Ok-Su Kim

Antioxidant profile of whole saliva after scaling and root planing in periodontal disease.

Purpose This study compared the total antioxidant status (TAS) and superoxide dismutase (SOD) activity in the saliva of periodontally compromised patients before and after scaling and root planing (SRP) to assess their diagnostic utility. Methods Severe chronic periodontitis patient (test group) and subjects with no attachment loss, sites showing a 3 mm or more probing depth and a sulcus bleeding index < 10% (control group) were enrolled in this study. Saliva sampling and clinical examination were performed at one week, one month and 3 months after SRP. The TAS and SOD activity in each patients saliva was measured for the comparative analysis between the groups. Results In the test group, the TAS decreased directly after SRP. With time, it increased slightly and was relatively unchanged compared to the baseline. In the control group, the TAS also decreased immediately after SRP but increased gradually with time until 3 months. The SOD activity in the test and control subjects decreased immediately after SRP until 1 month. At 3 months, the SOD activity had increased. Both groups had a similar profile of SOD activity. However, the SOD activity of the control group was significantly higher than that of the test group at each point in time (P < 0.05). Conclusions There was a significant difference in the total salivary antioxidant level between the periodontitis and healthy or gingivitis (control) group during the experiment period. The total antioxidant level in the saliva was higher in the patients with severe chronic periodontitis than the healthy or gingivitis control before SRP. The SOD activity of the periodontitis patients was lower than the control at each time point. These findings conclusively reveal the possible use of saliva as a diagnostic tool for periodontal health.

In Vitro Bactericidal Effects of 625, 525, and 425 nm Wavelength (Red, Green, and Blue) Light-Emitting Diode Irradiation

OBJECTIVE The purpose of this study was to evaluate the relationship of 625, 525, and 425 nm wavelengths, providing average power output and effects on three common pathogenic bacteria. BACKGROUND DATA Ultraviolet (UV) light kills bacteria, but the bactericidal effects of UV may not be unique, as 425 nm produces a similar effect. The bactericidal effects of light-emitting diode (LED) wavelengths such as 625 and 525 nm have not been described. Before conducting clinical trials, the appropriate wavelength with reasonable dose and exposure time should be established. MATERIALS AND METHODS The bactericidal effects of 625, 525, and 425 nm wavelength LED irradiation were investigated in vitro for the anaerobic bacterium Porphyromonas gingivalis and two aerobes (Staphylococcus aureus and Escherichia coli DH5α). Average power output was 6 mW/cm(2) for 1 h. The bacteria were exposed to LED irradiation for 1, 2, 4, and 8 h (21.6, 43.2, 86.4, and 172.8 J/cm(2), respectively). LED irradiation was performed during growth on agar and in broth. Control bacteria were incubated without LED irradiation. Bacterial growth was expressed in colony-forming units (CFU) and at an optical density at 600 nm in agar and broth. RESULTS The bactericidal effect of LED phototherapy depended upon wavelength, power density, bacterial viable number, and bacteria species. The bactericidal effect of 425 and 525 nm irradiation varied depending upon the bacterial inoculation, compared with unirradiated samples and samples irradiated with red light. Especially, P. gingivalis and E. coli DH5α were killed by 425 nm, and S. aureus growth was inhibited by 525 nm. However, the wavelength of 625 nm was not bactericidal for P. gingivalis, E. coli DH5α, or S. aureus. CONCLUSIONS Irradiation at 625 nm light was not bactericidal to S. aureus, E. coli, and P. gingivalis, whereas wavelengths of 425 and 525 nm had bactericidal effects. S. aureus was also killed at 525 nm.

Diagnostic accuracy of panoramic radiography in the detection of calcified carotid artery

OBJECTIVES The purpose of this study was to assess the diagnostic accuracy of the panoramic radiograph in the detection of carotid artery calcification using CT as the gold standard. METHODS 110 dental patients (average age 65.2 years, range 50-82 years) with both panoramic radiographs and CT scans available were selected for the evaluation of carotid artery calcification. Two oral and maxillofacial radiologists interpreted the panoramic radiographs for the presence of carotid artery calcification. CT scans were independently interpreted by a neuroradiologist. RESULTS The accuracy of panoramic radiographs in the detection of carotid artery calcification was 62.3%. The sensitivity and the specificity were 22.2% and 90.0%, respectively. CONCLUSIONS Panoramic radiography has a moderate diagnostic accuracy in the detection of carotid artery calcification, but the sensitivity is low.

Inflammatory cytokines are suppressed by light-emitting diode irradiation of P. gingivalis LPS-treated human gingival fibroblasts

Human gingival fibroblasts (hGFs) play an important role in the inflammatory reaction to lipopolysaccharide (LPS) from P. gingivalis, which infects periodontal connective tissue. In addition, although light-emitting diode (LED) irradiation has been reported to have biostimulatory effects, including anti-inflammatory activity, the pathological mechanisms of these effects are unclear. This study examined the effects of 635-nm irradiation of P. gingivalis LPS-treated human gingival fibroblasts on inflammatory cytokine profiles and the mitogen-activated protein kinase (MAPK) pathway, which is involved in cytokine production. Gingival fibroblasts treated or not treated with P. gingivalis LPS were irradiated with 635-nm LED light, and cytokine profiles in the supernatant were assessed using a human inflammation antibody array. Expression of cyclooxyginase-2 (COX-2) protein and phosphorylation of extracellular signal-regulated kinase (ERK 1/2), p38, and c-Jun-N-terminal kinase (JNK) were assessed by Western-blot analysis to determine the effects on the MAPK pathway, and prostaglandin E2 (PGE2) in the supernatant was measured using an enzyme-linked immunoassay. COX-2 protein expression and PGE2 production were significantly increased in the LPS-treated group and decreased by LED irradiation. LPS treatment of gingival fibroblasts led to the increased release of the pro-inflammatory-related cytokines interleukin-6 (IL-6) and IL-8, whereas LED irradiation inhibited their release. Analysis of MAPK signal transduction revealed a considerable decrease in p38 phosphorylation in response to 635-nm radiation either in the presence or absence of LPS. In addition, 635-nm LED irradiation significantly promoted JNK phosphorylation in the presence of LPS. LED irradiation can inhibit activation of pro-inflammatory cytokines, mediate the MAPK signaling pathway, and may be clinically useful as an anti-inflammatory tool.

The effects of cadmium on VEGF-mediated angiogenesis in HUVECs.

Cadmium (Cd) is a highly toxic element that causes morphologic alterations and dysfunction in blood vessels. The altered vascular function caused by cadmium has been implicated in a range of chronic diseases, including hypertension. The effects of cadmium are a multisystem phenomenon involving inflammation, hypertrophy, apoptosis, angiogenesis and important processes involved in vascular remodeling systems. Vascular endothelial growth factor (VEGF) plays a major role in cell growth and angiogenesis under pathologic conditions. VEGF secretion is related to anti‐apoptosis protein expression and attenuates apoptosis in endothelial cells. This study examined the VEGF‐dependent mechanisms of angiogenesis and apoptosis in cadmium‐treated endothelial cells (HUVECs). The effects and mechanisms of cadmium in endothelial cells (HUVECs) were examined by exposing the cells to different doses of cadmium chloride (2.5–40 μ m). After the cadmium treatment, the angiogenesis and apoptosis mechanisms related to VEGF in cadmium‐treated HUVECs were examined. As a result, the low concentration of cadmium increased the tube formation in HUVECs. In addition, cadmium at concentrations of 5 and 10 μ m increased VEGF secretion and VEGFR2 activity, which suggest that cadmium affects the growth of blood vessels. All three MAPK pathways, namely ERK, JNK and p38, were activated by cadmium in HUVECs. However, high concentrations of cadmium caused cell damage, disrupted tube formation and inhibited VEGF expression and the activities of VEGFR2 and MAPK in HUVECs. Cadmium has dual functions through VEGF‐dependent mechanisms in a dose‐dependent manner. In this study, the dual effects of cadmium might alter angiogenesis and induce apoptosis through VEGF pathways in HUVECs. Copyright

Effects of 635nm light‐emitting diode irradiation on angiogenesis in CoCl2‐exposed HUVECs

It is recognized that hypoxic/ischemic conditions leading to production of reactive oxygen species (ROS) are an important mediator of angiogenesis in the wound‐healing process. Recently, low level light irradiation at 635 nm, which is used in many clinical fields, was found to decrease intracellular ROS levels, and consequently alleviate oxidative stress. The purpose of the present study was to investigate the effects of 635 nm light‐emitting diode (LED) irradiation on angiogenesis in human umbilical vein endothelial cells, in an in vitro CoCl2‐induced severe hypoxia model.

Lactone form 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase inhibitors (statins) stimulate the osteoblastic differentiation of mouse periodontal ligament cells via the ERK pathway

BACKGROUND AND OBJECTIVE Recent studies reported that the lactone forms of 3-hydroxy- 3-methylglutaryl-coenzyme A reductase inhibitors, which are also known as statins, have a bone stimulatory effect. However, there are few reports on the effect of statins on periodontal ligament cells. This study examined the statin-induced osteoblastic differentiation of mouse periodontal ligament cells as well as its mechanism. MATERIAL AND METHODS Mouse periodontal ligament cells were cultured with lovastatin or simvastatin, and their viability was measured. The levels of alkaline phosphatase (ALP), osteocalcin, bone sialoprotein and bone morphogenetic protein-2 mRNA expression were evaluated by RT-PCR. The osteoblastic differentiation was characterized by the ALP activity and Alizarin Red-S staining for calcium deposition. The activity of the osteocalcin gene (OG2) and synthetic osteoblast-specific elements (6× OSE) promoter with statins was also measured using a luciferase assay. For the signal mechanism of statins, the ERK1/2 MAPK activity was determined by western blot analysis. RESULTS A statin treatment at concentrations < 1 μM did not affect the cell viability. Lovastatin or simvastatin at 0.1 μM increased the levels of ALP, osteocalcin, bone sialoprotein and bone morphogenetic protein-2 mRNA in mouse periodontal ligament cells. In addition, the ALP activity, mineralized nodule formation and OG2 and OSE promoter activity were higher in the lovastatin- or simvastatin-treated cells than the control cells. Western blot analysis confirmed that the statins stimulated the phosphorylation of ERK1/2. CONCLUSION Lovastatin and simvastatin may stimulate the osteoblastic differentiation of periodontal ligament cells via the ERK1/2 pathway. This suggests that the statins may be useful for regenerating periodontal hard tissue.

Surface characteristics of thermally treated titanium surfaces.

Purpose The characteristics of oxidized titanium (Ti) surfaces varied according to treatment conditions such as duration time and temperature. Thermal oxidation can change Ti surface characteristics, which affect many cellular responses such as cell adhesion, proliferation, and differentiation. Thus, this study was conducted to evaluate the surface characteristics and cell response of thermally treated Ti surfaces. Methods The samples were divided into 4 groups. Control: machined smooth titanium (Ti-S) was untreated. Group I: Ti-S was treated in a furnace at 300℃ for 30 minutes. Group II: Ti-S was treated at 500℃ for 30 minutes. Group III: Ti-S was treated at 750℃ for 30 minutes. A scanning electron microscope, atomic force microscope, and X-ray diffraction were used to assess surface characteristics and chemical composition. The water contact angle and surface energy were measured to assess physical properties. Results The titanium dioxide (TiO2) thickness increased as the treatment temperature increased. Additional peaks belonging to rutile TiO2 were only found in group III. The contact angle in group III was significantly lower than any of the other groups. The surface energy significantly increased as the treatment temperature increased, especially in group III. In the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, after 24 hours of incubation, the assessment of cell viability showed that the optical density of the control had a higher tendency than any other group, but there was no significant difference. However, the alkaline phosphatase activity increased as the temperature increased, especially in group III. Conclusions Consequently, the surface characteristics and biocompatibility increased as the temperature increased. This indicates that surface modification by thermal treatment could be another useful method for medical and dental implants.

Digital panoramic radiographs are useful for diagnosis of osteoporosis in Korean postmenopausal women

OBJECTIVE The purpose of this study was to determine whether digital panoramic radiographs could be used for the diagnosis of osteoporosis through evaluation of the radiographs based on the correlation with bone mineral density (BMD). METHODS One hundred and ninety-four post-menopausal women were selected from participants who had participated in the Dong-gu study. Panoramic radiographic indices measured are mental index (MI), mandibular cortical index (MCI) and simple visual estimation (SVE). BMD at the lumbar spine and proximal femur was measured by dual-energy X-ray absorptiometry (DXA). The Pearsons correlation test was performed to analyse the correlation between MI and age and BMD at the lumbar spine, femoral neck and total hip. Multiple linear regression analysis was performed to analyse the association of MI, MCI and SVE with BMD after adjusting for age, height and weight. To determine the optimal cut-off point of MI for the diagnosis of osteoporosis, the receiver operating characteristic analysis was performed. RESULTS The MI was positively correlated with BMDs: lumbar spine: r = 0.36, femoral neck: r = 0.59 and total hip: r = 0.58 (p < 0.001). As age increased, MI decreased (r = -0.46). BMD at the lumbar spine and total hip were significantly lower in participants with reduction of mandibular width, thinning and resorption of mandibular cortex by the MI, SVE and MCI, respectively. The optimal cut-off value of MI for the diagnosis of spinal osteoporosis was 2.22 mm. CONCLUSION Thickness and morphological changes of mandibular inferior cortical bone are associated with BMD, independent of age, height and weight. These results suggest that MI, MCI and SVE may be useful indices for the diagnosis of osteoporosis in a Korean population.

Relationship between periodontal disease and subclinical atherosclerosis: the Dong-gu study.

AIM We assessed the association of periodontal disease and number of missing teeth with subclinical atherosclerosis in an adult Korean population. MATERIALS AND METHODS Cross-sectional data from 5404 individuals aged ≥50 years were obtained from the 2008-2010 Dong-gu study. Periodontal examinations were conducted to determine the number of missing teeth, pocket depth (PD), clinical attachment loss (CAL), and bleeding on probing (BOP). The percentages of sites with PD ≥ 4 mm (PD 4%), CAL ≥ 4 mm (CAL 4%), and BOP (BOP%) were recorded for each participant. B-mode ultrasound was performed to determine common carotid artery intima-media thickness (CCA IMT) and the presence of carotid plaques. Multivariate linear regression models were used to assess the associations between periodontal parameters and CCA IMT and carotid plaque. RESULTS Number of missing teeth was associated with increased CCA IMT, and BOP% was associated with increased CCA IMT in females only. This association was robust in never smokers. CONCLUSIONS The number of missing teeth was associated with CCA IMT, and BOP% was associated with CCA IMT in females only. These associations were robust in never smokers. Our results suggest that tooth loss due to oral disease may play a role in subclinical carotid atherosclerosis.