Static magnetic fields promote osteoblastic/cementoblastic differentiation in osteoblasts, cementoblasts, and periodontal ligament cells

PURPOSE: Although static magnetic fields (SMFs) have been used in dental prostheses and osseointegrated implants, their biological effects on osteoblastic and cementoblastic differentiation in cells involved in periodontal regeneration remain unknown. This study was undertaken to investigate the effects of SMFs (15 mT) on the osteoblastic and cementoblastic differentiation of human osteoblasts, periodontal ligament cells (PDLCs), and cementoblasts, and to explore the possible mechanisms underlying these effects. METHODS: Differentiation was evaluated by measuring alkaline phosphatase (ALP) activity, mineralized nodule formation based on Alizarin red staining, calcium content, and the expression of marker mRNAs assessed by reverse transcription polymerase chain reaction (RT-PCR). Signaling pathways were analyzed by western blotting and immunocytochemistry. RESULTS: The activities of the early marker ALP and the late markers matrix mineralization and calcium content, as well as osteoblast- and cementoblast-specific gene expression in osteoblasts, PDLCs, and cementoblasts were enhanced. SMFs upregulated the expression of Wnt proteins, and increased the phosphorylation of glycogen synthase kinase-3β (GSK-3β) and total β-catenin protein expression. Furthermore, p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB) pathways were activated. CONCLUSIONS: SMF treatment enhanced osteoblastic and/or cementoblastic differentiation in osteoblasts, cementoblasts, and PDLCs. These findings provide a molecular basis for the beneficial osteogenic and/or cementogenic effect of SMFs, which could have potential in stimulating bone or cementum formation during bone regeneration and in patients with periodontal disease.

Radiographic assessment of clinical root-crown ratios of permanent teeth in a healthy Korean population

PURPOSE: The aim of this study was to determine the absolute value of the root/crown ratio (R/C ratio) using panoramic radiographs (PRGs) in a healthy Korean population. MATERIALS AND METHODS: In total, 99 patient radiographs (of 50 males and 49 females subjects; aged 16 to 24 years old) were examined, and 2,770 teeth were analyzed. Crown lengths and root lengths were measured with modified Lind's measurements using PACS tools by two examiners in two separate sessions two months apart. All data were analyzed using SPSS. The independent t-test was used to assess for gender differences, and the paired t-test was used to compare both arches with a significance level of P<.05. RESULTS: The mean R/C ratios varied from 1.29 to 1.89 (male: 1.28-1.84; females: 1.31-1.94). The highest R/C ratios were recorded for the mandibular canines (1.89), followed by the maxillary canines (1.79). The lowest R/C ratios were recorded for the maxillary second molars (1.31). In comparison with the maxillary teeth (1.29-1.78), the mandibular teeth yielded the higher R/C ratio (1.47-1.89), and this difference was significant in the females (P<.05). The difference between the genders was not statistically significant, except for the maxillary central incisors, mandibular canines and mandibular first premolars. CONCLUSION: These data may enhance the understanding of the clinical R/C ratio as a useful guideline for determining the status of teeth and the ethnic difference.

Simvastatin inhibits osteoclast differentiation by scavenging reactive oxygen species

Osteoclasts, together with osteoblasts, control the amount of bone tissue and regulate bone remodeling. Osteoclast differentiation is an important factor related to the pathogenesis of bone-loss related diseases. Reactive oxygen species (ROS) acts as a signal mediator in osteoclast differentiation. Simvastatin, which inhibits 3-hydroxy-3-methylglutaryl coenzyme A, is a hypolipidemic drug which is known to affect bone metabolism and suppresses osteoclastogenesis induced by receptor activator of nuclear factor-kappaB ligand (RANKL). In this study, we analyzed whether simvastatin can inhibit RANKL-induced osteoclastogenesis through suppression of the subsequently formed ROS and investigated whether simvastatin can inhibit H2O2-induced signaling pathways in osteoclast differentiation. We found that simvastatin decreased expression of tartrate-resistant acid phosphatase (TRAP), a genetic marker of osteoclast differentiation, and inhibited intracellular ROS generation in RAW 264.7 cell lines. ROS generation activated NF-kappaB, protein kinases B (AKT), mitogen-activated protein kinases signaling pathways such as c-JUN N-terminal kinases, p38 MAP kinases as well as extracellular signal-regulated kinase. Simvastatin was found to suppress these H2O2-induced signaling pathways in osteoclastogenesis. Together, these results indicate that simvastatin acts as an osteoclastogenesis inhibitor through suppression of ROS-mediated signaling pathways. This indicates that simvastatin has potential usefulness for osteoporosis and pathological bone resorption.

Study for the Ureteral Reconstruction with Tissue Engineering Using Poly (glycolide/epsilon-caprolactone) Scaffold-1 / 대한비뇨기과학회지

PURPOSE: Transplantation is one modality saving human life. But not only lack of the living or cadaveric human organs but also immunologic problems or some ethical situations limit transplantation in terminal stage patients. Recent research for escaping from those problems resulted in the reconstruction of the artificial organ using patients' own cells with tissue engineering. The goal of this study is, for the better reconstruction of urinary system using tissue engineering, to perform basic researches on techniques related with seeding and viability of cells. MATERIALS AND METHODS: We used 16 adult dogs, 4 female and 12 male, for primary culture of the dog bladder mucosal cell and muscle cell. The scaffold we used was made of absorbable substance polyglycolide/epsilon-caprolactone (GL/CL) in thin sponge like shape. Fibroblast 3T3 cell was used for control and 16 primary cultured mucosal cell and smooth muscle cells were used. For dynamic culture, rocker was adapted with for 5 hours. Attached cells were evaluated by 562nm ELISA reader using BCA method and scanning electron microscope. RESULTS: Successful primary culture was achieved with cells from dog bladder, and results were much better by using male dog. The dynamic culture increased attachment of the cell in scaffold and the cell attached at deeper portion of the scaffold. Long term culture showed formation of the cellular sheets on the surface of scaffold preventing inner passage of the suggesting disadvantageous condition for cells in core of the scaffold. CONCLUSIONS: We conclude that for the better attachment of the cultured cells on scaffolds, dynamic culture would be desirable. And for the better in vivo reconstruction of the organ with primary cultured cell attached scaffold, evaluation of culture state with repeated in vitro experiments are necessary.

Attachment and Growth of Cultured Fibroblasts on Chitosan Sponge

Closure of large skin wounds with split-thickness skin graft requires extensive harvesting of autologous skin. The limitation of available donor areas has sought various kinds of skin equivalents for coverage of skin defects. Concept of living skin equivalent using fibroblast and keratinocyte is the most promising one. For seeking ideal artificial skin, we conducted a research of new dermal alternative using chitosan. Fibroblast scattered on chitosan and chitosan-collagen sponge polymers were cultured for 3 weeks and chitosan and chitosan-collagen sponge polymers were grafted on the back of 250 gm Sprague-Dawley rat. There was statistically significant difference in fibroblast attachment as well as fibroblast proliferation between chitosan and chitosan-collagen sponge. Four weeks after grafting, the grafted area was examined. In the area of chitosan sponge graft, there was no clinical sign of inflammation. However, mild inflammatory infiltration and a few multinucleated giant cells were observed. In contrast, chitosan-collagen sponge grafted area showed no foreign body reaction clinically and histologically. In conclusion, concomitant use of chitosan and collagen resulted in better fibroblast attachment and proliferation and minimal immunologic reaction than chitosan sponge.