Rheumatoid arthritis (RA) is characterized by the infiltration of leukocytes into the synovial tissue and synovial fluid of joints, ultimately leading to destruction of cartilage and bone. Low-level laser irradiation (LLLI) is evaluated for treating RA, however, the molecular basis mechanism underlying the effectiveness of LLLI is unclear. Chemokines and those receptors play a central role in the progression of RA inflammation. CXCR3 may be recruited directly from the circulation into the synovial sublining regions by its ligand, CXCL9, produced by synovial fibroblasts. The objectives of this study were to determine whether LLLI decreased production of CXCR3 and CXCL9 in RA joints of type II collagen induced RA (CIA) rats. Total RNA was isolated from rat knee joints with or without treatment of 830 nm LLLI irradiation, and gene expression profiles were analyzed by DNA microarray (Affymetrix, 41,000 genes). As results, LLLI significantly reduced CXCR3 mRNA level, but not significantly reduced CXCL9. The reduction of CXCR3 mRNA levels was confirmed by RT-PCR and real-time PCR. Since CXCR3 plays an important role of the progression of RA, the reduction of CXCR3 gene expression may be one of important mechanisms in reduction of inflammation in RA joints by LLLI.

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Odontogenesis is a complex biological process both with epithelial and mesenchymal tissues, and this process directly reflects the development of odontogenic neoplasms. Therefore, we have examined Notch signaling in a case of calcifying cystic odontogenic tumor, with ameloblastic fibroma and odontogenic myxoma cases as controls. In these specimens, Notch-positive-products were present both in the epithelial and ectomesenchymal components in the calcifying cystic odontogenic tumor and the ameloblastic fibroma case, but negative in the odontogenic myxoma case, having no odontogenic epithelial islands to IHC and ISH examinations. Therefore, the examination results suggest that Notch signaling plays some important roles in cytological differentiation or acquisition of tissue-specific characteristics between odontogenic epithelium and odontogenic ectomesenchymal tissues.

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While periodontal membrane has important functions for orthodontic mechanical stress, bone morphogenetic protein families (BMPs) show crucial roles on differentiation of osteoblasts. Since our studies revealed interesting findings on expression of these molecules, we investigated BMPs and its related factors by using immunohistochemical methods in the current study. Eight-week-old ddY mice were used as experimental animals. To add continuous mechanical stress on periodontal membrane, rubber dam sheet between maxillary molars was inserted by using Waldo method. Experimental conditions with a time range between 15 minutes to 3 hours after mechanical stress application were studied by immunohistochemistry. Immunohistochemistry was performed using primary antibodies for BMP-2, BMP-4, Smad, P-Smad and DAKO-envision kit, and color was developed by DAB. As results, BMPs and Smad expressions after mechanical stress were extremely weak positive in periodontal membrane in the control group. Positive reaction was detected in fibroblasts of periodontal membrane. In experimental group, enhancement of BMP-2, BMP-4, Smad and P-Smad expressions 15 minutes after mechanical stress was recognized in periodontal membrane of the tension side. Increase of the expressions continued till 3 hours after starting of mechanical stress. In the sample of 15 minutes, even in the compression side enhancement of the positive reaction of BMP and Smad was detected to some extent. However, the expressions disappeared after this time point. These results suggest that expression of BMPs increases at the tension side and BMP signaling has a role for shifting of the tension side to bone forming state after execution of mechanical stress.

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The aims of this study are to evaluate the effectiveness of calcium hydroxide removal by using different irrigation regimens and the effect of the canal seals influenced by debris in root canal. 200 human premolar teeth were prepared, and divided randomly into two groups. Group A was filled with chemical calcium hydroxide and group B was filled with finished product calcium hydroxide. Each group was divided into 6 subsets and the calcium hydroxide in the root canal was removed in different ways: Group A1 and B1 by injection syringe and distilled water; group A2 and B2 by injection syringe and 2.5% sodium hypochlorite; group A3 and B3 by injection syringe, 2.5% sodium hypochlorite and 17% EDTA; group A4 and B4 by ultrasonic and distilled water; group A5 and B5 by ultrasonic and 2.5% sodium hypochlorite; group A6 and B6 by ultrasonic, 2.5% sodium hypochlorite and 17% EDTA. Then, 8 teeth were randomly selected from each subset group and observed by scanning electron microscope. The other specimens were obturated by lateral condensation of cold gutta-percha, stained by Indian ink and then made into transparent teeth models. The results showed that in the same irrigation regimen, there was no significant difference between group A and group B; the result of groups associated with ultrasonic was better than that with injection syringe, which was of significant difference. The rinse solution of EDTA was the best, while distilled water was the worse. The length of dye staining had no significant difference among all groups. The conclusions are that ultrasonic is better than injection syringe; association of sodium hypochlorite and EDTA is the best rinse solution to remove the calcium hydroxide. However, none of these methods or rinse solutions can remove all the calcium hydroxide. The calcium hydroxide remains exert no remarkable influence on the root canal sealer.

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Notch signaling pathway mediates diverse biological processes including cell fate decisions during odontogenesis. Dysregulation of Notch has been implicated in the tumorigenesis of some odontogenic neoplasms but its role in the calcifying epithelial odontogenic tumor (CEOT) remains unclarified. The aim here was to investigate Notch expression in CEOT and to speculate on its significance. Receptors Notch1-4 and their ligands (Jagged1, Jagged2 and Delta1) were examined immunohistochemically in six CEOT cases. Expression levels were quantified according to the percentage of positive tumor cells, amyloid-like proteins and calcifications: (-), negative staining; (+), mild and focal positivity <25%; (++), moderate positivity in significant areas 25-50%; (+++), strong positivity in predominant areas >50%. CEOT epithelium demonstrated variable expression levels for Notch1, 3, 4, Jagged1 and Delta1 suggesting upregulation of these molecules at sites of tumor differentiation. Distribution patterns were distinct with some overlap. Their localizations were largely membranous and/or cytoplasmic. Notch2 and Jagged2 were absent. Amyloid-like materials strongly expressed Jagged1 but variably Notch1, 3 and Delta1 implicating that these signaling proteins maybe competitive substrates with CEOT amyloid-like proteins for proteolysis. Notch2, 4 and Jagged2 were absent. Mineralized substances including Liesegang rings were negative for Notch receptors and ligands suggesting that calcification process is associated with downregulation of these molecules. Stromal endothelium and fibroblasts were stained variably positive. Taken together, current data suggest that Notch receptors and their ligands may play differing roles in the acquisition of cell fates in CEOT. Notch accumulations within amyloid-like protein suggest impaired proteolysis.

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Minerals and collagen are major components of bone. At present, little is known about the material property of the jaw bone compared to other bones of the body. The purpose of this study was to characterize the material property of mandibular bone expressed by the amount of mineral, collagen, and hydroxylysine (Hyl) in comparison with humeral and femoral bones using human cadavers. Mineral and collagen contents were significantly higher in the mandible than in humerus and femur but Hyl was significantly lower in the mandible. Among the three indices, a weak but significantly positive correlation between collagen and mineral contents was observed. On the contrary, Hyl showed a weak but significantly negative correlation with mineral. The three indices were almost not affected by aging, gender, and dental status which were thought to influence bone quantity. These results suggest that human mandibular bone differs in material property from humeral and femoral bones, and may possess a higher mechanical property explained by the hypothesis that adequate and no excessive extent of lysine hydroxylation of collagen leads to optimal collagen fibrillogenesis and matrix mineralization. The assessment of bone property as shown in this study could disclose unknown characteristics which cannot be expressed by bone quantity.

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We developed a porous chitosan/ hydroxyapatite (HAp) composite, in which the HAp nanocrystals align along the chitosan molecules, and examined the biocompatibility, osteoinductive activity, and the ability to act as a carrier of recombinant human bone morphogenetic protein-2 (rhBMP-2) of this novel biomaterial. The composite was subcutaneously implanted into the backs of 11-week-old SD rats, with or without rhBMP-2 (5 μg). At 2 and 8 weeks after the implantation, the composite was explanted for morphohistological evaluation. In the presence of rhBMP-2, ectopic bone formation was found at 2 weeks and maturation of the newly formed bone around the composite at 8 weeks. Chitosan/HAp composite alone caused little inflammation, and new blood vessel growth and multinucleated giant cells were found around the composite, accompanied with roughening of the surface due to degradation at 2 weeks; however, neither cartilage nor bone formation was found around the composite. With rhBMP-2, the bioabsorption of the composite was accelerated as the rhBMP-2-induced bone matured. Histomorphometrical analysis showed that the mean value of the composite areas with rhBMP-2 was significantly smaller than that without rhBMT-2 at 2 and 8 weeks after the implantation. These results suggested that the novel chitosan/ HAp composite was an effective bioabsorbable material as a carrier of rhBMP-2.

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This study investigated the effect of various treatments with TGF-β1 in osteogenic differentiation of human periodontal ligament (HPDL) cells. HPDL cells were treated with single 1 ng/ml, 100 ng/ml or multiple (12-h intervals) 1 ng/ml TGF-β1. Alkaline phosphatase (ALP) activity was detected by ALP activity staining at 4 days. Phospho-Smad3 was detected by western blotting and transcription of osteogenic differentiation markers (RUNX2, ALPL, IBSP: bone sialoprotein, BGLAP: osteocalcin) were determined by real-time PCR at various culture periods. Cells were pretreated with or without SB505124, a TGF-β/Smad pathway inhibitor, for 1 h before 1 ng/ml TGF-β1 treatment at 12-h intervals. ALP activity and phosphorylated Smad3 were detected. Single treatment with 1 ng/ml TGF-β1 significantly induced Smad3 phosphorylation, subsequent ALP upregulation and transcription of osteogenic differentiation markers, compared to these inductions with 100 ng/ml TGF-β1 treatment. In multiple treatments with 1 ng/ml TGF-β1 at 12-h intervals, only the first treatment significantly induced Smad3 phosphorylation but not the succeeding treatments. Inductive effects of single 1 ng/ml TGF-β1 in osteogenic differentiation were almost completely abolished by multiple treatments. Furthermore, multiple treatments with 1 ng/ml TGF-β1 did not induce ALP activity although the TGF-β/Smad pathway was inhibited by SB505124. Single treatment with low dose TGF-β1 significantly induced osteogenic differentiation. Multiple treatments inhibited osteogenic differentiation despite inhibition of TGF-β/Smad pathway. These findings suggest that TGF-β1 both positively and negatively regulates osteogenic differentiation and the inhibitory effect may be mediated by the non-Smad signaling pathway in HPDL cells.

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How transition of fluorine from orally applied sealant into dental matrix occurs and inhibits caries remains unknown. In the current study, we investigated mechanism of caries protection evaluating movement of fluoride ions from sustained-releasing fluoride sealant by EPMA from a crystallographic point and also from inorganic chemical view. Furthermore, we also evaluated differences of 2 kinds of sealant as a fluoride source, which have different releasing mechanism. Our results demonstrated that fluoride ion released from sealant abundantly accumulated in porous structure of tooth. From this result, it was considered that fluoride ion contributed to caries inhibition by infiltrating into porous structure appeared due to decalcification and enhancing pH environment. This result suggests thinking morphological viewpoint upon efficiency of fluorine in clinical dentistry for caries. When 2 different sealant materials were compared, GI-based sealant significantly released more fluoride ion than resin-based fluorine. Moreover GI-based sealant fluoride ion infiltrated significantly much more into decalcified area than resin-based fluorine. Thus in clinical dentistry, selection of GI-based fluoride ion at early periods and then alternation to long-term keeping resin-based fluorine should be considered to treat caries in a better way.

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There are few studies reporting observation of invasion state of fluorine applied for white spots of enamel as well as healthy parts with a non-invasive method. Thus we used EPMA method to observe fluorine invasion state in a normal human tooth. We clearly observed that more fluorine infiltrated in the decalcified porous structured enamel organ as compared to normal healthy enamel. Our results showed that when teeth were considered to be protected from caries by application of oral fluorine, more fluorine accumulation occurred in the white spot area as compared to healthy enamel section, suggesting its useful clinical use.

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