studies. There are vast differences in methodologies, follow-ups, and multifactorial characteristics of bone loss around implants, which makes direct comparison impossible. Therefore, further well-structured studies are needed.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.23 no.3
• /
• pp.613-618
• /
• 2009

Although the effect of Eucommie umoides oliver in osteoporosis has been studied, direct action of Eucommis ulmoides Oliver on osteoclasts remains unknown. Here we examined whether Eucommiae cortex inhibits osteoclast differentiation and bone resorption, a process known to be involved in bone diseases such as osteoporosis. Water extract from Eucommiae cortex (WE-EC) inhibited differentiation of bone marrow macrophages (BMMs) into osteoclasts without causing cytotoxicity. WE-EC suppressed the phosphorylation of p38, ERK, and JNK in BMMs treated with RANKL. WE EC specifically suppressed the mRNA expression of NFATc1 induced by RANKL. However, WE-EC inhibited stability of c-Fos protein induced by RANKL. Furthermore, WE-EC inhibited osteoclast survival induced by RANKL and in turn suppressed bone resorption. Taken together, our results suggest that WE-EC may be better agents for therapeutic use in bone diseases.

• Polymer(Korea)
• /
• v.26 no.5
• /
• pp.680-690
• /
• 2002

Implantable biodegradable wafers were prepared with pamidronate -loaded poly (L-lactide-co-glycolide) (PLGA, 75 : 25 mole ratio by lactide to glycolide, molecular weight : 20000 and 90000 g/mole) by direct compression method for the sustained release of pamidronate to investigate the possibility for the treatment of bone resorption. Pamidronate-loaded PLGA powders were prepared by means of physical mixing and spray drying with the control of formulation factors and characterized by scanning electron microscope and X-ray diffractometer. The pamidronate-loaded PLGA powders fabricated into wafers by direct compression under the constant pressure and time at room temperature. These wafers were also observed for their structural characteristic, release pattern, and degradation pattern. The release rate of pamidronate increased with increasing their initial loading ratio as well as increasing wafer thickness. The molecular weight of PLGA affects the release pattern : the higher molecular weight of PLGA, the faster release rate. It can be explained that the higher viscosity of high molecular PLGA solution at same concentration tends to aggregate PLGA and pamidronate resulting in unstable pharmaceutical dosage form. This system had advantages in terms of simplicity in design and obviousness of drug release rate and nay be useful as an implantable dosage form for the treatment of aural cholesteatoma.

• Development and Reproduction
• /
• v.17 no.1
• /
• pp.1-8
• /
• 2013

Osteoprotegerin (OPG) is a secreted glycoprotein that regulates bone resorption by inhibiting differentiation and activation of osteoclast, thereby potentially useful for the treatment of many bone diseases associated with increased bone loss. In this study, we designed a novel cDNA expression cassette by modifying the potent and mammary gland-specific goat ${\beta}$-casein/hGH hybrid gene construct and examined human OPG (hOPG) cDNA expression in transgenic mice. Six transgenic mice all successfully expressed hOPG in their milk at the level of 0.06-2,000 ${\mu}g/ml$. An estimated molecular weight of the milk hOPG was 55 kDa in SDS-PAGE, which is the same as a naturally glycosylated monomer. This hOPG expression was highly specific to the mammary glands of transgenic mice. hOPG mRNA was not detected in any organs analyzed except mammary gland. Functional integrity of milk hOPG was evaluated by TRAP (tartrate-resistant acid phosphatase) activity assay in bone marrow cell cultures. OPG ligand (OPG-L) treatment increased TRAP activity by two fold but it was completely abolished by co-treatment with transgenic milk containing hOPG. Taken together, our novel cDNA expression cassette could direct an efficient expression of biologically active hOPG, a potential candidate pharmaceutical for bone diseases, only in the mammary gland of transgenic mice.