Young-Guk Park

Effects of Corticision on Paradental Remodeling in Orthodontic Tooth Movement

OBJECTIVE To investigate the biologic effects of Corticision on alveolar remodeling in orthodontic tooth movement. MATERIALS AND METHODS In this study, 16 cats were divided into 3 groups: group A, only orthodontic force (control); group B, orthodontic force plus Corticision; and group C, orthodontic force plus Corticision and periodic mobilization. Histologic and histomorphometric studies were performed on tissue specimens on days 7, 14, 21, and 28. RESULTS Extensive direct resorption of bundle bone with less hyalinization and more rapid removal of hyalinized tissue were observed in group B. The accumulated mean apposition area of new bone on day 28 was observed to be 3.5-fold higher in group B than in the control group A. CONCLUSIONS Corticision might be an efficient procedure for accelerating orthodontic tooth movement accompanied with alveolar bone remodeling.

Melatonin promotes osteoblastic differentiation through the BMP/ERK/Wnt signaling pathways

Abstract:  Although melatonin has a variety of biological actions such as antitumor, antiangiogenic, and antioxidant activities, the osteogenic mechanism of melatonin still remains unclear. Thus, in the present study, the molecular mechanism of melatonin was elucidated in the differentiation of mouse osteoblastic MC3T3‐E1 cells. Melatonin enhanced osteoblastic differentiation and mineralization compared to untreated controls in preosteoblastic MC3T3‐E1 cells. Also, melatonin increased wound healing and dose‐dependently activated osteogenesis markers such as runt‐related transcription factor 2 (Runx2), osteocalcin (OCN), bone morphogenic protein (BMP)‐2 and ‐4 in MC3T3‐E1 cells. Of note, melatonin activated Wnt 5 α/β, β‐catenin and the phosphorylation of c‐Jun N‐terminal kinase (JNK), and extracellular signal‐regulated kinase (ERK) in a time‐dependent manner while it attenuated phosphorylation of glycogen synthase kinase 3 beta (GSK‐3β) in MC3T3‐E1 cells. Consistently, confocal microscope observation revealed that BMP inhibitor Noggin blocked melatonin‐induced nuclear localization of β‐catenin. Furthermore, Western blotting showed that Noggin reversed activation of β‐catenin and Wnt5 α/β and suppression of GSK‐3β induced by melatonin in MC3T3‐E1 cells, which was similarly induced by ERK inhibitor PD98059. Overall, these findings demonstrate that melatonin promotes osteoblastic differentiation and mineralization in MC3T3‐E1 cells via the BMP/ERK/Wnt pathways.

Ginsenoside Re lowers blood glucose and lipid levels via activation of AMP-activated protein kinase in HepG2 cells and high-fat diet fed mice

Ginsenoside Re is a protopanaxatriol-type saponin isolated from Panax ginseng berry. Although anti-diabetic and anti-hyperlipidemic effects of Re have been reported by several groups, its mechanism of action is largely unknown until now. Here, we examine anti-diabetic and anti-hyperlipidemic activities of Re and action mechanism(s) in human HepG2 hepatocytes and high-fat diet fed C57BL/6J mice. Re suppresses the hepatic glucose production via induction of orphan nuclear receptor small heterodimer partner (SHP), and inhibits lipogenesis via suppression of sterol regulatory element binding protein-1c (SREBP-1c) and its target gene [fatty acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD1)] transcription. These effects were mediated through activation of AMP-activated protein kinase (AMPK), and abolished when HepG2 cells were treated with an AMPK inhibitor, Compound C. C57BL/6J mice were randomly divided into five groups: regular diet fed group (RD), high-fat diet fed group (HFD) and the HFD plus Re (5, 10, 20 mg/kg) groups. Re treatment groups were fed a high-fat diet for 6 weeks, and then orally administered Re once a day for 3 weeks. The in vitro results are likely to hold true in an in vivo experiment, as Re markedly lowered blood glucose and triglyceride levels and protected against hepatic steatosis in high-fat diet fed C57BL/6J mice. In conclusion, the current study suggest that ginsenoside Re improves hyperglycemia and hyperlipidemia through activation of AMPK, and confers beneficial effects on type 2 diabetic patients with insulin resistance and dyslipidemia.

Effects of low-level laser therapy after Corticision on tooth movement and paradental remodeling

Both Corticision and low‐level laser therapy (LLLT) are known to affect the rate of tooth movement. Our objective was to investigate the combined effects of Corticision and LLLT on the tooth movement rate and paradental remodeling in beagles.

Assessment of IL-6, IL-8 and TNF-α levels in the gingival tissue of patients with periodontitis

In periodontal diseases, inflammatory mediators, including interleukin (IL)-6, IL-8 and tumor necrosis factor-α (TNF-α), may promote the degeneration of inflamed periodontal tissues. In previous studies, levels of these three cytokines were demonstrated to be elevated in inflammatory gingival tissues and gingival crevicular fluid. The aim of the present study was to quantify IL-6, IL-8 and TNF-α levels in the human gingival tissues of patients with periodontitis and to assess the correlation of these three cytokines with each other. In this study, human gingival tissues from 19 patients with periodontitis (male, n=14; female, n=5) were collected. The tissues were homogenized, centrifuged and the protein in the supernatant was quantified. Enzyme-linked immunosorbent assay (ELISA) was used in the measurement of the IL-6, IL-8 and TNF-α levels, and the mean levels were observed to be 8.41±0.25, 34.01±1.09 and 20.70±0.31 pg/ml, respectively. The mean levels of IL-8 were higher than those of the other two cytokines. In each sample, the level of TNF-α expression was consistently high, with little difference between the results, which contrasted with the fluctuations in IL-6 and IL-8 levels. The expression of the two ILs (IL-6 and IL-8) showed a positive correlation (r=0.932, P=0.01), whereas TNF-α levels were not correlated with IL-6 or IL-8 levels. These results suggest that IL-6, IL-8 and TNF-α may be relevant in the pathophysiology of periodontitis, and the measurement of these cytokines may be beneficial in the identification of patients with periodontitis.

Inhibitory effect of a Korean traditional medicine, Honghwain–Jahage (water extracts of Carthamus tinctorius L. seed and Hominis placenta) on interleukin-1-mediated bone resorption

A Korean herbal formulation, Honghwain-Jahage (HJ), which is comprised of a herb of Carthamus tinctorius L. seed and Hominis Placenta, was investigated for inhibiting effects on IL-1 beta-stimulated bone resorption in the fetal mouse bone culture system. Results of in vitro cytotoxicities showed that HJ extracts have no any cytotoxicities in concentrations of 1-200 microg/ml on the cultured osteoblast cells derived from mouse calvarial bone explants. Cell viability was not significantly affected by treatment with the indicated concentration of the extracts. The HJ extracts were shown to have inhibitory effects against the synthesis of PGE(2). We also examined the effect of the pretreatment with various concentrations of the HJ extracts then treated by the PGE(2)-induction agents. Pretreatment of the HJ extracts for 1 h, which by itself had little effect on cell survival, reduced the synthesis of PGE(2). Furthermore, the HJ extracts were shown to have protective effects against plasminogen dependent fibrinolysis induced by IL-1 beta. Pretreatment of the HJ extracts for 1 h did not enhance the plasminogen dependent fibrinolysis. Finally, co-treatment of HJ with calcitonin showed significant inhibitory activity on the IL-1 beta-stimulated bone resorption. From these results, it was found that HJ extracts inhibited IL-1 beta-induced bone resorption.

Saucerneol F, a new lignan, inhibits iNOS expression via MAPKs, NF-κB and AP-1 inactivation in LPS-induced RAW264.7 cells.

Saucerneol F (SF), a new tetrahydrofuran-type sesquilignan isolated from Saururus chinensis, dose-dependently inhibited nitric oxide (NO) production, with concomitant reduction of inducible nitric oxide synthase (iNOS) protein and mRNA expression in lipopolysaccharide (LPS)-stimulated murine macrophage RAW264.7 cells. To elucidate the molecular mechanism underlying the inhibition of iNOS expression by SF, we assessed the effects of SF on nuclear factor-κB (NF-κB) DNA-binding activity, NF-κB-dependent reporter gene activity, inhibitory factor-κB (IκB) phosphorylation and degradation, and p65 nuclear translocation. Treatment with SF decreased the luciferase activities of NF-κB reporter promoters in a dose-dependent manner and translocation of NF-κB p65. In addition, pretreatment of SF reduced LPS-stimulated activation of mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated kinase 1/2 (ERK1/2), p38 MAPK, and c-Jun NH(2)-terminal kinase (JNK). Furthermore, SF attenuated the luciferase activities of AP-1 reporter promoters and the DNA-binding capacity of AP-1. Taken together, the present results indicate that SF attenuates NO production and iNOS expression by blocking LPS-induced activation of NF-κB, MAPKs, and AP-1, suggesting that SF is potentially applicable as an anti-inflammatory drug.

Compressive stress induced the up-regulation of M-CSF, RANKL, TNF-α expression and the down-regulation of OPG expression in PDL cells via the integrin-FAK pathway

OBJECTIVES This study was performed to elucidate the involvement of integrin-FAK (focal adhesion kinase) pathway in compressive stress-induced mRNA expression of macrophage colony stimulating factor (M-CSF), tumour necrosis factor (TNF)-α, receptor activator of nuclear factor κB (RANKL) and osteoprotegerin (OPG) and to further confirm the role of the integrin-FAK complex as a mechanoreceptor in PDL cells. DESIGN Periodontal ligament (PDL) cells were obtained from patients having healthy first premolars extracted for orthodontic purposes. Cultured PDL cells were divided into three groups: the control group in which compressive stress was administered; the negative control group in which mechanical stress was administered after transfection of negative control siRNA; and FAK knockdown group in which mechanical stress was administered after FAK siRNA treatment. Compressive stress (2g/cm(2)) was for various time durations (0.5, 2, 6, 24, 48h). Total RNA was collected after the experiment and real-time PCR analysis was performed to determine the mRNA expression levels of M-CSF, TNF-α, RANKL and OPG. Also the supernatant was analysed with ELISA to detect the corresponding cytokine concentrations. RESULTS The cells of the control group and the negative control group expressed higher mRNA levels of M-CSF, TNF-α, and RANKL but a lower mRNA level of OPG compared to those of baseline. FAK knockdown cells showed lower mRNA expression levels of M-CSF, TNF-α, and RANKL but a higher mRNA expression level of OPG than that in the control. The OPG mRNA expression level in FAK knockdown cells was even higher than that of baseline. ELISA results showed similar pattern of cytokine concentration changes. CONCLUSIONS Results of this study indicate that the integrin-FAK pathway regulates compressive stress-induced expression of M-CSF, TNF-α, RANKL and OPG and suggests that the integrin-FAK complex acts as a mechanoreceptor in PDL cells.

Accelerated decompensation of mandibular incisors in surgical skeletal class III patients by using augmented corticotomy: a preliminary study.

INTRODUCTION Our objectives were to evaluate the amount of decompensation of the mandibular incisors and the change of periodontal support around them after corticotomy with bone augmentation before orthognathic surgery. METHODS Before orthognathic surgery for 15 skeletal Class III patients, orthodontic treatment was combined with corticotomy and bone augmentation labially to the anterior mandibular roots. Lateral cephalograms were taken before orthodontic treatment and before surgery (completion of preoperative orthodontic treatment). The amounts of mandibular incisor proclination, alveolar bone thickness, and periodontal support (gingival margin levels and augmentation pattern) were evaluated. RESULTS Significant proclination of the mandibular incisors was shown after decompensation (P <0.001; incisor mandibular plane angle, 10.45°; incisor symphyseal plane angle, 10.74°). The incisor edge moved labially by 3.47 mm. The alveolar bone thickness increased by 1.56 mm at the root apex and 1.98 mm at the level of B-point (P <0.001). There was no gingival recession irrespective of the degree of proclination of the mandibular incisiors. Two types of bone augmentation pattern were evident. One was characterized by alveolar bone proclination proportional to the labial tipping of the mandibular incisors. Buccal alveolar bone at the cervical area was well maintained (60%, 9 subjects). The other showed greater increases in alveolar thickness at B-point than at the cervical area (40%, 6 subjects). CONCLUSIONS The augmented corticotomy provided effective decompensation of the mandibular incisors in skeletal Class III patients while maintaining labial bone thickness and with no periodontal side effects. This technique reduces or eliminates the risk of moving the roots through the labial plate during decompensation with the associated risk of gingival recession.

A quantitative AFM analysis of nano-scale surface roughness in various orthodontic brackets.

In orthodontics, the surface roughnesses of orthodontic archwire and brackets affect the effectiveness of arch-guided tooth movement, corrosion behavior, and the aesthetics of orthodontic components. Atomic force microscopy (AFM) measurements were used to provide quantitative information on the surface roughness of the orthodontic material. In this study, the changes in surface roughness of various orthodontic bracket slots before and after sliding movement of archwire in vitro and in vivo were observed through the utilization of AFM. Firstly, we characterized the surface of four types of brackets slots as follows: conventional stainless steel (Succes), conventional ceramic (Perfect), self-ligating stainless steel (Damon) and self-ligating ceramic (Clippy-C) brackets. Succes) and Damon brackets showed relatively smooth surfaces, while Perfect had the roughest surface among the four types of brackets used. Secondly, after in vitro sliding test with beta titanium wire in two conventional brackets (Succes and Perfect), there were significant increases in only stainless steel bracket, Succes. Thirdly, after clinical orthodontic treatment for a maximum of 2 years, the self-ligating stainless steel bracket, Damon, showed a significant increase in surface roughness. But self-ligating ceramic brackets, Clippy-C, represented less significant changes in roughness parameters than self-ligating stainless steel ones. Based on the results of the AFM measurements, it is suggested that the self-ligating ceramic bracket has great possibility to exhibit less friction and better biocompatibility than the other tested brackets. This implies that these bracket slots will aid in the effectiveness of arch-guided tooth movement.