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en: Job shadowing for early undergraduate dental students: Validation of educational effectiveness using structural equation modeling

en: This study aimed to evaluate and validate the educational effectiveness of a job shadowing class as a dental teaching programme for preclinical dental students through a questionnaire that assessed related student perceptions. A total of 124 preclinical (second year) dental students at Tokushima University participated in job shadowing placements from 2017 to 2019. Each student observed dental practice or surgery for 1 day in the university hospital. After shadowing, the students were requested to fill out a nine-item questionnaire based on a five-point scale. The first analysis was performed to calculate the correlation for each item. Furthermore, regression analysis for the categorical data was performed to show the relationship between eight questions (Items 1-8) and one question (Item 9: comprehensive evaluation). Next, factor analysis was performed to determine students' perceptions regarding the shadowing class. Ninety-eight students (response rate: 79%) completed the questionnaire. There was a strong relationship amongst Items 1, 8 and 9 ("interested in dentistry as a job," "learning motivation" and "comprehensive evaluation" respectively) based on the results of the correlation and regression analysis. The factor analysis led to three student perceptions as latent factors, namely, "Interesting," "Self-awareness" and "Future Goal," which had a relatively close inter-factor correlation (0.465-0.772). The finding suggests that job shadowing may increase a students' interest in a dentistry career at an early stage of their education and learning motivation, along with generating self-awareness. This programme may present possible educational effectiveness in dental education.

en: European Journal of Dental Education

ja: European Journal of Dental Education


en: Possibility and Future of Intraoral Scanner Application to Change the Method of Taking Impressions

en: Journal of Oral Health and Biosciences

ja: Journal of Oral Health and Biosciences


en: Dental students' awareness after clinical training between dental treatment and systemic health: A questionnaire-based survey

en: Frontiers in Dental Medicine

ja: Frontiers in Dental Medicine


en: Local administration of calcitonin inhibits alveolar bone loss in an experimental periodontitis in rats.

en: Calcitonin (CTN), a calcium regulatory hormone, promotes calcium diuresis from the kidney and suppresses bone resorption. The objective of this study was to evaluate whether the topical and intermittent application of CTN inhibits alveolar bone resorption using ligature-induced experimental periodontitis in rats. Experimental periodontitis was induced by placing a nylon ligature around maxillary molars of 8-week-old male Wistar rats for 20 days. Thirty-two rats were divided into four groups: basal sham control group, periodontitis group, periodontitis plus 0.2 U CTN (low dose), and periodontitis plus 1.0 U CTN (high dose) group. To investigate the effects of CTN on alveolar bone resorption, CTN was topically injected into the palatal gingivae every 2 days after ligature removal (day 0). Micro-computed tomography (CT) analysis was performed for linear parameter assessment of alveolar bone on day 5 and day 14. Periodontal tissues were examined histo-pathologically to assess the differences among the study groups. Micro-CT images showed that alveolar bone resorption was induced statistically around the molar of ligatured rats on day 5 and day 14. The amount of bone resorption was more severe on day 14 than that on day 5. On day 5, only high-dose CTN treatment significantly suppressed bone resorption. In addition, both doses of CTN significantly suppressed bone resorption on day 14. Histological examination clarified that there were fewer TRAP-positive cells in the CTN treatment groups than in the periodontitis group on day 5. Local administration of CTN decreased alveolar bone resorption by regulating osteoclast activation in rats with periodontitis.

en: Biomedicine & Pharmacotherapy

ja: Biomedicine & Pharmacotherapy


en: Inhibitory effects of advanced glycation end-products and Porphyromonas gingivalis lipopolysaccharide on the expression of osteoblastic markers of rat bone marrow cells in culture

en: Diabetes is a major risk factor for periodontitis and there is a close relationship between the degree of hyperglycemia and the severity of periodontitis. Advanced glycation end-products (AGEs) accumulate in various tissues under diabetic conditions. AGEs in the periodontal tissues probably play a role in upregulating periodontal inflammation; however, the association of AGEs with the severity of periodontitis has not been fully clarified. Lipopolysaccharide from Porphyromonas gingivalis (P-LPS) is a potent pathogenic factor in periodontitis. Although the independent effect of AGE or P-LPS on osteoblastic cells has been reported in vitro, the effect of adding both has not been clearly elucidated. In this study, to explore factors aggravating diabetic periodontitis, we investigated the effects of AGE and P-LPS on the expression of osteoblastic markers and the expression of inflammation-related markers in vitro. Rat bone marrow cells were cultured, and alkaline phosphatase activity and bone nodule formation were evaluated as osteoblastic markers. Reverse transcription-polymerase chain reaction was performed to determine the mRNA expression of molecules associated with bone and inflammation. Protein levels of osteocalcin and interleukin-1β (IL-1β) were measured using enzyme-linked immunosorbent assay. AGEs and P-LPS independently reduced alkaline phosphatase activity and bone nodule formation. The addition of both AGE and P-LPS (AGE+P-LPS) further decreased these markers. Reverse transcription-polymerase chain reaction analysis revealed that AGE+P-LPS markedly decreased the mRNA expression of osteoblast-related molecules such as type 1 collagen, osteocalcin and Cbfa1, and markedly increased that of inflammation-related molecules such as IL1β and S100A8. AGE and P-LPS decreased the protein level of osteocalcin and increased that of IL-1β, and a further increase of IL-1β was detected for AGE+P-LPS. AGEs and P-LPS inhibited the expression of osteoblastic markers and increased the levels of inflammatory markers in rat bone marrow cells, suggesting that both AGE and P-LPS may be important factors associated with the aggravation of diabetic periodontitis.

en: Journal of Periodontal Research

ja: Journal of Periodontal Research


en: Topical injection of osteoprotegerin prevents alveolar bone loss in rat experimental periodontitis

ja: ラット実験的歯周炎におけるオステオプロテジェリンの局所投与による歯槽骨吸収抑制効果

en: Journal of the Japanese Association of Periodontology

ja: 日本歯周病学会会誌


en: Resistin in gingival crevicular fluid and induction of resistin release by Porphyromonas gingivalis lipopolysaccharide in human neutrophils

en: Resistin is an adipocytokine that induces insulin resistance and is predominantly expressed in adipocytes and peripheral blood mononuclear cells. Resistin expression increases in inflammatory diseases as well as diabetes mellitus, and is upregulated by bacterial pathogens and proinflammatory cytokines. The aim of this study was to identify resistin in human gingival crevicular fluid, to compare the resistin levels in gingival crevicular fluid between subjects with and without periodontitis and diabetes mellitus and to investigate the regulation of resistin release from human neutrophils by Porphyromonas gingivalis lipopolysaccharide (P-LPS). Gingival crevicular fluid samples were collected from patients with chronic periodontitis (n = 24), patients with diabetes mellitus-related periodontitis (n = 18) and healthy subjects (n = 21). Resistin in gingival crevicular fluid was determined using western blot analysis and an ELISA kit. The glycated hemoglobin (HbA(1c)) value was obtained from patients with diabetes mellitus-related periodontitis by a medical interview. Human neutrophils were cultured with P-LPS (0-1000 ng/mL), or incubated with inhibitors of actin or microtubule polymerization in the absence or presence of P-LPS. The medium and cellular fractions were used for determination of resistin by ELISA. The resistin level in gingival crevicular fluid from patients with periodontitis or diabetes mellitus-related periodontitis was significantly higher than that of healthy subjects. The resistin level in gingival crevicular fluid was correlated with gingival index score, but not blood HbA(1c) value. The P-LPS increased resistin release from human neutrophils, and its induction was decreased by actin polymerization inhibitors. We show, for the first time, the presence of resistin in gingival crevicular fluid. A high resistin level in gingival crevicular fluid samples from periodontitis patients may to some extent be related to P-LPS-induced resistin release from neutrophils.


en: Topical and intermittent application of parathyroid hormone recovers alveolar bone loss in rat experimental periodontitis.

en: Periodontitis is characterized by periodontal tissue inflammation and alveolar bone loss. The intermittent administration of parathyroid hormone (PTH), a major regulator of bone remodeling, has been demonstrated to stimulate osteoblastic activity. Although the systemic administration of PTH has been reported to protect against periodontitis-associated bone loss, the effect of the topical administration of PTH is unclear. In this study, the effect of intermittent administration of PTH on osteoblastic differentiation was examined in cultured calvaria cells and then the effect of topical and intermittent administration of PTH was determined by measuring the recovery of alveolar bone loss after inducing experimental periodontitis in rats. Alkaline phosphatase activity and bone nodule formation were measured in fetal rat calvaria cells. Experimental periodontitis was induced by placing nylon ligature around rat maxillary molars for 20 d. After ligature removal (day 0), PTH was topically injected into buccal gingiva three times a week for 10 wk. Micro-computed tomography analysis and histological examination were performed on days 35 and 70. Intermittent exposure of PTH in calvaria cells increased alkaline phosphatase activity and bone nodule formation by 1.4- and 2.4-fold, respectively. Ligature procedures induced marked alveolar bone loss around the molars on day 0 and greater bone recovery was observed in the PTH-treated rats on day 70. An increase in osteoid formation on the surface of alveolar bone was detected in the PTH-treated rats. Intermittent treatment with PTH stimulated osteoblastic differentiation in fetal rat calvaria cell cultures, and topical and intermittent administration of PTH recovered alveolar bone loss in rat experimental periodontitis.


en: Regulation of Calprotectin Expression by IL-1α and TGF-β in Human Gingival Keratinocytes

en: Calprotectin, a heterodimer of S100A8 and S100A9 with antimicrobial properties, is expressed in gingival keratinocytes and plays an important role in innate immunity. Because calprotectin expression is localized in the spinous cell layer of the gingival epithelium, we hypothesized that the expression of calprotectin in keratinocytes is related to the differentiation stage. The aim of the present study was to investigate the relationship between calprotectin expression and keratinocyte differentiation using some factors that regulated its differentiation. Normal human gingival keratinocytes were isolated from gingival tissues obtained at the extraction of wisdom teeth, and were cultured in serum-free keratinocyte medium supplemented with interleukin-1alpha or calcium, which promote keratinocyte differentiation, and transforming frowth factor-beta (TGF-beta) or retinoic acid, which suppress its differentiation. The expression of S100A8/A9 mRNA and the production of calprotectin in normal human gingival keratinocytes were examined by northern blotting and enzyme-linked immunosorbent assay, respectively. The expression of cytokeratin 14, involucrin and filaggrin (marker proteins of keratinocyte differentiation) was investigated by immunohistochemical staining, and the DNA-binding activity of CCAAT/enhancer binding protein alpha (C/EBPalpha), a transcription factor, was examined by electrophoretic mobility shift assay. The expression of S100A8/A9 mRNA and the production of calprotectin were increased by interleukin-1alpha and calcium, but decreased by TGF-beta. RA inhibited the expression of S100A8/A9 and keratinocyte differentiation, which were induced by interleukin-1alpha. C/EBPalpha DNA-binding activity in normal human gingival keratinocytes was enhanced by interleukin-1alpha and calcium, but suppressed by TGF-beta. The present study suggests that calprotectin expression is related to keratinocyte differentiation and that C/EBPalpha is a regulator of calprotectin expression in keratinocytes.


en: High-turnover osteoporosis is induced by cyclosporin A in rats.

en: Cyclosporin A (CsA) is used widely as an immunosuppressive agent, but it induces osteoporosis as a prominent side effect. To elucidate the mechanisms involved in CsA-induced osteoporosis, the effects of CsA on bone metabolism were investigated in a rat experimental model. Fifteen-day-old rats were fed a powdered diet containing or lacking CsA for 8-30 days. Analysis was performed by micro-computed tomography (muCT) and light microscopy to examine histomorphometric changes in rat tibiae on days 8, 16, and 30. Plasma parathyroid hormone (PTH) and osteocalcin (OCN) levels were determined by enzyme-linked immunosorbent assay (ELISA) on days 8, 16, and 30. The expression of OCN, osteopontin (OPN), and cathepsin K mRNAs in tibial bone marrow was examined by Northern blot analysis on days 8 and 16. Although no significant differences were observed in tibial length during the experimental periods, or in histomorphometric parameters on day 8, an apparent decrease in bone volume was observed in the CsA-treated group after day 16. Histologic analysis showed that the number of osteoblasts and osteoclasts on the surface of trabecular bone in the CsA-treated group had increased significantly on day 16. Plasma PTH and OCN levels in CsA-treated rats were significantly higher than those in control animals on day 8. Northern blot analysis revealed that the CsA-treated group showed an increase in the expression of OCN, OPN, and cathepsin K mRNAs on day 8 compared with the controls. These findings suggest that bone resorption in CsA-treated rats is induced by high-turnover osteoporosis and that bone remodeling activity may be activated by PTH.

en: Journal of Bone and Mineral Metabolism

ja: Journal of Bone and Mineral Metabolism


en: Alpha 2 integrin +807 polymorphism in drug-induced gingival overgrowth

en: Alpha2 integrin on fibroblasts is reported to play an important role in the induction of drug-induced gingival overgrowth, which is characterized by excessive accumulation of type I collagen in gingival connective tissue. Silent polymorphism 807 T/C within the alpha2 integrin gene is associated with high/low alpha2 integrin expression. The aim of this study was to test the hypothesis that expression of alpha2 integrin 807 T/C polymorphism correlates with drug-induced gingival overgrowth. A case-control study comparing 136 subjects taking calcium channel blockers (72 with vs. 64 without drug-induced gingival overgrowth) demonstrated that the frequency of the +807 C allele was significantly higher in the case group than in the controls (odds ratio, 3.61; 95% confidence interval, 2.14 - 6.10; P < 0.05). The present findings suggest that the alpha2 +807 C allele is one of the genetic risk factors for drug-induced gingival overgrowth.

en: Journal of Dental Research

ja: Journal of Dental Research


en: Diagnosis of Periodontal Diseases using Biomarkers in Gingival Crevicular Fluid

ja: 歯肉溝滲出液中のバイオマーカーを用いた歯周病診断

en: Periodontal diseases cause an inflammation and degradation of periodontal tissues and missing of teeth. The incidence rate of periodontal diseases is high in middle-aged and elderly people.A reasonable diagnosis of periodontal diseases is very important to keep teeth, however, conventional examinations of periodontal diseases is not necessarily exact and objective. Gingival crevicular fluid (GCF) is an exudate secreted from periodontal tissues and contains many components including proteolytic enzymes, inflammatory cytokines, blood-associated proteins, cellular and bacterial fragments. Because some proteins in GCF are related to inflammation, tissue degradation and bone metabolism, those proteins have been studying as a diagnostic marker of periodontal diseases. GCF is noninvasively collected using a sterile paper strip and biomarkers are determined using enzyme-linked immunosorbent assay (ELISA) and enzyme activity assay. We identified calprotectin, an inflammationrelated protein, in GCF and calprotectin level in GCF from periodontitis sites was significantly higher than that of healthy control. Calprotectin level in GCF was positively correlated to gingival index and other biomarkers and decreased by periodontal treatments. Resistin is an adipocytokine and its level increases in some inflammatory diseases. Resistin level in GCF from periodontitis sites was high compared to the level of healthy control samples. Procollagen type I C-terminal peptide (PICP) is a biomarker for bone metabolism and its level was high in GCF collected from periodontitis sites. These results suggested that calprotectin, resistin and PICP are useful biomarkers for periodontal diseases. On the other hand, we showed that glycated albumin (GA), a marker of diabetes mellitus (DM), was contained in GCF and GA level in GCF from DM patients was significantly higher than that of non-DM individuals. Components in GCF may be biomarkers of systemic diseases as well as periodontal diseases and their determination will be useful diagnostic examination of some diseases. Recently, we have been studying the determining system of GCF calprotectin, including microchip ELISA, surface plasmon resonance assay and immuno-chromatography assay. When GCF biomarkers are determined using the determining systems, we will simply, exactly and objectively diagnose periodontal diseases at our dental offices.

en: Journal of Oral Health and Biosciences