Hikaru Arakawa

Okayama University, Okayama-shi, Okayama-ken, Japan

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Publications (14)12.46 Total impact

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    ABSTRACT: This study aimed to compare the various complication-free rates and survival rates of remaining teeth among implant-supported fixed dentures (IFDs), removable partial dentures (RPDs) and no-restoration (NR) patients with unilateral free-end edentulism. The study subjects were selected among those who received prosthodontic treatment at Okayama University Dental Hospital for their unilateral free-end edentulism (2 or 3 missing teeth). Thirty-three patients were included in the IFD group, 41 matched patients in the RPD group, and 10 patients who received RPDs but refused their use were regarded as NR group. The remaining dentition was classified into five subcategories in relation to the missing portion: adjacent teeth to the missing portion (AD), contralateral posterior dentition in the same jaw (CS) and in the opposite jaw (CO), ipsilateral opposing posterior dentition (IO), and anterior dentition (AN). Complications were defined as tooth extraction, periodontal lesions, periapical lesions or loss of retention of the prosthesis and were assessed by one examiner based on the hospital chart records. The cumulative complication-free rates in the remaining teeth were significantly different among each of the three groups (p<0.01), with a significantly lower incidence rate in the IFD group. Regarding the cumulative survival rate of the remaining teeth, there was a significant difference only between IFD and NR group (p=0.01), especially in the CO region (p=0.04). Stable posterior occlusal support obtained with IFD treatment for unilateral free-end edentulism may reduce the incidence of complications in the remaining teeth, by decreasing the adverse mechanical stress.
    Journal of prosthodontic research. 10/2013;
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    ABSTRACT: This study aimed to compare the survival rates of remaining teeth between implant-supported fixed dentures (IFDs) and removable partial dentures (RPDs) in patients with large edentulous cases. The second goal was to assess the risk factors for remaining tooth loss. The study subjects were selected among those who received prosthodontic treatment at Okayama University Dental Hospital for their edentulous space exceeding at least four continuous missing teeth. Twenty-one patients were included in the IFD group and 82 patients were included in the RPD group. Survival rates of remaining teeth were calculated in three subcategories: (1) whole remaining teeth, (2) adjacent teeth to intended edentulous space, and (3) opposing teeth to intended edentulous space. The ten-year cumulative survival rate of the whole remaining teeth was significantly higher in the IFD group (40.0%) than in the RPD group (24.4%). On the other hand, there was no significant difference between two groups in the survival rate of teeth adjacent or opposing to intended edentulous space. A Cox proportional hazard analysis revealed that RPD restoration and gender (male) were the significant risk factors for remaining tooth loss (whole remaining teeth). These results suggest that IFD treatment can reduce the incidence of remaining tooth loss in large edentulous cases.
    Journal of prosthodontic research. 07/2013;
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    ABSTRACT: This retrospective study identified the risk factors for fracture of veneering materials and screw loosening of implant-supported fixed partial dentures in partially edentulous cases. The study group included a total of 182 patients who were installed 219 suprastructures at the Fixed Prosthodontic Clinic of Okayama University Dental Hospital between February 1990 and March 2005 and were subdivided in two subgroups: 120 patients (149 facing suprastructures) were included in the subgroup to investigate the risk factors of fracture of veneering materials, and 81 patients (92 suprastructures) were included in the subgroup to identify the risk factors of abutment screw loosening. Each patient was followed up from the day of suprastructure installation until March, 2005. A Cox proportional hazards regression model was used to identify the risk factors related to technical complications, and eight factors were regarded as candidate risk factors. Screw retention was the significant risk factor for fracture of veneering materials, whereas connection of suprastructures with natural tooth was the significant risk factor for screw loosening. It was suggested that screw retention was a significant risk factor for the fracture of veneering materials, and connection of suprastructures with natural tooth was a significant risk factor for screw loosening. Future studies, involving dynamic factors (e.g. bruxism) as predictors as well, are more helpful to discuss the risk factor of fracture of veneering materials and screw loosening.
    Journal of Oral Rehabilitation 01/2013; · 2.34 Impact Factor
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    ABSTRACT: This educational trial was an eight-day problem-based learning (PBL) course for fourth-year predoctoral students at Okayama University's dental school who interviewed elderly residents living in a nursing home. The purpose of this PBL course was to introduce geriatric dentistry to the students by allowing them, independently, to discover the clinical problems of elderly patients as well as the solutions. The sixty-five students were divided into nine small groups and received patient information (age, gender, degree of care needed, medical history, food type, medications, and oral condition) in datasheets before visiting the nursing home. Each group of students directly interviewed one patient and the caregivers and identified the patient's medical, psychological, and social problems. After the interview, the students participated in a PBL tutorial to delineate a management approach for the patient's problems. To measure the efficacy of this program, the students completed a questionnaire before and after the course regarding their level of understanding of and attitudes toward geriatric dentistry, clinical research, and self-study. The results showed that student's perceptions of their knowledge about and attitudes toward oral health care for the elderly significantly increased after the PBL course, which suggests that such tutorials should be an option for dental curricula.
    Journal of dental education 12/2012; 76(12):1580-8. · 0.99 Impact Factor
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    ABSTRACT: PURPOSE: Current clinical procedures to control or regenerate bone loss due to peri-implantitis are not predictable neither accomplish complete resolution. Therefore, early detection of the onset and the active periods of bone loss are crucial for prevention of extensive peri-implant bone resorption. This study aimed to determine a possible association between the presence of collagenases (MMP-1, MMP-8 and MMP-13) in peri-implant sulcular fluid (PISF) and active periods of bone loss by annually adjusted vertical bone loss (AVBL) measurements. METHODS: Intended sample consisted of 76 consecutive patients who received oral implant treatment at the Fixed Prosthodontic Clinic of Okayama University Hospital from 1990 to 2000. Twelve subjects were lost to follow-up or refused to participate. Consequently, the actual sample consisted of 64 patients who were followed-up for at least one year. Those patients with AVBL>0.6mm were included in the severe peri-implantitis group, and randomly selected, age-, gender- and implantation site-matched healthy patients (AVBL<0.3mm) comprised the control group. PISF samples were collected from both groups and further analyzed by western blot for detection of collagenases. RESULTS: Four patients presented severe peri-implantitis. MMP-8 was the only collagenase detected in peri-implant sites with ongoing bone loss. PISF samples from control group showed no positive reactions to any collagenase. CONCLUSION: This study showed MMP-8 as a possible marker for progressive bone loss in peri-implantitis.
    Journal of prosthodontic research. 10/2012;
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    ABSTRACT: The purposes of this study were to determine whether a response shift was observable after partial denture treatment and to identify the predictors that influenced the response shift magnitude and direction. A total of 173 consecutive patients with no more than eight missing teeth who received implant-supported, fixed or removable partial dentures at Okayama University Dental Hospital were asked to complete a full-version Oral Health-Related Quality of Life (OHRQoL) questionnaire before (pre-test) and after treatment (post-test). Additionally, a short form (then-test) consisting of seven questions selected from the full version had its reliability verified and was utilised to retrospectively assess the pre-treatment OHRQoL status. The difference between the summary scores of the then-test and the pre-test determined the response shift magnitude and direction. The then-test mean score (22·9 ± 6·6) was significantly lower (worse OHRQoL) than that of the pre-test (26·4 ± 5·2). The response shift effect size was of moderate magnitude and negative direction (d = -0·78). A multiple regression analysis showed that age (younger patients) (P < 0·01), number of replaced teeth (fewer) (P < 0·01) and pre-test scores (lower) (P < 0·01) were the significant predictors for response shift. In conclusion, a response shift phenomenon with negative and moderate effect size was observed after partial denture treatment. The significant predictor variables were young age, fewer numbers of replaced teeth and lower pre-test scores.
    Journal of Oral Rehabilitation 08/2011; 39(1):44-54. · 2.34 Impact Factor
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    ABSTRACT: Objective: Conventional assessment of medical treatment efficacy related to patient-reported quality of life (QOL) is based on the difference between pre- and post-treatment scores. Recently, a new assessment method is utilized to retrospectively assess treatment efficacy based on the post-treatment internal standards. The purpose of this study was to investigate whether the retrospective appraisal method can assess prosthodontic treatment efficacy similarly to the conventional method. Methods: Intended sample comprised 184 patients (mean age: 60.112.2 years; female:65%) with dental caries and/or missing teeth who started and finished the prosthodontic treatment at five university-based prosthodontic clinics from November 2006 to Februaly 2009. All subjects were asked to fill Japanese version of the Oral Health Impact Profile (OHIP-J54, Yamazaki et al., 2007) before and after treatment as well as a newly-developed retrospective appraisal questionnaire after treatment to evaluate treatment efficacy. The retrospective appraisal questionnaire consisted of 6 items; aesthetics, mastication, oral discomfort, swallowing, pain and pronunciation. Like OHIP-J54, the five rating scale (0-4) of each item indicates higher score means lower patient-reported treatment efficacy. 113 patients (mean age: 68.412.2 years; female:63%) answered the questionnaires completely (response rate: 61.4%). The mean total scores of OHIP-J54 before and after treatment were compared by Wilcoxon analysis and OHIP-J54 change score was calculated (OHIP-J54 total score after treatment minus before treatment). Spearmanns correlation analysis was performed to test relationship between the OHIP-J54 change score and the retrospective appraisal total score. Results: The OHIP-J54 total score after treatment (meanSD: 40.0 29.7) was significantly lower (better QOL) than that before treatment (53.9 38.2) (p<0.01). The retrospective appraisal total score was significantly correlated with the OHIP-J54 change score (p=0.04, ρ=0.29). Conclusions: Even with the short form questionnaire (6 items), the retrospective appraisal method could assess prosthodontic treatment efficacy similarly to the conventional (before/after comparison) method.
    IADR General Session 2010; 07/2010
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    ABSTRACT: This systematic review assessed the potential benefits of growth factors for bone augmentation prior to the placement of dental implants in human. A systematic online review of the Medline database, using the PubMed search machine was performed between 1966 and November 2008 by entering the MeSH terms. The primary outcome of the included studies was bone regeneration of localized alveolar ridge defects. The initial search identified 119 papers from the electronic database. This review produced seven eligible papers that reported on bone augmentation with recombinant human Bone Morphogenetic Protein-2 (rhBMP-2), recombinant human Platelet-Derived Growth Factor (rhPDGF) and Plasma-Rich Growth Factor (PRGF). The rhBMP-2 affected local bone augmentation with increasing volume for higher doses. Both rhPDGF and PRGF showed a positive effect in favor of the growth factor. Differing levels and quantity of evidence were noted to be available for the growth factors evaluated, revealing that rhBMP-2, rhPDGF, and PRGF may stimulate local bone augmentation to various conditions. Especially the potential of rhBMP-2 is supportive. However, the confined number of investigators using these techniques and the low number of patient treatments reported in the literature, the generalizability of this approach is limited at this time.
    Japanese Dental Science Review 01/2010; 46(1):43-53.
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    ABSTRACT: Objectives: An increasing number of well-conducted follow-up studies successfully identified risk factors for dental implant failure. However, most studies estimated the risk factors on a fixture basis and did not adjust subject-based risk to account for the clustered data (multiple fixtures per patient). The aim of this study was to identify risk factors for implant failure by a logistic regression analysis with generalized estimating equations (GEEs). Methods: Consecutively treated 296 patients who received 721 rough surface dental implants at Okayama University Hospital from February 1990 and March 2007 were included in this retrospective cohort study. Early and late implant failure were estimated by inspecting clinical record as an outcome. Age, gender, tobacco use, number of remaining teeth, implant length, diameter, position of implantation (maxilla/mandible or anterior/posterior), with or without bone augmentation, opposing teeth condition and super-structure type (fixed or removable) were estimated as predictors. We estimated the risk factors for early and late implant failure by a logistic regression analysis and a Poisson regression model with GEEs with an intention-to-treat regime, respectively. Results: Early failure rate was 1.5%, and 10- year cumulative survival rate was 94.0%. The risk factor for early failure was tobacco use (OR=10.67, p<0.01), and late failures were the super-structure type (removable)(relative ratio [RR]=29.88, p<0.01) and tobacco use (RR=2.95, p=0.02). Conclusion: Tobacco use was identified as the risk factor for early and late implant failure and super-structure type (removable) was also indicated as the risk factor for late implant failure in this study.
    IADR General Session 2009; 04/2009
  • Okayama Igakkai Zasshi (Journal of Okayama Medical Association) 01/2009; 121(3):183-187.
  • Takuo Kuboki, Hajime Minakuchi, Hikaru Arakawa
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    ABSTRACT: The choice of statistic methods and interpretation of these results are annoying issues to accomplish clinical epidemiologic researches. Especially beginners who have less experience in conducting clinical studies would often feel difficulty due to the mental hurdle of these statistical procedures. However, the major principles of clinical epidemiological research were setting of hypothesis and study design, thus predictor variables, outcome variables and related statistical methods would be automatically determined after decision of these steps. In this article, the essential knowledge to start clinical study such as various type of variables, selection of statistical procedures was reviewed following the previous review article that mainly focused on study designs.
    Nihon Hotetsu Shika Gakkai Zasshi 02/2007; 51(1):1-10.
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    ABSTRACT: Dental implants have become increasingly popular in the prosthetic rehabilitation of patients with bounded edentulous spaces. Oral condition-related quality of life (QOL) levels have rarely been assessed in these patients. Two groups of subjects with bounded edentulous spaces were studied: an implant-supported fixed prosthesis group (11 patients) and a resin-bonded fixed prosthesis group (33 patients). The two groups were well matched in terms of sex, age, missing units and location of missing units. The patients were requested to answer a self-administered QOL questionnaire with two major subscales - oral condition- and general condition-related QOL scores. The test-retest reliability of each question was pre-examined and found acceptable (mean Spearman rank correlation coefficient was 0.55 +/- 0.16). Mean QOL score differences between the two groups were analyzed by the Mann-Whitney U-test. Mean oral condition-related QOL scores of the implant-supported and resin-bonded fixed prosthesis groups were 87.8 +/- 9.5 and 87.1 +/- 12.3% (P = 0.85), and mean general condition-related QOL scores were 73.8 +/- 14.8 and 71.6 +/- 15.2% (P = 0.95), respectively. No significant QOL differences between the two groups were observed in the two subscales. In patients with bounded edentulous spaces, multidimensional QOL levels of patients with an implant-supported fixed prosthesis do not exceed those of patients with a resin-bonded fixed prosthesis in a short follow-up period.
    Clinical Oral Implants Research 09/2002; 13(4):359-64. · 3.43 Impact Factor
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    ABSTRACT: Dental implants are expanding their use among partially edentulous patients. However, whether implants can promote the quality of life (QOL) of these patients has not been sufficiently examined. This study compared the QOL level among implant denture, removable partial denture, and no restoration patients with distal extension type unilateral mandibular edentulism. Three groups (n = 12 each) of subjects with unilateral mandibular distal-extension edentulism who were matched for age, sex, and missing teeth were studied. The groups were (1) implant denture, (2) removable partial denture, and (3) no restoration. QOL levels of these 3 groups were compared using a self-administered questionnaire with 3 major subscales: oral condition, general condition, and dental treatment. The implant denture group showed higher oral condition related QOL score than the other groups. There was no significant difference in oral condition-related QOL scores between the removable partial denture and no restoration groups. There was no significant difference in the general condition related QOL score and dental treatment-related score among the 3 groups. In unilateral mandibular distal extension edentulous patients, oral-condition-related QOL levels for dental implant patients were higher than those of removable partial denture or no restoration patients. The QOL levels of the removable partial denture patients were almost identical to those of no restoration patients.
    Journal of Prosthetic Dentistry 09/1999; 82(2):182-7. · 1.72 Impact Factor
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    ABSTRACT: Purpose: To compare the complication rate of natural teeth adjacent to implant supported dentures (IFDs) with that of teeth serving as abutments for fixed partial dentures (FPDs). The second goal was to assess the risk factors for complications in teeth adjacent to bounded edentulous spaces. Materials and Methods: The study subjects were selected from patients who received prosthodontic treatment for their bounded edentulous space not exceeding two missing teeth between February 1990 and March 2007. Sixty-one patients were included in the IFD group and 66 patients were included in the FPD group. Tooth complications were defined as tooth extraction, periodontal lesion, periapical lesion, and loss of prosthesis and were assessed by one examiner based on dental records. Results: The 8-year cumulative complication rate for the IFD group (7.9%) was significantly lower than for the FPD group (40.7%). Additionally, the 8-year cumulative complication rate of vital teeth (6%) was significantly lower than that of nonvital teeth (45.9%). A cox proportional hazard analysis revealed that nonvitality of dental pulp was a significant risk factor for tooth complications, whereas treatment modality was not. Conclusions: Teeth adjacent to IFD-treated edentulous spaces presented fewer complications than natural teeth serving as abutments for FPDs. Conservation of teeth adjacent to edentulous spaces as vital teeth was the key finding to limit further tooth loss.
    The International journal of prosthodontics 26(3):260-4. · 1.63 Impact Factor