Atsuro Yokoyama

Hokkaido University | Hokudai · Graduate School of Dental Medicine

Background: In recent years, implant-assisted removable partial dentures (IARPDs) have been used clinically. However, the extent to which additional implants reduce the burden of supporting tissues is unclear. The aim of this study was therefore to investigate the influence of implanted IARPDs on stress sharing among supporting tissues, using finit...

Dental implant therapy is a reliable treatment for replacing missing teeth. However, as dental implants become more widely used, peri-implantitis increasingly has become a severe complication, making successful treatment more...

TThis study developed a novel antibacterial conjugate based on carbon nanohorns for peri-implantisis, an inflammatory disease around dental implants, which may result in failing implants by bone loss around them....

Purpose: To verify the effect of sitting posture with and without sole-ground contact on chewing stability and masticatory performance. Methods: Thirty healthy subjects were evaluated. The Conformat was used to analyze the center of sitting pressure (COSP), and the three-dimensional motion analysis system was used to analyze changes in head and tru...

Purpose: The purpose of this study was to test the hypothesis in healthy subjects that masticatory movements affect head and trunk sways, and sitting and foot pressure distributions during sitting position. Methods: A total of 30 healthy male subjects with an average age of 25.3 years (range, 22-32 years) were evaluated. The CONFORMatTM and MatS...

Objectives: We investigated the behavior of macrophages in the defined microtopography of materials. Methods: Patterned cyclo-olefin polymer films were implanted into the femurs of seven-week-old rats. After 1 and 4 weeks, the rats were fixed with glutaraldehyde and OsO4, and their bones were observed with transmission electron microscopy (TEM)....

Background: Implant-supported removable partial dentures (ISRPDs) provide effective prosthodontic treatment for partially edentulous patients. ISRPDs offer greater patient satisfaction and better oral function compared with removable partial dentures (RPDs) by enhancing denture stability and support. However, few clinical studies have focused on R...

Objective To evaluate the effect of body posture on occlusal contact. Methods 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...

Residual ridge resorption (RRR) is a chronic and progressive bone resorption following tooth loss. It causes deterioration of the oral environments and leads to the pathogenesis of various systemic diseases. However, the molecular mechanisms and risk factors for RRR progression are still unclear and controversial. In this study, we developed a toot...

The article “Different micro/nano-scale patterns of surface materials influence osteoclastogenesis and actin structure”, written by Tsukasa Akasaka, Miho Tamai, Yoshitaka Yoshimura, Natsumi Ushijima, Shinichiro Numamoto, Atsuro Yokoyama, Hirofumi Miyaji, Ryo Takata, Shuichi Yamagata, Yoshiaki Sato, Ko Nakanishi, and Yasuhiro Yoshida, was originally...

The surface topography of a material can influence osteoclast activity. However, the surface structural factors that promote osteoclast activity have not yet been investigated in detail. Therefore, we investigated osteoclastogenesis by testing various defined patterns with different dimensions and shapes. The systematic patterns, made of a cyclo-ol...

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 comp...

Residual ridge resorption (RRR) is a chronic and progressive bone resorption following tooth loss. It causes deterioration of the oral environments and leads to the pathogenesis of various systemic diseases. However, the molecular mechanisms and risk factors for RRR progression are still unclear and controversial. In this study, we developed a toot...

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 antimi...

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 sh...

Direct contact between bone and implant materials is required for dental implants. Titanium is used for the implant material owing to its mechanical and biological properties. The anodisation as the surface treatment was employed to enhance osteogenesis around titanium. Moreover, carbon nanohorn (CNH), a type of nanometer-sized carbon material, was...

Abstract Background Implant-supported removable partial dentures (ISRPDs) are an effective treatment for partially edentulous patients. ISRPDs improve patients’ satisfaction and oral function to a greater extent than RPDs by improving denture stability and enhancing support. However, the effect of a type of direct retainer on displacement of the ab...

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 minocycl...

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. Antimicr...

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,...

Purpose: There are few reports on the relationship between the items examined for deterioration of oral function and the oral health related quality of life (OHRQoL), while it is considered that four phases of early frailty signs in the food environment and oral function are related to OHRQoL. In this study, the morbidity of deterioration of oral f...

Carbon nanomaterials (CNMs) are used in various functional materials and products as well as in basic research, mainly 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...

PURPOSE: 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. METHODS: Human enamel blocks were incubated in lactic acid solution (pH 4.0) with and without a disk (n...

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-d...

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 ma...

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...

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 1α (ERO1α) functions as an oxidat...

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 par...

We investigated patterning with curable dental materials via micro/nano-molding as a screening trial. We used typical curable dental materials such as a composite resin (CR), acrylic resin, varnish, adhesive resin, restoration, sealer, cement, tooth desensitizer, and gypsum with either a cyclo-olefin polymer (COP) mold or polydimethylsiloxane (PDMS...

We investigated the influence of micro/nano-grooved gelatin sheets on human osteoblasts (NHOst) and human gingival fibroblasts (HGF) for implant surface engineering purposes. We prepared grooved gelatin sheets with widths of 500 nm, 1 µm, and 2 µm via nano-imprinting and thermal crosslinking. We then compared the adhesion behavior and alignment of...

Various designs are used for surface textures of implants to achieve bone osseointegration on the implant for clinical success. In this in vitro study, Ti sheets with groove and pillar shapes of 500 nm, 1 μm, and 2 μm were made by a nanoimprinting method. Osteoblast-like cells (Saos-2 cells) were seeded on the Ti sheets at a density of 5000 cells/c...

Surface topography influences cell growth and differentiation. In this study, we used a nano-imprinting method to develop a titanium sheet with 500 nm-, 1 μm-, and 2 μm-wide grooved and pillared structures. We investigated the effects of the surfaces with the micro- and nano-structures on Ca9-22 cell adhesion and proliferation. Ca9-22 cells were cu...

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 i...

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 tita...

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 P...

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/nanogrooved dental c...

In the present study, we developed patterned apatites with grooves, pillars, and holes by micro-molding. The effects of the patterns on adhesion of the human osteoblastic cell line Saos-2 were investigated. The patterned apatites were fabricated with apatite cement paste using the micro-molding method. The number of attached cells and ratio of cell...

Purpose: The aim of this study was to compare masticatory performance, occlusal force, and oral health-related quality of life (OHRQoL) in patients with mandibular distal-extension edentulism between those with implant-supported fixed prostheses (ISFPs) and those with removable partial dentures (RPDs), and to evaluate relationships among them. Ma...

Carbon nanohorns (CNHs), formed by a rolled graphene structure and terminating in a cone, are promising nanomaterials for the development of a variety of biological applications. Here we demonstrate that alkaline phosphatase activity is dramatically increased by coculture of human monocyte derived macrophages (hMDMs) and human mesenchymal stem cell...

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...

Clinical guidelines or definitive criteria for “Occlusal consideration for fixed implant prosthesis in mandibular posterior region” have not been established yet although the dental implant is an essential treatment option for current prosthetic dentistry. This position paper aimed to propose a critical recommendation and consequently indicate a te...

The purpose of this study was to investigate the influence of occlusal forces (the contractile force of masticatory muscles) exerted during occlusal adjustment on the distribution of the forces among teeth, implants, and temporomandibular joints (TMJs) in intercuspal clenching in cases with bilateral missing molars and premolars by using finite ele...

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 i...

Purpose: The aim of this retrospective study was to compare the five-year survival and complication-free rates of the teeth adjacent to partial edentulous spaces of implant-supported fixed prostheses (ISFP) and removable partial dentures (RPD). Methods: The subjects were patients with ISFP or RPD inserted from 2003 to 2011 at the Clinic of Removabl...

Purpose: The short-form oral health impact profile (OHIP-14) is an effective tool for measuring oral health-related quality of life (OHRQoL). It is reported that the OHIP-14 is associated with oral condition and function, but there are few reports on the relationship between OHRQoL and psychophysiological background. In this study, we investigated...

Multi-walled carbon nanotubes (MWCNTs) were functionalized with fibroblast growth factor (FGF) and the advantages of their use as scaffolds for bone augmentation were evaluated in vitro and in vivo. The activity of FGF was assessed by measuring the effect on the proliferation of rat bone marrow stromal cells (RBMSCs). The presence of FGF enhanced t...

Because of their mechanical strength, chemical stability, and low molecular weight, carbon nanotubes (CNTs) are attractive biological implant materials. Biomaterials are typically implanted into subcutaneous tissue or bone; however, the long-term biopersistence of CNTs in these tissues is unknown. Here, tangled oxidized multi-walled CNTs (t-ox-MWCN...

Supplementary Information

Objective: We previously demonstrated that both masseter (MMNs) and digastric (DMNs) motoneurons in postnatal day (P) 1-5 rats receive convergent glutamatergic inputs from the supratrigeminal (SupV) and intertrigeminal (IntV) regions, the principal sensory trigeminal nucleus (PrV) and the region dorsal to the PrV (dRt). Furthermore, the lateral Sup...

Whole cells of wild-type strains of S. gordonii and S. mutans induced TLR2-mediated NF-κB activation, whereas those of lipoprotein-deficient strains did not. All strains upregulated proliferation of TLR2(+/+) splenocytes more strongly than TLR2(-/-) splenocytes. However, significant differences were not observed between the cytokine-inducing activi...

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. Sti...

The surface of a polylactic acid (PLLA) was coated multiwalled carbon nanotubes (MWCNTs) in order to improve the surface properties. In addition, its surface characteristics and cell culturing properties were examined. Whole surface of PLLA was homogeneously covered by MWCNTs maintained a unique tubular structure. MWCNT-coated PLLA showed remarkabl...

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 compo...

Carbon nanotubes (CNTs) have excellent chemical, physical, and biological properties such as strong cell adhesion, protein adsorption and cell proliferation in vitro. Excellent osteocompatibility for the CNT monolith was also reported in vivo. The purpose of this study was to evaluate the effects of anodized titanium coated with multiwalled CNTs (M...

The purpose of this study was to investigate the influence of occlusal forces (the contractile forces of the masticatory muscles) during occlusal adjustment on the distribution of forces on combinations of implants and teeth during intercuspal clenching by means of finite element analysis. Three-dimensional finite element models of the mandible, on...

Brain activity associated with manual stereognosis has been the focus of increasing recent research effort. However, although oral stereognosis, defined as the ability to recognize and discriminate the food bolus in the mouth, is important for mastication and swallowing, there is little information available about the neural network relating to thi...

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...

The purpose of this study was to quantitatively evaluate the effects of experimental leg length discrepancies on body posture and dental occlusion. Thirty asymptomatic subjects (15 males and 15 females, ages 19-33, mean age 25.6 years) were included in this study and randomly assigned to one of two groups based on a table of random numbers. The onl...

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 t...

A recent study showed that carbon nanohorns (CNHs) have biocompatibility and possible medical uses such as in drug delivery systems. It was reported that some kinds of carbon nanomaterials such as carbon nanotubes were useful for bone formation. However, the effect of CNHs on bone tissue has not been clarified. The purpose of this study was to eval...

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 cytoplas...

The purpose of this study was to temporally and spatially analyze movements of lower facial skin during left- and right-side chewing in order to examine, from the viewpoint of kinematics, whether functional differences existed between these movements on the two sides. Ten healthy young subjects (aged 24-32 years, mean age 26.7 years) were included...

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. The shapes of casts and waxed complete dentures were digitized. The determined shapes of the ridges were uniformly divided circumferentially and radially. Principal compone...

Objectives: We have studied various biological activities of microbial lipoproteins/lipopeptides. In this study, we investigated effects of oral Streptococci lacking of lipoproteins on the growth and immunosuppressive activity of regulatory T cells (Treg), which play important roles in maintaining and restoring a homeostatic environment by suppress...

Objectives: The purpose of this study was to evaluate the effect of changing body posture on body sway, head position, head and neck muscle activities and dental occlusion. Methods: Fifteen asymptomatic subjects (7 males and 8 females) volunteered for this study. The MatScan system was used to measure changes in body posture (center of foot press...

Objectives: The authors have reported the improvement of cell adhesion with multi-walled carbon nanotubes (MWCNT) coating. In this report, the cell adhesion and proliferation in the central region of the MWCNT-coated sponge were observed and bone tissue engineering by primary osteoblast cell culturing were investigated. Methods: Collagen sponge hon...

Objectives: It is not clear how the three-dimensional morphology of edentulous alveolar ridges influences denture movement. The purpose of this study was to clarify the morphological factors of ridges that determine the stability of complete dentures during intercuspal clenching and could serve as efficient criteria for evaluation. Methods: Seventy...

The cell adhesion in a multiwalled carbon nanotube-coated collagen sponge (MWCNT-coated sponge) was investigated. Immediately after seeding, the cells adhered to the inner surface of the MWCNT-coated sponge and a significantly larger number of cells were observed there than for a pure collagen sponge used as control. On the MWCNT-coated sponge, the...

One strategy used for the regeneration of bone is the development of cell culture substrates and scaffolds that can control osteoblast proliferation and differentiation. In recent investigations, carbon nanotubes (CNTs) have been utilized as scaffolds for osteoblastic cell cultures; however, there are only a few reports describing the proliferation...