12 results on '"D Hidaka"'
Search Results
2. Gender difference in tooth autotransplantation with complete root formation: a retrospective survey
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I Kikukawa, O Hokkedo, Y Takahashi, Takashi Matsukubo, T Hayashi, Koichi Yoshino, M Kimura, S Okudaira, S Shioji, H Nishihara, Masatsugu Fujiseki, Yoichi Ishizuka, M Nojima, T Toake, Kenneth K. Tanabe, A Fukuda, K Ito, Masahiko Kuroda, H Kimura, Atsushi Saito, N Hattori, A Fukuyama, D Namura, H Fukuda, K Tsukiyama, K Mitsuhashi, Naoki Sugihara, J Shinoda, R Matsushima, K Fukai, N Kariya, Masakazu Nishibori, Mieko Toyoda, M Nakano, D Hidaka, Y Shimakura, Yasushi Miyata, N Yamazaki, F Kamei, Kazuhiro Umehara, I Noji, H Mibu, T Kimura, S Ikumi, and K Yamamoto
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Adult ,Male ,Molar ,medicine.medical_specialty ,Time Factors ,medicine.medical_treatment ,Dentistry ,Transplantation, Autologous ,Tooth Loss ,Sex Factors ,Risk Factors ,Periodontal Attachment Loss ,Tooth loss ,medicine ,Humans ,Bicuspid ,Tooth Root ,General Dentistry ,Survival rate ,Aged ,Retrospective Studies ,Root formation ,business.industry ,Graft Survival ,Retrospective cohort study ,Middle Aged ,Prognosis ,Autotransplantation ,Surgery ,Transplantation ,stomatognathic diseases ,Treatment Outcome ,Clinical attachment loss ,Odontogenesis ,Female ,medicine.symptom ,business ,Tooth ,Follow-Up Studies - Abstract
Gender-related risk factors in the survival of transplanted teeth with complete root formation have not yet been identified. The purpose of this study was to investigate gender differences in tooth autotransplantation at dental clinics. We asked participating dentists to provide information on transplantations they had undertaken from 1 January 1990 to 1931 December 2010. The data were screened to exclude patients who underwent more than one transplantation, smokers or those whose smoking habits were unknown, patients under 30 or who were 70 years old and over, cases where the transplanted teeth had incomplete root formation or multiple roots and those with fewer than 20 present teeth post-operation. We analysed 73 teeth of 73 males (mean age, 47.2 years) and 106 teeth of 106 females (mean age, 45.3 years) in this study. The cumulative survival rate and mean survival time were calculated using the Kaplan-Meier method. The cumulative survival rate for males was 88.3% at the 5-year mark, 64.8% at 10 years and 48.6% at 15 years; for females, it was 97.2% at the 5-year mark, 85.9% at 10 years and 85.9% at 15 years. A log-rank test indicated the difference between males and females to be significant (P = 0.011). There was also a significant difference in the main causes for the loss of transplanted teeth: males lost more transplanted teeth due to attachment loss than females (P < 0.05). These results indicate that males require more attention during the autotransplantation process, particularly at the stage of pre-operation evaluation and that of follow-up maintenance.
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- 2013
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3. Risk factors affecting third molar autotransplantation in males: a retrospective survey in dental clinics
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A Fukuda, Takashi Matsukubo, I Kikukawa, T Kimura, K Mitsuhashi, J Shinoda, H Mibu, O Hokkedo, K Tsukiyama, K Yamamoto, Yasushi Miyata, Y Takahashi, S Okudaira, Atsushi Saito, H Fukuda, Masamoto Toyoda, T Hayashi, H Kimura, N Yamazaki, F Kamei, Kazuhiro Umehara, Y Shimakura, M Kimura, S Ikumi, Masatsugu Fujiseki, I Noji, Kenneth K. Tanabe, Masahiko Kuroda, Koichi Yoshino, N Hattori, H Nishihara, A Fukuyama, D Namura, N Kariya, M Nakano, Masakazu Nishibori, D Hidaka, R Matsushima, T Toake, S Shioji, K Ito, and M Nojima
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Molar ,business.industry ,Proportional hazards model ,medicine.medical_treatment ,Dentistry ,Retrospective cohort study ,Autotransplantation ,Transplantation ,stomatognathic diseases ,Medicine ,Young adult ,business ,General Dentistry ,Survival rate ,Survival analysis - Abstract
The aim of this study was to investigate the risk factors affecting long-term prognosis of autotransplantation of third molars with complete root formation in males at dental clinics. Participating dentists were requested to provide information on transplantations they had undertaken from 1 January 1990 to 31 December 2010. Data on a total of 708 teeth from 637 patients were collected. After data screening and elimination, participants of this study consisted of 183 teeth of 171 males ranging from 20 to 72 years of age (mean age, 44·8 years). The cumulative survival rate was 86·0% at the 5-year mark, 59·1% at 10 years and 28·0% at 15 years. The mean survival time was 134·5 months, as calculated by the Kaplan-Meier method. Single factor analysis using the log-rank test showed that the following factors had significant influence (P < 0·05) on survival of transplanted teeth: periodontal disease as the reason for recipient site tooth extraction, fewer than 25 present teeth and Eichner index Groups B1 to C. Cox regression analysis examined five factors: age, smoking habit, recipient site extraction caused by periodontal disease, fewer than 25 present teeth and Eichner index. This analysis showed that two of these factors were significant: fewer than 25 present teeth was 2·63 (95% CI, 1·03-6·69) and recipient site extraction caused by periodontal disease was 3·80 (95% CI, 1·61-9·01). The results of this study suggest that long-term survival of transplanted teeth in males is influenced not only by oral bacterium but also by occlusal status.
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- 2012
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4. A retrospective survey of autotransplantation of teeth in dental clinics
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N Yamazaki, F Kamei, Kazuhiro Umehara, A Fukuda, Masatsugu Fujiseki, Koichi Yoshino, Y Takahashi, K Mitsuhashi, J Shinoda, S Okudaira, H Mibu, Kenneth K. Tanabe, H Nishihara, T Toake, T Hayashi, Masahiko Kuroda, H Kimura, K Tsukiyama, Y Shimakura, D Hidaka, M Nojima, M Kimura, Atsushi Saito, R Matsushima, D Namura, I Noji, I Kikukawa, O Hokkedo, S Shioji, Yasushi Miyata, K Ito, N Kariya, M Nakano, Masamoto Toyoda, H Fukuda, Takashi Matsukubo, T Kimura, S Ikumi, K Yamamoto, Masakazu Nishibori, N Hattori, and A Fukuyama
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Molar ,Orthodontics ,business.industry ,medicine.medical_treatment ,Dentistry ,Mandibular first molar ,Autotransplantation ,Log-rank test ,Mandibular second molar ,Transplantation ,stomatognathic diseases ,stomatognathic system ,Medicine ,business ,Bridge (dentistry) ,General Dentistry ,Survival rate - Abstract
The aim of this study was to investigate the usage of tooth autotransplantation in dental clinics which offer the treatment and evaluate its practicality. Participating dentists were requested to provide information on transplantations they had undertaken from 1 January 1990 to 31 December 2010. A total of 614 teeth from 552 patients (37 dentists) ranging in age from 17 to 79 (mean age: 44·1) were examined. Cumulative survival rate and mean survival time were calculated using the Kaplan-Meier method, and log rank test was used for analysis of factors. The mean number of autotransplantation patients per clinic per year was 1·4. Upper third molars constituted 36·8% of donor teeth, while 37·1% were lower third molars. The lower first molar region was the most common recipient site at 32·6%, followed by the lower second molar region (28·0%). Prosthodontic treatment of transplanted teeth involved coverage with a single crown (72·5%) and abutment of bridge (18·9%). A total of 102 transplanted teeth were lost owing to complications such as attachment loss (54·9%) and root resorption (25·7%). The cumulative survival rate in cases where donor teeth had complete root formation was 90·1% at 5 years, 70·5% at 10 years and 55·6% at 15 years. The mean survival time was 165·6 months. Older age was a significant risk factor (P < 0·05) for survival. In cases where suitable donor teeth are available, autotransplantation of teeth may be a plausible treatment option for dealing with missing teeth in dental clinics.
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- 2011
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5. Detection of eyes from human faces by Hough transform and separability filter
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Tsuyoshi Kawaguchi, D. Hidaka, and Mohamed Rizon
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Brightness ,Computer Networks and Communications ,Computer science ,business.industry ,Template matching ,Feature extraction ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Physics and Astronomy ,Pattern recognition ,Filter (signal processing) ,Measure (mathematics) ,Facial recognition system ,Object detection ,Image (mathematics) ,Hough transform ,law.invention ,Position (vector) ,law ,Face (geometry) ,Computer vision ,Artificial intelligence ,Electrical and Electronic Engineering ,business - Abstract
Detection of the eyes in human facial images is important in preprocessing for face recognition, since the results can be used to determine the position, size, and direction of the face. This paper describes a method of detection of both irises from a gray-scale facial image. In this method, first a small region (“blob”) which is likely to be an iris is determined by using a separability filter (developed by Fukui and Yamaguchi). Second, taking all the blobs, the costs of all segments connecting the irises and the inclinations of the segments which are within a predetermined value are computed. This cost can be calculated from the regions surrounding the blobs, by using the number of votes for the maximum-voting circle, the separability of the surrounding small regions, the mean brightness within the iris, and the normalized correlation coefficient between a partial image including a pair of blobs and the template for the eyes. The pair of blobs that minimizes the cost is regarded as the irises. The proposed method has been tested by using all 150 images (excluding images with glasses) from the University of Bern Facial Image Database. The experimental results show that the success rates are between 95.3% (worst) and 97.3% (best). If minor errors are tolerated, the success rates are between 96.7% (worst) and 99.3% (best). © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 88(5): 29–39, 2005; Published online in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/ecjb.20178
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- 2005
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6. Risk factors affecting third molar autotransplantation during 5 and 10 years
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Kazuie Yamamoto, Masatsugu Fujiseki, Yoichi Ishizuka, S Ikumi, T Toake, Kakuhiro Fukai, Akihito Saito, Tomoko Hayashi, Hirofumi Fukuda, Masahiro Nakano, Takashi Matsukubo, M Nojima, Y Shimakura, Hiroyuki Kimura, Morihiro Kimura, S Okudaira, I Kikukawa, Koji Ito, Masahiko Kuroda, O Hokkedo, H Mibu, R Matsushima, Kazunari Tanabe, Toshiyuki Kimura, K Tsukiyama, I Noji, Yasushi Miyata, H Nishihara, Naoyuki Yamazaki, S Shioji, K Mitsuhashi, J Shinoda, N Hattori, A Fukuyama, Masamoto Toyoda, F Kamei, Naoki Sugihara, Kazuhiro Umehara, Masakazu Nishibori, Toru Takiguchi, Koichi Yoshino, N Kariya, Yoshito Takahashi, D Hidaka, Akiharu Fukuda, and D Namura
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Molar ,Adult ,Male ,medicine.medical_treatment ,Dentistry ,Operational risk ,Dental Prosthesis ,Young Adult ,Sex Factors ,stomatognathic system ,Risk Factors ,medicine ,Maxilla ,Humans ,Tooth Root ,Tooth Socket ,Autografts ,Periodontitis ,Survival rate ,Aged ,Root formation ,Tooth, Nonvital ,business.industry ,Proportional hazards model ,Smoking ,Age Factors ,General Medicine ,Odds ratio ,Middle Aged ,Autotransplantation ,Survival Rate ,stomatognathic diseases ,Treatment Outcome ,Tooth Extraction ,Odontogenesis ,Female ,Molar, Third ,Clinical Competence ,business ,Follow-Up Studies - Abstract
The aim of this study was to investigate risk factors affecting 5- and 10-year survival in autotransplantation of third molars with complete root formation at dental clinics. Participating dentists were requested to provide information on transplantations performed between 1 January 1990 and 31 December 2009. After data screening and elimination, 183 teeth in 171 men aged 20-72 years (mean, 44.8 years) and 205 teeth in 189 women aged 20-74 years (mean, 42.0 years) were included in the study. A single-factor analysis using the log-rank test revealed that the following factors had a significant influence (p
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- 2014
7. Procedures for treating spaces vacated by loss of transplanted teeth
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F Kamei, S Okudaira, Kazuhiro Umehara, Masakazu Nishibori, Kazuie Yamamoto, I Kikukawa, Koji Ito, D Hidaka, O Hokkedo, S Shioji, N Kariya, R Matsushima, Koichi Yoshino, Masamoto Toyoda, S Ikumi, Y Shimakura, Kazunari Tanabe, Akiharu Fukuda, Hiroyuki Kimura, K Tsukiyama, T Toake, N Hattori, A Fukuyama, H Mibu, Hirofumi Fukuda, D Namura, H Nishihara, Naoyuki Yamazaki, Yasushi Miyata, K Mitsuhashi, Morihiro Kimura, J Shinoda, Toshiyuki Kimura, I Noji, Akihito Saito, Tomoko Hayashi, Masahiro Nakano, Yoshito Takahashi, Masatsugu Fujiseki, Masahiko Kuroda, M Nojima, and Takashi Matsukubo
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Adult ,Male ,Survival period ,medicine.medical_treatment ,Dentistry ,Mandibular first molar ,Transplantation, Autologous ,Mandibular second molar ,Dental Prosthesis ,Tooth Loss ,stomatognathic system ,Tooth loss ,Medicine ,Humans ,Dental Restoration Failure ,Bridge (dentistry) ,Aged ,Orthodontics ,business.industry ,General Medicine ,Middle Aged ,Masticatory force ,Transplantation ,stomatognathic diseases ,Female ,medicine.symptom ,Dentures ,business ,Tooth - Abstract
The main reasons for loss of autotransplanted teeth are different from those involved in natural teeth loss. The aim of this study was to investigate which procedures were employed to treat spaces vacated when autotransplanted teeth were lost. Participating dentists were requested to provide information on transplantations they had undertaken. A total of 614 teeth in 552 patients (37 dentists) ranging in age from 17 to 79 years (mean age: 44.1 years) were examined. A total of 102 transplanted teeth were lost during the observation period. Procedures for treatment of spaces vacated were not influenced by main reason for transplanted tooth loss. The procedure used to treat depended on the original prosthodontic treatment of the transplanted teeth. For single crowns, the spaces were left empty (33.9%) or replaced by bridge work (30.5%), implants (20.3%), or dentures (10.2%). For single crowns in the upper and lower second molar regions, the spaces were usually left empty (upper 100%, lower 71.4%), while for those in the upper and lower first molar regions, the spaces were often replaced by bridge work (upper 41.7%, lower 50.0%). For bridge abutments, spaces were replaced by dentures (42.9%), implants (33.3%), or left empty (14.3%), and in the lower second molar region, they were mostly replaced by implants (5 cases, 41.7%). For most denture abutment cases, the spaces were replaced by dentures (88.9%). During the survival period of the transplanted teeth, the masticatory burden on the other teeth is reduced and the adjacent teeth are supported by the transplanted tooth. Even if transplanted teeth are eventually lost, traditional procedures can be performed to fill the vacated space.
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- 2013
8. Influence of age on tooth autotransplantation with complete root formation
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Takashi Matsukubo, K Yamamoto, K Tsukiyama, N Kariya, Toru Takiguchi, H Mibu, H Kimura, Koichi Yoshino, S Shioji, Atsushi Saito, R Matsushima, N Yamazaki, F Kamei, Kazuhiro Umehara, Y Takahashi, M Nojima, S Okudaira, H Fukuda, M Nakano, Masatsugu Fujiseki, I Kikukawa, Masamoto Toyoda, K Mitsuhashi, J Shinoda, O Hokkedo, Y Shimakura, T Toake, Kenneth K. Tanabe, I Noji, Masahiko Kuroda, A Fukuda, T Hayashi, K Fukai, M Kimura, D Hidaka, Yasushi Miyata, D Namura, Masakazu Nishibori, S Ikumi, N Hattori, A Fukuyama, H Nishihara, K Ito, and T Kimura
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Molar ,Adult ,Male ,medicine.medical_treatment ,Dentistry ,Kaplan-Meier Estimate ,Transplantation, Autologous ,stomatognathic system ,medicine ,Humans ,Tooth Root ,General Dentistry ,Survival rate ,Survival analysis ,Aged ,Proportional Hazards Models ,Root formation ,business.industry ,Proportional hazards model ,Age Factors ,Tooth autotransplantation ,Middle Aged ,Prognosis ,Autotransplantation ,Transplantation ,stomatognathic diseases ,Female ,Molar, Third ,business ,Tooth - Abstract
The aim of this study was to investigate risk factors with age in the long-term prognosis of autotransplantation of teeth with complete root formation at dental clinics. Participating dentists were asked to provide information on transplantations they had undertaken from 1 January 1990 to 31 December 2010. Data on a total of 708 teeth from 637 patients were collected. The data were screened to exclude patients who were under 25 or 70 years of age and over, those who were smokers or whose smoking habits were unknown, those whose transplanted teeth had incomplete root formation or multiple roots and those with fewer than 25 present teeth post-operation. The participants in this study were 71 men (74 teeth) and 100 women (107 teeth) ranging from 25 to 69 years of age. Third molars were used as donor teeth in 89·0% of the cases. The participants were divided into three age groups of 25-39, 40-54 and 55-69. Survival analysis was conducted using the Kaplan-Meier method, and a log-rank test revealed that there were no significant differences in age groups for men or women. Cox regression analysis indicated that the survival of transplanted teeth was not influenced by age. However, although not statistically significant, the clinical success rate was lower in the 55-69-year-old group than that in the younger groups. These results indicate that if suitable donor teeth are available and the conditions are right, autotransplantation is a viable treatment for missing teeth regardless of the age of the patient.
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- 2012
9. Comparison of prognosis of separated and non-separated tooth autotransplantation
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K Tsukiyama, H Fukuda, Masakazu Nishibori, D Namura, Masamoto Toyoda, Takashi Matsukubo, Masatsugu Fujiseki, R Matsushima, S Ikumi, T Kimura, S Shioji, D Hidaka, I Kikukawa, Kenneth K. Tanabe, K Yamamoto, T Hayashi, O Hokkedo, Masahiko Kuroda, K Ito, H Mibu, N Kariya, A Fukuda, T Toake, M Nakano, Y Takahashi, I Noji, M Kimura, S Okudaira, N Yamazaki, F Kamei, Atsushi Saito, Kazuhiro Umehara, Koichi Yoshino, M Nojima, Y Shimakura, H Kimura, K Mitsuhashi, J Shinoda, N Hattori, A Fukuyama, Yasushi Miyata, and H Nishihara
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Adult ,Male ,medicine.medical_treatment ,Oral Surgical Procedures ,Dentistry ,Transplantation, Autologous ,Mandibular second molar ,stomatognathic system ,Maxilla ,Medicine ,Humans ,Tooth Root ,General Dentistry ,Survival rate ,Aged ,Orthodontics ,Root formation ,business.industry ,Jaw, Edentulous, Partially ,Mean age ,Tooth autotransplantation ,Middle Aged ,Prognosis ,Molar ,Autotransplantation ,Transplantation ,Log-rank test ,stomatognathic diseases ,Female ,business - Abstract
The aim of this study was to compare the prognosis of separated and non-separated tooth autotransplantation of the upper first and second molars with complete root formation undertaken at dental clinics. The participating dentists were requested to provide information on transplantations they had undertaken from 1 January 1990 to 31 December 2010. Data on a total of 708 teeth from 637 patients were collected. This study analysed 35 separated teeth and 22 non-separated teeth of 47 participants ranging from 27 to 76 years of age (mean age: 55·0 years) after data screening and elimination. The cumulative post-transplantation survival rate at 10 years was 77·1% for separated teeth and 63·6% for non-separated teeth as calculated with the Kaplan-Meier method. There were no significant differences between separated teeth and non-separated teeth in a log rank test (P = 0·687). Separated-tooth autotransplantation can help fill narrow recipient sites and increase occlusal supporting zones, but the clinical success rate was only 48·6%. Although transplantation of teeth with complete root formation has limited prognosis, transplantation of upper first and second molars, whether separated or non-separated, is a viable option to replace missing teeth.
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- 2012
10. Risk factors affecting third molar autotransplantation in males: a retrospective survey in dental clinics
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K, Yoshino, N, Kariya, D, Namura, I, Noji, K, Mitsuhashi, H, Kimura, A, Fukuda, I, Kikukawa, T, Hayashi, N, Yamazaki, M, Kimura, K, Tsukiyama, K, Yamamoto, A, Fukuyama, D, Hidaka, J, Shinoda, H, Mibu, Y, Shimakura, A, Saito, S, Ikumi, K, Umehara, F, Kamei, H, Fukuda, T, Toake, Y, Takahashi, Y, Miyata, S, Shioji, M, Toyoda, N, Hattori, H, Nishihara, R, Matsushima, M, Nishibori, O, Hokkedo, M, Nojima, T, Kimura, M, Fujiseki, S, Okudaira, K, Tanabe, M, Nakano, K, Ito, M, Kuroda, and T, Matsukubo
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Adult ,Male ,Tooth Ankylosis ,Root Resorption ,Dental Abutments ,Dental Caries ,Transplantation, Autologous ,Tooth Fractures ,Young Adult ,Postoperative Complications ,Sex Factors ,Risk Factors ,Periodontal Attachment Loss ,Humans ,Tooth Root ,Tooth Socket ,Periodontitis ,Aged ,Retrospective Studies ,Crowns ,Smoking ,Age Factors ,Middle Aged ,Survival Analysis ,Root Canal Therapy ,Treatment Outcome ,Tooth Extraction ,Molar, Third ,Follow-Up Studies - Abstract
The aim of this study was to investigate the risk factors affecting long-term prognosis of autotransplantation of third molars with complete root formation in males at dental clinics. Participating dentists were requested to provide information on transplantations they had undertaken from 1 January 1990 to 31 December 2010. Data on a total of 708 teeth from 637 patients were collected. After data screening and elimination, participants of this study consisted of 183 teeth of 171 males ranging from 20 to 72 years of age (mean age, 44·8 years). The cumulative survival rate was 86·0% at the 5-year mark, 59·1% at 10 years and 28·0% at 15 years. The mean survival time was 134·5 months, as calculated by the Kaplan-Meier method. Single factor analysis using the log-rank test showed that the following factors had significant influence (P0·05) on survival of transplanted teeth: periodontal disease as the reason for recipient site tooth extraction, fewer than 25 present teeth and Eichner index Groups B1 to C. Cox regression analysis examined five factors: age, smoking habit, recipient site extraction caused by periodontal disease, fewer than 25 present teeth and Eichner index. This analysis showed that two of these factors were significant: fewer than 25 present teeth was 2·63 (95% CI, 1·03-6·69) and recipient site extraction caused by periodontal disease was 3·80 (95% CI, 1·61-9·01). The results of this study suggest that long-term survival of transplanted teeth in males is influenced not only by oral bacterium but also by occlusal status.
- Published
- 2012
11. Robust extraction of eyes from face
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D. Hidaka, Tsuyoshi Kawaguchi, and Mohamed Rizon
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business.industry ,Computer science ,Feature extraction ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Pattern recognition ,Filter (signal processing) ,Facial recognition system ,Hough transform ,law.invention ,Image (mathematics) ,law ,Face (geometry) ,Computer vision ,Artificial intelligence ,Face detection ,business - Abstract
In this paper we propose a new algorithm to detect the irises of both eyes from a human face in an intensity image. Using the separability filter proposed by Fukui et al. (1997), the algorithm first extracts intensity valleys, which we call blobs in this paper, as the candidates for the irises. Next, for each pair of blobs, the algorithm computes a cost using Hough transform and separability filter to measure the fit of the pair of blobs to the image. And then, the algorithm selects a pair of blobs with the smallest cost as the irises of both eyes. As the result of the experiment using all faces without spectacles in the face database of the University of Bern, the success rate of the proposed algorithm was 96.5% on average.
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- 2002
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12. THU0128 The extra-low-dose methotrexate treatment facilitates the intracellular accumulation of longer chain subgroups of methotrexate polyglutamates
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S. Nagano, J. Nakagawa, T. Ota, D. Hidaka, K. Hase, Y. Koyama, and A. Uchino
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musculoskeletal diseases ,business.industry ,Immunology ,Pharmacology ,medicine.disease ,Low dose methotrexate ,General Biochemistry, Genetics and Molecular Biology ,Rheumatology ,immune system diseases ,Remission criteria ,Rheumatoid arthritis ,medicine ,High doses ,Immunology and Allergy ,Initial treatment ,Distribution (pharmacology) ,heterocyclic compounds ,Methotrexate ,skin and connective tissue diseases ,business ,Intracellular ,medicine.drug - Abstract
Background Despite methotrexate (MTX) is widely used as the first choice in the treatment of rheumatoid arthritis (RA), there is no universally accepted method of the optimal schedule for dose initiation and escalation. The higher starting dosage and faster increasing schedule is considered to be associated with higher efficacy, because it is expected to achieve steady state concentrations of intracellular MTX polyglutamates (MTX-Glu) more quickly. In contrast, in Japan, the officially approved dosage of MTX for RA treatment had been fixed up to 8mg/wk from 1996 to 2011, whereas the maximum doses of 20 to 30mg/wk were commonly used in the rest of world. As a result, we have very unique experience of extra-low-dose MTX (ExLD-MTX) treatment for RA. Objectives To evaluate the efficacy of ExLD-MTX treatment for RA; and to investigate the concentrations of intracellular MTX-Glu after ExLD-MTX treatment. Methods RA cases treated with ExLD-MTX (n=133) were retrospectively investigated. After 12 months of the treatment, the rates of achieving remission criteria and of withdrawing from the initial treatment were calculated. If dose escalation of MTX above 10mg/wk was required due to insufficient efficacy, the case was count as withdrawal. In order to compare the results with the MTX monotherapy arm in PREMIER study, the remission criteria was defined as DAS28 of Results After 12 months of ExLD-MTX treatment (mean MTX dosage: 6.13±0.69 mg/wk), 72.2% of cases were still maintained with the same treatment. The remission criteria for DAS28 ( Conclusions Although higher starting dosage and faster increasing schedule for MTX is considered to be better, we found that the efficacy of ExLD-MTX treatment is comparable to usual MTX treatments. As the longer-chain MTX-Glu is reported more important in the clinical response compared with the shorter-chain, the intensive distribution in MTX-Glu6-7 subtypes after ExLD-MTX treatment may be an explanation for the efficacy. Furthermore, since MTX exposure was known to induce up-regulation of folylpolyglutamate hydrolase, which removes glutamic acid from MTX-Glu, ExLD-MTX treatment could be favorable for accumulation of the longer-chain MTX-Glu. On the other hand, reaching high doses of MTX in a short period may be required to achieve the steady state concentrations of MTX-Glu more quickly. The optimal schedule for dose initiation and escalation of MTX may need a re-evaluation. Disclosure of Interest None Declared
- Published
- 2013
- Full Text
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