In JoVE (1)

Other Publications (66)

Articles by Kazuyoshi Baba in JoVE

Other articles by Kazuyoshi Baba on PubMed

Effect of Clenching Level on Mandibular Displacement in Kennedy Class II Partially Edentulous Patients

The International Journal of Prosthodontics. Mar-Apr, 2003  |  Pubmed ID: 12737252

Forceful clenching in the intercuspal position has the potential to cause significant mandibular displacement. Such a displacement can be expected to be exaggerated in patients without molar support. The appropriate clenching level for intercuspal position registration or evaluation in these patients has never been clarified. The aim of this study was to clarify the effect of clenching level and absence of posterior occlusal support on mandibular displacement.

Bruxism Force Detection by a Piezoelectric Film-based Recording Device in Sleeping Humans

Journal of Orofacial Pain. 2003  |  Pubmed ID: 12756932

To test the reliability and utility of a force-based bruxism detection system (Intra-Splint Force Detector [ISFD]) for multiple night recordings of forceful tooth-to-splint contacts in sleeping human subjects in their home environment.

Utility and Validity of a New EMG-based Bruxism Detection System

The International Journal of Prosthodontics. Jul-Aug, 2003  |  Pubmed ID: 12956499

The aim of this study was to test the utility and validity of a newly developed EMG-based bruxism recording system, which allowed high-resolution digital recordings of the masseter EMG in the patient's home environment and systematic discrimination of artifact signals with the aid of semiautomated software.

[Incident and Accident Reports in Tokyo Medical and Dental University Dental Hospital (FY 2001-2002)]

Kokubyo Gakkai Zasshi. The Journal of the Stomatological Society, Japan. Dec, 2003  |  Pubmed ID: 14733126

In 2002, the Dental Hospital of Tokyo Medical and Dental University set up a working group for risk management. This working group analyzed 225 incident and accident reports submitted to the hospital in 2001 and 2002. Each report was analyzed with regard to "type," "place," "reporter," "severity," and "cause" in order to diagnose hospital safety and prevent future incidents and accidents. The cause of incidents and accidents was analyzed using the SHEL model, where S stands for Software, H for Hardware, E for Environment, and L for Liveware. The severity of the consequence was classified into 6 levels, where level 0 = "error not applied," level 1 = "not affected," level 2 = "watch and see or additional test," level 3 = "treatment," level 4 = "aftereffect," and level 5 = "death." The incidents and accidents judged to have potentially high risk were given a score of "+H," irrespective of the level. The results of the analyses revealed that most of the incidents and accidents happened in "wards," "operation rooms," and "oral surgery clinics." This is probably because the incident and accident reporting system is well established by nurses working in these clinics. Additional analysis revealed that most of the reports were written and submitted by nurses. The frequencies of "treatment procedure," "misuse of dental instruments," "mis-prescription," "falling down" and "needlestick" related incidents and accidents were the highest and were caused mainly by L and S. There were only 3 accidents above level 4, however, less severe cases were given a score of +H due to the high potential risk involved.

Does Tooth Wear Status Predict Ongoing Sleep Bruxism in 30-year-old Japanese Subjects?

The International Journal of Prosthodontics. Jan-Feb, 2004  |  Pubmed ID: 15008231

This study investigated whether tooth wear status can predict bruxism level.

Accuracy and Precision of a System for Assessing Severity of Tooth Wear

The International Journal of Prosthodontics. Sep-Oct, 2004  |  Pubmed ID: 15543915

The purpose of this study was to introduce a computer-assisted quantitative tooth wear-analyzing system and test its accuracy and precision.

Electromyographic Evaluation of Masticatory Function in Denture Wearers in Related to Existing Occlusal Support

Journal of Medical and Dental Sciences. Sep, 2004  |  Pubmed ID: 15597823

The aim of this study was to clarify the relationship between partially edentulous pattern and the masticatory function in removable partial denture wearers. Eighty eight removable partial denture wearers and 7 subjects with intact dentition volunteered for this study. Using the Eichner's index, all subjects were divided into 6 groups. Electromyographic (EMG) activities of the masticatory muscle were recorded during chewing a piece of raw carrot. The masticatory function was analyzed by using the variation coefficient (VC) of the time parameter of EMG interval recorded during mastication. The association of the VC with group classification based on Eichner's index was analyzed using analysis of covariance with gender and age as the covariates. The result of the analysis revealed that the VC was significantly associated with group classification and the patients in groups without posterior occlusal supports exhibited significantly higher VC values than those in groups with posterior occlusal supports. These findings suggested that the reduced function in patients without the posterior occlusal contacts was difficult to attain improved and satisfactory outcome with removable partial dentures and that there is a significant need for posterior occlusal support for the preservation of masticatory function.

Bending Properties of Strengthened Ti-6Al-7Nb Alloy Major Connectors Compared to Co-Cr Alloy Major Connectors

The Journal of Prosthetic Dentistry. Mar, 2005  |  Pubmed ID: 15775928

Although Ti-6Al-7Nb alloy has several excellent mechanical properties, its poor rigidity has limited its clinical use as a material for the fabrication of a removable partial denture (RPD) major connector.

Association Between Masseter Muscle Activity Levels Recorded During Sleep and Signs and Symptoms of Temporomandibular Disorders in Healthy Young Adults

Journal of Orofacial Pain. 2005  |  Pubmed ID: 16106716

To examine whether any signs and symptoms of temporomandibular disorders were significantly associated with masseter muscle activity levels during sleep.

[Sensory Perceptive and Discriminative Abilities of Patients with Occlusal Dysesthesia]

Nihon Hotetsu Shika Gakkai Zasshi. Aug, 2005  |  Pubmed ID: 16121023

It is not rare for dentists to come across patients who complain of several uncomfortable feelings of occlusion despite the absence of any observable occlusal anomaly or discrepancy. These kinds of symptoms are well defined by the term "occlusal dysesthesia" (OD). This study evaluated the occlusal perceptive and discriminative abilities in OD patients.

Patients' Preference for Acrylic Resin Major Connector Analogues Formulated for Titanium Alloy Removable Partial Dentures

Journal of Medical and Dental Sciences. Jun, 2005  |  Pubmed ID: 16187618

Aim of this study was to determine patients' preference to acrylic resin major connector analogues (MCA) that simulated strengthened major connector designs formulated for Ti-6Al-7Nb alloy.

Do Patients Have a Preference for Major Connector Designs?

The Journal of Contemporary Dental Practice. Nov, 2006  |  Pubmed ID: 17091142

The aim of this research was to evaluate patients' preferences for resin analogs of four major connector designs formulated to have equal rigidity once fabricated in the same alloy.

Association Between the Amount of Alcohol Intake and Masseter Muscle Activity Levels Recorded During Sleep in Healthy Young Women

The International Journal of Prosthodontics. May-Jun, 2007  |  Pubmed ID: 17580455

The aim of this study was to determine if the amount of alcohol intake is associated with masseter muscle activity recorded during sleep.

[The Relationship Between Missing Occlusal Units and Oral Health-related Quality of Life in SDA Patients]

Nihon Hotetsu Shika Gakkai Zasshi. Oct, 2007  |  Pubmed ID: 17968151

The aim of this multi-center study was to explore the relationship between missing occlusal units and oral health-related quality of life (OHRQoL) in subjects with the shortened dental arches (SDAs). Subjects with SDAs were recruited consecutively for one month from six university-based prosthodontic clinics. In total, 115 SDA subjects participated (mean age, 58.5 +/- 10.0 yrs; 71% female). The location and number of missing teeth were examined and the number of missing occlusal units was calculated. To evaluate OHRQoL, the Japanese version of the Oral Health Impact Profile (OHIP-J) was administered and the summary score of OHIP-J was calculated. The SDA subjects were categorized depending upon the anterior-posterior lengths of the missing or remaining occlusal units. Regression analyses were performed to investigate 1) the association between missing OU and OHIP-J summary scores and 2) the OHIP-J differences between groups of subjects with various anterior-posterior SDA lengths. The first analyses revealed that one missing OU was significantly related to an increase of 2.1 OHIP-J units (95% CI: 0.6-3.5, P=0.016). The second analysis revealed that subjects who only lost the second molar contact exhibited significantly better OHRQoL than those who lost more teeth (Coefficient: 11.1, 95% CI: 2.8-19.2, P=0.02). Furthermore a statistically significant group difference was observed between the groups with and without the first molar occlusal contact (Coefficient: 12.8, 95% CI: 1.4 to 24.1, P=0.03). These results suggest that missing occlusal units are related to the OHRQoL impairment in subjects with SDAs. They also suggest that the patterns of missing occlusal units are likely to be related to the OHRQoL impairment in SDA subjects with the presence of first molar contact having an important role.

Management of Bruxism-induced Complications in Removable Partial Denture Wearers Using Specially Designed Dentures: a Clinical Report

Cranio : the Journal of Craniomandibular Practice. Jan, 2008  |  Pubmed ID: 18290528

In patients with a limited number of remaining teeth, bruxism force can be destructive for both the remaining teeth and periodontal structures. This paper reports the successful management of four such patients with severe sleep bruxism, using conventional removable partial dentures and specially designed, splint-like removable partial dentures called a night denture. The night denture was fabricated in two different designs, which depended upon the pattern of the remaining tooth contacts. The patients were followed up for 2-6 years using a night denture in either of the two designs. Within the limitations of these four reports of clinical cases, the night denture appeared to be effective in managing the problems related to sleep bruxism.

The Relationship Between Missing Occlusal Units and Oral Health-related Quality of Life in Patients with Shortened Dental Arches

The International Journal of Prosthodontics. Jan-Feb, 2008  |  Pubmed ID: 18350952

This study aimed to investigate the relationship between missing occlusal units and oral health-related quality of life (OHRQoL) in subjects with shortened dental arches (SDAs). Subjects with SDAs (N = 115) were recruited consecutively from 6 university-based prosthodontic clinics. OHRQoL was measured using the Japanese version of the Oral Health Impact Profile (OHIP-J). An increase of 1 missing occlusal unit was associated with an increase of 2.1 OHIP-J units (95% CI: 0.6-3.5, P = .02) in a linear regression analysis. Missing occlusal units are related to OHRQoL impairment in subjects with SDAs.

Effects of Sleep Bruxism on Periodontal Sensation and Tooth Displacement in the Molar Region

Cranio : the Journal of Craniomandibular Practice. Oct, 2008  |  Pubmed ID: 19004309

The purpose of this study was to investigate the effects of sleep bruxism on periodontal sensation and tooth displacement in the molar region. Twenty-eight (28) subjects lacking objective or subjective abnormalities in stomatognathic function were divided into two groups representing bruxers (n=14) and controls (n=14). Sleep bruxism was confirmed based on the nocturnal electromyography activity of the masseter muscle. Periodontal sensation was assessed based on interocclusal tactile threshold (ITT), which refers to the minimal thickness that can be detected between the occlusal surfaces of the teeth. ITT was measured in the first molar region. Displacement of teeth during clenching was measured using a two-dimensional tooth displacement transducer. Statistical analysis of the differences in ITT and tooth displacement between the bruxers and controls was performed by Mann Whitney U-test (p < 0.05). Mean ITT for bruxers was significantly lower than that for controls (p < 0.01). The mean displacement of both the maxillary and mandibular first molar for the bruxers was significantly larger than that for the controls (p < 0.05). The results of this study suggest that sleep bruxism affects both periodontal sensation and tooth displacement.

Validating an Alternate Version of the Chewing Function Questionnaire in Partially Dentate Patients

BMC Oral Health. Mar, 2009  |  Pubmed ID: 19291293

The aim of this study was to investigate the dimensionality, reliability, and validity of an alternate version of the chewing function questionnaire in partially dentate patients in Japan.

Predicting the Outcome of a Physical Medicine Treatment for Temporomandibular Disorder Patients

Journal of Orofacial Pain. 2009  |  Pubmed ID: 19639102

To investigate whether any of the pretreatment physical signs, symptoms, and responses on psychological questionnaires would predict treatment outcomes after a standardized temporomandibular disorder (TMD) treatment program.

The Enhanced Characteristics of Osteoblast Adhesion to Photofunctionalized Nanoscale TiO2 Layers on Biomaterials Surfaces

Biomaterials. May, 2010  |  Pubmed ID: 20153521

Recently, UV photofunctionalization of titanium has been shown to be effective in enhancing osteogenic environment around this functional surface, in particular for the use of endosseous implants. However, the underlying mechanism remains unknown and its potential application to other tissue engineering materials has never been explored. We determined whether adhesion of a single osteoblast is enhanced on UV-treated nano-thin TiO(2) layer with virtually no surface roughness or topographical features. Rat bone marrow-derived osteoblasts were cultured on UV-treated or untreated 200-nm thick TiO(2) sputter-coated glass plates. After an incubation of 3 h, the mean critical shear force required to initiate detachment of a single osteoblast was determined to be 1280 +/- 430 nN on UV-treated TiO(2) surfaces, which was 2.5-fold greater than the force required on untreated TiO(2) surfaces. The total energy required to complete the detachment was 37.0 +/- 23.2 pJ on UV-treated surfaces, 3.5-fold greater than that required on untreated surfaces. Such substantial increases in single cell adhesion were also observed for osteoblasts cultured for 24 h. Osteoblasts on UV-treated TiO(2) surfaces were larger and characterized with increased levels of vinculin expression and focal contact formation. However, the density of vinculin or focal contact was not influenced by UV treatment. In contrast, both total expression and density of actin fibers increased on UV-treated surfaces. Thin layer TiO(2) coating and UV treatment of Co-Cr alloy and PTFE membrane synergistically resulted in a significant increase in the ability of cell attachment and osteoblastic production of alkaline phosphatase. These results indicated that the adhesive nature of a single osteoblast is substantially enhanced on UV-treated TiO(2) surfaces, providing the first evidence showing that each individual cell attached to these surfaces is substantially more resistant to exogenous load potentially from blood and fluid flow and mechanical force in the initial stage of in vivo biological environment. This enhanced osteoblast adhesion was supported synergistically but disproportionately by enhancement in focal adhesion and cytoskeletal developments. Also, this study demonstrated that UV treatment is effective on nano-thin TiO(2) depositioned onto non-Ti materials to enhance their bioactivity, providing a basis for TiO(2)-mediated photofunctionalization of biomaterials, a new method of developing functional biomaterials.

Carbonic Anhydrase II Regulates Differentiation of Ameloblasts Via Intracellular PH-dependent JNK Signaling Pathway

Journal of Cellular Physiology. Nov, 2010  |  Pubmed ID: 20533306

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.

Temporal Expression Pattern of Adhesion Genes in Human Oral Mucosal Keratinocytes on Type IV Collagen-coated Titanium

Journal of Biomedical Materials Research. Part A. Oct, 2010  |  Pubmed ID: 20623668

The cell adhesion extracellular matrix (ECM), and the cell adhesive system mediate various adhesion molecules. Cell adhesion regulates proliferation and differentiation. However, the cell adhesive systems between titanium and epithelial cells are still not clearly understood. In this study, we cultured human epithelial cells on type IV collagen-coated titanium (TiCol-4) and non-coated titanium (Ti). We used titanium disks of 30 mm diameter and 1.0 mm thickness. The titanium disks were first abraded using #800, #1200, #2400, and #4000 diamond pads and 0.3 mum alumina, and then washed with acetone, ethanol, and ultra-pure water in an ultrasonic cleaner for 10 min each. Human oral keratinocytes (hOMK) were seeded with 5.0 x 10(4) cells on TiCol-4 and Ti and placed in 6-well culture dishes. The cell adhesion examination was conducted with a Cell Coulter Counter after 1, 3, and 5 h. hOMK were observed using scanning electron microscopy (SEM). Real-time PCR was performed with four primers: gene laminin beta3, integrin beta4, integrin alpha1, and integrin alpha3. The results suggest that TiCol-4 could be used as a means for obtaining better hOMK than Ti. Type IV collagen could provide an excellent substratum for hOMK attachment on titanium surfaces.

Bone Morphogenetic Protein 2 Enhances Mouse Osteoclast Differentiation Via Increased Levels of Receptor Activator of NF-κB Ligand Expression in Osteoblasts

Cell and Tissue Research. Nov, 2010  |  Pubmed ID: 20941510

1α,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] induces osteoclast formation via induction of receptor activator of NF-κB ligand (RANKL, also called TNF-related activation-induced cytokine: TRANCE) in osteoblasts. In cocultures of mouse bone marrow cells and osteoblasts, 1,25(OH)(2)D(3) induced osteoclast formation in a dose-dependent manner, with maximum osteoclast formation observed at concentrations greater than 10(-9) M of 1,25(OH)(2)D(3). In the presence of bone morphogenetic protein 2 (BMP-2), the maximum formation of osteoclasts was seen with lower concentrations of 1,25(OH)(2)D(3) (greater than 10(-11) M), suggesting that BMP-2 enhances osteoclast formation induced by 1,25(OH)(2)D(3). In addition, the expressions of RANKL mRNA and proteins were induced by 1,25(OH)(2)D(3) in osteoblasts, and further upregulated by BMP-2. In mouse bone marrow cell cultures without 1,25(OH)(2)D(3), BMP-2 did not enhance osteoclast differentiation induced by recombinant RANKL and macrophage colony-stimulating factor (M-CSF), indicating that BMP-2 does not target osteoclast precursors. Furthermore, BMP-2 up-regulated the expression level of vitamin D receptor (VDR) in osteoblasts. These results suggest that BMP-2 regulates mouse osteoclast differentiation via upregulation of RANKL in osteoblasts induced by 1,25(OH)(2)D(3).

Association Between Perceived Chewing Ability and Oral Health-related Quality of Life in Partially Dentate Patients

Health and Quality of Life Outcomes. Oct, 2010  |  Pubmed ID: 20955614

One of the most immediate and important functional consequences of many oral disorders is a reduction in chewing ability. The ability to chew is not only an important dimension of oral health, but is increasingly recognized as being associated with general health status. Whether perceived chewing ability and oral health-related quality of life (OHRQoL) are correlated to a similar degree in patient populations has been less investigated. The aim of this study was to examine whether perceived chewing ability was related to OHRQoL in partially dentate patients.

The Role of Macrophages in the Disappearance of Meckel's Cartilage During Mandibular Development in Mice

Acta Histochemica. Feb, 2011  |  Pubmed ID: 19853894

Meckel's cartilage is a supporting tissue in the embryonic mandible that disappears during development; however, the precise mechanisms of this disappearance process are still undetermined. In this study, we observed morphological changes of Meckel's cartilage with development and analyzed the factors which might be related to this process. Meckel's cartilage of ICR strain mice from 14 to 19 days gestation (E14-19) were used in this study. Histological and immunohistochemical studies indicated the decrease in the amount of sulfated glycoconjugates and the localization of type I collagen in the Meckel's cartilage matrix during development. Chondrocytes also expressed high acid phosphatase activities at these stages. An organ culture study indicated that Meckel's cartilage at E17 disappeared during the cultivation period, while the cartilage at E14 did not disappear. Massive penetration of macrophages into the perichondrium was detected at E16. RT-PCR analysis of Meckel's cartilage indicated the expression of interleukin-1β, type I collagen, MMP-9 at E17, but not at E14. MIP-1α, the candidate molecule for macrophage chemoattractant factor, was expressed at E14. These results indicated the dynamic matrix changes of Meckel's cartilage during development and suggested that the functional changes of chondrocytes in synthesis of type I collagen might be induced by interleukin-1β secreted by the penetrating macrophages.

Enhancement of Bone Morphogenetic Protein-2-induced Ectopic Bone Formation by Transforming Growth Factor-β1

Tissue Engineering. Part A. Mar, 2011  |  Pubmed ID: 20874259

Bone morphogenetic proteins (BMPs) possess osteoinductive activities and are useful for clinical treatments, including bone regeneration. We found that transforming growth factor (TGF)-β1 strongly enhances the osteoinductive activity of BMP-2. Collagen sponges containing 5 μg of BMP-2 were implanted into mouse muscle tissues, after which lump-like masses appeared and grew until day 7. Subsequently, calcification occurred in the lump-like masses by day 14. Addition of 50 ng of TGF-β1 to the BMP-2-containing sponges markedly accelerated the growth of the lump-like masses and resulted in a fivefold increase in total bone volume as compared with BMP-2 alone. The number of osteoblasts in ectopic bone tissues at 14 days after implantation induced by BMP-2+TGF-β1 was twofold greater than that with BMP-2 alone, whereas the number of osteoclasts was decreased by half. On the other hand, TGF-β1 accelerated the differentiation of both osteoblasts and osteoclasts in the early stage (2-7 days after implantation) of ectopic bone formation. We also implanted collagen sponges into bone defects surgically created in mouse calvaria. Sponges containing 2.5 μg of BMP-2 and 25 ng of TGF-β1 caused complete filling of the defects with orthotopic bone, whereas those containing 2.5 μg of BMP-2 alone caused only partial filling. These results suggest that TGF-β1 enhances BMP-2-induced ectopic bone formation by accelerating the growth of lump-like masses, and regulates osteoblast and osteoclast generation. Our findings may contribute to the development of a new treatment method for skeletal disorders.

Developing and Providing an Online (web-based) Clinical Research Design Course in Japan: Lessons Learned

Journal of Prosthodontic Research. Apr, 2011  |  Pubmed ID: 21353661

This article reports on the lessons learned while teaching an 8-week-long online course about the principles of clinical research design in Japan. Student activity data and how it relates to performance in the course are presented. As prolog, this article focuses on the barriers and solutions to creating and delivering a web-based course and it lists and discusses the most common concerns that educators often have about this process, namely, cost of the system and time requirement of the faculty. Options that must be considered when selecting the support software and hardware needed to conduct live streaming lecture, online video-based conference course are presented. The ancillary role of e-mail based distribution lists as an essential instruction tool within an interactive, instructor-supervised online course is discussed. This article then discusses the inclusion of active learning elements within an online course as well as the pros and cons regarding open-book versus closed book, proctored testing. Lastly, copyright issues the online instructor should know about are discussed. The student tracking data show that as the course progresses, students will reduce the number for page viewings. We speculate that this reduction is due to a combination of conflicting priorities plus increasing efficiency of the students at extracting the critical information. The article also concludes that software and hardware costs to deliver an online course are relatively minor but the faculty's time requirement is initially substantially higher than teaching in a conventional face-to-face course.

Monocarboxylate Transporter-1 is Required for Cell Death in Mouse Chondrocytic ATDC5 Cells Exposed to Interleukin-1beta Via Late Phase Activation of Nuclear Factor KappaB and Expression of Phagocyte-type NADPH Oxidase

The Journal of Biological Chemistry. Apr, 2011  |  Pubmed ID: 21372137

Interleukin-1β (IL-1β) induces cell death in chondrocytes in a nitric oxide (NO)- and reactive oxygen species (ROS)-dependent manner. In this study, increased production of lactate was observed in IL-1β-treated mouse chondrocytic ATDC5 cells prior to the onset of their death. IL-1β-induced cell death in ATDC5 cells was suppressed by introducing an siRNA for monocarboxylate transporter-1 (MCT-1), a lactate transporter distributed in plasma and mitochondrial inner membranes. Mct-1 knockdown also prevented IL-1β-induced expression of phagocyte-type NADPH oxidase (NOX-2), an enzyme specialized for production of ROS, whereas it did not have an effect on inducible NO synthase. Suppression of IL-1β-induced cell death by Nox-2 siRNA indicated that NOX-2 is involved in cell death. Phosphorylation and degradation of inhibitor of κBα (IκBα) from 5 to 20 min after the addition of IL-1β was not affected by Mct-1 siRNA. In addition, IκBα was slightly decreased after 12 h of incubation with IL-1β, and the decrease was prominent after 36 h, whereas activation of p65/RelA was observed from 12 to 48 h after exposure to IL-1β. These changes were not seen in Mct-1-silenced cells. Forced expression of IκBα super repressor as well as treatment with the IκB kinase inhibitor BAY 11-7082 suppressed NOX-2 expression. Furthermore, Mct-1 siRNA lowered the level of ROS generated after 15-h exposure to IL-1β, whereas a ROS scavenger, N-acetylcysteine, suppressed both late phase degradation of IκBα and Nox-2 expression. These results suggest that MCT-1 contributes to NOX-2 expression via late phase activation of NF-κB in a ROS-dependent manner in ATDC5 cells exposed to IL-1β.

Oral Health in the Japan Self-defense Forces - a Representative Survey

BMC Oral Health. Apr, 2011  |  Pubmed ID: 21501526

The oral health of military populations is usually not very well characterized compared to civilian populations. The aim of this study was to investigate two physical oral health characteristics and one perceived oral health measure and their correlation in the Japan self-defense forces (JSDF).

Calcified Tissue Formation of Subcutaneously Transplanted Mouse Dental Pulp

Acta Histochemica. Jan, 2012  |  Pubmed ID: 21397933

It is well established that dental pulp has the ability to form calcified tissue, however, the precise process of calcified tissue formation and its characteristics are still undetermined. In this study we examined the process and the matrix components of the calcified tissues by means of subcutaneously transplanted dental pulp tissue. The mid-third of the mouse incisor pulp was transplanted into abdominal subcutaneous tissue. Two calcified tissues were independently formed within the implanted pulp at 7 days after the implantation, one developed in the peripheral region and the other was formed in the middle region of the pulp. Histological investigation indicated the existence of hypertrophic chondrocytes in the peripheral calcified tissue. Immunohistochemical study indicated the colocalization of types I and II collagen surrounding these cells. RT-PCR analysis indicated the transient expression of type II collagen at 7 days and the constant expression of type I collagen, osteonectin, osteocalcin and dentin matrix protein-1 and 2 at all examined times. Dentin sialophosphoprotein was only detected at 28 days after the transplantation. These results indicated that dental pulp cells might have the capacity to form calcified tissue by implanted dental pulp and it is possible that the difference of local environments induced the cells to form different types of calcified tissues within the implanted pulp.

Oral Health-related Quality of Life in Patients Treated by Implant-supported Fixed Dentures and Removable Partial Dentures

Clinical Oral Implants Research. Aug, 2012  |  Pubmed ID: 21806685

This study investigated the association between denture status [implant-supported fixed dentures (IDs) and removable partial dentures (RPDs)] and oral health-related quality of life (OHRQoL).

R848, a Toll-like Receptor 7 Agonist, Inhibits Osteoclast Differentiation but Not Survival or Bone-resorbing Function of Mature Osteoclasts

Cytotechnology. May, 2012  |  Pubmed ID: 22358541

R848, also known as resiquimod, acts as a ligand for toll-like receptor 7 (TLR7) and activates immune cells. In this study, we examined the effects of R848 on differentiation, survival, and bone-resorbing function of osteoclasts. R848 inhibited osteoclast differentiation of mouse bone marrow-derived macrophages (BMMs) and human peripheral blood-derived monocytes induced by receptor activator of NF-κB ligand in a dose-dependent manner. In addition, it inhibited mouse osteoclast differentiation induced in cocultures of bone marrow cells and osteoblasts in the presence of dihydroxyvitamin D(3) [1,25(OH)(2)D(3)]. However, R848 did not affect the survival or bone-resorbing activity of mouse mature osteoclasts. R848 also upregulated the mRNA expression levels of interleukin (IL)-6, IL-12, interferon (IFN)-γ, and inducible nitric oxide synthase in mouse BMMs expressing TLR7. IFN-β was consistently expressed in the BMMs and addition of neutralizing antibodies against IFN-β to the cultures partially recovered osteoclast differentiation inhibited by R848. These results suggest that R848 targets osteoclast precursors and inhibits their differentiation into osteoclasts via TLR7.

A Multi-centered Epidemiological Study Evaluating the Reliability of the Treatment Difficulty Indices Developed by the Japan Prosthodontic Society

Journal of Prosthodontic Research. Apr, 2012  |  Pubmed ID: 22534566

The diagnostic assessment of the level of difficulty in treating patients who need prosthodontic care is useful to establish a medico-economically efficient system with primary care dentists and prosthodontic specialists.

Association of Genetic, Psychological and Behavioral Factors with Sleep Bruxism in a Japanese Population

Journal of Sleep Research. Jun, 2012  |  Pubmed ID: 22545912

Sleep bruxism is a sleep-related movement disorder that can be responsible for various pains and dysfunctions in the orofacial region. The aim of the current case-control association study was to investigate the association of genetic, psychological and behavioral factors with sleep bruxism in a Japanese population. Non-related participants were recruited and divided into either a sleep bruxism group (n = 66) or control group (n = 48) by clinical diagnoses and 3-night masseter electromyographic recordings by means of a portable miniature device. The Epworth Sleepiness Scale, Temperament and Character Inventory, NEO-Five Factor Inventory and custom-made questionnaires that asked about familial aggregation, alcohol intake, caffeine intake, cigarette smoking, past stressful life events, daytime tooth-contacting habit, temporomandibular disorder, daily headache, snoring, apnea/hypopnea symptoms, leg-restlessness symptoms and nocturnal-myoclonus symptoms were administered. In addition, 13 polymorphisms in four genes related to serotonergic neurotransmission (SLC6A4, HTR1A, HTR2A and HTR2C) were genotyped. These factors were compared between case (sleep bruxism) and control groups in order to select potential predictors of sleep-bruxism status. The statistical procedure selected five predictors: Epworth Sleepiness Scale, leg-restlessness symptoms, rs6313 genotypes, rs2770304 genotypes and rs4941573 genotypes. A multivariate stepwise logistic regression analysis between the selected predictors and sleep-bruxism status was then conducted. This analysis revealed that only the C allele carrier of HTR2A single nucleotide polymorphism rs6313 (102C>T) was associated significantly with an increased risk of sleep bruxism (odds ratio = 4.250, 95% confidence interval: 1.599-11.297, P = 0.004).This finding suggests a possible genetic contribution to the etiology of sleep bruxism.

BMP2 Differentially Regulates the Expression of Gremlin1 and Gremlin2, the Negative Regulators of BMP Function, During Osteoblast Differentiation

Calcified Tissue International. Jul, 2012  |  Pubmed ID: 22644325

Bone morphogenetic proteins (BMPs) control the expressions of many genes involved in bone formation. On the basis of our hypothesis that BMP2 stimulation-regulated gene expression plays a critical role in osteoblast differentiation, we performed genome-wide screening of messenger RNA from BMP2-treated and -untreated C2C12 cells using a DNA microarray technique. We found that the expressions of Gremlin1 and Gremlin2, which are known BMP antagonists, were bidirectionally regulated by BMP2. Gremlin1 was down-regulated by BMP2, while Gremlin2 was up-regulated in both time- and dose-dependent manners. Ablation of Gremlin1 or Gremlin2 enhanced osteoblast differentiation induced by BMP2. On the other hand, treatment with recombinant Gremlin1 inhibited BMP2-induced osteoblast differentiation. Furthermore, treatment with Smad4 siRNA and the p38 MAPK inhibitor SB203580 suppressed BMP2-induced Gremlin2 gene expression. The differential regulation of Gremlin1 and Gremlin2 gene expressions by BMP2 may explain the critical function of these genes during osteoblast differentiation.

Implant-supported Fixed Dental Prostheses with CAD/CAM-fabricated Porcelain Crown and Zirconia-based Framework

Journal of Prosthodontics : Official Journal of the American College of Prosthodontists. Jul, 2013  |  Pubmed ID: 23289495

Recently, fixed dental prostheses (FDPs) with a hybrid structure of CAD/CAM porcelain crowns adhered to a CAD/CAM zirconia framework (PAZ) have been developed. The aim of this report was to describe the clinical application of a newly developed implant-supported FDP fabrication system, which uses PAZ, and to evaluate the outcome after a maximum application period of 36 months. Implants were placed in three patients with edentulous areas in either the maxilla or mandible. After the implant fixtures had successfully integrated with bone, gold-platinum alloy or zirconia custom abutments were first fabricated. Zirconia framework wax-up was performed on the custom abutments, and the CAD/CAM zirconia framework was prepared using the CAD/CAM system. Next, wax-up was performed on working models for porcelain crown fabrication, and CAD/CAM porcelain crowns were fabricated. The CAD/CAM zirconia frameworks and CAD/CAM porcelain crowns were bonded using adhesive resin cement, and the PAZ was cemented. Cementation of the implant superstructure improved the esthetics and masticatory efficiency in all patients. No undesirable outcomes, such as superstructure chipping, stomatognathic dysfunction, or periimplant bone resorption, were observed in any of the patients. PAZ may be a potential solution for ceramic-related clinical problems such as chipping and fracture and associated complicated repair procedures in implant-supported FDPs.

Downregulation of Carbonic Anhydrase IX Promotes Col10a1 Expression in Chondrocytes

PloS One. 2013  |  Pubmed ID: 23441228

Carbonic anhydrase (CA) IX is a transmembrane isozyme of CAs that catalyzes reversible hydration of CO(2). While it is known that CA IX is distributed in human embryonic chondrocytes, its role in chondrocyte differentiation has not been reported. In the present study, we found that Car9 mRNA and CA IX were expressed in proliferating but not hypertrophic chondrocytes. Next, we examined the role of CA IX in the expression of marker genes of chondrocyte differentiation in vitro. Introduction of Car9 siRNA to mouse primary chondrocytes obtained from costal cartilage induced the mRNA expressions of Col10a1, the gene for type X collagen α-1 chain, and Epas1, the gene for hypoxia-responsible factor-2α (HIF-2α), both of which are known to be characteristically expressed in hypertrophic chondrocytes. On the other hand, forced expression of CA IX had no effect of the proliferation of chondrocytes or the transcription of Col10a1 and Epas1, while the transcription of Col2a1 and Acan were up-regulated. Although HIF-2α has been reported to be a potent activator of Col10a1 transcription, Epas1 siRNA did not suppress Car9 siRNA-induced increment in Col10a1 expression, indicating that down-regulation of CA IX induces the expression of Col10a1 in chondrocytes in a HIF-2α-independent manner. On the other hand, cellular cAMP content was lowered by Car9 siRNA. Furthermore, the expression of Col10a1 mRNA after Car9 silencing was augmented by an inhibitor of protein kinase A, and suppressed by an inhibitor for phosphodiesterase as well as a brominated analog of cAMP. While these results suggest a possible involvement of cAMP-dependent pathway, at least in part, in induction of Col10a1 expression by down-regulation of Car9, more detailed study is required to clarify the role of CA IX in regulation of Col10a1 expression in chondrocytes.

Effect of Stabilization Splint on Occlusal Force Distribution During Voluntary Submaximal Tooth Clenching: a Preliminary Sleep Simulation Study

Cranio : the Journal of Craniomandibular Practice. Apr, 2013  |  Pubmed ID: 23795399

The purpose of the study was to clarify the effect of a stabilization splint (SS) on the distribution of occlusal force around the dental arch during voluntary submaximal tooth clenching. Ten healthy volunteers participated in this study. For each subject, the maxillary SS was made of heat-cured hard acrylic resin with approximately one mm thickness at the molar regions. The subjects were asked to perform static clenching at either 40% or 80% maximum voluntary contraction (MVC) levels, with and without the SS in place, using visual feedback. The occlusal contact area and occlusal force were analyzed. When the SS was inserted, the mean tooth contact area and occlusal force significantly decreased at both 40% and 80% MVC levels (p < 0.01). The location of the occlusal balancing point changed towards the anterior after insertion of the SS. The results suggest that the SS has potential to reduce individual tooth-loading forces by evenly distributing the forces generated during sleep bruxism.

BMP-2 Induced Expression of Alx3 That Is a Positive Regulator of Osteoblast Differentiation

PloS One. 2013  |  Pubmed ID: 23825702

Bone morphogenetic proteins (BMPs) regulate many aspects of skeletal development, including osteoblast and chondrocyte differentiation, cartilage and bone formation, and cranial and limb development. Among them, BMP-2, one of the most potent osteogenic signaling molecules, stimulates osteoblast differentiation, while it inhibits myogenic differentiation in C2C12 cells. To evaluate genes involved in BMP-2-induced osteoblast differentiation, we performed cDNA microarray analyses to compare BMP-2-treated and -untreated C2C12 cells. We focused on Alx3 (aristaless-like homeobox 3) which was clearly induced during osteoblast differentiation. Alx3, a homeobox gene related to the Drosophilaaristaless gene, has been linked to developmental functions in craniofacial structures and limb development. However, little is known about its direct relationship with bone formation. In the present study, we focused on the mechanisms of Alx3 gene expression and function during osteoblast differentiation induced by BMP-2. In C2C12 cells, BMP-2 induced increase of Alx3 gene expression in both time- and dose-dependent manners through the BMP receptors-mediated SMAD signaling pathway. In addition, silencing of Alx3 by siRNA inhibited osteoblast differentiation induced by BMP-2, as showed by the expressions of alkaline phosphatase (Alp), Osteocalcin, and Osterix, while over-expression of Alx3 enhanced osteoblast differentiation induced by BMP-2. These results indicate that Alx3 expression is enhanced by BMP-2 via the BMP receptors mediated-Smad signaling and that Alx3 is a positive regulator of osteoblast differentiation induced by BMP-2.

Journal of Prosthodontic Research in Great Shape and Continues to Grow

Journal of Prosthodontic Research. Jul, 2013  |  Pubmed ID: 23838064

Phasic Jaw Motor Episodes in Healthy Subjects with or Without Clinical Signs and Symptoms of Sleep Bruxism: a Pilot Study

Sleep & Breathing = Schlaf & Atmung. Mar, 2014  |  Pubmed ID: 23775827

To investigate the association between each clinical diagnosis criterion for sleep bruxism (SB) and the frequency of jaw motor events during sleep.

Paradigm Shifts in Prosthodontics

Journal of Prosthodontic Research. Jan, 2014  |  Pubmed ID: 24412149

Factor Analyses of the Oral Health Impact Profile - Overview and Studied Population

Journal of Prosthodontic Research. Jan, 2014  |  Pubmed ID: 24440578

A desideratum of oral health-related quality of life (OHRQoL) instruments - such as the Oral Health Impact Profile (OHIP) - is that they accurately reflect the structure of the measured construct(s). With this goal in mind, the Dimensions of Oral Health-Related Quality of Life (DOQ) Project was proposed to investigate the number and nature of OHRQoL dimensions measured by OHIP. In this report, we describe our aggregate data set for the factor analyses in the project, which consists of responses to the 49-item OHIP from general population subjects and prosthodontics patients from 6 countries, including a large age range of adult subjects and both genders.

Clinical Application of Removable Partial Dentures Using Thermoplastic Resin-part I: Definition and Indication of Non-metal Clasp Dentures

Journal of Prosthodontic Research. Jan, 2014  |  Pubmed ID: 24461323

This position paper proposes a definition and naming standard for removable partial dentures (RPDs) using thermoplastic resin, and presents a guideline for clinical application. A panel of 14 experts having broad experience with clinical application of RPDs using thermoplastic resin was selected from members of the Japan Prosthodontic Society. At a meeting of the panel, "non-metal clasp denture" was referred as the generic name of RPDs with retentive elements (resin clasps) made of thermoplastic resin. The panel classified non-metal clasp dentures into two types: one with a flexible structure that lacks a metal framework and the other having a rigid structure that includes a metal framework. According to current prosthetic principles, flexible non-metal clasp dentures are not recommended as definitive dentures, except for limited cases such as patients with a metal allergy. Rigid non-metal clasp dentures are recommended in cases where patients will not accept metal clasps for esthetic reasons. Non-metal clasp dentures should follow the same design principles as conventional RPDs using metal clasps.

Evaluation of the Durability and Antiadhesive Action of 2-methacryloyloxyethyl Phosphorylcholine Grafting on an Acrylic Resin Denture Base Material

The Journal of Prosthetic Dentistry. Aug, 2014  |  Pubmed ID: 24461942

The polymer 2-methacryloyloxyethyl phosphorylcholine is currently used on medical devices to prevent infection. Denture plaque-associated infection is regarded as a source of serious dental and medical complications in the elderly population, and denture hygiene, therefore, is an issue of considerable importance for denture wearers. Furthermore, because denture bases are exposed to mechanical stresses, for example, denture brushing, the durability of the coating is important for retaining the antiadhesive function of 2-methacryloyloxyethyl phosphorylcholine.

Clinical Application of Removable Partial Dentures Using Thermoplastic Resin. Part II: Material Properties and Clinical Features of Non-metal Clasp Dentures

Journal of Prosthodontic Research. Apr, 2014  |  Pubmed ID: 24746524

This position paper reviews physical and mechanical properties of thermoplastic resin used for non-metal clasp dentures, and describes feature of each thermoplastic resin in clinical application of non-metal clasp dentures and complications based on clinical experience of expert panels. Since products of thermoplastic resin have great variability in physical and mechanical properties, clinicians should utilize them with careful consideration of the specific properties of each product. In general, thermoplastic resin has lower color-stability and higher risk for fracture than polymethyl methacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethyl methacrylate. Studies related to material properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to provide definitive conclusions at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be provided.

Porphyromonas Gingivalis-derived Lysine Gingipain Enhances Osteoclast Differentiation Induced by Tumor Necrosis Factor-α and Interleukin-1β but Suppresses That by Interleukin-17A: Importance of Proteolytic Degradation of Osteoprotegerin by Lysine Gingipain

The Journal of Biological Chemistry. May, 2014  |  Pubmed ID: 24755218

Periodontitis is a chronic inflammatory disease accompanied by alveolar bone resorption by osteoclasts. Porphyromonas gingivalis, an etiological agent for periodontitis, produces cysteine proteases called gingipains, which are classified based on their cleavage site specificity (i.e. arginine (Rgps) and lysine (Kgps) gingipains). We previously reported that Kgp degraded osteoprotegerin (OPG), an osteoclastogenesis inhibitory factor secreted by osteoblasts, and enhanced osteoclastogenesis induced by various Toll-like receptor (TLR) ligands (Yasuhara, R., Miyamoto, Y., Takami, M., Imamura, T., Potempa, J., Yoshimura, K., and Kamijo, R. (2009) Lysine-specific gingipain promotes lipopolysaccharide- and active-vitamin D3-induced osteoclast differentiation by degrading osteoprotegerin. Biochem. J. 419, 159-166). Osteoclastogenesis is induced not only by TLR ligands but also by proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-17A, in inflammatory conditions, such as periodontitis. Although Kgp augmented osteoclastogenesis induced by TNF-α and IL-1β in co-cultures of mouse osteoblasts and bone marrow cells, it suppressed that induced by IL-17A. In a comparison of proteolytic degradation of these cytokines by Kgp in a cell-free system with that of OPG, TNF-α and IL-1β were less susceptible, whereas IL-17A and OPG were equally susceptible to degradation by Kgp. These results indicate that the enhancing effect of Kgp on cytokine-induced osteoclastogenesis is dependent on the difference in degradation efficiency between each cytokine and OPG. In addition, elucidation of the N-terminal amino acid sequences of OPG fragments revealed that Kgp primarily cleaved OPG in its death domain homologous region, which might prevent dimer formation of OPG required for inhibition of receptor activator of nuclear factor κB ligand. Collectively, our results suggest that degradation of OPG by Kgp is a crucial event in the development of osteoclastogenesis and bone loss in periodontitis.

Influence of the Rigidity of a Provisional Restoration Supported on Four Immediately Loaded Implants in the Edentulous Maxilla on Biomechanical Bone-implant Interactions Under Simulated Bruxism Conditions: a Three-dimensional Finite Element Analysis

The International Journal of Prosthodontics. Sep-Oct, 2014  |  Pubmed ID: 25191887

The aims of this study were to (1) establish a biomechanical model that simulates the full-arch restoration supported by immediately loaded implants, which is customized for individual patients, and (2) clarify the effect of the implant placement and rigidity of a provisional restoration on the biomechanical response at the bone-implant interface.

Effects of Antibody to Receptor Activator of Nuclear Factor κ-B Ligand on Inflammation and Cartilage Degradation in Collagen Antibody-induced Arthritis in Mice

Journal of Negative Results in Biomedicine. Dec, 2014  |  Pubmed ID: 25495344

Rheumatoid arthritis (RA) is an inflammatory disease that leads to destruction of both articular cartilage and bone tissues. In rheumatic joints, synoviocytes and T-lymphocytes as well as bone cells produce the receptor activator of nuclear factor κ-B (RANK) ligand (RANKL), which binds to RANK on the surface of osteoclasts and their precursor cells to induce differentiation and activation of osteoclasts. Hence, inhibition of RANKL may be a promising approach to suppress osteolysis in RA. On the other hand, RANKL production by lymphocytes indicates the possibility that its inhibition would be effective to suppress inflammation in RA. In addition, it has been reported that cathepsin K, a predominant cysteine protease in osteoclasts, is involved in cartilage destruction in RA model mice. Here, we evaluated the effects of an anti-RANKL antibody on inflammation in footpads and degradation of articular cartilage in RA model mice.

Cdc42 is Critical for Cartilage Development During Endochondral Ossification

Endocrinology. Jan, 2015  |  Pubmed ID: 25343271

Cdc42 is a widely expressed protein that belongs to the family of Rho GTPases and controls a broad variety of signal transduction pathways in a variety of cell types. To investigate the physiological functions of Cdc42 during cartilage development, we generated chondrocyte-specific inactivated Cdc42 mutant mice (Cdc42(fl/fl); Col2-Cre). The gross morphology of mutant neonates showed shorter limbs and body as compared with the control mice (Cdc42(fl/fl)). Skeletal preparations stained with alcian blue and alizarin red also revealed that the body and the long bone length of the mutants were shorter than those of the control mice. Furthermore, severe defects were found in growth plate chondrocytes in the femur sections of mutant mice, characterized by a reduced proliferating zone height, wider hypertrophic zone, and loss of columnar organization in proliferating chondrocytes. The expression levels of chondrocyte marker genes, such as Col2, Col10, and Mmp13, in mutant mice were decreased as compared with the control mice. Mineralization of trabecular bones in the femur sections was also decreased in the mutants as compared with control mice, whereas osteoid volume was increased. Together these results suggested that chondrocyte proliferation and differentiation in growth plates in the present mutant mice were not normally organized, which contributed to abnormal bone formation. We concluded that Cdc42 is essential for cartilage development during endochondral bone formation.

A 3-year Follow-up of Ceria-stabilized Zirconia/alumina Nanocomposite (Ce-TZP/A) Frameworks for Fixed Dental Prostheses

Journal of Prosthodontic Research. Jan, 2015  |  Pubmed ID: 25541099

Zirconia/alumina nanocomposite stabilized with cerium oxide (Ce-TZP/A) shows significantly higher mechanical strength than yttrium-oxide-partially-stabilized zirconia (Y-TZP) and allows post-sintered machining that does not require any subsequent treatment. The aim of this prospective study was to assess the clinical performance of veneered Ce-TZP/A frameworks for fixed dental prostheses.

Bending Properties of Ce-TZP/A Nanocomposite Clasps for Removable Partial Dentures

The International Journal of Prosthodontics. Mar-Apr, 2015  |  Pubmed ID: 25822308

Ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) has excellent fracture toughness and bending strength that could be useful for partial denture framework application. The aim of this study was to investigate the effects of three-dimensional (3D) geometry on the bending and fatigue properties of a model simulation of Ce-TZP/A clasps.

Dark/light Transition and Vigilance States Modulate Jaw-closing Muscle Activity Level in Mice

Neuroscience Research. Dec, 2015  |  Pubmed ID: 26188127

Bruxism is associated with an increase in the activity of the jaw-closing muscles during sleep and wakefulness. However, the changes in jaw-closing muscle activity across states of vigilance over a 24-h period are unclear. In this study, we investigated the effects of dark/light transition and sleep/wake state on EMG activity of the masseter (jaw-closing) muscle in comparison with the activity of the upper trapezius muscle (a neck muscle) over a 24-h period in mice. The activities of the masseter and neck muscles during wakefulness were much greater than during non-REM and REM sleep. In contrast, the activities of both muscles slightly, but significantly, decreased during the transition period from dark to light. Histograms of masseter activity during wakefulness and non-REM sleep showed bimodal distributions, whereas the neck muscle showed unimodal activation in all states. These results suggest that the activities of jaw-closing and neck muscles are modulated by both sleep/wake state and dark/light transition, with the latter being to a lesser degree. Furthermore, even during non-REM sleep, jaw-closing muscles display bimodal activation, which may contribute to the occurrence of exaggerated aberrant muscle activity, such as sleep bruxism.

Bone Mineral Density of Postmenopausal Women with Rheumatoid Arthritis Depends on Disease Duration Regardless of Treatment

Journal of Bone and Mineral Metabolism. Sep, 2015  |  Pubmed ID: 26369319

The aim of this study was to determine the associations of disease activity and disease duration with the bone mineral density (BMD) in rheumatoid arthritis (RA) patients. We also evaluated the associations of biological drugs with bone loss. A total of 138 postmenopausal RA patients were retrospectively assessed to identify the associations of disease activity, disease duration, and biological drug use with BMD. We assessed the associations of disease duration, a C-reactive protein based disease activity score in 28 joints (DAS28), simplified disease activity index, clinical disease activity index, health assessment questionnaire scores, and the use of biological drugs with the lumbar spine, total hip, and femoral neck BMDs using univariate and multivariate linear regression analyses in bisphosphonate treatment and non-bisphosphonate treatment groups at 1 year of follow-up. The multivariate linear regression analyses showed that disease duration was significantly related to the BMD of the femoral neck and total hip regardless of bisphosphonate treatment. The use of biological drugs was not significantly associated with BMD. Hip BMD in postmenopausal women with RA depends on the disease duration regardless of bisphosphonate use. Biological drugs for RA treatment were not negatively associated with general bone loss.

A 7-day Recall Period for a Clinical Application of the Oral Health Impact Profile Questionnaire

Clinical Oral Investigations. Jan, 2016  |  Pubmed ID: 25944561

Aims were to investigate and compare the validity and reliability of Oral Health Impact Profile (OHIP) scores referencing 7-day and 1-month recall periods in international prosthodontic patients.

Immediate Loading of Two Freestanding Implants Placed by Computer-guided Flapless Surgery Supporting a Mandibular Overdenture with Magnetic Attachments

Journal of Prosthodontic Research. Jan, 2016  |  Pubmed ID: 26431687

The present article describes a novel clinical procedure for mandibular overdentures supported by two freestanding implants loaded immediately after placement via computer-guided flapless surgery.

Japan Prosthodontic Society Position Paper on "occlusal Discomfort Syndrome"

Journal of Prosthodontic Research. Jul, 2016  |  Pubmed ID: 26868189

Dentists may encounter patients who present with a sense of a malocclusion but in whom no objective findings can be detected. For the patient who insists that there is occlusal discomfort, in the absence of evidence some dentists elect to perform an occlusal adjustment that not only fails to alleviate symptoms, and may, in fact, exacerbate the discomfort. The patient-dentist relationship is then likely compromised because of a lack of trust.

Enhanced Intracellular Signaling Pathway in Osteoblasts on Ultraviolet Lighttreated Hydrophilic Titanium

Biomedical Research (Tokyo, Japan). 2016  |  Pubmed ID: 26912135

Ultraviolet (UV) light treatment of titanium immediately prior to use, or photofunctionalization, reactivates the time-dependent degradation of bioactivity of titanium (biological aging of titanium) and increases its osseointegration capacity beyond the inherent maximal level. Although the initial osteoblast attachment is reportedly enhanced on UV-treated titanium surfaces, the detailed mechanism behind the increase in osseointegration is unknown. This study examined the potential modulation of intracellular signaling pathway in osteoblasts on UV-treated titanium surfaces. Rat bone marrow-derived osteoblasts were cultured on 4-week-old, new, and UV-treated titanium surfaces. The new and UV-treated surfaces were superhydrophilic, whereas the 4-week-old surface was hydrophobic. Although the rate of protein adsorption was similarly increased on the new and UV-treated surfaces compared with the 4-week-old surface, the number of attached cells and their spreading behavior were further enhanced on the UV-treated surface. This additional enhancement was associated with the remarkably upregulated expression of paxillin and phospho-paxillin and exclusive upregulation of Rho GTPase family genes. This study provides with the first molecular evidence of the enhanced initial behavior of osteoblasts on UV-treated titanium surfaces. The enhancement was accentuated and distinct from the new titanium surface with similar hydrophilicity, suggesting that surface properties other than the level of hydrophilicity are responsible.

Longitudinal Measurement Invariance in Prospective Oral Health-related Quality of Life Assessment

Health and Quality of Life Outcomes. Jun, 2016  |  Pubmed ID: 27267885

Prospective assessments of oral health-related quality of life (OHRQoL) changes are prone to response shift effects when patients reconceptualize, reprioritize, or recalibrate the perceived meanings of OHRQoL test items. If this occurs, OHRQoL measurements are not "invariant" and may reflect changes in problem profiles or perceptions of OHRQoL test items. This suggests that response shift effects must be measured and controlled to achieve valid prospective OHRQoL measurement. The aim of this study was to quantify response shift effects of Oral Health Impact Profile (OHIP) scores in prospective studies of prosthodontic patients.

Integration of Oral Health-related Quality of Life Instruments

Journal of Dentistry. Oct, 2016  |  Pubmed ID: 27353210

To integrate items from two widely used oral health-related quality of life (OHRQoL) questionnaires, the General Oral Health Assessment Index (GOHAI) and the Oral Impacts on Daily Performances (OIDP), as well as culturally-specific items of the Oral Health Impact Profile (OHIP) into a four-dimensional OHRQoL model consisting of Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact.

Effect of Resorption Rate and Osteoconductivity of Biodegradable Calcium Phosphate Materials on the Acquisition of Natural Bone Strength in the Repaired Bone

Journal of Biomedical Materials Research. Part A. Nov, 2016  |  Pubmed ID: 27391056

The purpose of this study was to compare the biodegradation rate and quality of regenerated bone among four materials. A short time period of 8 weeks was chosen to examine early bone healing. The rod-shaped implants of commercially available two β-tricalcium phosphate (β-TCP) ceramics with porosity 60% and 71-80%, respectively, laboratory prepared octacalcium phosphate/gelatin composite (OCP/Gel), which has been proven to have a highly osteoconductive and biodegradable property in rat calvarial defect, and gelatin sponge (Gelatin) were implanted in rabbit tibia defect of 6 mm diameter and 7 mm depth for 2, 4 and 8 weeks. Analyses by μCT, histomorphometry and push-in test were carried out to evaluate the extent of the tissue regeneration and the material biodegradation in the long bone. OCP/Gel and Gelatin were completely resorbed but only OCP/Gel induced cortical bone bridge until 8 weeks that has strength compatible to that of the natural bone. β-TCP (71%-80%) and β-TCP (60%) were not completely resorbed and never induced the amount of new bone formation beyond that by OCP/Gel. The results indicate that the new bone having enough strength could be regenerated if the material shows not only higher biodegradation rate but also higher osteoconductivity. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2833-2842, 2016.

Effects of Citalopram on Jaw-closing Muscle Activity During Sleep and Wakefulness in Mice

Neuroscience Research. Dec, 2016  |  Pubmed ID: 27453206

In this study, we investigated the effects of chronic administration of the selective serotonin reuptake inhibitor (SSRI) citalopram on sleep/wake cycles and masseter (jaw-closing) muscle electromyogram (EMG) activity over a 24-h period. From the dark to the light period, the times of wakefulness decreased, while those of non-rapid eye movement (NREM) and REM sleep increased. Citalopram did not induce major alterations in the temporal changes of sleep-wake distributions, except for leading to a decrease in the time of NREM sleep during the light period and an increase in the durations of REM sleep episodes. Moreover, citalopram did not modify mean masseter EMG activity during any of the vigilance states and did not affect the temporal changes related to the shifts between dark/light periods. However, citalopram increased the time engaged in masseter EMG activation during NREM sleep in the second and the first halves of the dark and light periods, respectively. These results suggest that chronic citalopram treatment does not affect the temporal changes of sleep-wake distributions, but has a limited facilitatory influence that fails to increase the number of epochs of high levels of masseter muscle activation.

Effect of Clonazepam and Clonidine on Primary Sleep Bruxism: a Double-blind, Crossover, Placebo-controlled Trial

Journal of Sleep Research. Aug, 2016  |  Pubmed ID: 27485389

The aim of this study was to assess the acute effects of clonazepam and clonidine on rhythmic masticatory muscle activity in young adults with primary sleep bruxism, as well as accompanying effects on sleep architecture and cardiac activity. This study used a double-blind, crossover, placebo-controlled design. Polysomnography was performed on 19 subjects [nine men and 10 women; mean age (±SE): 25.4 ± 2.7 years] for 5 nights. The first 2 nights were used for the habituation and diagnosis of sleep bruxism. The other 3 nights were randomly assigned for clonazepam (1.0 mg), clonidine (0.15 mg) or placebo (all administered 30 min before bedtime). Sleep, oromotor activity and cardiac activity variables were assessed and compared among the three drug conditions. Clonidine significantly reduced the median percentage of time spent in the rapid eye movement sleep stage compared with placebo and clonazepam. The number of rhythmic masticatory muscle activity episodes was reduced with clonidine by >30% compared with placebo and clonazepam. The reduction of rhythmic masticatory muscle activity index by clonidine was associated with an increase of mean RR intervals (slower heart rate) during quiet sleep periods and during a 70-s period before the onset of rhythmic masticatory muscle activity episodes. However, no changes in cardiac activity variables were observed for clonazepam. In young adults with primary sleep bruxism, clonidine was significantly more effective in suppressing sleep bruxism than clonazepam. The acute effects of clonidine on rhythmic masticatory muscle activity episodes may be mediated by suppression of autonomic nervous system activity and non-rapid eye movement-rapid eye movement sleep processes.

Reliability and Validity of the Patient Disability-oriented Diagnostic Nomenclature System for Prosthetic Dentistry

Journal of Prosthodontic Research. Aug, 2016  |  Pubmed ID: 27514568

The Japan Prosthodontic Society (JPS) has proposed a new diagnostic nomenclature system (DNS), based on pathogenesis and etiology, to facilitate and improve prosthodontic treatment. This system specifies patient disability and the causative factor (i.e. "B (disability) caused by A (causative factor)"). The purpose of this study was to examine the reliability and validity of this DNS.

Generation of Neural Cells Using IPSCs from Sleep Bruxism Patients with 5-HT2A Polymorphism

Journal of Prosthodontic Research. Dec, 2016  |  Pubmed ID: 27916472

Sleep bruxism (SB) is classified as a sleep-related movement disorder characterized by grinding and clenching of the teeth during sleep, which is responsible for a variety of clinical problems such as abnormal tooth attrition and fracture of teeth or roots. Little is known about the etiology of SB. Our previous study identified a genomic association of the serotonin 2A receptor (5-HT2A) single nucleotide polymorphism (SNP), rs6313 C>T, with SB, where the C allele carrier is associated with a 4.25-fold increased risk of SB. Based on this finding, the aim of this study was to generate of neural cells using SB patient-specific induced pluripotent stem cells (iPSCs).

Association Between Patterns of Jaw Motor Activity During Sleep and Clinical Signs and Symptoms of Sleep Bruxism

Journal of Sleep Research. Dec, 2016  |  Pubmed ID: 27996170

The aim of this study was to investigate the association between patterns of jaw motor activity during sleep and clinical signs and symptoms of sleep bruxism. A total of 35 university students and staff members participated in this study after providing informed consent. All participants were divided into either a sleep bruxism group (n = 21) or a control group (n = 14), based on the following clinical diagnostic criteria: (1) reports of tooth-grinding sounds for at least two nights a week during the preceding 6 months by their sleep partner; (2) presence of tooth attrition with exposed dentin; (3) reports of morning masticatory muscle fatigue or tenderness; and (4) presence of masseter muscle hypertrophy. Video-polysomnography was performed in the sleep laboratory for two nights. Sleep bruxism episodes were measured using masseter electromyography, visually inspected and then categorized into phasic or tonic episodes. Phasic episodes were categorized further into episodes with or without grinding sounds as evaluated by audio signals. Sleep bruxism subjects with reported grinding sounds had a significantly higher total number of phasic episodes with grinding sounds than subjects without reported grinding sounds or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). Similarly, sleep bruxism subjects with tooth attrition exhibited significantly longer phasic burst durations than those without or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). Furthermore, sleep bruxism subjects with morning masticatory muscle fatigue or tenderness exhibited significantly longer tonic burst durations than those without or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). These results suggest that each clinical sign and symptom of sleep bruxism represents different aspects of jaw motor activity during sleep.

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