Yasufumi Nishikawa, Yoritoki Tomotake, Hiromichi Kawano, Koji Naruishi, Jun-ichi Kido, Yuka Hiroshima, Akikazu Murakami, Tetsuo Ichikawa and Hiromichi Yumoto : Effects of Candidalysin Derived from Candida albicans on the Expression of Pro-Inflammatory Mediators in Human Gingival Fibroblasts, International Journal of Molecular Sciences, Vol.24, No.4, 3256, 2023.
Rie Kido, Jun-ichi Kido, Yasufumi Nishikawa, Eijiro Sakamoto, Yoritoki Tomotake and Hiromichi Yumoto : Diagnosis of inflammatory peri-implant diseases using an immunochromatographic assay for calprotectin in peri-implant crevicular fluid, International Journal of Implant Dentistry, Vol.7, No.1, 106, 2021.
(要約)
The incidence rate of peri-implant diseases is increasing with implant placement. Early detection of peri-implant diseases is important to prevent and treat these diseases, and a simple and objective diagnostic method is expected. Immunochromatographic (IC) assays are used for rapid diagnostic methods for some diseases. The aim of this clinical study was to determine the amount of calprotectin, an inflammatory marker, in peri-implant crevicular fluid (PICF) using an IC chip, and estimate the possibility of this diagnostic system. Forty-six individuals with dental implants participated in a pilot study. PICF samples were collected from the peri-implant sites with or without inflammation after clinical examinations including probing depth (PD), bleeding on probing (BOP) and gingival index (GI). Calprotectin in PICF was determined by an IC chip and enzyme-linked immunosorbent assay (ELISA) for calprotectin. The density of calprotectin line on the IC chip was measured using an IC reader (IC reader value). The relationship between IC reader value and ELISA value or clinical parameters was investigated. A receiver operating characteristic (ROC) curve analysis of IC reader value of calprotectin was performed to predict inflammation in peri-implant diseases. IC reader value of calprotectin was significantly correlated with its ELISA value and PD. IC reader values of calprotectin in PICF samples from periodontal sites with GI-1 and GI-2, and with BOP-positive sites were significantly higher than those of PICF samples from GI-0 sites, and BOP-negative sites, respectively. The IC reader value for calprotectin in PICF samples from inflammatory diseased sites was significantly higher than that of non-diseased sites. ROC analysis suggested that the IC reader value of PICF calprotectin was useful for predicting inflammatory peri-implant diseases. IC assay for PICF calprotectin may be a possible system for diagnosing the inflammatory peri-implant diseases.
友竹 偉則, 川野 弘道, 西川 泰史, 武川 香織, 富永 賢, 市川 哲雄 : 徳島大学病院口腔インプラントセンターにおける新来患者の臨床統計, Journal of Oral Health and Biosciences, Vol.33, No.2, 39-44, 2021年.
(要約)
<b>Purpose:</b> Oral Implant Center established in April 2014 as specialized clinical section at Tokushima University Hospital. The aim of this study was to report a survey of new patients of preoperative registration at Oral Implant Center during the five years since its establishment.<br> <b>Subjects and methods:</b> Investigation of gender and age, chief complaint, details of treatment requests, sites of missing teeth, number of missing teeth, cause of tooth extraction, and treatment status for patients registered at Oral Implant Center from April 2014 to March 2019 were performed.<br> <b>Results:</b> Regarding the chief complaint, 605 (88.3%) patients consulted preoperatively for a request for implant treatment, and 80 (11.7%) consulted about complain of previous implant treatment or a request for continued maintenance. The average number of missing teeth for which treatment was requested was 3.8. The proportion of patients who wished to be treated for the number of missing teeth was 32.2% for missing one tooth, 56.1% for missing few teeth (2 to 6 teeth), 7.8% for missing many teeth (7 or more teeth) and edentulous 3.9%. As for the details of treatment requests of 80 patients who had already received implant treatment, 33 (41.3%) consulted on the improper superstructure, 29 (36.3%) wished to examine and treat peri-implantitis, 4 (5%) wished to remove the implant and 14 (17.5%) requested continued maintenance.<br> <b>Discussion and conclusion:</b> The number of new patients regarding implant treatment has been about the same each year, and it was reconfirmed that it was recognized as a treatment method for dental prostheses. In particular, many patients wished to receive implant treatment for a single tooth missing, suggesting that the patients also recognized the importance of preserving the remaining teeth. On the other hand, the number of patients complaining of previous implant treatment tends to increase, and it is necessary to consider future correspondence.
(キーワード)
Oral Implant Center / implant treatment / preoperative registration
Takaharu Goto, Nobuaki Higaki, Takahiro Kishimoto, Yoritoki Tomotake and Tetsuo Ichikawa : Does periodontal tactile input uniquely increase cerebral blood flow in the prefrontal cortex?, Brain Sciences, Vol.10, No.8, E482, 2020.
(要約)
We previously studied the effect of peripheral sensory information from sensory periodontal ligament receptors on prefrontal cortex (PFC) activity. In the dental field, an alternative dental implant without periodontal sensation can be applied for missing teeth. In this study, we examine whether periodontal tactile input could increase cerebral blood flow (CBF) in the PFC against elderly patients with dental implants lacking periodontal tactile (implant group), elderly individuals with natural teeth (elderly group), and young individuals with natural teeth (young group). The experimental task of maintaining occlusal force as closed-loop stimulation was performed. Compared with the young group, the elderly group showed significantly lower CBF. Contrastingly, compared with the young group, the implant group showed significantly lower CBF. There were no significant differences between the elderly and implant groups. Regarding the mean occlusal force value, compared with the young group and the elderly group, the implant group had a numerically, but not significantly, larger occlusal force exceeding the directed range. In conclusion, the periodontal tactile input does not uniquely increase PFC activity. However, increased CBF in the PFC due to the periodontal tactile input in the posterior region requires existing attention behavior function in the PFC.
Eijiro Sakamoto, Rie Kido, Yoritoki Tomotake, Yoshihito Naitou, Yuichi Ishida and Jun-ichi Kido : Calprotectin and cross-linked N-telopeptides of type I collagen levels in crevicular fluid from implant sites with peri-implant diseases: a pilot study, International Journal of Implant Dentistry, Vol.4, No.1, 26, 2018.
(要約)
Peri-implant crevicular fluid (PICF) contains calprotectin and NTx, which are markers for inflammation and bone resorption, respectively. The aims of this pilot study were to compare calprotectin and NTx levels in PICF from implant sites with or without peri-implant diseases and to evaluate the usefulness of calprotectin and NTx as diagnostic markers for peri-implant diseases. Thirty-five patients with dental implants participated in this pilot study. PICF samples were collected from peri-implant disease sites (n = 40) and non-diseased (healthy) sites (n = 34) after clinical indicators including probing depth (PD), bleeding on probing (BOP), gingival index (GI), and bone loss (BL) rate were investigated. Calprotectin and NTx amounts in PICF were measured using their respective ELISA kits and then compared between diseased and healthy samples. The relationship between PICF calprotectin or NTx levels and clinical indicator levels was investigated. A receiver operating characteristic (ROC) curve analysis of calprotectin and NTx was performed to predict peri-implant diseases. Calprotectin and NTx levels in PICF were significantly higher from peri-implant disease sites than from healthy sites. PICF calprotectin amounts correlated with PD, and its levels were significantly higher in the GI-1 and GI-2 groups than in the GI-0 group. PICF NTx amounts correlated with PD and the BL rate. ROC curves indicated that PICF calprotectin and NTx are useful biomarkers for peri-implant diseases. Calprotectin and NTx in PICF have potential as biomarkers for the diagnosis of peri-implant diseases.
Yoshihito Naitou, Hiromichi Yumoto, K Hs Kumar, Takashi Matsuo, Katsuhiko Hirota, Yoichiro Miyake, Kan Nagao, Yoritoki Tomotake, R Jimbo and Tetsuo Ichikawa : Antifungal and Mechanical Properties of Tissue Conditioner Containing Plant-Derived Component, --- An In Vitro Study ---, Journal of Prosthodontics, Vol.27, No.7, 665-669, 2018.
(要約)
To evaluate the antifungal activity and mechanical properties of a novel antifungal tissue conditioner containing Juncus powder. Juncus powder was mixed with GC tissue conditioner at concentrations of 2.5%, 5.0%, and 10.0% by mass. The cylindrical specimens of Juncus-mixed tissue conditioner (dimensions: 10 mm in diameter and 2 and 6 mm in height for antimicrobial and mechanical tests, respectively) were prepared. The specimens placed on the bottom of the 24-well tissue culture plate were cultured with Candida albicans CAD1 for 2 and 4 days. The proliferation of the C. albicans in the wells was determined by measuring the optical density of fungal culture, and the surface of the specimens were also observed by scanning electron microscopy (SEM). To assess the mechanical properties of the specimens, the fluidity and hardness of Juncus-mixed tissue conditioner were measured using the methods certified according to ISO 10139-1. Juncus-mixed tissue conditioner significantly exhibited growth inhibitory effect in a Juncus concentration-dependent manner after both 2- and 4- day cultures. SEM observation showed that the amount of C. albicans on Juncus-mixed specimens drastically decreased, and biofilm formation was markedly inhibited. Moreover, both mechanical properties were found to be within the ranges regulated and specified by ISO. These findings demonstrated that the tissue conditioner including Juncus powder has a significant growth inhibitory effect against C. albicans, and it is suggested that the application of Juncus-mixed tissue conditioner may prevent denture stomatitis and oral candidiasis in denture wearers.
Gantumur Chimeddulam, Keisuke Nishigawa, Yoshihito Naitou, Junhel Dalanon, S Afroz, Rika Hayama, Masamitsu Ohshima, Yoritoki Tomotake, Tetsuo Ichikawa and Yoshizo Matsuka : Radiographic investigation of the marginal bone loss on dental implants, a retrospective cohort study, Journal of Oral Health and Biosciences, Vol.31, No.1, 13-24, 2018.
(要約)
Background: During functional loading, the design of the dental implant may have an effect on the response of marginal bone.Objectives: The purpose of this study was to report the prevalence of peri-implantitis, and to compare radiographic parameters around Brånemark and Replace Select dental implants and evaluate whether disparities in the morphologic features of these two indistinct implant systems, particularly their abutment-implant attachment, had an influence on the health of surrounding tissues and marginal bone loss (MBL).Materials and Methods: Collection of data was done at the Department of Fixed Prosthodontics, the Department of Maxillo-Facial Prosthodontics, and Oral Implant Center of Tokushima University Hospital, in Tokushima, Japan; between March 2003 and followed until January 2017. Patients who have been treated with the Replace Select internal type implant and the Brånemark variety were selected as cohort. Marginal bone level measurements were evaluated via periapical and panoramic radiographs taken at regular follow-up visit. These dimensions were calculated, starting from the orientation mark at the implant abutment interface to the bottommost perceived contact area of marginal bone with the aforementioned implant system. The change in the level of bone was estimated by calculating the variation involving an initial reference value and the follow-up values.Results: An average loss of bone at 0.65 ± 1.51 mm (range 0.36 to 7.89 mm) in the Replace Select group was observed, while in the Brånemark group 0.7 ± 1.32 mm (range 0.62 to 8.64 mm) was observed. Spearman rank correlation exhibited a statistically significant positive correlation between progress of bone loss around implant body and interval from implantation in the Brånemark group, whereas in the Replace Select group it was not significant. The Brånemark group exhibited significant (P = 0.0269) negative correlation of MBL and its diameters, whereas the Replace Select group did not exhibit such correlation.Conclusion: Within the limits of this study, it can be concluded that deviations in the morphologic attributes of these two diverse implant systems had an influence on the health of surrounding tissues and MBL. The Brånemark implants showed a significant increase in MBL (> 1.8mm) as the time of placement elapses. This marked MBL was greater in females than males, in posterior than in anterior, and in the narrow platform implants than the regular platform implants or the wide platform implants. On the other hand, results suggested that this bone loss was greater in the mandible than the maxilla, in single-unit implant crowns than multiple implant restorations in the Replace Select group.
(キーワード)
dental implant / marginal bone loss / retrospective cohort study / implant design
市川 哲雄, 友竹 偉則, 田島 登誉子, 内藤 禎人, 清水 裕次, 石田 雄一 : グラスファイバーで補強された高強度コンポジットレジンを用いた3ユニットブリッジ治療について(原著論文), Journal of Oral Health and Biosciences, Vol.28, No.2, 55-62, 2016年.
(要約)
Mechanical strength to withstand occlusal force is required to the crown restorations of molars. Ag-Pd-Au alloy has been used as the acceptable material of the National Health Insurance system in Japan. However, the metallic color of prosthesis does not meet the aesthetic requirements of the patients, and there is also a problem to the provider side of the treatment that the price fluctuation is large by soaring material costs. A fiber reinforced metal-less bridge is proposed to resolve these problems and we began clinical application of this prosthetic treatment from September, 2012 on the approval of Tokushima University Hospital ethics committee. So far, six patients have been treated with 8 fiber reinforced bridges, and this treatment in Tokushima University Hospital was approved in Shikoku Regional Bureau of Health and Welfare as the advanced medical. We have followed the treatment for a maximum of more than two years, and it has been passed successfully with patient's satisfaction. Slightly problems which were caused in the hybrid resin material, could be easily solved by the direct procedures. This clinical results in short term suggested that the fiber reinforced metalless bridge have a sufficiently high therapeutic effect as a prosthetic method.
Takashi Matsuda, Takaharu Goto, Kosuke Kurahashi, Toshiya Kashiwabara, Megumi Watanabe, Yoritoki Tomotake, Kan Nagao and Tetsuo Ichikawa : Digital assessment of preliminary impression accuracy for edentulous jaws: Comparisons of 3-dimensional surfaces between study and working casts, Journal of Prosthodontic Research, Vol.60, No.3, 206-212, 2016.
(要約)
The aim of this study was to compare 3-dimensional surfaces of study and working casts for edentulous jaws and to evaluate the accuracy of preliminary impressions with a view to the future application of digital dentistry for edentulous jaws. Forty edentulous volunteers were serially recruited. Nine dentists took preliminary and final impressions in a routine clinical work-up. The study and working casts were digitized using a dental 3-dimensional scanner. The two surface images were superimposed through a least-square algorithm using imaging software and compared qualitatively. Furthermore, the surface of each jaw was divided into 6 sections, and the difference between the 2 images was quantitatively evaluated. Overall inspection showed that the difference around residual ridges was small and that around borders were large. The mean differences in the upper and lower jaws were 0.26mm and 0.45mm, respectively. The maximum values of the differences showed that the upward change mainly occurred in the anterior residual ridge, and the downward change mainly in the posterior border seal, and the labial and buccal vestibules, whereas every border of final impression was shortened in the lower jaw. The accuracy in all areas except the border, which forms the foundation, was estimated to be less than 0.25mm. Using digital technology, we here showed the overall and sectional accuracy of the preliminary impression for edentulous jaws. In our clinic, preliminary impressions have been made using an alginate material while ensuring that the requisite impression area was covered.
Yuki Iwawaki, Noriko Mizusawa, Takeo Iwata, Nobuaki Higaki, Takaharu Goto, Megumi Watanabe, Yoritoki Tomotake, Tetsuo Ichikawa and Katsuhiko Yoshimoto : MiR-494-3p induced by compressive force inhibits cell proliferation in MC3T3-E1 cells., Journal of Bioscience and Bioengineering, Vol.120, No.4, 456-462, 2015.
(要約)
Mechanical stimuli regulate fundamental cell processes such as proliferation, differentiation, and morphogenesis. We attempted to identify microRNA (miRNA) whose expression is changed during compressive treatment in MC3T3-E1, a pre-osteoblastic cell line. Microarray analysis followed by reverse transcription-quantitative polymerase chain reaction revealed that compressive force at 294 Pa for 24 h in MC3T3-E1 cells increased levels of miR-494-3p, miR-146a-5p, miR-210-3p, and miR-1247-3p. Among these miRNAs, miR-494-3p was found to inhibit cell proliferation in MC3T3-E1 cells. Furthermore, cells subjected to compressive force showed slower cell growth compared with control cells. Levels of mRNA for fibroblast growth factor receptor 2 (FGFR2) and Rho-associated coiled-coil kinase 1 (ROCK1), which were predicted to be targets of miR-494-3p, were decreased by compressive force or overexpression of miR-494-3p mimics in MC3T3-E1 cells. Furthermore, binding sites of miR-494-3p within 3'-untranslated regions of Fgfr2 and Rock1 were determined using luciferase reporter assay. In conclusion, compressive force affected expressions of several miRNAs including miR-494-3p in MC3T3-E1 cells. Compressive force might inhibit cell proliferation in osteoblasts by up-regulating miR-494-3p followed by FGFR2 and ROCK1 gene repressions.
Takaharu Goto, Kan Nagao, Yuichi Ishida, Yoritoki Tomotake and Tetsuo Ichikawa : Influence of female attachment installation load on movement and resultant forces in implant overdentures, Journal of Prosthodontics, Vol.24, No.2, 156-163, 2015.
(要約)
This in vitro study investigated the effect of attachment installation conditions on the load transfer and denture movements of implant overdentures, and aims to clarify the differences among the three types of attachments, namely ball, Locator, and magnet attachments. Three types of attachments, namely ball, Locator, and magnetic attachments were used. An acrylic resin mandibular edentulous model with two implants placed in the bilateral canine regions and removable overdenture were prepared. The two implants and bilateral molar ridges were connected to three-axis load-cell transducers, and a universal testing machine was used to apply a 50 N vertical force to each site of the occlusal table in the first molar region. The denture movement was measured using a G(2) motion sensor. Three installation conditions, namely, the application of 0, 50, and 100 N loads were used to install each attachment on the denture base. The load transfer and denture movement were then evaluated. The resultant force decreased with increasing installation load for all attachments. In particular, the resultant force on implants on the loading side of the Locator attachment significantly decreased when the installation load was increased from 0 to 50 N, and that for magnetic attachment significantly decreased when the installation load was increased from 50 to 100 N. For the residual ridges on the loading side, the direction of the forces for all attachments changed to downward with increasing installation load. Furthermore, the yaw Euler angle increased with increasing installation load for the magnetic attachment. Subject to the limitations of this study, the use of any installation load greater than 0 N is recommended for the installation of ball and Locator attachments on a denture base. Regarding magnetic attachments, our results also recommend installation on a denture base using any installation load greater than 0 N, and suggest that the resultant force acting on the implant can be decreased by increasing the installation load; however, a large installation load of 100 N should be avoided when installing the attachment on the denture base to avoid increasing the denture movement.
Many studies on surface modifications of titanium have been performed in an attempt to accelerate osseointegration. Recently, anatase titanium dioxide has been found to act as a photocatalyst that expresses antibiotic properties and exhibits hydrophilicity after ultraviolet exposure. A blue-violet semiconductor laser (BV-LD) has been developed as near-ultraviolet light. The purpose of this study was to investigate the effects of exposure to this BV-LD on surface modifications of titanium with the goal of enhancing osteoconductive and antibacterial properties. The surfaces of pure commercial titanium were polished with #800 waterproof polishing papers and were treated with anatase titania solution. Specimens were exposed using BV-LD (λ = 405 nm) or an ultraviolet light-emitting diode (UV-LED, λ = 365 nm) at 6 mW/cm(2) for 3 h. The surface modification was evaluated physically and biologically using the following parameters or tests: surface roughness, surface temperature during exposure, X-ray diffraction (XRD) analysis, contact angle, methylene blue degradation tests, adherence of Porphyromonas gingivalis, osteoblast and fibroblast proliferation, and histological examination after implantation in rats. No significant changes were found in the surface roughness or XRD profiles after exposure. BV-LD exposure did not raise the surface temperature of titanium. The contact angle was significantly decreased, and methylene blue was significantly degraded. The number of attached P. gingivalis organisms was significantly reduced after BV-LD exposure compared to that in the no exposure group. New bone was observed around exposed specimens in the histological evaluation, and both the bone-to-specimen contact ratio and the new bone area increased significantly in exposed groups. This study suggested that exposure of titanium to BV-LD can enhance the osteoconductivity of the titanium surface and induce antibacterial properties, similar to the properties observed following exposure to UV-LED.
The purpose of this study was to evaluate stress analysis of a magnet-retained mini-implant overdenture on an in vitro mandibular model. Mini implants less than 3.0 mm in diameter have been used as not only provisional use, but also permanent use to support overdentures.<br/>Four mini implants (MagDen Fixture MFI4010RF, Shinwon Dental, Seoul, Korea) were placed in edentulous regions between bilateral canines in an acrylic resin mandibular model and the abutments (MagDen Keeper MFK4020, Shinwon Dental, Seoul, Korea) for magnet attachments were used. Seven strain gauges were attached on the resin surface around the right side of two mini implants. The surface of the model was covered with silicone impression material to simulate oral mucosa and an experimental complete denture was placed on the model. A vertical force of 50 N was applied to either one of the premolar, first molar and second molar of the experimental denture using a universal testing machine. <br/>When four mini implants were supported, compressive strains were caused at the lingual side of the distal mini implant. The more posterior the loading point was, the lower the strain around the implant was generally. Although tensile strain was caused at the buccal side of the mesial mini implant, it decreased at the moment when compressive strain arose. When four implants were supported, the strain around the mini implants was distributed more evenly than those in the two implant-supported ones. The influence of implant positioning was examined by removing either two mesial or two distal attachments in the four mini implants. The maximum strain in two mesial implant-supported attachments was smaller than that in two distal implant-supported attachments.
(キーワード)
mini implant / stress analysis / magnetic attachment / overdenture / strain
Hideki Suito, Yuki Iwawaki, Takaharu Goto, Yoritoki Tomotake and Tetsuo Ichikawa : Oral factors affecting titanium elution and corrosion: an in vitro study using simulated body fluid., PLoS ONE, Vol.8, No.6, e66052, 2013.
(要約)
Ti, which is biocompatible and resistant to corrosion, is widely used for dental implants, particularly in patients allergic to other materials. However, numerous studies have reported on Ti allergy and the in vitro corrosion of Ti. This study investigated the conditions that promote the elution of Ti ions from Ti implants. Specimens of commercially pure Ti, pure nickel, a magnetic alloy, and a gold alloy were tested. Each specimen was immersed in a simulated body fluid (SBF) whose pH value was controlled (2.0, 3.0, 5.0, 7.4, and 9.0) using either hydrochloric or lactic acid. The parameters investigated were the following: duration of immersion, pH of the SBF, contact with a dissimilar metal, and mechanical stimulus. The amounts of Ti ions eluted were measured using a polarized Zeeman atomic absorption spectrophotometer. Eluted Ti ions were detected after 24 h (pH of 2.0 and 3.0) and after 48 h (pH of 9.0). However, even after 4 weeks, eluted Ti ions were not detected in SBF solutions with pH values of 5.0 and 7.4. Ti elution was affected by immersion time, pH, acid type, mechanical stimulus, and contact with a dissimilar metal. Elution of Ti ions in a Candida albicans culture medium was observed after 72 h. Elution of Ti ions in the SBF was influenced by its pH and by crevice corrosion. The results of this study elucidate the conditions that lead to the elution of Ti ions in humans, which results in implant corrosion and Ti allergy.
Yoshihito Naitou, Jiyon Be, Yoritoki Tomotake, Kenichi Hamada, Kenzo Asaoka and Tetsuo Ichikawa : Formability and mechanical properties of porous titanium produced by a moldless process, Journal of Biomedical Materials Research. Part B, Applied Biomaterials, Vol.101, No.6, 1090-1094, 2013.
(要約)
Tailor-made porous titanium implants show great promise in both orthopedic and dental applications. However, traditional powder metallurgical processes require a high-cost mold, making them economically unviable for producing unique devices. In this study, a mixture of titanium powder and an inlay wax binder was developed for moldless forming and sintering. The formability of the mixture, the dimensional changes after sintering, and the physical and mechanical properties of the sintered porous titanium were evaluated. A 90:10 wt % mixture of Ti powder and wax binder was created manually at 70°C. After debindering, the specimen was sintered in Ar at 1100°C without any mold for 1, 5, and 10 h. The shrinkage, porosity, absorption ratio, bending and compressive strength, and elastic modulus were measured. The bending strength (135-356 MPa), compression strength (178-1226 MPa), and elastic modulus (24-54 GPa) increased with sintering time; the shrinkage also increased, whereas the porosity (from 37.1 to 29.7%) and absorption ratio decreased. The high formability of the binder/metal powder mixture presents a clear advantage for fabricating tailor-made bone and hard tissue substitution units. Moreover, the sintered compacts showed high strength and an elastic modulus comparable to that of cortical bone.
As the connection mechanism between the superstructure and implant, the cement-retained type and screw-retained type are mainly used. The choice of a screw-retained versus a cement-retained superstructure is a complex and comprehensive decision involving many points of consideration. On the other hand, various retained methods that is complementary with each retained type have been proposed. In this article, various retained types which have been reported in the literatures and developed by us, were systematically assorted from the standpoints of retreivability, and the advantages were pointed out showing case photographs. This systematical information would help the selection of retained type of the superstructure.
Chen Rong Jian, Yoritoki Tomotake, Megumi Watanabe, Yuichi Ishida, Kan Nagao and Tetsuo Ichikawa : Telescopic Magnetic Attachment for Implant-Supported Denture: Evaluation of Splint Effect, The International Journal of Oral & Maxillofacial Implants, Vol.26, No.3, 657-664, 2011.
(要約)
Retrievability, connecting strength, and ease of laboratory work are important but conflicting prerequisites for the success of an implant superstructure, particularly with regard to immediate function. To resolve this issue, a telescopic magnetic attachment system has been developed for implant-supported removable dentures. The splinting effect of the attachment was evaluated for stress distribution and elevation with an in vitro model of three implants in an edentulous mandible. Two types of telescopic magnetic attachments were prepared; the inclination angles of the axial wall of the abutment were 2.5 and 6.0 degrees. Three types of three-unit superstructures--a screw-retained superstructure and two telescopic magnet-retained superstructures--were fabricated. Static loads of 24.5, 49, and 98 N were applied vertically at three loading points on one side of each occlusal table. The elevation was measured as the height at which the magnet-retained superstructure detached from the abutment (on the other side of the prosthesis). In addition, by means of strain gauges, the stress distribution around the implants was evaluated and compared among the superstructures with the same three loads applied at six different points. The magnet-retained superstructure with the axial wall inclined at 2.5 degrees did not detach from the abutment. The differences in stress distribution between the screw-retained and magnet-retained superstructures with a 2.5-degree inclination were found to be statistically insignificant. The magnet-retained superstructure with a 6-degree inclination detached from the abutment, and the stress was concentrated during loading to a cantilever site. Because of its stress distribution and elevation, the new telescopic magnetic attachment, which has properties such as splinting the implants, ease of fabrication, and retrievability, is expected to be a viable alternative for the retention of implant-supported removable dentures.
Hideki Suito, Yoritoki Tomotake, Megumi Watanabe, Daisuke Nagao, Yuichi Ishida and Tetsuo Ichikawa : Survival of immediate implant restoration: A retrospective study through 9-year-observation, Journal of Prosthodontic Research, Vol.55, No.3, 141-145, 2011.
(要約)
The purpose of this retrospective study was to assess the implant survival rate and the risk factors associated with implant failure in patients who had undergone immediate implant restoration. We performed a retrospective review and an outcome assessment of all patients who received immediate implant restoration between 2000 and 2010 in our department at Tokushima University Hospital. The patients were divided into groups on the basis of the predictor variables: age, gender, implant location, and number of implants per jaw. The cumulative implant survival rate in the paired groups was determined by using Kaplan-Meier analysis and the log-rank test. Cox proportional hazards model was subsequently used to identify exposures associated with implant failure. Using the Kaplan-Meier method, the survival rates at 1, 3, and 9 years were calculated to be 98.8%, 98.0%, and 94.7%, respectively. No statistically significant association was observed between the implant survival rates and the predictor variables: gender, age, location, and number of implants. Immediate implant restoration is a reliable prosthetic procedure with an acceptable survival rate compared to the conventional implant procedure.
Jing Li, Yoshihito Naitou, Jian-Rong Chen, Takaharu Goto, Yuichi Ishida, Takanori Kawano, Yoritoki Tomotake and Tetsuo Ichikawa : New glass polyalkenoate temporary cement for cement-retained implant restoration: Evaluation of elevation and retentive strength, Dental Materials Journal, Vol.29, No.5, 589-595, 2010.
(要約)
The purpose of this study was to evaluate four luting agents for cement-retained implant restorations in two aspects: post-cementation elevation of the superstructure and the retentive strength before and after thermocycling and mechanical cycling. The four evaluated luting agents were: new glass polyalkenoate hard-type (GH) and soft-type (GS) cements, polycarboxylate hard-type (HH) and soft-type (HS) cements. Elevation and retentive strength were measured using a CCD laser displacement sensor and a universal testing machine respectively. Elevation increased in this order: GH, GS, HH, and HS. Thermal and mechanical stresses significantly decreased retentive strength, and the mean values exhibited by GH were significantly higher than the other luting agents. The novel glass polyalkenoate cements (hard- and soft-type) experimentally prepared in the present study augured well as luting agents by virtue of their reduced film thickness and their excellent post-cementation retention and elevation.
Toshiya Kashiwabara, Takaharu Goto, Yutaka Sato, Yoritoki Tomotake, Kan Nagao and Tetsuo Ichikawa : A new method to prevent the corrosion of dental materials, during disinfection using functional water: Sacrificial protection, Journal of Prosthodontic Research, Vol.54, No.3, 147-149, 2010.
(要約)
This paper demonstrates a simple method using sacrificial protection for preventing the corrosion of dental metals. Dental metals are directly connected or/and wound with a pure commercial aluminum/zinc wire/plate with high ionization tendency, before their immersion into oxidizing functional water. Dental materials such as Co-Cr alloy wires, stainless steel, and Au-Ag-Pd alloys did not corrode when this method was used. Thus, this method is very simple and effective for preventing corrosion of dental metals during disinfection using functional water.
Tetsuo Ichikawa, Osamu Ishida, Megumi Watanabe, Yoritoki Tomotake and Hua Wei : A new retrieval system for cement-retained implant superstructures., Journal of Prosthodontics, Vol.17, No.6, 487-489, 2008.
(要約)
This article discusses two methods for improving the retrievability of cement-retained implant superstructures. One method involves incorporating a removal screw in the superstructure and the second method uses a small dimple on the abutment, accessed through a vent in the superstructure.
Wei Hau, Yoritoki Tomotake, Kan Nagao and Tetsuo Ichikawa : Implant prostheses and adjacent tooth migration: preliminary retrospective survey using 3-dimensional occlusal analysis., The International Journal of Prosthodontics, Vol.21, No.4, 302-304, 2008.
(要約)
Occlusal force analysis was retrospectively evaluated to clarify the proximal contact loss after fixed implant prosthesis placement. Twenty-eight patients (55 prostheses) with fixed implant prostheses in the posterior region were divided into 2 groups: proximal contact loss and unchanged groups. The occlusal force and its distribution were 3-dimensionally measured using the Dental Prescale system. A high proportion of lingual and anterior component forces and high occlusal force distribution in the intercanine region were observed in the contact loss group. The high occlusal force of the adjacent tooth may enhance the mesial migration.
(キーワード)
Bite Force / Dental Prosthesis, Implant-Supported / Dental Stress Analysis / Humans / Malocclusion / Mesial Movement of Teeth / Retrospective Studies
(文献検索サイトへのリンク)
● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 18717086
Chen Jianrong, Kan Nagao, Yoritoki Tomotake and Tetsuo Ichikawa : Influence of a Vent Hole on the Retentive Force of a Cement-retained Superstructure before/after Thermocycling, Prosthodontic Research & Practice, Vol.5, No.3, 157-160, 2006.
(要約)
<B>Purpose:</B> The purpose of this study was to evaluate the influence of a vent hole on the retentive force of a cement-retained superstructure to an abutment.<BR><B>Methods:</B> The retentive force of superstructures with/without a vent hole, retained using one of two luting cements, was measured using a universal testing machine both before and after thermocycling<BR><B>Results:</B> The retentive force of the cement-retained superstructure with the vent hole was greater than that of the cement-retained superstructure without the vent hole. While the retentive force decreased significantly after thermocycling, the size of the vent hole had little influence on the retentive force.<BR><B>Conclusion:</B> It was concluded that placement of a vent hole in the superstructure is useful, with little adverse effect on the retentive force of the restoration.
(キーワード)
retentive force / cement-retained superstructure / vent hole / thermocycling
Hua Wei, Yoritoki Tomotake, Kan Nagao, Takafumi Ohguri, Daisuke Nagao and Tetsuo Ichikawa : In vitro Study of Stress Distribution on Additional Posterior Mandibular Implants, Prosthodontic Research & Practice, Vol.3, No.1, 84-91, 2004.
(要約)
Purpose : This in vitro study investigated the influence of implant splinting on stress distribution in two experimental implant-bone models.Materials and Methods : Two experimental implant-bone models simulated the original Brånemark model with four implants between the mental foramina and one additional implant placed on each side posterior to the mental foramen. The stress distribution on each implant in the models was examined by applying a static load to the superstructure. Three types of superstructures were studied to determine the effect of additional implants in the posterior region : 1) a metal superstructure supported by all six implants (Full dental arch ; Metal FDA) ; 2) the same type of superstructure made of resin instead of metal (Resin FDA) ; and 3) the metal superstructure supported by four anterior implants, with the conical abutments removed from the two posterior implants (Short dental arch ; Metal SDA).Results : Regardless of the type of superstructure tested, high stress was observed around each loaded implant. The highest stress was concentrated on the distal implants of the FDA compared to the stress on the anterior implants.Conclusion : The elevated stress concentration around the implants found in the present in vitro study is considered to be one of the reasons for the high failure rate of additional posterior mandibular implants.
(キーワード)
stress distribution / splinting / posterior installation of implant / mandibular distortion
Purpose: Misfit of superstructure-supported osseointegrated implants causes adverse stress in the prosthesis, components, and surrounding bone. A passive fit of the implant-supported prosthesis is essential for successful long-term osseointegration. Various clinical methods for evaluating the fit of implant-supported prostheses have been suggested. However, the methods have little scientific evidence to determine the acceptable fit. The present study evaluated the misfit of implant-supported prostheses by measuring the rotational angle/tightening torque in screwing the prosthesis on master models.<BR>Materials and Methods: Twenty-four implant-supported prostheses (3 single standing, 20 fixed partial, 1 full bridge) of fourteen patients were evaluated using a custom-made rotational angle/ tightening torque measuring apparatus on the master models. The influence of the order of tightening and unit number on the value was also evaluated.<BR>Results: The mean of the rotational angle/tightening torque was 2.6 (SD: 0.6) degree/Ncm in all prostheses. The value was significantly higher than that in the abutment screw as a control. The order of tightening and unit number did not significantly affect the values.<BR>Conclusions: The results suggest that measurements of rotational angle/tightening torque be useful for evaluating the fit of implant-supported prostheses. Misfit of the prostheses was below the level of acceptable fit.
Yoritoki Tomotake, Tetsuo Ichikawa, Hideo Kanitani, Masahide Nakao and Naoki Kitaoka : Dynamics of bone marrow pressure with tapping of titanium and hydroxyapatite implants in rabbit, Clinical Oral Implants Research, Vol.13, No.2, 221-224, 2002.
(要約)
The purpose of the present study was to evaluate the difference in stress transfer between titanium (Ti) and hydroxyapatite (HA) by the measurement of bone marrow pressure using a catheter pressure transducer. Ti and HA implants were inserted in the tibiae of rabbits. A hole of 1 mm in diameter was drilled in the bone and a fine catheter pressure transducer was placed in the bone marrow through a tube. The top of the abutment was vertically tapped with an impulse hammer, and the acceleration signal from the hammer and pressure signal from the catheter pressure transducer were examined. The time of contact (impulse duration) recorded in the impulse with Ti and HA was 166+/-17 micro sec and 164 +/- 17 micro sec, respectively. Maximum bone marrow pressure (BMP) with Ti and HA was 54.2 +/- 32.6 and 47.5 +/- 10.0 mmHg, respectively. Variation of the BMP with Ti was significantly larger than that with HA (P < 0.05). A negative correlation coefficient between impulse duration and BMP was found. The results of the present study suggest that the stress transfer is different between Ti and HA implants using dynamics of the bone marrow pressure.
Screw tightening of the superstructure of osseointegrated implants often produces unsuitable strain on the prosthesis and surrounding bone The purpose of this study was to investigate the effects of screw tightening on surrounding bone in several conditions <br/> Three Steri-oss® implants were placed in an acrylic resin experimental model and a three-unit framework was fabricated on the implants The fit of the framework was judged excellent by laboratory microscopy Ten strain gauges were attached on the experimental model surface around the implants The strain was measured after every screw was tightened by a custom-designed torque controller Static and dynamic strain was recorded Each test was repeated five times under the same conditions <br/> The results were as follows:<br/> 1 The order of screw tightening affected stress distribution The distribution was unequal and asymmetrical to the implants <br/> 2 Staged tightening of the screws decreased the sum of all strains <br/> 3 Tightening torque does not affect stress distribution <br/> 4 Misfit of the abutment/superstructure joint increased the sum of all strains <br/> 5 Strain induced by tightening of the second or third implant was greater than that by tightening the first one
Purpose: The purpose of the present study was to evaluate the difference for stress transfer between titanium (Ti) and hydroxyapatite (HA) implants by measuring bone marrow pressure using a catheter pressure transducer, and then to clarify the relationship between the histological and biomechanical properties.<BR>Methods: Ti and HA implants were inserted in the tibiae of rabbits. About 10 weeks following implantation, a hole, 1mm in diameter, was drilled in the bone distal to the implant, and a fine catheter pressure transducer was placed in the bone marrow through a tube. After the abutment was connected to the implant, the top of the abutment was vertically tapped with an impulse hammer, and the acceleration signal from the hammer, and the pressure signal from the catheter pressure transducer, were examined. In addition, histological examination was performed on each implant.<BR>Results: Maximum bone marrow pressure (BMP) with Ti and HA was 117.4±54.8mmHg and 90.3±30.6mmHg, respectively. A significant difference was observed (p<0.05). Moreover, variation of the BMP with Ti was significantly larger than that with HA (p<0.05). A negative correlation coefficient between the time of contact recorded in the impulse and BMP was found with Ti. As to histological examination of the bone structure around several implants, no significant difference was found between Ti and HA implants.<BR>Conclusion: The results show that the stress transfer is different between Ti and HA implants, using dynamics of bone marrow pressure. Little relation was found between biomechanical properties and histological views. The present study suggests that the evaluation of osseointegration requires consideration of biomechanical properties.
Yoritoki Tomotake, Osamu Ishida, Hideo Kanitani and Tetsuo Ichikawa : Immediate implant-supported oral rehabilitation using a photocurable plastic skull model and laser welding: A technical Note of Screw Retained type: Part 1, The International Journal of Prosthodontics, Vol.15, No.3, 303-306, 2002.
(要約)
This article describes a new procedure for immediate implant-supported oral rehabilitation using a photocurable resin skull model and a laser-welding apparatus. Preoperatively, the framework was fabricated on a photocurable resin skull model produced from a CT scan and individually designed guide template. The implants were immediately placed using the guide template; laser welding connected the components of framework. Despite the custom-made prosthesis, the total treatment from implant placement to superstructure placement can be completed within only 1 day. This procedure for immediate implant-supported oral rehabilitation using a photocurable resin skull model and a laser-welding apparatus may be useful for any implant system and patient.
(キーワード)
TITANIUM FRAMEWORKS / EDENTULOUS JAW / PLACEMENT
(文献検索サイトへのリンク)
● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 12066496
Hideo Kanitani, Yoritoki Tomotake, Wigianto Rudi, Naeko Kawamoto and Tetsuo Ichikawa : Bone changes around hydroxyapatite and titanium implants after abutment placement in rabbits, --- observations using histological and three-dimensional examinations ---, The Journal of Oral Implantology, Vol.26, No.4, 251-256, 2000.
(要約)
We have previously developed a computer-aided system for examination of the three-dimensional bone structure around implants and observed the bone changes in the healing period after implant placement. This paper describes the bone changes around hydroxyapatite (HA) and titanium (Ti) implants after abutment placement using histological and three-dimensional examinations. Twenty-four HA and Ti implants were embedded in the tibias of adult male New Zealand white rabbits. After 8 weeks, the abutment had passed through periosteum and was placed under the skin. Rabbits were sacrificed 4 and 8 weeks following abutment placement. In conclusion, histological examination showed that, at 4 weeks after abutment placement, bone resorption around the implant neck was seen in both HA and Ti implants, and at 8 weeks, excessive bone formation was seen around the implant neck. Three-dimensional bone examination showed that abutment placement may affect bone formation and cause additional bone hypertrophy in the bone marrow area.
Prananingrum Widyasri, Yoritoki Tomotake, Yoshihito Naitou, Kazumitsu Sekine, Kenichi Hamada and Tetsuo Ichikawa : Sintering Time and Its Influence on Moldless-Processed Porous Titanium's Properties, 94th General Session and Exhibition of the International Association for Dental Research, Seoul, Jun. 2016.
2.
Takaharu Goto, Yoritoki Tomotake, Yuichi Ishida, Nobuaki Higaki, Kan Nagao and Tetsuo Ichikawa : Functional Significance of the Main Occluding Area for Partially Edentulous, 16th Biennial Meeting of International College of Prosthodontists, Sep. 2015.
3.
Yuki Iwawaki, Noriko Mizusawa, Yoritoki Tomotake, Tetsuo Ichikawa and Katsuhiko Yoshimoto : Mechanical stress - responsive microRNA, The 3rd ASEAN plus and TOKUSHIMA Joint International Conference, Makassar, Indonesia, Dec. 2014.
4.
Takaharu Goto, Yoritoki Tomotake, Yuichi Ishida, Nobuaki Higaki, Kan Nagao and Tetsuo Ichikawa : Clinical significance of the main occluding in prosthodontic treatment, The 3rd ASEAN plus and TOKUSHIMA Joint International Conference on ``Strategic Achievement of Oral Sciences and Promotion of Quality of Life'', Makassar, Dec. 2014.
5.
Takaharu Goto, Yuichi Ishida, Megumi Watanabe, Yoritoki Tomotake, Kan Nagao and Tetsuo Ichikawa : Location of the main occluding area after implant treatment, 38th Annual Conference of The European Prosthodontic Association, Istanbul, Sep. 2014.
6.
Yuichi Ishida, Hideki Suito, Yoritoki Tomotake and Tetsuo Ichikawa : Prediction of prosthetic complications in the superstructure by assessing changes in the provisional restoration., The 15th Biennnial Meeting of International College of Prosthodontics, Turin, Sep. 2013.
7.
Yuichi Ishida, 水頭 英樹, Yoritoki Tomotake and Tetsuo Ichikawa : Prediction of prosthetic complications in the superstructure by assessing changes in the provisional restoration., The 15th Biennnial Meeting of International College of Prosthodontics, Turin, Sep. 2013.
8.
Osamu Isida, Yoritoki Tomotake and Tetsuo Ichikawa : The development of implant superstructures: especially considering the retrievability., Programs and Abstracts of Biennial Meeting of Asian Academy of Prosthodontics., Vol.8, 135, Dec. 2012.
9.
Takaharu Goto, Yoritoki Tomotake and Tetsuo Ichikawa : Systematic literature review on sensation of osseointegrated implants., Programs and Abstracts of Biennial Meeting of Asian Academy of Prosthodontics., Vol.8, 137, Dec. 2012.
10.
Yoritoki Tomotake, Takaharu Goto and Tetsuo Ichikawa : The Relationship between Main Occluding Area and Prosthetic Complains in Implant Superstructure., The 8th Biennial Meeting of Asian Academy of Prosthodontics, Vol.8, 139, Chennai, Dec. 2012.
11.
Hideki Suito, Takaharu Goto, Yuki Iwawaki, Yoritoki Tomotake and Tetsuo Ichikawa : Oral factors affecting titanium elution and corrosion; in vitro study using SBF solution., ASEAN plus and TOKUSHIMA Joint International Conference"Strategic Achievement of Oral Sciences and Promotion of Quality of Life", Dec. 2012.
12.
Takaharu Goto, Nobuaki Higaki, Yoritoki Tomotake, Kan Nagao and Tetsuo Ichikawa : Sensation of osseointegrated implants: literature review and new neurophysiological approach, ASEAN plus and TOKUSHIMA Joint International Conference"Strategic Achievement of Oral Sciences and Promotion of Quality of Life", Dec. 2012.
13.
Takaharu Goto, Kan Nagao, Yuichi Ishida, Yoritoki Tomotake and Tetsuo Ichikawa : Influence of Attachments On Load Transfer in Implant Overdentures: Effect Of Denture Rigidity, 14th Meeting of International College of Prosthodontists, Hawaii, Sep. 2011.
14.
Kenichi Hamada, Yoshihito Naitou, Daisuke Nagao, Yoritoki Tomotake, Tetsuo Ichikawa and Kenzo Asaoka : Properties of Porous Titanium using Moldless Process, International Joint Symposium on Oral Science, Denpasar, Dec. 2010.
15.
Takaharu Goto, Kan Nagao, Yuichi Ishida, Yoshihito Naitou, Yoritoki Tomotake and Tetsuo Ichikawa : Observation of the Main ccluding Area with Partually bentate, changes before/after Prosthetic Treatments., 6th Scientific Meeting Asian Academy of Osseointegration, Seoul, Nov. 2010.
16.
Yoshihito Naitou, Kenichi Hamada, Takaharu Goto, Megumi Watanabe, Daisuke Nagao, Yoritoki Tomotake and Tetsuo Ichikawa : Powder-size effect on biocompatibility of porous-titanium produced using moldless-process, 19th Annual Scientific Meeting European Assocoation for Osseintegration, Glasgow, Oct. 2010.
17.
Takaharu Goto, Kan Nagao, Yuichi Ishida, Yoshihito Naitou, Megumi Watanabe, Yoritoki Tomotake and Tetsuo Ichikawa : Influence of Attachments on Load Transfer in Implant Overdentures, 19th Annual Scientific Meeting European Assocoation for Osseintegration, Glasgow, Oct. 2010.
18.
Kenichi Hamada, Yoshihito Naitou, Daisuke Nagao, Yoritoki Tomotake, Tetsuo Ichikawa and Kenzo Asaoka : Smart process of porous titanium for tailor-made medical and dental devices, Thermec (International Conference on Processing & Manufacturing of Advanced Materials) 2009, Berlin, Aug. 2009.
19.
Yoshihito Naitou, Daisuke Nagao, Yoritoki Tomotake, Kenichi Hamada, Kenzo Asaoka and Tetsuo Ichikawa : Bioactivity of porous titanium prodeced by a newly developing moldless process, 2nd International Symposium and Workshop "The future Direction of Oral Sciences in the 21st Century", Tokushima, Dec. 2007.
20.
Yoshihito Naitou, Kenichi Hamada, Daisuke Nagao, Yoritoki Tomotake, Tetsuo Ichikawa and Kenzo Asaoka : Bioactivity of porous titanium produced using moldless process, 6th International Symposium on Titanium in Dentistry, Kyoto, Jul. 2007.
21.
Kenichi Hamada, Yoshihito Naitou, Daisuke Nagao, Yoritoki Tomotake, Tetsuo Ichikawa and Kenzo Asaoka : Moldless Process of Producing Porous Titanium for Dental Applications, 6th International Symposium on Titanium in Dentistry, Kyoto, Jun. 2007.
22.
Daisuke Nagao, Katsuhiko Yoshimoto, Yoritoki Tomotake, Megumi Watanabe, Y Yoshijima and Tetsuo Ichikawa : Gene expression in a mouse osteoblast like cell line in response to compressing force., 11th International College of Prosthodontists, Crete, Greece, May 2005.
23.
Takao Hanawa, Fumiaki Kawano, Masayuki Kon, Kenji Oka, Yoritoki Tomotake, Kenzo Asaoka and Matsumoto Naoyuki : Estimation of residual stress of porcelain by laser Raman spectroscopy, Journal of Dental Research, Vol.75, No.Spec, 125, San Francisco, Mar. 1996.
24.
Kenji Oka, Yoritoki Tomotake, Fumiaki Kawano, Masayuki Kon and Kenzo Asaoka : Effect of ion exchange on Weibull parameter of dental porcelains, Journal of Dental Research, Vol.74, No.Spec, 489, Singapore, Jun. 1995.
Ch. Gantumur, Keisuke Nishigawa, R. Hayama, Toyoko Tajima, Yoritoki Tomotake, Yoshihito Naitou, Tetsuo Ichikawa and Yoshizo Matsuka : Etiological investigation of the marginal bone loss on the peri-implant area: a retrospective cohort study, Tokushima University Bioscience Retreat, Sep. 2017.
T Goto, H Nishinaka, Toshiya Kashiwabara, Yoritoki Tomotake, Kan Nagao and Tetsuo Ichikawa : Significance of the Main Occluding Area in Implant Treatment, 社団法人日本補綴歯科学会 第120回記念学術大会, May 2011.