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To evaluate the effect of body posture on occlusal contact.A total of 30 healthy subjects were evaluated. T-Scan™ III was used to analyze the center of occlusal force (COF) and occlusal force distribution while subjects remained supine (SP), upright sitting with the head fixed (UP-HFI), upright sitting with the head free (UP-HFR), and natural standing (NS).The total trajectory length of COF was significantly longer in NS than in SP, UP-HFI, and UP-HFR. The COF area was significantly larger in UP-HFR than in SP and UP-HFI and also significantly larger in NS than in SP, UP-HFI, and UP-HFR. The anteroposterior occlusal force distribution (AOD) in NS shifted significantly forward, compared to SP, UP-HFI, and UP-HFR. AOD in UP-HFI and UP-HFR shifted significantly forward, compared to the SP position.Changes in body posture affect the stability and anteroposterior balance of occlusal contacts.

This study examined the controlled release of cetylpyridinium chloride (CPC) from a tissue conditioner (TC) containing CPC-montmorillonite (CPC-Mont), the associated antimicrobial activity, and oral mucosa irritation. The CPC release test was performed daily for 28 days in three test solutions: distilled water, 0.2 M NaCl, and 0.2 M HCl. The antimicrobial activities for 7, 14, 21, and 28 days against Candida albicans, Staphylococcus aureus, and Streptococcus mutans were assessed according to the JIS Z 2801/ISO 22196 standard. An oral mucosa irritation test was conducted using cheek pouches in five male hamsters according to the ISO 10993-10:2010 standard. The amount of CPC released each day and the cumulative amount released over 28 days (6.12 mg) were less than the daily safe maximum of sore throat medicines (8 mg). Additionally, TC with CPC-Mont could sustain antimicrobial activity against adherent bacteria for 14 days and has no oral mucosa irritation potential.

Background There have been several reports about the prognosis of teeth adjacent to edentulous spaces for implant-supported fixed prostheses (ISFPs) and removable partial dentures (RPDs). However, there are few reports about the prognosis of the other remaining teeth comparing ISFPs with RPDs. Purpose The aim of this study was to evaluate and compare the prognosis of the remaining teeth for ISFPs and RPDs in terms of survival and complication-free rates. Methods Subjects were partially edentulous patients with ISFPs or RPDs inserted in 2003-2016. Teeth adjacent to edentulous spaces (A-teeth), teeth not adjacent to edentulous spaces (R-teeth), and teeth opposing edentulous spaces (O-teeth) were investigated. The endpoints were tooth extraction and complications. A multivariate cox regression model was used to estimate the risk factors for survival of the investigated teeth. Results A total of 233 (ISFP: 89, RPD: 144) patients were included in the statistical analyses. An IFSP prosthesis, when compared to an RPD prosthesis did not significantly decrease the tooth loss rate for A-teeth (hazard ratio [HR]: 0.76; 95% confidence interval [CI]: 0.30-1.92), for R-teeth (HR: 0.54; 95% CI: 0.28-1.05), or for O-teeth (HR: 0.45; 95% CI: 0.10-2.09). Conclusions In partially edentulous spaces, the difference between ISFPs and RPDs does not affect the prognosis of teeth adjacent to edentulous spaces, teeth not adjacent to edentulous spaces, and teeth opposing edentulous spaces. Namely, our findings suggest that it depends largely on the tooth type, jaw, endodontic therapy performed, not on the type of prostheses.

Purpose The mechanical properties, antimicrobial activity, and biocompatibility of a novel antimicrobial tissue conditioner containing cetylpyridinium chloride with montmorillonite (CPC-Mont) were evaluated. Methods To examine the mechanical properties of the novel material, hardness, consistency, and penetration tests were conducted. Antimicrobial activity against Candida albicans (C. albicans) and Staphylococcus aureus (S. aureus) was evaluated. Cell viabilities of fibroblasts and epithelial cells using eluates from materials were measured to evaluate cytotoxicity. In addition, to assess tissue response, animal experiments were conducted. Results The hardness test results were similar to those of other commercially available materials. The novel tissue conditioner showed good antimicrobial activity against C. albicans and S. aureus compared with other materials. This effect was sustained for a week for C. albicans. In the case of S. aureus, microbial growth was suppressed for up to 3 weeks. Cell viability of the novel material for the eluate at 1 day was significantly less than those of other material for both cells. However, the cell viability at 7 days showed no significant difference. Animal experiments demonstrated that inflammatory responses around materials were not observed on the oral mucosa as other material. Conclusion Within the limitations of this in vitro and in vivo study, the results suggest that the newly developed tissue conditioner containing CPC-Mont has not only excellent antimicrobial properties, but also the same mechanical properties and biocompatibility as tissue conditioners on the market.

This work demonstrates that certain medically-approved drugs possess dual functions such that they exhibit intrinsic drug effects and can assist in dispersing carbon nanomaterials. Two types of carbon nanohorns (CNHs) (unoxidized: as-CNH, oxidized: CNHox550) and carbon nanotubes (CNTs) were successfully dispersed in aqueous solutions using minocycline (MC) as a dispersant. Absorption spectra, thermogravimetric analyses and theoretical calculations demonstrated that the MC was attached to the CNHs in these dispersions. The antibacterial activities of these MC/CNH complexes were examined using Streptcoccus mutans and Aggregatibacter actinomycetemcomitans, and the MC/as-CNH complex was found to maintain the same bacterial growth inhibition activity as the original MC. Electron microscopy observations suggested direct contact of the MC/CNH complexes with the bacteria, presumably allowing delivery of the MC. The results obtained from our study demonstrate that drug/nanocarbon complexes have potential applications in drug delivery.

Carbon nanotubes (CNTs) are potentially important biomaterials because of their chemical, physical, and biological properties. Our research indicates that CNTs exhibit high compatibility with bone tissue. The guided bone regeneration (GBR) technique is commonly applied to reconstruct alveolar bone and treat peri-implant bone defects. In GBR, bone defects are covered with a barrier membrane to prevent the entry of nonosteogenic cells such as epithelial cells and fibroblasts. The barrier membrane also maintains a space for new bone formation. However, the mechanical and biological properties of materials previously used in clinical practice sometimes delayed bone regeneration. In this study, we developed a CNT-based membrane for GBR exhibiting high strength to provide a space for bone formation and provide cellular shielding to induce osteogenesis. The CNT membrane was made via the dispersion of single-walled CNTs (SWCNTs) in hyaluronic acid solution followed by filtration. The CNT membrane assumed a nanostructure surface due to the bundled SWCNTs and exhibited high strength and hydrophilicity after oxidation. In addition, the membrane promoted the proliferation of osteoblasts but not nonosteogenic cells. CNT membranes were used to cover experimental bone defects made in rat calvaria. At 8 weeks after surgery, more extensive bone formation was observed in membrane-covered defects compared with bone defects not covered with membrane. Almost no diffusion of CNTs was observed around the membrane. These results indicate that the CNT membrane has adequate strength, stability, and surface characteristics for osteoblasts, and its shielding properties promote bone formation. Demonstration of the safety and osteogenic potential of the CNT membranes through further animal studies should facilitate their clinical application in GBR.

Carbon nanomaterials (CNMs) are used in various functional materials and products as well as in basic research, predominantly in engineering. Because of their high biocompatibility, use of CNMs in bioapplications is widely anticipated. Many researchers have examined the kinetics and toxicity of intravenously administered CNMs. However, little research on the in vivo kinetics of locally implanted CNMs has been reported. In this study, single-walled carbon nanotubes (SWCNTs) were implanted between the periosteum and parietal bone of mice. The in vivo kinetics of the implanted SWCNTs were observed by near-infrared (NIR) fluorescence imaging (excitation wavelength, 730 nm; emission wavelength, >1000 nm), because the body is highly transparent to light in the NIR region, and autofluorescence in this region is low, making NIR fluorescence suitable for bioimaging. SWCNTs were visible in the subcutaneous tissue and medullary cavity. Fluorescence was observed in the cranial region, and its intensity gradually decr...

In this study, we examined the immunolocalization of podoplanin/E11, CD44, actin filaments, and phosphorylated ezrin in the osteoblasts on the verge of differentiating into osteocytes in murine femora and tibiae. When observing under stimulated emission depletion microscopy, unlike podoplanin-negative osteoblasts, podoplanin-positive osteoblasts showed a rearranged assembly of actin filaments along the cell membranes which resembled that of embedded osteocytes. In the metaphysis, i.e., the bone remodeling site, CD44-bearing osteoclasts were either proximal to or in contact with podoplanin-positive osteoblasts, but the podoplanin-positive osteoblasts also localized CD44 on their own cell surface. These podoplanin-positive osteoblasts, which either possessed CD44 on their cell surface or were close to CD44-bearing osteoclasts, showed phosphorylated ezrin-positivity on the cell membranes. Therefore, the CD44/podoplanin interaction on the cell surface may be involved in the osteoblastic differentiation into osteocytes in the metaphyses, via the mediation of podoplanin-driven ezrin phosphorylation and the subsequent reorganized assembly of actin filaments. Consistently, the protein expression of phosphorylated ezrin was increased after CD44 administration in calvarial culture. Conversely, in modeling sites such as the cortical bones, podoplanin-positive osteoblasts were uniformly localized at certain intervals even without contact with CD44-positive bone marrow cells; furthermore, they also exhibited phosphorylated ezrin immunoreactivity along their cell membranes. Taken together, it seems likely that the CD44/podoplanin interaction is involved in osteoblastic differentiation into osteocytes in the bone remodeling area but not in modeling sites.

Background Surface nanostructures in titanium (Ti) oral implants are critical for rapid osseointegration. Objective The purpose of this study was to evaluate the growth of osteoblast-like (Saos-2) and epithelial-like (Ca9-22) cells on nanopatterned Ti films. Methods Ti films with 500 nm grooves and pillars were fabricated by nanoimprinting, and seeded with Saos-2 and Ca9-22 cells. Cell viability and morphology were assessed by cell proliferation assay and scanning electron microscopy, respectively. Results As assessed after 1 hour, proliferation of Saos-2 cells was most robust on grooved films than on pillared and smooth films, in this order. These cells approximately doubled on grooved and pillared substrates in 24 hours and after 5 days, but not on smooth surfaces. In contrast, Ca9-22 cells favored smooth surfaces, followed by grooved and pillared films. Indeed, cells sparsely adhered to pillared films over 5 days of incubation (p Conclusions The data show that Saos-2 and Ca9-22 cells respond differently to different nanostructures, and highlight the potential use of nanopatterns to promote bone regeneration or to prevent epithelial downgrowth at the implant-bone interface.

The present study provides scientific evidence that a new chemical treatment process using calcium phosphate slurry promotes bone regeneration on titanium (Ti) implants. The material's surface modified by the treatment was analyzed using microscopic observation and the bone regeneration efficacy was evaluated both in vitro and in vivo. Formation of a thin hydroxyapatite layer with a thickness of about 50 nm and an increase of surface roughness were confirmed by microscopic observations. Histological evaluation of rat femora implanted with the specimens showed that the areas of the specimens directly attached to bone tissue were significantly more extensive than those implanted with control Ti at 2 and 8 weeks. Likewise, on the treated Ti, ALP activity, osteopontin, osteocalcin, and calcium contents of rat bone marrow stromal cells were significantly higher than on the control Ti. Furthermore, reverse transcription polymerase chain reaction showed greater expression of messenger ribonucleic acid encoding Cbfa1 and collagen type1 on the treated Ti at 2 weeks. Based on these results, we concluded that the new process was effective to enhance the osteoconductivity of Ti. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2716-2724, 2018.

Background Dental implants are frequently applied to unilateral defects in the mandible. However, implant placement in the molar region of the mandible can be difficult due to anatomical structure. The aim of this study was to evaluate the distribution of occlusal force in a mandibular shortened dental arch (SDA) with implants. Methods Three-dimensional finite element (FE) models of the mandible with varying numbers of teeth and implants were constructed. Models Im6 and Im67 contained one and two implants in the defect of the left molar region, respectively. Models Im456 and Im4567 contained three and four implants in the defect of the left premolar and molar regions, respectively. Model MT67 contained a defect in the molar region with no implant placed. Model MT7 represented natural dentition without a left second molar, as a control. Modification of the condition of occlusal contacts assuming the intercuspal position was performed before analysis under load 400 N; therefore, the load condition as total force on the occlusal surface was 400 N. FE analyses were subsequently performed under load conditions of loads 100, 200, and 800 N. The distribution of reaction forces on the occlusal surface and the mandibular condyle was investigated. Results Force distribution in models Im67 and Im4567 appeared to be symmetrical under all load conditions. Occlusal force distribution in models Im6 and Im456 was similar to that in model MT7. However, the occlusal force at the second premolars on the defect side in those models was larger under loads 100 and 200 N. Conversely, the occlusal force on the first molars was much larger than that in model MT7 under load 800 N. Conclusions Within the limitations of this theoretical study, we demonstrated that restoration with the same number of implants as missing teeth will show almost symmetric occlusal force distribution, and it will produce less biomechanically stress for a unilateral defect of the mandible. However, if restoration of a missing second molar with an implant is impossible or difficult, then an SDA with implants may also be acceptable except for individuals with severe bruxism.

Upon liver injury, excessive deposition of collagen from activated hepatic stellate cells (HSCs) is a leading cause of liver fibrosis. An understanding of the mechanism by which collagen biosynthesis is regulated in HSCs will provide important clues for practical anti-fibrotic therapy. Endoplasmic reticulum oxidase 1 alpha (ERO1 alpha) functions as an oxidative enzyme of protein disulfide isomerase, which forms intramolecular disulfide bonds of membrane and secreted proteins. However, the role of ERO1 alpha in HSCs remains unclear. Here, we show that ERO1 alpha is expressed and mainly localized in the endoplasmic reticulum in human HSCs. When HSCs were transfected with ERO1 alpha siRNA or an ERO1 alpha shRNA-expressing plasmid, expression of ERO1 alpha was completely silenced. Silencing of ERO1 alpha expression in HSCs markedly suppressed their proliferation but did not induce apoptosis, which was accompanied by impaired secretion of collagen type 1. Silencing of ERO1 alpha expression induced impaired disulfide bond formation and inhibited autophagy via activation of the Akt/mammalian target of rapamycin signaling pathway, resulting in intracellular accumulation of collagen type 1 in HSCs. Furthermore, silencing of ERO1 alpha expression also promoted proteasome-dependent degradation of membrane type 1-matrix metalloproteinase (MT1-MMP), which stimulates cell proliferation through cleavage of secreted collagens. The inhibition of HSC proliferation was reversed by treatment with MT1-MMP-cleaved collagen type 1. The results suggest that ERO1 alpha plays a crucial role in HSC proliferation via posttranslational modification of collagen and MT1-MMP and, therefore, may be a suitable therapeutic target for managing liver fibrosis.

Purpose: The purpose of this study was to investigate the influences of bone quality and implant size on the maximum equivalent elastic strain (MES) in peri-implant bone using finite element (FE) analysis, and to minimize implant size via optimized calculation based on MES. Methods: Three-dimensional FE models consisting of a mandible and a titanium implant with a superstructure were constructed and applied a vertical load or an oblique load of 60 N. We investigated the effects of four variables: the thickness of the cortical bone (C), Young's modulus of the trabecular bone (T), and the diameter (D) and length (L) of the implant. According to the variables determined using Latin hypercube sampling, 500 FE models were constructed and analyzed under each of the loads following the construction of response surfaces with the MES as a response value. D and L were minimized by optimized calculation with the MES limited to the physiological limit with reference to the mechanostat theory. Results: The MES was significantly influenced by D more than L, and could be restricted to the physiological limit unless both C and T were small. Larger MES than physiological limit was observed around the bottom of implants. Conclusions: From the viewpoint of the mechanostat theory, we calculated minimum size of implants according to the bone quality. However, the results should be verified with more detailed FE models made using CT data, animal studies and clinical prognoses. (C) 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Purpose The present study compared the clinical prognosis of double crown-retained removable dental prostheses (D-DRPs) with that of clasp-retained removable dental prostheses (C-RDPs). Methods Clinical records of 201 patients who had received 52 D-RDPs with 144 abutment teeth (D-teeth) and 199 C-RDPs with 399 abutment teeth (C-teeth) at the Prosthetic Dentistry Clinic in Hokkaido University Hospital between April 2005 and June 2015 were analyzed. Survival and complication probabilities of the two types of prostheses and abutment teeth were evaluated using the Kaplan–Meier method and compared using the log-rank test. Cox regression analysis was used to determine the impact of covariates on abutment teeth survival and complications such as gender, age, type of retainer, Eichner classification, jaw, type of tooth, endodontic therapy performed, type of edentulous space, and presence of opposing teeth. Results Statistical analysis showed no significant differences between the two types of prostheses in terms of prostheses survival, prostheses complication, and abutment teeth survival. However, a significant difference was observed for complications of abutment teeth. Decementation was the most frequent cause of failure, which occurred in 76.9% of D-teeth and 28.3% of C-teeth. Patient's age, jaw, endodontic therapy performed, and type of edentulous space affected the survival of abutment teeth, whereas the type of retainer and edentulous space affected complications of abutment teeth. Conclusion The prognosis of both types of prostheses was considered to be acceptable. Although D-RDP had lower complication-free rates for abutment teeth, most of the observed complications were decementation, which was considered to be reparable.

Objectives We previously reported that masseter motoneurons (MMNs) and digastric motoneurons (DMNs) in postnatal day (P) 1–5 rats receive convergent inputs from the lateral (l-) and medial (m-) supratrigeminal regions (SupV), intertrigeminal region (IntV), and dorsal region of the principal sensory trigeminal nucleus (PrV). The l-SupV sends burst inputs predominantly to the MMNs. We compared the synaptic inputs to P9–12 rat MMNs and DMNs with those found in the previous study involving P1–5 rats. Methods We performed whole-cell recordings and laser photolysis of caged glutamate in the MMNs and DMNs of P9–12 rats. Results Similar to P1–5 rats, the photostimulation of multiple regions within the l-SupV, m-SupV, IntV, and dorsal PrV, induced postsynaptic currents (PSCs) in both P9–12 MMNs and DMNs. Photostimulation induced predominantly low-frequency PSCs in both P9–12 motoneurons, whereas l-SupV photostimulation predominantly induced burst PSCs in P1–5 rats. However, when the caged glutamate concentration was doubled, l-SupV photostimulation evoked burst PSCs in all P9–12 MMNs. Furthermore, l-SupV and m-SupV photostimulation evoked burst or low-frequency PSCs at significantly higher rates in the MMNs compared to in the DMNs. Conclusions These results suggested that, similar to P1–5 motoneurons, both P9–12 motoneurons received convergent inputs from the SupV, IntV, and PrV; however, the input–output gains of some of the premotor neurons decreased. These synaptic input changes may contribute to the proper development of chewing.

This prospective cohort study investigated the relationship between patient neuroticism and oral health-related quality of life (OHRQoL) before and after prosthetic treatment as well as changes in OHRQoL-namely, treatment efficacy. Sixty-three patients (23 men and 40 women; mean age 67.2 ± 8.6 years), who were scheduled to receive new removable partial dentures (RPDs), were recruited. OHRQoL was assessed using the Japanese version of the Oral Health Impact Profile (OHIP-J). The Japanese version of the NEO Five-Factor Inventory (NEO-FFI) was used to assess neuroticism. Spearman's rank correlation coefficient was calculated to determine the association between neuroticism and OHIP-J scores before and after treatment. After stratifying patients according to neuroticism score, the Wilcoxon signed-rank test was used for intragroup comparison of OHIP-J scores before and after treatment. Moreover, logistic regression analysis was used to determine the impact of covariates on treatment efficacy such as age, sex, Eichner classification, neuroticism, changes in maximal occlusal force, and OHIP-J scores before treatment. Statistical analyses showed that higher neuroticism scores were associated with higher total OHIP-J scores before treatment ( r = 0.41, P = 0.001) but were not associated with OHIP-J scores after treatment ( r = 0.07, P = 0.566). When the effect of all independent variables was analyzed in multivariate analysis, neuroticism and OHIP-J scores before treatment affected treatment efficacy. These results suggest that OHRQoL of patients with higher levels of neuroticism was low before prosthetic treatment but significantly improved by oral rehabilitation with RPDs to the same level as patients with lower levels of neuroticism. Knowledge Transfer Statement: The results of this study may change the clinical perception of the effect of prosthetic rehabilitation with removable partial dentures in patients with higher levels of neuroticism. The study concluded that prosthetic rehabilitation could contribute toward satisfaction even in neurotic patients, who are presumed to show less satisfaction with their oral status.

To evaluate the inhibitory effect of a surface pre-reacted glass-ionomer (S-PRG) filler-containing tooth-coating material on enamel demineralization. The outer surface of the S-PRG filler is in a state in which ions are readily released.Human enamel blocks were incubated in lactic acid solution (pH 4.0) with and without a disk (n=6) made of the cured tooth-coating material. Test solutions were changed every 24 hours and incubation was continued for 4 days. The pH and amount of fluoride released were measured with an electrode and ion meter, respectively. The concentrations of ions (aluminum, boron, calcium, phosphorus, silicon, sodium, and strontium) were measured by inductively coupled plasma atomic emission spectroscopy. The surface of the enamel block was observed with a scanning electron microscope.Enamel demineralization was not observed in an enamel block incubated with a disk of the tooth-coating material. Ions released from S-PRG filler had an acid buffering action in the low pH lactic acid solution. However, in the enamel block-only solution showing high levels of calcium ion release, the degree of demineralization was correlated with morphological changes of the enamel surface.Due to the buffering effects of the pre-reacted glass-ionomer surface by ion release, the S-PRG filler-containing tooth-coating material inhibited enamel demineralization by neutralizing the acidic environment at an early time point.

Groove patterns on the surface of implants act as an effective barrier to the apical migration of epithelial attachment, after which the grooves facilitate gingival fibroblast attachment. Cell alignment on grooves is largely influenced by the adsorbed protein type. However, cell attachment and cell alignment properties of micro/nano-grooved dental composite resins using osteoblasts and fibroblasts have not been investigated. Further, the effect of saliva-related protein adsorption has not investigated. In this study, we prepared composite resins with grooves that were 2 μm, 1 μm, and 500 nm wide and estimated the effect of pre-coating of some proteins, mainly mucin, on attachment and alignment of human gingival fibroblasts(HGF). In the cell attachment assay on mucin-coated grooves, the number of attached cells on mucin-coated planar or grooved composite resins was lower compared to that on both composite resins without pre-coating of mucin. Interestingly, the number of attached cells on grooves pre-coated with mucin was 5.7-fold higher than those on planar pre-coated with mucin. Grooves at the micro/nano level may act as a hook for floating cells during the cell attachment assay. Furthermore, the degree of cell alignment was strongly dependent on the pre-coating protein types. The cells were radially spread or round-shaped, but not have sufficient alignment on non-, mucin-, and albumin-coated grooves. Although the cells were attached on the grooves, they were not aligned along the direction of grooves. The cells on fetal bovine serum- or fibronectin-coated grooves exhibited good alignment in the groove direction, particularly on fibronectin-coated grooves. Thus, our patterning method creates an effective seal between soft tissue and dental materials to protect against microorganism invasion.

The primary cilium, a sensory apparatus, functions as both a chemical and mechanical sensor to receive environmental stimuli. The present study focused on the primary cilia in the epithelialmesenchymal interaction during tooth development. We examined the localization and direction of projection of primary cilia in the tooth germ and oral cavity of mice by immunohistochemical observation. Adenylyl cyclase 3 (ACIII)-immunolabeled cilia were visible in the inner/outer enamel epithelium of molars at the fetal stage and then conspicuously developed in the odontoblast layer postnatally. The primary cilia in ameloblasts and odontoblasts-shown by the double staining of acetylated tubulin and γ-tubulin-were regularly arranged from postnatal Day12, projecting apart from each other. The periodontal ligament possessed ACIII-positive cilia, which gathered on both sides of the dentin/cement and alveolar bone in postnatal days. In the oral cavity, numerous long primary cilia immunoreactive for ACIII were condensed at subepithelial stromal cells in the oral processes in fetuses, while postnatally a small number of short cilia were dispersed throughout the stroma of the oral cavity. These findings suggest that the primary cilia showing stage- and regionspecific morphology are involved in the epithelial-mesenchymal interaction during tooth development via mechano- and/or chemoreception for growth factors.

Early and immediate loading of dental implants has become a routine procedure in dental practices throughout the world, but the histological feature of peri-implant bone has not been fully understood. Therefore, we aimed to elucidate the histological response of peri-implant bone bearing the early occlusal loading using rat models. Four-week-old male Wistar rats were subjected to extraction of their maxillary left first molars and had titanium implants inserted immediately into the post-extraction sockets. In experimental groups at 1 week after placement, implants were loaded for 1 or 2 weeks by adding adhesive resin on the top of the screws. In control groups, no adhesive resin was added to the implants. After 1 or 2 weeks with loading, rats were fixed with an aldehyde solution for histochemical assessment. Newly-formed bone adhered broadly to the implant surface in both the control and experimental groups. The experimental group loaded for 2 weeks showed thicker trabeculae between the implant threads compared to those in the control group. Osteopontin- and osteocalcin-positive cement lines, which are histological hallmarks of bone remodeling, were narrow and smooth in the experimental groups, while featuring a complex meshwork with thick scalloped lines in the control groups. The index of sclerostin-positive osteocytes located close to implants loaded for 2 weeks was significantly lower than in controls, suggesting that osteoblast activity was preserved. Summarizing, our experimental model suggested that early implant loading increases trabecular thickness in the peri-implant bone tissue in a process that involves the regulation of bone remodeling.

Tooth development is regulated by various growth factors and their receptors. However, the overall mechanism of growth factor-mediated odontogenesis remains to be elucidated. The present study examined expression sites and intensities of major growth factors and receptors in the tooth germ of murine fetuses and neonates. Signals of TGF-β and CTGF in fetuses were released from the enamel epithelium, while their neonatal signals arose in odontoblasts. Moreover, BMP/Smad signaling may affect the differentiation of ameloblasts, in contrast to PDGFα whose signals may cause odontoblast differentiation. Growth factors associated with the formation of the periodontium were IGF1, IGF2, IGFBP3, CTGF, and PDGFα. Concerning cusp formation, the enamel knot selectively expressed FGF4, BMP2, and BMP4 with an expression of PDGFα in the enamel-free area. It is concluded that many molecules play critical roles in the epithelium-mesenchyme interaction of tooth germ differentiation, and their expressions are precisely controlled.

The present study provides scientific evidence that a new chemical treatment process using calcium phosphate slurry promotes bone regeneration on titanium (Ti) implants. The material's surface modified by the treatment was analyzed using microscopic observation and the bone regeneration efficacy was evaluated both in vitro and in vivo. Formation of a thin hydroxyapatite layer with a thickness of about 50 nm and an increase of surface roughness were confirmed by microscopic observations. Histological evaluation of rat femora implanted with the specimens showed that the areas of the specimens directly attached to bone tissue were significantly more extensive than those implanted with control Ti at 2 and 8 weeks. Likewise, on the treated Ti, ALP activity, osteopontin, osteocalcin, and calcium contents of rat bone marrow stromal cells were significantly higher than on the control Ti. Furthermore, reverse transcription polymerase chain reaction showed greater expression of messenger ribonucleic acid encoding Cbfa1 and collagen type1 on the treated Ti at 2 weeks. Based on these results, we concluded that the new process was effective to enhance the osteoconductivity of Ti. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2716-2724, 2018.

This study was designed to determine whether oral streptococci modulate the growth and functions of regulatory T cells. Heat-killed cells of wild-type strains of Streptococcus gordonii and Streptococcus mutans induced the Toll-like receptor 2 (TLR2) -mediated nuclear factor-κB (NF-κB) activation, but their lipoprotein-deficient strains did not. Stimulation with these streptococci resulted in a significant increase in the frequency of CD4(+) CD25(+) Foxp3(+) regulatory T cells in splenocytes derived from both TLR2(+/+) and TLR2(-/-) mice, but the level of increase in TLR2(+/+) splenocytes was stronger than that in TLR2(-/-) splenocytes. Both strains of S. gordonii enhanced the proliferation of CD4(+) CD25(+) Foxp3(+) regulatory T cells isolated from TLR2(+/+) mice at the same level as those from TLR2(-/-) mice in an interleukin-2-independent manner. However, wild-type and lipoprotein-deficient strains of both streptococci did not enhance the suppressive activity of the isolated regulatory T cells in vitro, but rather inhibited it. TLR ligands also inhibited the suppressive activity of the regulatory T cells. Inhibition of the suppressive activity was recovered by the addition of anti-IL-6 antibody. Pretreatment of antigen-presenting cells with the NF-κB inhibitor BAY11-7082 enhanced the suppressive activity of the regulatory T cells. These results suggested that interleukin-6 produced by antigen-presenting cells inhibits the suppressive activity of the regulatory T cells. Wild-type strain, but not lipoprotein-deficient strain, of S. gordonii reduced the frequency of CD4(+) CD25(+) Foxp3(+) regulatory T cells in the acute infection model, whereas both strains of S. gordonii increased it in the chronic infection model mice. Hence, this study suggests that oral streptococci are capable of modulating the growth and functions of regulatory T cells in vitro and in vivo.

The primary cilium, a sensory apparatus, functions as both a chemical and mechanical sensor to receive environmental stimuli. The present study focused on the primary cilia in the epithelialmesenchymal interaction during tooth development. We examined the localization and direction of projection of primary cilia in the tooth germ and oral cavity of mice by immunohistochemical observation. Adenylyl cyclase 3 (ACIII)-immunolabeled cilia were visible in the inner/outer enamel epithelium of molars at the fetal stage and then conspicuously developed in the odontoblast layer postnatally. The primary cilia in ameloblasts and odontoblasts-shown by the double staining of acetylated tubulin and γ-tubulin-were regularly arranged from postnatal Day12, projecting apart from each other. The periodontal ligament possessed ACIII-positive cilia, which gathered on both sides of the dentin/cement and alveolar bone in postnatal days. In the oral cavity, numerous long primary cilia immunoreactive for ACIII were condensed at subepithelial stromal cells in the oral processes in fetuses, while postnatally a small number of short cilia were dispersed throughout the stroma of the oral cavity. These findings suggest that the primary cilia showing stage- and regionspecific morphology are involved in the epithelial-mesenchymal interaction during tooth development via mechano- and/or chemoreception for growth factors.

Multi-wall carbon nanotubes/hydroxyapatite (MWCNTs/HA) composites with 20%, 40% and 60% HA were successfully fabricated at 1200 °C and 120 MPa by spark plasma sintering (SPS). Scanning electron microscope (SEM) observations showed that MWCNTs/HA composites kept the nanostructure of MWCNTs after SPS treatment. The bulk density of the MWCNTs/HA composites was increased by the addition of HA. However, the Vickers hardness, porosity, Young's modulus, flexure strength and compression strength of the MWCNTs/HA composites were decreased with increasing content of HA. To test their biocompatibility, the MWCNTs/40% HA composites were inserted into rat femur. The in vivo reaction of four weeks showed that the composites possessed better osseointegration compared to pure MWCNTs. The results indicated that the MWCNTs/HA composites have potential for a wide variety of bonegraft applications in the future.

Surface coating treatment with multiwalled carbon nanotubes (MWCNTs) was applied to 3D collagen scaffold for bone tissue engineering. Rat primary osteoblasts (ROBs) were cultured on an MWCNT-coated collagen sponge (MWCNT-coated sponge) in a 3D dynamic flow cell culture system and differentiation markers were measured. Alkaline phosphatase activity at 1 day, and calcium and osteopontin contents of the MWCNT-coated sponges at 7 days were significantly higher than those of uncoated sponges. ROBs on the MWCNT-coated sponge differentiated earlier than on the uncoated sponge. In addition, the tissue response to the MWCNT-coated sponge was evaluated. Slight inflammation was observed around MWCNTs at 7 and 28 days after implantation in subcutaneous tissue. Significantly more bone formation was observed around the MWCNT-coated sponges than around the uncoated sponges and new bone attached to MWCNTs directly at 28 and 56 days after implantation in the femur. Moreover, at 28 days after implantation of the MWCNT-coated sponge with osteoblasts cultured for 1 day, bone tissues were successfully formed in the pores according to its honeycomb structure. Therefore, MWCNT coating appears to be effective for bone tissue engineering.

Induced pluripotent stem (iPS) cells have attracted worldwide interest. However, there have been only a few studies investigating effective culture substrates for feeder-free culturing for the maintenance of iPS cells. In this study, we cultured mouse iPS cells under feeder-free conditions on carbon nanotube (CNT)-coated dishes and then evaluated the colony morphology and differentiation state of the cells on the dishes. After 5 d of cultivation in a medium containing 15% fetal bovine serum (FBS) and leukemia inhibitory factor (LIF), the colonies on thick films of multi-walled CNTs (MWCNTs) were observed to be hemiround; further, the cells expressed early undifferentiation markers. On the other hand, the colonies on a cell culture polystyrene dish and a collagen-coated polystyrene dish showed indistinct outline and spread well, and most spreading cells only weakly expressed early undifferentiation markers. These results indicate that the thick films of MWCNTs could maintain hemiround colonies and undifferentiated state of mouse iPS cells cultured under feeder-free conditions.

Purpose The aim of this study was to determine the importance of each morphological factor of edentulous alveolar ridges according to its influence on the movement of complete dentures. Methods The shapes of casts and waxed complete dentures were digitized. The determined shapes of the ridges were uniformly divided circumferentially and radially. Principal component (PC) analysis was performed using the coordinates of the points on the grid as the variables (morphological PC). The denture movement under bilateral and unilateral loads was analyzed using a finite element (FE) model constructed from the digitized shape, following PC analysis of the displacement of representative points on the denture (displacement PC). The effects of the morphological PCs were evaluated by means of stepwise multiple regression analysis with displacement PC as a dependent variable. Results The ridge height, clearance between the ridge and the occlusal plane, and various inclinations, were significantly selected as independent variables where the dependent variable was the displacement PC under a bilateral load. Under a unilateral load, the displacement PC was mainly influenced by the ridge height. The influence of morphological PCs of the non-loaded side tended to be larger than that of loaded side. Conclusion Under a bilateral load, ridge height, clearance to the occlusal plane, and inclination of the ridge are considered to account for denture movement. To evaluate the effect of the ridge morphology on denture movement under a unilateral load, it is effective to determine the partitioned shape together with the height in general.

The cell structure and interface between cultured cells and a multiwalled carbon nanotube (MWCNT)-coated sponge (MWCNT-coated sponge) were observed by transmission electron microscopy (TEM). Moreover, the atomic structure of MWCNTs that entered the cells was also examined by means of high-resolution TEM (HRTEM). MWCNTs were observed in the cytoplasm, and a few MWCNTs were recognized in the cell nuclei. Those MWCNTs maintained their structure there. Subcellular organelles did not appear to be different from those on the collagen sponge despite the cellular uptake of MWCNTs.