Journal of Oral Science
Online ISSN : 1880-4926
Print ISSN : 1343-4934
ISSN-L : 1343-4934
Volume 60 , Issue 4
December
Showing 1-23 articles out of 23 articles from the selected issue
Original
  • Shigenori Hirai, Yusuke Hayashi, Motohiro Ito, Toshihiko Amemiya, Ko D ...
    2018 Volume 60 Issue 4 Pages 473-478
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: August 25, 2018
    JOURNALS FREE ACCESS

    Brain and muscle Arnt-like protein-1 (BMAL1) knockout mice exhibit accelerated aging, abnormal glucose metabolism, and impaired adipocyte differentiation, among other phenotypes, which are effects associated with the BMAL1 gene. No study has investigated temporal changes in the deformation of the mandibular condyle and the presence of calcification in areas surrounding the mandibular condyle. In a study of 12 C57/BL strain mice under inhalation anesthesia, we collected images of the mandibular condyle at 6 weeks after birth and then every 5 weeks from 10 to 25 weeks after birth. At 25 weeks, deformation of the mandibular condyle was seen in 8 of 12 joints in BMAL1 knockout mice and in 2 of 12 joints in wild-type mice. At 20 and 25 weeks, deformation in areas surrounding the mandibular condyle, which are known to undergo calcification, was seen in 2 of 12 joints in BMAL1 knockout mice and in 0 of 12 joints in wild-type mice. BMAL1 knockout mice exhibited premature aging of the mandibular condyle, which suggests that circadian rhythms affect mandibular condyle morphology.

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  • Kae Ishii, Keisuke Hatori, Osamu Takeichi, Kosuke Makino, Kazuma Himi, ...
    2018 Volume 60 Issue 4 Pages 479-483
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: November 15, 2018
    JOURNALS FREE ACCESS

    It has been reported that Forkhead box transcription factor class O3a (Foxo3a) is expressed in rheumatoid arthritis, a chronic inflammatory condition accompanied by bone resorption, and plays a role in its pathology. However, it has remained unclear whether Foxo3a is involved in the pathogenesis of periapical granulomas. The present study was performed to compare the expression of Foxo3a in periapical granulomas and healthy gingival tissues. Samples were obtained surgically from patients, and subjected to hematoxylin-eosin staining for histopathologic diagnosis. Two-color immunofluorescence staining was also performed using antibodies against Foxo3a and markers for three types of inflammatory cells: neutrophils, T lymphocytes, and B lymphocytes. This revealed that Foxo3a was expressed in all three cell types in periapical granulomas but not in healthy gingival tissues. Foxo3a was expressed in 82.1%, 78.3%, and 77.5% of neutrophils, T lymphocytes, and B lymphocytes, respectively, and statistical analysis using the Kruskal-Wallis test followed by the Steel-Dwass test showed no significant difference of Foxo3a expression among the three cell types. Our results suggest that Foxo3a transcription factors may be involved in the pathogenesis of periapical granulomas.

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  • Satoshi Shimizu, Yohei Sato, Mai Shirai, Toshimitsu Matsumoto, Minoru ...
    2018 Volume 60 Issue 4 Pages 484-492
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: August 30, 2018
    JOURNALS FREE ACCESS

    To evaluate the occlusion accuracy of a novel impression technique, excessively high occlusion and the occlusal contact area during lateral movements were compared between metal restorations (restorations) and removable partial dentures (RPDs) fabricated using conventional and novel techniques. Both restorations and RPDs were fabricated on the simulation model with the precise displacement of the remaining teeth and soft tissue. For the novel technique, functionally generated path (FGP) recording and impression under occlusal force were simultaneously performed using a custom tray with an FGP table. For the two conventional techniques, definitive casts were mounted on an average value articulator and a semi-adjustable articulator in the typical manner. Prostheses were placed on the simulation models, and excessively high occlusion in the intercuspal position and occlusal contact areas during lateral movements were measured. Statistical analyses were performed using Kruskal-Wallis and Steel-Dwass tests (α = 0.05). For both prostheses, conventional techniques showed significantly higher occlusion in the intercuspal position than the novel technique. Moreover, the new technique demonstrated better guidance contact during lateral movements than conventional techniques. This novel technique can be recommended for the fabrication of highly accurate prostheses with appropriate occlusal contact without corrections at delivery.

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  • Hiroki Komiya, Kohei Shimizu, Kae Ishii, Hiroshi Kudo, Teinosuke Okamu ...
    2018 Volume 60 Issue 4 Pages 493-499
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    Pulpitis often causes referred pain in opposing teeth. However, the precise mechanism underlying ectopic pain associated with tooth-pulp inflammation remains unclear. We performed the present study to test the hypothesis that functional interactions between satellite glial cells (SGCs) and trigeminal ganglion (TG) neurons are involved in ectopic orofacial pain associated with tooth-pulp inflammation. Digastric muscle electromyograph (D-EMG) activity elicited by administration of capsaicin into the upper second molar pulp (U2) was analyzed to evaluate noxious reflex responses. D-EMG activity was significantly increased in rats with lower first molar (L1) inflammation relative to saline-treated rats. Significantly increased expression of glial fibrillary acid protein (GFAP), a marker of activated glial cells, and connexin 43 (Cx43), a gap-junction protein, was observed in activated SGCs surrounding U2-innervating TG-neurons after L1-pulp inflammation. Daily administration of Gap26, a Cx43-inhibiting mimetic peptide, into the TG significantly suppressed capsaicin-induced D-EMG activity enhancement and reduced the percentage of fluorogold-labeled (U2-innervated) cells that were surrounded by GFAP-immunoreactive (IR) and Cx43-IR cells after L1-pulp inflammation. These findings indicate that tooth-pulp inflammation induces SGC activation and subsequent spread of SGC activation in the TG via Cx43-containing gap junctions. Thus, remote neuron excitability becomes enhanced in the TG following tooth-pulp inflammation, resulting in ectopic tooth-pulp pain in the contralateral tooth.

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  • Tatsuro Suzuki, Masahiro Kondo, Ikuko Shibuta, Hidekazu Nagashima, Nao ...
    2018 Volume 60 Issue 4 Pages 500-506
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    The inferior alveolar nerve (IAN) comprises several types of sensory fibers. To clarify whether each type of primary afferent is regenerated comparably after injury, we developed a model of complete IAN transection (IANX) in mice. A retrograde tracer, fluoro-gold, injected into the mental skin was transferred to the cell bodies of a subset of isolectin B4 (IB4)-binding (non-peptidergic C) or CGRP-positive (peptidergic C) neurons at 2 weeks post-axotomy, indicating that the injured C afferents had regenerated anatomically. IANX led to a decrease of IB4-binding and CGRP immunoreactivity (IR) in the trigeminal ganglion (TG) and within the trigeminal spinal subnucleus caudalis (Vc) (i.e. terminals of the central branch of TG neurons). Two weeks after IANX, the reduction in IB4-binding activity and CGRP expression in the TG recovered to the control level; however, IB4-binding within the Vc did not, suggesting that central branch non-peptidergic neurons remained impaired. Two weeks after IANX, pinching or heat stimulus-induced extracellular signal-regulated kinase phosphorylation (pERK) was restored to the control level, but in the case of pinch stimulation the distribution pattern of pERK-IR cells was altered in the Vc. Taken together, our results support the possibility that peptidergic neurons regenerate more efficiently than non-peptidergic neurons after trigeminal nerve injury.

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  • Katsumitsu Shimada, Takanaga Ochiai, Fa-Chih Shen, Hiromasa Hasegawa
    2018 Volume 60 Issue 4 Pages 507-513
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: August 25, 2018
    JOURNALS FREE ACCESS

    In oral lichen planus, extracellular matrix and basal cells are damaged by T-lymphocytes. As a consequence, changes in expression of collagen fibers within the connective tissue and cytoskeletons of the epithelial tissue can be observed. With the goal of examining the characteristic changes undergone by basal cells as a consequence of T-lymphocytes damage in oral lichen planus, we investigated protein expression in the epithelial-connective junction. We selected 20 cases of oral lichen planus and 5 control samples of buccal mucosa. Subsequently, we divided the oral lichen planus cases into thin and thick parts based on the mean values of epithelial thickness from the control samples, and counted the positive rate of collagen IV, keratin 19, desmoglein 1, and Ki-67. Collagen IV immune-reactivity partially disappeared or thickened in oral lichen planus. The keratin 19 positive rate in oral lichen planus cases was significantly lower than in the controls. Desmoglein 1 positive rate of the thick part was significantly higher compared to the thin part of oral lichen planus. Thus, modifications in basal cells with both reduced keratin 19 expression and alterations of desmoglein 1 expression suggest that in oral lichen planus, as a consequence of cell injury or regeneration in the interface area, there is a disappearance of the “true basal cell nature”.

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  • Yasumasa Ozawa, Tatsuya Kubota, Takanobu Yamamoto, Naoya Tsukune, Ryos ...
    2018 Volume 60 Issue 4 Pages 514-518
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: October 26, 2018
    JOURNALS FREE ACCESS

    The present study was designed to compare the bone augmentation ability of absorbable collagen sponge (ACS) with that of hydroxyapatite/collagen composite (HAP/Col) using a rat calvaria defect model. Bone defects were created artificially on the surface of the calvariae of 10-week-old male Fisher rats, and then cylindral plastic caps filled with ACS or HAP/Col were placed on the defects. This area was designated as the region of interest (ROI) and new bone formation was observed at 0, 4, 8, and 12 weeks after surgery using micro-CT. Histological examinations were performed using sections obtained from 12-week-old rats. Prominent new bone formation was observed in the HAP/Col group relative to the ACS group; onset of new bone augmentation was evident from 4 weeks after surgery in the HAP/Col group and from 8 weeks in the ACS group. Histological examination revealed that the entire area of the cap was filled with newly formed bone intermingled with the HAP/Col composite. Bone mineral density in the HAP/Col group was double that in the ACS group. These results indicate that the use of HAP/Col contributes significantly to new bone augmentation.

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  • Takashi Kifune, Hisanori Ito, Misa Ishiyama, Satoko Iwasa, Hiroki Take ...
    2018 Volume 60 Issue 4 Pages 519-525
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    Hypoxia induces complex cellular responses that are mediated by a key transcription factor, hypoxia-inducible factor-1 (HIF-1). HIF-1 promotes production of cytokines and angiogenic factors and contributes to recovery of injured tissues. In the present study, expressions of angiogenin (ANG) and vascular endothelial growth factor (VEGF), which are potent angiogenic factors in mammalian tissues, were examined in immortalized fibroblasts exposed to hypoxia. After 24 h of exposure to hypoxia, ANG and VEGF mRNAs expressions were significantly elevated in periodontal ligament (PDL) fibroblasts but not in embryonic fibroblasts. Hypoxia also increased productions of ANG and VEGF proteins in PDL fibroblasts. HIF-1α mRNA expression was not affected by hypoxia in either fibroblast, although HIF-1α protein expression was enhanced after exposure to hypoxia. Treatment of PDL fibroblasts with dimethyloxaloylglycine, a prolyl hydroxylase inhibitor that stabilizes the HIF-1α protein, significantly increased expressions of ANG and VEGF mRNAs under normoxia. This suggests that stabilization of HIF-1α is crucial for upregulation of ANG and VEGF in PDL fibroblasts. These results indicate that, under hypoxic conditions, HIF-1α upregulates synthesis of ANG and VEGF in PDL fibroblasts and promotes angiogenesis.

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  • Yuta Okuwa, Taku Toriumi, Hidenori Nakayama, Tatsuaki Ito, Keita Otake ...
    2018 Volume 60 Issue 4 Pages 526-535
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    The effects of transplanted human dental pulp-derived cells (DPCs) on peripheral nerve regeneration were studied in a rat model of sciatic nerve crush injury. In one group, DPCs were transplanted into the compression site (cell transplantation group); the control group underwent no transplantation (crushed group). Sciatic nerve regeneration was determined based on the recovery of motor function and histological and immunohistochemical analyses. The cell transplantation group showed improved motor function compared with the crushed group using the CatWalk XT system, which corresponded to a higher ratio of tibialis to anterior muscle weight 14 days after surgery. Histological analysis revealed a smaller interspace area and few vacuoles in the sciatic nerve after cell transplantation compared with the crushed group. The myelin sheath was visualized with Luxol Fast Blue (LFB) staining and anti-myelin basic protein (anti-MBP) antibody labeling; the percentages of LFB- and MBP-positive areas were higher in the cell transplantation group than in the crushed group. Human mitochondria-positive cells were also identified in the sciatic nerve at the transplantation site 14 days after surgery. Taken together, the observed correlation between morphological findings and functional outcomes following DPC transplantation indicates that DPCs promote peripheral nerve regeneration in rats.

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  • Hirofumi Mizuno, Shinsuke Mizutani, Daisuke Ekuni, Ayano Tabata-Tanigu ...
    2018 Volume 60 Issue 4 Pages 536-543
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: August 30, 2018
    JOURNALS FREE ACCESS

    Using a controlled pre/post study design, we investigated the effects of professional mechanical cleaning of the oral cavity with benzethonium chloride, interdental brushes, and hydrogen peroxide on the number of oral bacteria and postoperative complications among esophageal cancer patients in an intensive care unit. Before surgery, 44 patients with esophageal cancer were recruited at Okayama Hospital from January through August 2015. The control group (n = 23) received routine oral hygiene care in the intensive care unit. The intervention group (n = 21) received intensive interdental cleaning with benzethonium chloride solution and tongue cleaning with hydrogen peroxide. The number of oral bacteria on the tongue surface and plaque index were significantly lower in the intervention group than in the control group on postoperative days 1 and 2 (P < 0.05). Additionally, the number of days with elevated fever during a 1-week period was significantly lower in the intervention group than in the control group (P = 0.037). As compared with routine oral hygiene, a new oral hygiene regimen comprising benzethonium chloride, interdental brushes, and hydrogen peroxide significantly reduced the number of oral bacteria and days with elevated fever in patients with esophageal cancer.

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  • Hisanori Ito, Takashi Kifune, Misa Ishiyama, Satoko Iwasa, Hiroki Take ...
    2018 Volume 60 Issue 4 Pages 544-551
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    Hypoxia after traumatic injuries to a tooth is one of the causes of subsequent root resorption. Inflammatory cytokines produced under hypoxic conditions are associated with root resorption, but the mechanism has not been fully understood. In this study, the role of hypoxia-inducible factor-1 (HIF-1) signaling in the regulation of CCAAT (cytosine-cytosine-adenosine-adenosine-thymidine)/enhancer-binding protein-β (C/EBPβ) and the receptor activator of nuclear factor kappa-B ligand (RANKL) expressions in immortalized human periodontal ligament (PDL) cells was investigated. PDL cells cultured under a hypoxic condition showed an increase in the expression of C/EBPβ and RANKL messenger RNAs (mRNAs), whereas the expression of osteoprotegerin and HIF-1α mRNAs was unaffected. Hypoxia had no effects on the secretion of interleukin (IL)-1β, IL-6, IL-8, IL-17A, tumor necrosis factor-alpha, macrophage migration inhibitory factor, monocyte chemoattractant protein-1, and macrophage colony-stimulating factor in the culture media. Treatment of the cells with dimethyloxaloylglycine, a competitive HIF prolyl hydroxylase inhibitor, significantly increased the expression of C/EBPβ and RANKL mRNAs. This suggested that the hypoxia-induced elevation of C/EBPβ and RANKL mRNAs was dependent on the HIF-1 activity. PDL cells transfected with a specific small interfering RNA designed to target the C/EBPβ gene showed a significant suppression of the RANKL mRNA. These findings indicated that C/EBPβ may play an important role in tooth root resorption via RANKL activation in hypoxia-exposed PDL cells.

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  • Stefano Mummolo, Alessandro Nota, Maria Elena De Felice, Domenico Marc ...
    2018 Volume 60 Issue 4 Pages 552-556
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: July 09, 2018
    JOURNALS FREE ACCESS

    This study investigated differences in periodontal health variables between buccally impacted maxillary canines (BIMC) and palatally impacted maxillary canines (PIMC) after surgical-orthodontic treatment with open technique. Nineteen patients were enrolled: 10 with unilateral BIMC (5 men, 5 women; mean age 18.50 ± 1.96 years) and 9 with unilateral PIMC (4 men, 5 women; mean age 19.44 ± 2.40 years). Probing depth and keratinized tissue were recorded 12 months after surgical-orthodontic treatment, and the differences between the 2 sides were analyzed as primary outcomes. In addition, data for BIMC and PIMC were directly compared. In the BIMC group, probing depths were significantly higher for lateral incisors than for the untreated side (P = 0.044), and keratinized tissue values were significantly lower for canines than for the untreated side (P = 0.006). No significant differences were observed in the PIMC group. In BIMC, surgical-orthodontic treatment with open technique resulted in loss of periodontal keratinized tissue in the treated tooth and periodontal attachment loss in adjacent lateral incisors. However, the periodontal status of PIMC was not affected by surgical-orthodontic treatment with open technique.

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  • Thu N. Y. Nguyen, Oranart Matangkasombut, Patcharee Ritprajak
    2018 Volume 60 Issue 4 Pages 557-566
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: November 15, 2018
    JOURNALS FREE ACCESS

    Mannan (mannosylated glycoproteins) in the outermost layer of the Candida cell wall may be the first molecules that interact with host dendritic cells (DCs) and activate immune responses that determine disease outcomes. However, little is known about how different mannan structures of common oral Candida species affect DC activation. The effects of heat-inactivated (HI) yeast cells and soluble mannan of Candida albicans, Candida parapsilosis, and Candida dubliniensis on bone marrow-derived DC (BMDC) responses were compared. HI Candida and the mannan exhibited different effects on BMDC activation and functions, which could be due to other carbohydrate compositions in the yeast cell wall. Among Candida mannan, the C. albicans mannan was the weakest stimulus and induced only interferon (IFN)-γ production. This suggests the possibility that C. albicans mannan may skew T helper (Th) responses from protective Th17 toward Th1. In contrast, C. parapsilosis mannan caused strong BMDC activation and high production of several proinflammatory cytokines which possibly promote hyperinflammation. Meanwhile, C. dubliniensis mannan induced moderate BMDC responses, which may correlate with its lower pathogenicity. Therefore, mannan of each Candida species play distinct roles in DC responses and may be involved in the immunopathogenesis and disease severity of oral candidiasis as well as other Candida infection.

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  • Takahisa Okubo, Naoki Tsukimura, Takashi Taniyama, Manabu Ishijima, Ko ...
    2018 Volume 60 Issue 4 Pages 567-573
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    Titanium mesh plate (Ti mesh) used for bone augmentation inadvertently comes into contact with medical gloves during trimming and bending. We tested the hypotheses that glove contact degrades the biological capability of Ti mesh and that ultraviolet treatment (UV) can restore this capability. Three groups of Ti mesh specimens were prepared: as-received (AR), after glove contact (GC), and after glove contact followed by UV treatment. The AR and GC meshes were hydrophobic, but GC mesh was more hydrophobic. AR and GC meshes had significant amounts of surface carbon, and Si content was higher for GC mesh than for AR mesh. UV mesh was hydrophilic, and carbon and silicon content values were significantly lower in this group than in the AR and GC groups. The number, alkaline phosphatase activity, and mineralization ability of attached osteoblasts were significantly lower in the GC group than in the AR group and markedly higher in the UV group than in the AR group. In conclusion, glove contact caused chemical contamination of Ti mesh, which significantly reduced its bioactivity. UV treatment restored bioactivity in contaminated Ti mesh, which outperformed even the baseline Ti mesh.

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  • Yusuke Miyake, Keiji Shinozuka, Kosuke Ueki, Jun Teraoka, Manabu Zama, ...
    2018 Volume 60 Issue 4 Pages 574-578
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: November 15, 2018
    JOURNALS FREE ACCESS

    To better understand the clinical features of mass lesions of the tongue, we retrospectively evaluated frequency, recurrence rate, and complications in 296 patients who had undergone surgery for such lesions. The diagnoses were fibroma (43.6%), mucous cyst (14.2%), papilloma (11.8%), hemangioma (7.8%), granuloma (6.4%), lipoma (1.4%), schwannoma (1.0%), ectopic tonsil (0.7%), and other (13.2%). Recurrence was noted in two patients (0.7%). Twenty-two patients (7.4%) developed surgical complications, including lingual nerve paralysis (6.4%), glossodynia (0.6%), and postoperative infection (0.3%). Lingual nerve paralysis was observed in the ventral portion (42.1%) of the tongue, apex (36.8%), lateral border (10.5%), and dorsum (10.5%). When all sites were considered together, there was no significant difference in the number of patients presenting with lingual nerve paralysis (P = 0.075). However, there were significant differences in lingual nerve paralysis at the lateral border (P < 0.05), apex (P < 0.05), and dorsum (P < 0.001) but not at the ventral portion (P > 0.05) in the size of the patients with versus without it which suggests that the risk of lingual nerve paralysis is higher at the ventral tongue, regardless of tumor size. These results shed light on the clinical features of mass lesions of the tongue.

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  • Masahiro Noguchi, Isao Yamawaki, Saitatsu Takahashi, Yoichiro Taguchi, ...
    2018 Volume 60 Issue 4 Pages 579-587
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    It is widely accepted that vitamin E (VE) acts as an antioxidant and is involved in various metabolic systems including the regulation of gene expression and inhibition of cell proliferation. The most predominant isoform of VE in the living body is α-tocopherol. However, the influence of α-tocopherol on bone marrow mesenchymal cells (BMMCs) in a background of type II diabetes mellitus (DM) has not been investigated. The focus of the present study was to clarify the effect of α-tocopherol on BMMCs derived from rats with type II DM and the underlying mechanisms involved. BMMCs were isolated from rats with type II DM. The BMMCs were either untreated or exposed to α-tocopherol at concentrations of 1.0, 10, and 100 μM, and the resulting effects of α-tocopherol on cell proliferation, H2O2 activity, and antioxidant and inflammatory cytokine production were examined. At 100 μM, α-tocopherol had no effect on cell proliferation, but H2O2 activity was significantly increased. At 10 μM, α-tocopherol increased the gene expression of IL-1β, and markedly promoted that of TNF-α. Expression of catalase in the presence of 100 μM α-tocopherol was lower than for the other concentrations. At a low concentration, α-tocopherol exerted good antioxidant and anti-inflammatory effects on BMMCs. The study suggests that maintaining α-tocopherol at a low concentration might promote the recovery of BMMCs from oxidative stress.

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  • Kenji Takeuchi, Mikari Asakawa, Takafumi Hashiba, Toru Takeshita, Youj ...
    2018 Volume 60 Issue 4 Pages 588-594
    Published: 2018
    Released: December 27, 2018
    [Advance publication] Released: November 15, 2018
    JOURNALS FREE ACCESS

    In this interventional study, a randomized controlled trial was used to evaluate the short-term effects of xylitol-containing chewing gum on the salivary microbiota. In total, 70 healthy adult men recruited from the Japan Ground Self Defense Force participated in the study during a 2-day training at Yamaguchi camp, Yamaguchi Prefecture, Japan. The men were randomly divided into two groups: one group chewed two pieces of xylitol-containing chewing gum 7 times/day for 2 days (n = 34) and the other did not (n = 36). Baseline and follow-up stimulated saliva samples were collected and the salivary microbial composition was assessed using the 16S rRNA gene next-generation sequencing analysis. The total salivary bacterial count was quantified using a quantitative real-time PCR system. No statistically significant difference was found between the two groups regarding any parameter analyzed in the baseline samples; however, the follow-up samples of the test group showed significantly lower total salivary bacterial count than those of the control group. Conversely, no significant difference was observed in the overall composition of the salivary microbiota between the baseline and follow-up samples of the two groups. These results indicate that xylitol-containing chewing gum inhibits the increase in total salivary bacteria over a short time during which the salivary microbial composition is not affected.

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  • Tomohiro Yasumitsu, Osamu Shimizu, Hiroshi Shiratsuchi, Yusuke Miyake, ...
    2018 Volume 60 Issue 4 Pages 595-600
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    The aim of this study was to determine the localization of aquaporin-5 (AQP5), transforming growth factor-β1 (TGF-β1) and laminin during regeneration of the rat submandibular gland. After duct ligation for 7 days, the regenerating glands were collected on days 0, 1, 3, 7, and 14 after ligation release to study the process of regeneration. Immunohistochemical staining revealed apical expression of AQP5 in many acinar cells, strong expression in intercalated ducts (ICDs) of the normal submandibular gland at Day 14, and strong expression in duct-like structures (DLSs) during regeneration from Day 0 to 7. However, a few AQP5-negative acinar cells were detected during regeneration. At Day 0, immunopositivity for TGF-β1 was detected in connective tissue. At Days 3 and 7 during regeneration, TGF-β1 immunostaining was observed in DLSs, which were surrounded by α-smooth muscle actin-positive thickened myoepithelial cells. Laminin staining was strong in the thickened basement membrane of DLSs at Day 3 during regeneration, but weak around acinar cells at Day 14. These findings suggest that TGF-β1 is involved in the environment around DLSs, myoepithelial cells and laminin, that DLSs have the same functional properties as ICDs, and that AQP5-negative acinar cells may be mucous cells.

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  • Yasunobu Iwai, Keisuke Noda, Mizuho Yamazaki, Masaru Mezawa, Hideki Ta ...
    2018 Volume 60 Issue 4 Pages 601-610
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    Follicular dendritic cell-secreted protein (FDC-SP) is expressed in FDCs, human periodontal ligament (HPL) cells, and junctional epithelium. To evaluate the effects of interleukin-1 beta (IL-1β) on FDC-SP gene expression in immortalized HPL cells, FDC-SP mRNA and protein levels in HPL cells following stimulation by IL-1β were measured by real-time polymerase chain reaction and Western blotting. Luciferase (LUC), gel mobility shift, and chromatin immunoprecipitation (ChIP) analyses were performed to study the interaction between transcription factors and promoter regions in the human FDC-SP gene. IL-1β (1 ng/mL) induced the expression of FDC-SP mRNA and protein levels at 3 h, and reached maximum levels at 12 h. IL-1β increased LUC activities of constructs (−116FDCSP - −948FDCSP) including the FDC-SP gene promoter. Transcriptional inductions by IL-1β were partially inhibited by 3-base-pair (3-bp) mutations in the Yin Yang 1 (YY1), GATA, CCAAT-enhancer-binding protein2 (C/EBP2), or C/EBP3 in the −345FDCSP. IL-1β-induced −345FDCSP activities were inhibited by protein kinase A, tyrosine-kinase, mitogen-activated protein kinase (MEK)1/2, and PI3-kinase inhibitors. The results of gel shift and ChIP assays revealed that YY1, GATA, and C/EBP-β interacted with the YY1, GATA, C/EBP2, and C/EBP3 elements that were increased by IL-1β. These studies demonstrate that IL-1β increases FDC-SP gene transcription in HPL cells by targeting YY1, GATA, C/EBP2, and C/EBP3 in the human FDC-SP gene promoter.

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  • Mizuki Saito, Yoshihiro Shimazaki, Toshiya Nonoyama, Yasushi Tadokoro
    2018 Volume 60 Issue 4 Pages 611-617
    Published: 2018
    Released: December 27, 2018
    JOURNALS FREE ACCESS

    The aim of this study was to examine the association between type of dental visit and number of remaining teeth in Japanese elders. Data were collected from 3,163 adults aged 75 or 80 years who underwent an oral health examination. Type of dental visit was classified into four categories by treatment(s) received (none, periodontal, caries, or other treatment). Number of remaining teeth was classified as ≥20, 10-19, or 0-9 teeth. Multivariate multinomial logistic regression analysis was used to examine associations between type of dental visit and number of remaining teeth among all participants and the 3,032 dentate elderly. As compared with elders who did not visit a dentist, those who received periodontal or caries treatments had a significantly lower odds ratio for having 0-9 teeth, and those who received periodontal treatment had a significantly lower odds ratio of having 10-19 teeth. In the multivariate linear regression model, number of days of periodontal treatment was positively associated with number of remaining teeth. Our results suggest that type of dental visit is associated with number of remaining teeth in Japanese elders.

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  • Reiko Hoshi, Akemi Tetsumura, Satoshi Yamaguchi
    2018 Volume 60 Issue 4 Pages 618-625
    Published: 2018
    Released: December 29, 2018
    JOURNALS FREE ACCESS

    The purpose of the present study was to predict inferior alveolar nerve (IAN) exposure and associated neurosensory deficits after mandibular cyst surgery based on imaging findings. The study includes 193 sites in 184 consecutive patients who underwent enucleation of cystic lesions around a mandibular third molar (MM3) and extraction of the associated MM3. Absence/presence of white lines on panoramic radiographs (PR) and absence/presence of cortication surrounding the mandibular canal on computed tomography (CT) are evaluated as predictor variables. Outcome variables are operative IAN exposure and postoperative lower lip and/or chin dysesthesia. There is a significant correlation between interruption of white lines and loss of cortication. The predictor variables are statistically associated with IAN exposure and dysesthesia. Positive predictive values of CT findings (loss of cortication) for each outcome variable are slightly higher than those of PR findings (interruption of white lines). When considering the variables, type IV, with interruption of white lines and loss of cortication, shows a statistically significant difference compared to the other groups. White lines on PR images and cortication status of the mandibular canal on CT images predict operative IAN exposure and postoperative dysesthesia in mandibular cyst surgery.

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  • Shingo Kamijo, Kumiko Sugimoto, Meiko Oki, Yumi Tsuchida, Tetsuya Suzu ...
    2018 Volume 60 Issue 4 Pages 626-633
    Published: 2018
    Released: December 29, 2018
    [Advance publication] Released: October 26, 2018
    JOURNALS FREE ACCESS

    The need for domiciliary dental care (DDC) for people requiring long-term nursing care is increasing as the super-aged society of Japan grows still older. Dysphagia diagnosis and rehabilitation are becoming more important in DDC; thus, the need for prostheses used for dysphasia rehabilitation is presumed to be increasing. To identify DDC trends in Japan, as well as the need for prostheses and dental technicians for DDC, we sent a self-administered questionnaire to dentists providing DDC and analyzed responses from 138 dentists (valid response rate, 39.8%). The results showed that 37.7% of respondents reported treating ≥50 patients per month. The most frequently performed procedures were removable prosthetic treatment and oral care, followed by dysphagia rehabilitation. Use of palatal augmentation prostheses was experienced by 54.3% of respondents, and most indicated that the prostheses were effective for improvement of oropharyngeal function. The rates of cooperation with primary care doctors and nursing care professionals were 76.8% and 85.5%, respectively. Only 6.5% of respondents reported accompanying dental technicians to DDC. The present analysis of trends in DDC indicates that oral care and dysphagia rehabilitation have become more frequent and that cooperation with healthcare professionals other than dental technicians has increased in recent DDC.

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Short Communication
  • Takashi Matsuura, Kouji Sugimoto, Viviane K. S. Kawata-Matsuura, Kajir ...
    2018 Volume 60 Issue 4 Pages 634-637
    Published: 2018
    Released: December 29, 2018
    [Advance publication] Released: May 31, 2018
    JOURNALS FREE ACCESS

    Once a tooth develops deep caries and the dental pulp tissue is irreversibly infected, the infected dental pulp tissue should be removed, and filling material should be placed in the root canal. Endodontically treated teeth are prone to root fracture or periapical periodontitis; however, dental pulp tissue has the potential to prevent root fracture or periapical periodontitis. Therefore, dental pulp regeneration after pulpectomy may help prolong tooth life. In this study, a new method of dental pulp regeneration was developed. Vascular endothelial growth factor-adsorbed collagen gel was injected into the root canal of a prepared root canal model, placed into the dorsum of a rat, and cultured for 3 weeks. After retrieving the implant, histological analysis was performed. It was found that rat somatic cells were recruited into the root apex of the transplanted root canal model. These findings suggest a new potential technique for engineering dental pulp tissue.

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