Xiaogu Wang

Showa University, Shinagawa, Tōkyō, Japan

Are you Xiaogu Wang?

Claim your profile

Publications (17)60.57 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Synthetic octacalcium phosphate (OCP) has been suggested to be a useful biomaterial for the regeneration of hard tissues, including bone. However, it remains unknown whether OCP induces dentine formation by dental pulp. We investigated biomineralization of dental pulp exposed to synthetic OCP in vitro and in vivo. When dental pulp was exposed directly to OCP, rapid formation of reparative dentine (RD) was induced and expression of dentine sialoprotein synthesis was observed in dental pulp adjacent to newly synthesized RD. OCP inhibited the proliferation of rat pulp cells and also promoted their odontoblastic differentiation in vitro, as alkaline phosphatase activity, mineralization of pulp cells and the expression level of dentine sialophosphoprotein were enhanced. Direct contact between OCP and pulp cells is required for OCP to exhibit its effects in vitro. The expression level of Runx2, a transcription factor whose downregulation is closely related to odontoblast differentiation, was downregulated in pulp cells cultured with OCP. Structural changes of OCP during culture were determined by Fourier transform infrared spectroscopy. OCP tended to be converted to carbonate hydroxyapatite after incubation with or without pulp cells, which may be analogous to biological apatite crystals. Taken together, our data suggest that synthetic OCP supports RD formation by dental pulp and downregulation of Runx2 may be involved in that stimulatory activity. Furthermore, OCP-apatite conversion is involved in this stimulatory capacity of OCP. Copyright © 2013 John Wiley & Sons, Ltd.
    Journal of Tissue Engineering and Regenerative Medicine 01/2013; DOI:10.1002/term.1669 · 4.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Differentiation of ameloblasts from undifferentiated epithelial cells is controlled by diverse growth factors, as well as interactions between epithelium and mesenchyme. However, there is a considerable lack of knowledge regarding the precise mechanisms that control ameloblast differentiation and enamel biomineralization. We found that the expression level of carbonic anhydrase II (CAII) is strongly up-regulated in parallel with differentiation of enamel epithelium tissues, while the enzyme activity of CA was also increased along with differentiation in ameloblast primary cultures. The expression level of amelogenin, a marker of secretory-stage ameloblasts, was enhanced by ethoxzolamide (EZA), a CA inhibitor, as well as CAII antisense (CAIIAS), whereas the expression of enamel matrix serine proteinase-1 (EMSP-1), a marker for maturation-stage ameloblasts, was suppressed by both. These agents also promoted ameloblast proliferation. In addition, inhibition of ameloblast differentiation by EZA and CAIIAS was confirmed using tooth germ organ cultures. Furthermore, EZA and CAIIAS elevated intracellular pH in ameloblasts, while experimental decreases in intracellular pH abolished the effect of CAIIAS on ameloblasts and triggered the activation of c-Jun N-terminal kinase (JNK). SP600125, a JNK inhibitor, abrogated the response of ameloblasts to an experimental decrease in intracellular pH, while the inhibition of JNK also impaired ameloblast differentiation. These results suggest a novel role for CAII during amelogenesis, that is, controlling the differentiation of ameloblasts. Regulation of intracellular pH, followed by activation of the JNK signaling pathway, may be responsible for the effects of CAII on ameloblasts.
    Journal of Cellular Physiology 12/2010; 225(3):709-19. DOI:10.1002/jcp.22267 · 3.87 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: GPC-1 (glypican-1) is a cell surface heparan sulfate proteoglycan that acts as a co-receptor for heparin-binding growth factors and members of the TGF-β (transforming growth factor beta-1) family. The function of cell-surface proteoglycans in the reparative dentine process has been under investigation. Gpc-1 was detected with similar frequency as tgf-β1 in the cDNA library using mRNA from the odontoblast-like cell-enriched pulp of rat incisors. The aim of this study was to test our hypothesis that gpc-1 may be related to reparative dentine formation. We examined the expression of this gene during the reparative dentine process, as well as the effect of gpc-1 on odontoblast-like cell differentiation using siRNA (small interfering RNA) to down-regulate gpc-1 expression. Immunohistological examination showed that GPC-1 was expressed in pulp cells entrapped by fibrodentine and odontoblast-like cells as well as TGF-β1. The mRNAs for gpc-1, -3 and -4, except for gpc-2, were expressed during odontoblast-like cell differentiation in pulp cells. The relative levels of gpc-1 mRNA were increased prior to the differentiation stages and were decreased during the secretory and maturation stages of pulp cells. Down-regulation of gpc-1 expression resulted in a 3.9-fold increase in tgf-β1 expression in pulp cells and a 0.3-fold decrease in dspp (dentine sialophosphoprotein) expression compared with control. These results suggested that gpc-1 and tgfβ-1 expression are necessary for the onset of differentiation, but should be down-regulated before other molecules are implicated in the formation of reparative dentine. In conclusion, gpc-1 expression in odontoblast-like cells is associated with the early differentiation but not with the formation of reparative dentine.
    Cell Biology International 11/2010; 34(11):1069-74. DOI:10.1042/CBI20090062 · 1.64 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effect of mineral trioxide aggregate (MTA) on the odontoblast-like differentiation of pulp cells was evaluated using heat-shock protein 25 (hsp25) as a marker for odontoblast differentiation. The cells were cultured with tooth-colored MTA or calcium hydroxide-containing cement (Dycal). The effects of the materials on the pulp cells were observed using a confocal laser scanning microscope. The cells were labelled immunocytochemically using polyclonal antibodies against hsp25 and actin. The mRNA expression of hsp25 and dspp in the pulp cells at 2 days were examined by quantitative reverse transcription-polymerase chain reaction (RT-PCR). Most of the cells cultured with MTA showed an intense immunlabelling for hsp25 and the mRNA expressions of hsp25 and dspp at 2 days were higher than those cultured with Dycal. These findings indicate that MTA is an effective pulp capping material and is able to induce the differentiation of odontoblast-like cells and the formation of reparative tertiary dentin with minimum apoptosis.
    Acta Histochemica 09/2010; 112(5-112):452-458. DOI:10.1016/j.acthis.2009.05.001 · 1.76 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bone metabolism results from a balance between osteoclast-driven bone resorption and osteoblast-mediated bone formation. Diseases such as periodontitis and rheumatoid arthritis are characterized by increased bone destruction due to enhanced osteoclastogenesis. Here we report that interferon regulatory factor-8 (IRF-8), a transcription factor expressed in immune cells, is a key regulatory molecule for osteoclastogenesis. IRF-8 expression in osteoclast precursors was downregulated during the initial phase of osteoclast differentiation induced by receptor activator of nuclear factor-kappaB ligand (RANKL), which is encoded by the Tnfsf11 gene. Mice deficient in Irf8 showed severe osteoporosis, owing to increased numbers of osteoclasts, and also showed enhanced bone destruction after lipopolysaccharide (LPS) administration. Irf8-/- osteoclast precursors underwent increased osteoclastogenesis in response to RANKL and tumor necrosis factor-alpha (TNF-alpha). IRF-8 suppressed osteoclastogenesis by inhibiting the function and expression of nuclear factor of activated T cells c1 (NFATc1). Our results show that IRF-8 inhibits osteoclast formation under physiological and pathological conditions and suggest a model where downregulation of inhibitory factors such as IRF-8 contributes to RANKL-mediated osteoclastogenesis.
    Nature medicine 10/2009; 15(9):1066-71. DOI:10.1038/nm.2007 · 28.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To elucidate the role of the synovium in bone destruction by osteoclasts in rheumatoid arthritis (RA), primary synovial cells isolated from RA patients were cultured and characterized. The cultured primary cells did not produce RANKL (TRANCE/ODF/OPGL/TNFSF11/CD254), an inducer of osteoclast differentiation, but constitutively produced its inhibitor, osteoprotegerin (OPG). Addition of TNF-alpha to the primary cultures of synovial cells reduced the cell viability and strongly suppressed OPG production. We then established nine synovial cell clones, including SYM-1, responsible for OPG production from primary synovial cell cultures. TNF-alpha induced apoptosis of SYM-1 cells within 24h and decreased OPG levels, while infliximab, a chimerical form of the anti-TNF-alpha antibody drug, suppressed the apoptosis and restored OPG levels. These results suggest the existence of fibroblastic cells producing OPG in the synovium, while TNF-alpha suppresses OPG production by inducing apoptosis in those cells. Further, infliximab is considered to inhibit bone destruction through restoration of OPG levels in RA.
    Cytokine 02/2008; 41(1):61-70. DOI:10.1016/j.cyto.2007.10.013 · 2.87 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This in vitro study examines the whitening efficacy of a light-emitting diode (LED), a diode laser, and a KTP laser irradiation in dental bleaching by analyzing the change in color achieved from the treatment, the temperature increase induced in the pulpal cavity, as well as enamel microhardness measurement after treatment. Bleaching techniques achieved significant advances with the use of coherent or incoherent radiation sources to activate the bleaching agents. A hydrogen peroxide bleaching agent, Hi-Lite, was stimulated with an LED, a 980-nm diode laser at 0.8 W, or a 532-nm KTP laser at 1.0 W for 30 sec on 64 extracted human incisors. During irradiation, the temperature in the pulpal cavity was monitored. The color change was evaluated using the CIE L*a*b* color space measurement system, and Vikers enamel microhardness was tested after treatment. A mean total color difference value (DeltaE*) greater than 5.0 was obtained in each group. KTP-laser-induced bleaching gave a significantly higher DeltaL* (8.35) after treatment (p < 0.01). Neither LED nor the two lasers produced significant differences in the enamel microhardness after treatment (p > 0.01). Mean maximal pulpal temperature rise was 2.95 degrees C for LED, 3.76 degrees C for KTP laser, and 7.72 degrees C for diode laser, respectively. The results of this study suggest that KTP laser is effective at providing brighter teeth. According to the conditions used in this study, the LED and KTP laser induced a safer pulpal temperature increase when assisted with Hi-Lite bleaching gel.
    Photomedicine and Laser Surgery 04/2007; 25(2):91-5. DOI:10.1089/pho.2006.2025 · 1.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We evaluated the applicability of a novel Er:YAG laser under clinical conditions. The Er:YAG laser has been demonstrated to be a safe and effective alternative to the conventional turbine bur, but the relatively low cutting speed prevented the wide application of Er:YAG laser in clinical cavity preparation. A Smart 2940 D laser developed by Deka Corporation was used for cavity preparation in 95 teeth of 45 patients. Parameters were as follows: wavelength 2.94 microm, pulse energy 700 mJ, repetition rate 8 Hz. Pain, discomfort, assessment during cavity preparation, prognosis factor, and overall clinical evaluation were assessed during or after treatment. No adverse reaction was observed in any tooth. No intraoperative pain or only slight intraoperative pain was described in 85 teeth (89.5%). Cavity preparation was completed with the laser system alone in 90 teeth (94.7%). Overall clinical evaluation showed no safety problems, with a very good or good rating in 86 teeth (90.5%). The overall operation time was 49 sec on average. The Smart 2940 D is an efficient, effective, safe, and suitable instrument for caries removal and for cavity preparation. It greatly shortens operation time.
    Photomedicine and Laser Surgery 03/2007; 25(1):8-13. DOI:10.1089/pho.2006.2020 · 1.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the efficacy of Er,Cr:YSGG (erbium,chromium:yttrium scandium gallium garnet) laser irradiation in root canal preparation and to evaluate its effect on eruption of rat incisors after disturbance of the enamel organ in the pulp, 20 canals of lower left incisor teeth were prepared by K-files followed by Er,Cr:YSGG laser irradiation, and 20 canals of right incisors were subjected to K-files only (control). At 1 week after irradiation, both sides of incisors erupted at the same level from the gingival margin. Histological findings showed that laser irradiation produced a slightly larger damage in the pulp than that of control. Scanning electron microscope observation revealed that laser-treated surface revealed a rough, irregular, and very clean surface; there was almost no evidence of debris or smear layer, and dentinal tubules were opened. Adequate power of Er,Cr:YSGG laser irradiation is effective in root canal preparation without disturbance of the eruption.
    Lasers in Medical Science 10/2006; 21(3):165-9. DOI:10.1007/s10103-006-0394-x · 2.42 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study was to investigate the rise in temperature in root surfaces during and immediately after diode laser irradiation, to observe morphological changes of root canal wall after irradiation, and to evaluate the apical leakage after irradiation and obturation in vitro. There have been very few reports on root canal treatment by 980-nm wavelength diode laser. Sixty-six extracted human single-rooted teeth were instrumented up to size 60 K-file, and then randomly divided into three groups of 22 teeth each. Groups 1 and 2 were irradiated with a diode laser at 5 W for 7 sec using fibers of diameters 550 and 365 microm, respectively. Group 3 was not irradiated, and served as a control. The rise in temperature on root surfaces of the teeth in groups 1 and 2 were measured by thermography. Six teeth in each group were bisected longitudinally and observed morphologically. Other teeth were obturated and immersed in rhodamine B solution, and the degree of apical leakage was evaluated longitudinally and transversally. A maximum temperature rise of 8.1( degrees )C was recorded in group 1. The smear layer in the laser-treated groups was evaporated and removed, resulting in clean root canal walls, which was significantly superior to the control group (p < 0.05). After obturation, the laser-treated groups showed significantly less apical leakage than the control group (p < 0.05). These results indicate that the diode laser is useful for removing smear layer and debris from root canal walls, and reducing apical leakage after obturation in vitro, and suggest that it would be useful for root canal treatment in clinic.
    Photomedicine and Laser Surgery 12/2005; 23(6):575-81. DOI:10.1089/pho.2005.23.575 · 1.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the effects of pulsed neodymium:yttrium-aluminium-garnet (Nd:YAG) laser irradiation time on the eruption of 56 mandibular incisors in 28 rats. Clinically, some incisors erupted and the others did not. The incisors were irradiated at 2 W, 20 pulses/s for the period of 3 s, 5 s, 7 s, and 10 s, and the regeneration process was monitored at 20 days after laser treatment. Incisors irradiated for 3-5 s continued their eruption; five incisors irradiated for 7 s and all incisors irradiated for 10 s did not erupt. In the incisors that continued to erupt, the inner epithelial cells differentiated into ameloblast and a part of the pulp cavity was occupied by osteodentin. In the teeth in which eruption had ceased, the inner epithelium cells did not differentiate into ameloblast, and most of the pulp cavity was occupied by osteodentin. The results indicate that a relatively short time duration of pulsed Nd:YAG laser irradiation in the pulp induced the reparative process without disturbing the eruption.
    Lasers in Medical Science 10/2005; 20(2):95-8. DOI:10.1007/s10103-005-0346-x · 2.42 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of the present study was to compare the healing process of rabbit's skin after the ablation of continuous wave CO(2) laser and pulsed CO(2) laser at low irradiances. Because of its advantages, the CO(2) laser has been viewed as an alternative to the traditional scalpel. Simple thermal models suggest that suitably short pulses of laser irradiation can leave a smaller thermal damaged zone to ablated tissue, which may lead to faster healing. One continuous-wave (cw, 2 watt) and two pulsed CO(2) lasers (sp(1), 100 Hz, 2 watt; and sp(2), 25 Hz, 2 watt) were used to ablate twelve rabbits' ear skin for 2 min, respectively. After sacrifice at 0, 3, 7, 14, 28, and 56 days postsurgery, gross observation and histological examination were performed. sp(1) and sp(2) resulted in similar ablation rates to cw laser. At 3, 7, 14, and 28 days postsurgery, the scores of the group cw were significantly lower than both the sp(1) and sp(2) scores (p < 0.01). From 7 to 28 days, wounds of sp1 showed the best histological outcomes. At a relatively low irradiance, pulsed CO(2) laser is capable of bloodless skin ablation with improved wound healing. Increasing repetition rate of the CO(2) laser may help to achieve a better surgical outcome. Pulsed CO(2) laser may be a valuable instrument for ablation skin and skin lesions.
    Photomedicine and Laser Surgery 02/2005; 23(1):20-6. DOI:10.1089/pho.2005.23.20 · 1.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study investigates the healing process that takes place in the bone and soft tissue of the maxilla and the mandible after perforation by an Er,Cr:YSGG laser device. The jaws of New Zealand white rabbits were irradiated with an Er,Cr:YSGG laser, forming wounds 0.4 mm in diameter. Irradiation parameters were as follows: repetition rate was 20 pulse/s, pulse duration was 140-200 micros, power was 2 W, exposure time was 10 s, energy density was 80 J/cm(2). After sacrifice at 0-56 days post-surgery, gross observations and histological examinations were performed. Effective hemostasis was achieved after Er,Cr:YSGG laser surgery. There was a minimal delay before the healing began. After 56 days all of the bone defects had been completely replaced by new bone. In conclusion, the Er,Cr:YSGG laser allows precise surgical ablation with minimal thermal damage to adjacent tissues in vivo. The overall subsequent healing was favorable. This laser may potentially be used in minor oral surgery.
    Lasers in Medical Science 02/2005; 20(1):21-7. DOI:10.1007/s10103-005-0329-y · 2.42 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study was performed to investigate the temperature rises on root surfaces and morphological changes on root canal walls of extracted human teeth after irradiation by erbium, chromium: yttrium, scandium, gallium, garnet (Er, Cr:YSGG) laser and to evaluate the efficiency in removing smear layer and debris from the prepared root canal walls in vitro. Background Data: No report on Er, Cr:YSGG laser effects under various conditions and specific tips for endodontic treatments has been reported. Sixty extracted human teeth with single and straight root were used in this study. The teeth were prepared at 1 mm short of the apical foramen by a conventional technique using K-files. Fifty-four specimens were irradiated by Er, Cr:YSGG laser at the output powers of 2 W, 3 W, and 5 W for 7 sec with three fiber tips (200, 320, and 400 microm diameters). Temperature changes were recorded thermographically. All teeth were examined by light microscopy or scanning electron microscopy (SEM). Thermographic study showed that the average temperature rises on root surfaces were less than 8 degrees C. Observation by light microscopy revealed the ablation at the apical stop, and that by SEM indicated that laser irradiation at 5 W using a fiber tip with 400 microm diameter was efficient for removing smear layer and debris without carbonization or melting. The results of this study suggested that the temperature rises during Er, Cr:YSGG laser irradiation at the parameters used in this study are minimal to cause the damage on periodontal and bone tissues. Moreover, it was suggested that it is efficient to remove smear layer and debris without causing any carbonization and melting.
    Photomedicine and Laser Surgery 09/2004; 22(4):291-7. DOI:10.1089/1549541041797814 · 1.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effects of Er:YAG laser irradiation on the pulp tissue during a pulpotomy procedure were evaluated histopathologically. The effects on pulp tissue during laser pulpotomy using Er:YAG laser irradiation are not clear. Sixty mesial root canals of mandibular first molars in rats were divided into four groups. In three of these groups, root canals were irradiated using an Er:YAG laser at 2 Hz and 34, 68, and 102 mJ/pulse for 15 sec. Non-irradiated canals served as controls. The effects of laser irradiation on the remaining pulp tissue and periodontal tissues were evaluated at 0 days, 2 days, and 1 week after irradiation under light microscopy. At 1 week after treatment, no inflammation or resorption was observed in any cases in the control or 34 mJ/pulse-irradiated groups. However, moderate to severe inflammation was observed in 9 of 10 cases (90%) in the 68 and 102 mJ/pulse-irradiated groups. These results suggest that effects on pulp tissues during a pulpotomy procedure by Er:YAG laser irradiation are minimal, if appropriate parameters are selected, and this is a potential therapy for pulpotomy of human teeth.
    Journal of Clinical Laser Medicine & Surgery 01/2004; 21(6):345-50. DOI:10.1089/104454703322650149
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to examine the histopathological response of dental pulp tissue to enamel matrix derivative (EMD) used as a pulp capping material. Thirty-two teeth from two mongrel dogs were divided into four equal groups. One group served as controls, and the others were used for deep Class V cavity preparation followed by direct pulp capping with enamel matrix derivative. The treated teeth were extracted after 1, 4, and 8 weeks and prepared for histopathological examination by light microscopy. All teeth prepared after 4 and 8 weeks demonstrated an increase in tertiary dentin, suggesting that enamel matrix derivative exerts a considerable influence on odontoblasts and endothelial cells of capillaries in dental pulp tissue. These results imply that enamel matrix derivative used as a pulp capping material may play a role in the calcification of dental pulp tissue.
    Journal of Endodontics 04/2003; 29(3):176-9. DOI:10.1097/00004770-200303000-00003 · 2.79 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to investigate the morphological changes of bovine mandibular bone following Er,Cr:YSGG laser irradiation in different methods in vitro. Recently, an erbium, chromium/yttrium, scandium, garmet (Er,Cr:YSGG) laser device that emits a laser beam at the wavelength of 2.78 micro m was introduced. This type of infrared laser proved to ablate dental hard tissues effectively. However, the different effects of bone ablation by this laser in different irradiation methods were still unknown. Adult bovine mandibular bones were cut into 24 small pieces, 3-4 cm in length. The parameters of Er,Cr:YSGG laser irradiation were as follows: wavelength was 2.78 micro m, pulse duration was 140-200 micro sec, repetition rate was 20 pulse/sec, power was 4 W, spot size was 1.26 x 10(-3) mm(2), and energy density was 160 J/cm(2). Irradiation methods were different in four groups (six specimens in each group): group A, fixed position and contact mode; group B, fixed position and noncontact mode; group C, nonfixed position and contact mode; and group D, nonfixed position and noncontact mode. Ablation depth in group A was significantly greater than in group B (p < 0.01). In group A, thermal damage was apparent. In group B, C, and D, thermal damage was minimal. Er,Cr:YSGG laser allows for precise surgical bone cutting and ablation with minimal thermal damage to adjacent tissue. Irradiation in different methods may achieve different ablation rates and thermal damage.
    Journal of Clinical Laser Medicine & Surgery 10/2002; 20(5):245-50. DOI:10.1089/10445470260420740

Publication Stats

376 Citations
60.57 Total Impact Points

Institutions

  • 2002–2013
    • Showa University
      • • Department of Biochemistry
      • • Division of Endodontology
      • • School of Dentistry
      Shinagawa, Tōkyō, Japan
  • 2007
    • Peking University
      Peping, Beijing, China