Yoshiyuki Hagiwara

Photofunctionalization increases the bioactivity and osteoconductivity of the titanium alloy Ti6Al4V.

This study examined the effect of photofunctionalization on bioactivity and osteoconductivity of titanium alloy Ti6Al4V. We also tested a hypothesis that the effect of photofunctionalization is as substantial as the one of surface roughening. Two different surface morphology, a roughened surface (sandblasted and acid-etched surface) and relatively smooth surface (machined surface), was tested. Ti6Al4V samples were photofunctionalized with UV light for 15 min using a photo device. Photofunctionalization converted Ti6Al4V surfaces from hydrophobic to superhydrophilic. The attachment, spread, proliferation, and the expression of functional phenotype of bone marrow-derived osteoblasts were promoted on photofunctionalized Ti6Al4V surfaces. The strength of bone-implant integration examined using a biomechanical push-in test in a rat femur model was at least 100% greater for photofunctionalized implants than for untreated implants. These effects were seen on both surface types. The strength of bone-implant integration for photofunctionalized machined implants was greater than that for untreated roughened implants, indicating that the impact of photofunctionalization may be greater than that of surface roughening. Newly prepared Ti alloy was hydrophilic, whereas the hydrophilic status degraded with time and was converted to hydrophobic in 4 weeks. This finding uncovered biological aging of Ti alloy and allowed us to consider photofunctionalization as a countermeasure for aging. These results suggest that photofunctionalization accelerates and enhances bone-implant integration of Ti6Al4V regardless of smooth and roughened surface features, supporting photofunctionalization as an effective and viable measure for improving efficacy of a wide range of Ti6Al4V-based materials used in dental and orthopedic medicine.

Effects of professional oral health care on elderly: randomized trial.

OBJECTIVE To better understand the role of the professional oral health care for elderly in improving geriatric oral health, the effects of short-term professional oral health care (once per week for 1 month) on oral microbiological parameters were assessed. METHODS Parallel, open-labelled, randomize-controlled trial was undertaken in a nursing home for elderly in Shizuoka, Japan. Thirty-four dentate elderly over 74 years were randomly assigned from ID number to the intervention (17/34) and control (17/34) groups. The outcomes were changes in oral microbiological parameters (number of bacteria in unstimulated saliva; whole bacteria, Streptococcus, Fusobacterium and Prevotella: opportunistic pathogens detection: and index of oral hygiene evaluation [Dental Plaque Index, DPI]) within the intervention period. Each parameter was evaluated at before and after intervention period. Four elderly were lost from mortality (1), bone fracture (1), refused to participate (1) and multi-antibiotics usage (1). Finally, 30 elderly were analysed (14/intervention and 16/control). RESULTS At baseline, no difference was found between the control and intervention groups. After the intervention period, the percentage of Streptococcus species increased significantly in the intervention group (Intervention, 86% [12/14]; Control, 50% [8/16]: Fishers, right-tailed, P < 0.05). Moreover, DPI significantly improved in the intervention group (Intervention, 57% [8/14]; Control, 13% [2/16]: Fishers, two-tailed, P < 0.05). The improvement in DPI extended for 3 months after intervention. None of side effects were reported. CONCLUSION The short-term professional oral health care can improve oral conditions in the elderly.

Effect of photofunctionalization on fluoride-treated nanofeatured titanium

The objective of this study was to evaluate the effect of ultraviolet light treatment, known as photofunctionalization, on the biological and osseointegration capability of nanofeatured titanium created by a combination of sandblasting and hydrofluoric acid treatment. Titanium samples in disk and cylinder forms were photofunctionalized by treatment with ultraviolet light for 15 min. The nanofeatured surface was converted from hydrophobic to superhydrophilic after photofunctionalization. The strength of osseointegration measured by a biomechanical push-in test in a rat model was stronger for photofunctionalized implants than for untreated implants by 2.2 and 2.3 times, respectively, at the early (week 2) and late (week 4) stages of healing, implying that photofunctionalization did not only accelerate but also increased the degree of osseointegration. Culture studies using bone marrow-derived osteoblasts showed that the attachment, spread, and functional phenotypes of osteogenic cells, such as alkaline phosphatase activity and mineralization, were remarkably increased on photofunctionalized titanium. In conclusion, photofunctionalization substantially increased biological and osseointegration capability of a nanofeatured titanium surface. In light with proven effectiveness on microfeatured surfaces in the literature, photofunctionalization may provide a novel and practical avenue to further improve osseointegration capability of implants in a wide range of surface morphology with micro-to-nano features.

Application of Ce-TZP/Al2O3 nanocomposite to the framework of an implant-fixed complete dental prosthesis and a complete denture.

PATIENT A 69-year-old Japanese male visited Nihon University Dental Hospital for refabrication of his mandibular implant-supported complete fixed prosthesis (ISCFPD) and maxillary complete denture, which had been fabricated 15 years previously. In this case, Ce-TZP/Al2O3 nanocomposite (Ce-TZP/A) was applied to the framework of the mandibular ISCFPD and maxillary complete denture. Three years after deliver of the framework, no particularly notable biological or prosthetic complications were observed, and a high level of patient satisfaction had been achieved. DISCUSSION Conventional ISCFPD frameworks were fabricated by casting gold alloys; however, with the recent advancement of CAD/CAM technology, titanium (Ti) or yttria tetragonal zirconia polycrystal (Y-TZP) frameworks have become more common. In contrast, the main fabrication method for Ti or Co-Cr frameworks of removable dental prostheses has shifted from the conventional casting method to CAD/CAM fabrication. Ce-TZP/A, which was chosen as the framework material this time, shows higher strength and greater toughness than Y-TZP. However, since it has a low light-transmitting property and exhibits an opaque white color, the range of its application in fixed prostheses, particularly in the esthetic area, is limited. CONCLUSION We described a case in which Ce-TZP/A was applied to the frameworks of a mandibular ISCFPD and a maxillary complete denture. No particularly notable biological or prosthetic complications were observed in the mandibular ISCFPD or the maxillary complete denture, and a high level of patient satisfaction was achieved. Medium- and long-term observations with a greater number of cases are essential to obtain information concerning various phenomena related to this procedure.

Current status of implant prosthetics in Japan: a survey among certified dental lab technicians

BackgroundThere are many implant cases in which dental technicians take initiative with regard to the design of implant prostheses, and to a certain extent, this area of care is one in which dentists do not necessarily play the leading role. Moreover, inadequate communication between dental technicians and dentists and insufficient instructions for technicians has been highlighted as issues in the past. The purpose of this questionnaire is to improve the quality of implant prostheses and thereby contribute to patient service by clarifying, among other aspects of treatment, problem areas and considerations in the fabrication of implant prostheses, conceptual-level knowledge, and awareness of prosthodontics on the part of the dentists in charge of treatment and methods for preventing prosthetic complications.MethodsA cross-sectional survey was given to 120 certified dental technicians. To facilitate coverage of a broad range of topics, we classified the survey content into the following four categories and included detailed questions for (1) the conditions under which implant technicians work, (2) implant fixed prostheses, (3) implant overdentures, and (4) prosthetic complications.ResultsOut of 120 surveys sent, 74 technicians responded resulting in a response rate of 61.6%.ConclusionsThis survey served to clarify the current state of implant prosthodontics, issues, and considerations in the fabrication of implant prostheses, and the state of prosthetic complications and preventive initiatives, all from a laboratory perspective. The results of this survey suggested that, to fabricate prostheses with a high level of predictability, functional utility, and aesthetic satisfaction, it is necessary to reaffirm the importance for dentists to increase their prosthetic knowledge and work together with dental technicians to develop comprehensive treatment plans, implement an organized approach to prosthesis design, and accomplish occlusal reconstruction.

Dental Implant Status of Patients Receiving Long-Term Nursing Care in Japan

BACKGROUND The increase in implant patients is expected to give rise to a new problem: the changing general health status of those who have had implants placed. PURPOSE The aim of this present study was to find out the needs of and proper measures for elderly implant patients in long-term care facilities. MATERIALS AND METHODS A questionnaire was sent by mail to 1,591 long-term care health facilities, daycare services for people with dementia, and private nursing homes for the elderly in the Osaka area, which is in the middle area of Japan, in order to extract patients with cerebrovascular disease or dementia who were possibly at risk of inadequate oral self-care, as well as patients with implants. RESULTS Approximately half of all facilities responded that they cannot recognize implants, and many facilities did not know anything about oral care for implant patients. Residents with implants were reported at 19% of all facilities. Also, the facilities pointed out problems with implants relating to the difference in oral care between implants and natural teeth. CONCLUSIONS There are people with implants in some 20% of caregiving facilities, and there is a low level of understanding regarding implants and their care among nurses and care providers who are providing daily oral care.

Enhancement of Orthodontic Anchor Screw Stability Under Immediate Loading by Ultraviolet Photofunctionalization Technology

PURPOSE Ultraviolet (UV)-mediated photofunctionalization technology is intended to enhance the osseointegration capability of titanium implants. There are concerns about orthodontic anchor screws loosening under immediate loading protocols in adolescent orthodontic treatment. The purpose of this in vivo study was to evaluate the effects of photofunctionalization on the intrabony stability of orthodontic titanium anchor screws and bone-anchor screw contact under immediate loading in growing rats. MATERIALS AND METHODS Custom-made titanium anchor screws (1.4 mm in diameter and 4.0 mm in length) with or without photofunctionalization pretreatment were placed on the proximal epiphysis of the tibial bone in 6-week-old male Sprague-Dawley rats and were loaded immediately after placement. After 2 weeks of loading, the stability of the anchor screws was evaluated using a Periotest device, and the bone-anchor screw contact ratio (BSC) was assessed by a histomorphometric analysis using field-emission scanning electron microscopy. RESULTS In the unloaded group, Periotest values (PTVs) were ~25 for UV-untreated screws and 13 for UVtreated screws (P < .01), while in the immediate-loading group, PTVs were 28 for UV-untreated screws and 16 for UV-treated screws (P < .05). Significantly less screw mobility was observed in both UV-treated groups regardless of the loading protocol. The BSC was increased ~1.8 fold for UV-treated screws, compared with UV-untreated screws, regardless of the loading protocol. CONCLUSION Photofunctionalization enhanced the intrabony stability of orthodontic anchor screws under immediate loading in growing rats by increasing bone-anchor screw contact.

Bone Generation Profiling Around Photofunctionalized Titanium Mesh.

PURPOSE The aim of this study was to evaluate whether photofunctionalization of titanium mesh enhances its osteoconductive capability. MATERIALS AND METHODS The titanium mesh (0.2 mm thickness) used in this study was made of commercially pure grade-2 titanium and had hexagonal apertures (2 mm width). Photofunctionalization was performed by treating titanium mesh with UV light for 12 minutes using a photo device immediately before use. Untreated or photofunctionalized titanium mesh was placed into rat femurs, and bone generation around titanium mesh was profiled using three-dimensional (3D) microcomputed tomography (micro-CT). A set of in vitro experiments was conducted using bone marrow-derived osteoblasts. RESULTS Photofunctionalized titanium mesh surfaces were characterized by the regenerated hydrophilicity and significantly reduced surface carbon. Bone generation profiling at week 3 of healing showed that the hexagonal apertures in photofunctionalized mesh were 95% filled, but they were only 57% filled in untreated mesh, particularly with the center zone remaining as a gap. Bone profiling in slices parallel to the titanium surface showed that photofunctionalized titanium mesh achieved 90% bone occupancy 0 to 400 μm from the surface, compared with only 35% for untreated mesh. Bone occupancy remained as high as 55% 800 to 1,200 μm from photofunctionalized titanium mesh surfaces, compared with less than 20% for untreated mesh. In vitro, photofunctionalized titanium mesh expedited and enhanced attachment and spread of osteoblasts, and increased ALP activity and the rate of mineralization. CONCLUSION This study may provide novel and advanced metrics describing the osteoconductive property of photofunctionalized titanium mesh. Specifically, photofunctionalization not only increased the breadth, but also the 3D range, of osteoconductivity of titanium mesh, enabling space-filling and far-reaching osteoconductivity. Further translational and clinical studies are warranted to establish photofunctionalized titanium mesh as a novel clinical tool for better bone regeneration and augmentation.

External versus internal abutment connection implants: a survey of opinions and decision making among experienced implant dentists in Japan

Internal connection implants have been attracting attention in recent years leading to their being adopted for many implant systems and an increase in market share over other connections. However, internal connection implants have only been used clinically for a short period of time resulting in few clinical studies investigating outcomes and a lack of comparative clinical evidence to support their use over external hex systems at this time. Given the fact that clinical evidence is lacking regarding implant connection performance comparisons, it is important to understand what information clinicians use to choose between systems. The purpose of this study regarding implant decision-making was to ask clinicians to provide subjective evaluations of internal connection implants, in comparison with external connection implants. The survey was constructed to cover four aspects of interest; general responder information, surgical procedures and experience, prosthodontic treatments and outcomes, and implant complications. The dentists’ responses indicated that internal connection implants are as user-friendly as external hex implants with respect to implant surgery, but they are favored for prosthodontic handling because impression coping and abutment placement are felt to be easier. In addition, it was revealed that dentists strongly feel that there is a lack of biological and prosthodontic evidence to support the use of internal connection implants. The findings reveal the responding clinicians recognize that they often make decisions without compelling evidence to favor one system over another. Decisions are often based on perceived ease of use or third party (colleague or manufacturer) input. For future investigations, we will seek to better understand the relative influence and validity of all forms of information used (especially third party input), as well as what barriers exist to clinicians’ use of more evidence based data.

Repair of a Multiple Implant-Supported Fixed Superstructure With a Metal-Ceramic Resin-Bonded Fixed Partial Denture: A Clinical Report

Even in the case of implant loss, replacement of the implant and refabrication of the superstructure are often sufficient, as long as the bone and soft tissue are in good condition. However, if implant loss accompanied by serious bone resorption occurs with a fixed implant superstructure supported by multiple implants, it is very difficult to treat. This clinical report describes the process by which multiple implant-supported fixed metal ceramic restorations were repaired with a metal ceramic resin-bonded fixed partial denture without complete refabrication after removal of one of the implants due to severe bone resorption. The 3-year follow-up indicated excellent serviceability and a well-satisfied patient.Abstract Even in the case of implant loss, re-placement of the implant and re-fabrication of the superstructure are often sufficient, as long as the bone and soft tissue are in good condition. However, if implant loss accompanied by serious bone resorption occurs with a fixed implant superstructure supported by multiple implants, it is very difficult to treat. This clinical report is to describe the process by which a multiple implant-supported fixed metal ceramic restorations were repaired with a metal ceramic resin bonded FPD (MC RBFPD) without complete re-fabrication following removal of one of the implants due to severe bone resorption. The 3-year follow-up indicated excellent serviceability and a well-satisfied patient.