Ken-Ichi Matsuda

Osaka City University, Ōsaka-shi, Osaka-fu, Japan

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Publications (16)20.09 Total impact

  • Article: A combination impression technique by Accu-Dent(®) System broadly extends the surface area of primary casts.
    Journal of prosthodontic research. 03/2013;
  • Article: Comparison of GOHAI and OHIP-14 measures in relation to objective values of oral function in elderly Japanese.
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    ABSTRACT: The aims of this study were to assess the correlations between the Geriatric Oral Health Assessment Index (GOHAI) and the Oral Health Impact Profile-14 (OHIP-14) and to examine which survey is more sensitive to objectively measured oral function in the Japanese elderly. The subjects were 290 community-dwelling, cognitively healthy, and independently living people over the age of 60 years (mean: 66.3 years). Measures included the GOHAI and OHIP-14 questionnaires, as well as self-rating of general and oral health, dry mouth, number of residual teeth, and objective values of occlusal force, masticatory performance, and salivary flow rate. Bivariate and linear regression analyses were used to identify which of these variables predicted GOHAI and OHIP-14 scores. Spearman's correlation coefficient between the GOHAI and OHIP-14 scores was 0.728 (P < 0.001), although the OHIP-14 showed a greater number of 0 scores, suggesting a greater floor effect. At the bivariate level, self-rating of general and oral health, dry mouth, number of residual teeth, occlusal force, and masticatory performance were associated with GOHAI and OHIP-14 scores. Multiple linear regression analyses showed that after controlling for the other significant variables, both the occlusal force (standardized regression coefficient [β] = -0.164, P = 0.004) and masticatory performance (β = -0.125, P = 0.019) had significant associations with the GOHAI score, whereas this association was not found with the OHIP score. Although the GOHAI and OHIP-14 had a strong correlation, the GOHAI was more sensitive to the objective values of oral functions among independently living elderly persons in Japan.
    Community Dentistry And Oral Epidemiology 03/2012; 40(5):406-14. · 1.89 Impact Factor
  • Article: Masticatory performance in older subjects with varying degrees of tooth loss.
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    ABSTRACT: The purpose of this study was to establish the factors influencing the masticatory performance of older subjects with varying degrees of tooth loss and associated numbers of posterior occlusal contacts. The subjects consisted of 1274 independently living people aged 60 years and over. Individuals with partially or fully edentulous arches without a denture replacement or those having any symptoms related to an oral problem were excluded from the study participants. Masticatory performance, maximal occlusal force and stimulated whole saliva were measured. Subjects were grouped into three categories by posterior occlusal contact, according to the Eichner Index. Group A had contacts in four support zones; group B had one to three zones of contact or contact in the anterior region only; and group C had no support zones at all, although a few teeth could still remain. The masticatory performance in groups B and C was found to be 81% and 50% of that of group A, respectively. The multiple linear regression analysis showed that in all the groups, occlusal force was significantly associated with masticatory performance. In groups A and B, the number of residual teeth was significantly associated with masticatory performance, whereas in group C, it had no significant relationship with masticatory performance. Salivary flow rate had a significant correlation with masticatory performance only in group C. Declines in occlusal contact, occlusal force and salivary flow appear to be associated with reduction of masticatory performance in older adults. However, the crucial factors for masticatory performance varied, depending on the phase of occlusal collapse.
    Journal of dentistry 01/2012; 40(1):71-6. · 2.00 Impact Factor
  • Article: Subjective values of different age groups in Japan regarding treatment for missing molars.
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    ABSTRACT: To determine how patients and dentists in Japan value the outcomes of different treatment options for missing molars. Materials and Elderly removable-denture wearers and dentate persons (senior group), preclinical dental students (young group), and prosthodontists were presented with five possible treatment options for missing lower bilateral first and second molars. The participants indicated on a visual analogue scale how they would value the treatment (utility value: UV), if they had received each of the treatments. Two-way repeated measures anova was used for statistical analyses. The UV for the shortened dental arch (SDA) without replacement was the lowest in every group. The young group rated the value of cantilever fixed partial dentures (FPD) and implants significantly higher than removable partial dentures (RPD), while the senior group rated the value of FPD and RPD significantly higher than implants. Those having experience with removable dentures were likely to place a higher value on the acrylic RPD. The prosthodontists rated the value of implants significantly higher than any other options. The participants in every group placed the lowest value on the outcome from the SDA in Japan. The denture wearers preferred the RPD, while prosthodontists preferred implants.
    Gerodontology 09/2011; 28(3):192-6. · 1.03 Impact Factor
  • Article: Shortening the xerostomia inventory.
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    ABSTRACT: The aim of this study was to determine the validity and properties of the Summated Xerostomia Inventory-Dutch Version in samples from Australia, The Netherlands, Japan, and New Zealand. Six cross-sectional samples of older people from The Netherlands (n = 50), Australia (n = 637; n = 245), Japan (n = 401), and New Zealand (n = 167; n = 86) were enrolled. Data were analyzed by using the Summated Xerostomia Inventory-Dutch Version. All datasets revealed a single extracted factor which explained about one-half of the variance, with Cronbach alpha values ≥0.70. When mean scale scores were plotted against a "gold-standard" xerostomia question, statistically significant gradients were observed, with the highest score seen in those who always had dry mouth, and the lowest in those who never had it. The Summated Xerostomia Inventory-Dutch Version is valid for measuring xerostomia symptoms in clinical and epidemiologic research.
    Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 06/2011; 112(3):322-7. · 1.50 Impact Factor
  • Article: Association of masticatory performance with age, gender, number of teeth, occlusal force and salivary flow in Japanese older adults: is ageing a risk factor for masticatory dysfunction?
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    ABSTRACT: In general, ageing is a risk factor for sensory and motor deterioration, with the rate of decline varying amongst individuals. Concerning masticatory function, missing teeth along with oral disease seem to accelerate the dysfunction. Here, we aimed to confirm whether masticatory dysfunction by ageing is inevitable. This study investigated the effect of age, gender, number of natural teeth, occlusal force and salivary flow on the masticatory performance in a large sample of elderly adults. The study sample consisted of 1288 independently living people aged 60-84 years. Masticatory performance was determined by the comminuted particles of test food. Bilateral maximal occlusal force in the intercuspal position was measured with pressure sensitive sheets. Stimulated whole saliva was collected. Masticatory performance was significantly correlated to age, number of residual teeth, occlusal force and stimulated salivary flow rate by Pearson's correlation test. The multiple linear regression analysis showed that, with other variables controlled, masticatory performance was significantly associated with the number of residual teeth (β=0.456, P<0.001), occlusal force (β=0.244, P<0.001) and stimulated salivary flow rate (β=0.069, P=0.003). Age was not related to masticatory performance (β=-0.007, P=0.753). Declines in the number of residual teeth, occlusal force and salivary flow were associated with a reduction of masticatory performance in older adults. If tooth loss is not considered as an attribute of physiological ageing, then ageing by itself may not be a risk factor for masticatory dysfunction.
    Archives of oral biology 04/2011; 56(10):991-6. · 1.65 Impact Factor
  • Article: Incidence and association of root fractures after prosthetic treatment.
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    ABSTRACT: Common reasons for tooth extractions include periodontal disease, dental caries and root fracture. The purpose of this study was to investigate the association of tooth loss after prosthetic treatment, particularly incidences due to root fracture, which occur frequently and are difficult to prevent. Data were collected from consecutively selected medical records of patients taken over 3 years after their initial visit to Osaka University Dental Hospital. Collected data included (1) age and gender, (2) number of teeth at the initial visit and number of extracted teeth, (3) reasons for extraction, (4) restored with or without a post and (5) abutment of removable partial dentures (RPDs). A Chi-squared test was applied among the reasons for extraction, whether the tooth was restored with a post or not and clasped or not. A logistic regression analysis was used to determine the associations of root fracture with the patient data. This study included 101 patients (296 extracted teeth). The reasons for extraction included periodontal disease (64.6%), caries (25.3%) and root fracture (10.1%). The percentage of root fracture was significantly higher for female than male, for restored teeth with posts than without posts and for abutment of RPDs than for non-abutment teeth. Logistic regressions showed that root fractures were significantly associated with gender and abutments. The most frequently stated reasons for tooth extraction after prosthetic treatment were periodontal disease and dental caries, followed by root fracture. Root fractures were significantly associated with gender and abutment teeth of RPDs.
    Journal of prosthodontic research. 12/2010; 55(3):137-40.
  • Article: Increase of salivary flow rate along with improved occlusal force after the replacement of complete dentures.
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    ABSTRACT: We hypothesized that improvement of occlusal force would cause an increase in salivary flow rate (SFR) even in elderly complete denture wearers. The purpose of this study was to examine the change of SFR after the replacement of complete dentures. Subjects were 22 edentulous outpatients of the Osaka University Dental Clinic. Unstimulated whole saliva was collected for 5 minutes. Stimulated whole saliva was collected for 2 minutes. The maximal occlusal force was measured with pressure-sensitive sheets. All measurements were done before and after replacement of the dentures. The replacement of complete dentures improved maximal occlusal force and increased their stimulated and unstimulated SFR. Stimulated SFR was positively correlated with unstimulated SFR both before and after the replacement. Maximal occlusal force, stimulated SFR, and unstimulated SFR after the replacement were significantly correlated to the measurements before the replacement. These results suggest that proper prosthetic treatment can increase not only maximal occlusal force but also salivary flow rate.
    Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 09/2009; 108(2):211-5. · 1.50 Impact Factor
  • Article: Association of salivary Streptococcus mutans levels determined by rapid detection system using monoclonal antibodies with prevalence of root surface caries.
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    ABSTRACT: To examine the hypothesis that salivary Streptococcus mutans levels determined by a rapid detection system using monoclonal antibodies are associated with prevalence of root surface caries in a selected population of older adults. Oral examinations were performed in 241 elderly people aged over 60 years with at least 10 teeth, and root surface caries were recorded. Populations of S. mutans in saliva were classified into three groups (Low: < 1 x 10(5) CFU/mL; Moderate: < or = 1 x 10(5) CFU/mL, < 1 x 10(6) CFU/mL; High: < or = 1 x 10(6) CFU/mL) using the analyzing kit with species-specific monoclonal antibodies. Stimulated whole saliva was collected; the flow rate and pH value were determined. About 38% of subjects had at least one decayed lesion (inactive, active, or secondary lesions). Subjects were grouped according to levels of S. mutans into Low (51.5%), Moderate (39.4%), and High (9.1%). Significant associations were observed between inactive, secondary, or total decayed lesions and salivary S. mutans levels by Kruskal-Wallis test (P < 0.05). Multiple ordinary regression analyses demonstrated that numbers of inactive, secondary, and total decayed lesions were significantly associated with S. mutans levels (P < 0.05) independent of age, gender, frequency of brushing, salivary flow rate, or pH value of saliva.
    American journal of dentistry 11/2008; 21(5):283-7. · 0.76 Impact Factor
  • Article: Impact of dry mouth and hyposalivation on oral health-related quality of life of elderly Japanese.
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    ABSTRACT: To determine the association of hyposalivation and the perception of dry mouth with oral health-related quality of life for independently living elderly. The study sample consisted of 287 participants (mean age, 66.1 years) at a Senior Citizen educational system. Stimulated salivary flow rates during chewing were measured. The OHIP-14 to measure the impact of oral conditions on health-related quality of life was used, and summary OHIP-14 scores combining the response codes for the 14 items were analyzed. A logistic regression analysis showed that a higher OHIP-14 score indicating a poorer quality of life was related to fewer residual teeth, perception of dry mouth on eating (OR: 4.01, P = .012) and hyposalivation (OR: 2.71, P = .006). It is suggested that both dry mouth and hyposalivation are important problems influencing the quality of life in independently living, relatively healthy elderly Japanese.
    Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 03/2007; 103(2):216-22. · 1.50 Impact Factor
  • Article: The relationship between oral function and body mass index among independently living older Japanese people.
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    ABSTRACT: This study aimed to clarify the relationship between oral function and Body Mass Index (BMI) using data from independently living, relatively healthy older people. The hypothesis was that oral function is more important than dental status for healthy body weight. The subjects were community-dwelling, independently living elderly people over 60 years of age (N = 807, 408 men and 399 women). An oral health examination, an oral and general health interview, and measurement of oral function, such as masticatory performance and occlusal force, were carried out. BMI (kg/m2) was used to measure body fat. A multiple logistic regression analysis was used for 2 outcome variables of underweight and overweight. Overall, 70.1% of the subjects were in the normal category of BMI (20 to 25), 13.4% were in the underweight category (< 20), and 16.5% were in the overweight category (> 25). Neither occlusal force nor masticatory performance was significantly correlated with BMI. However, when the lowest 20% of occlusal force and masticatory performance values were used as explanatory variables, multiple logistic regression analyses showed that being underweight was significantly associated with having lower masticatory performance (odds ratio = 2.0, P= .015). In addition, being overweight was significantly associated with lower occlusal force (odds ratio = 1.8, P = .013). There was no statistical difference in the underweight or overweight proportions as a function of either number of teeth or type of dentition. Based on the results of this study, occlusal force and masticatory performance, rather than number of teeth or type of dentition, may play an important role in maintaining a normal BMI in independently living older Japanese people.
    The International journal of prosthodontics 19(6):539-46. · 1.38 Impact Factor
  • Article: Discrepancy between satisfaction with mastication, food acceptability, and masticatory performance in older adults.
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    ABSTRACT: The purpose of this study was to investigate the relationship between self-assessed satisfaction with mastication and food acceptability and masticatory performance in a large sample of older adults with various occlusal statuses. The subjects were 708 community-dwelling, independently living elderly persons (351 men and 357 women) with a mean age of 66.0 (SD: 4.2) years. Satisfaction with masticatory function and food acceptability (apples, grilled beef, and hard rice crackers) were evaluated using questionnaires. Masticatory performance was determined using test gummy jellies developed for measuring masticatory performance. Subjects were grouped into 3 categories by posterior occlusal contacts according to the Eichner Index. The Kruskal-Wallis test and a multiple logistic regression analysis for dissatisfaction with masticatory function were conducted. Overall, posterior occlusal contacts, food acceptability, and masticatory performance were associated with satisfaction with masticatory function when evaluated with bivariate analysis. Multiple logistic regression analysis showed that the number of foods that could be eaten without difficulty was the most important explanatory variable for dissatisfaction with masticatory function (P < .01). In contrast, objective masticatory performance was not significantly associated with dissatisfaction with masticatory function (P = .057) after controlling for posterior occlusal contacts and food acceptance. The subjective masticatory function was associated not only with objective masticatory performance, but also with an individual's posterior occlusal contacts.
    The International journal of prosthodontics 20(2):161-7. · 1.38 Impact Factor
  • Article: Association of masticatory performance with age, posterior occlusal contacts, occlusal force, and salivary flow in older adults.
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    ABSTRACT: This study aimed to investigate the effect of age, posterior occlusal contacts, occlusal force, and salivary flow on masticatory performance in older adults. The study sample consisted of 328 independently living people over the age of 60 years. Masticatory performance was determined by the concentration of dissolved glucose obtained from test gummy jellies, which are the standardized food developed for measuring masticatory performance. Bilateral maximal occlusal force in the intercuspal position was measured with pressure-sensitive sheets. Stimulated whole saliva was collected using the mastication method. Subjects were grouped into 3 categories by posterior occlusal contacts according to the Eichner Index. The multiple linear regression analysis showed that, with other variables controlled, masticatory performance was significantly associated with posterior occlusal contacts (beta = -.24, P < .001 for Eichner group B; beta = -.52, P < .001 for Eichner group C), occlusal force (P = .28, P < .001), and hyposalivation (beta = -.08, P < .046) (R(2) = 0.49). Within the groups classified by the Eichner Index, occlusal force was significantly associated with masticatory performance; however, age was not. For salivary flow rate, hyposalivation had a significant relationship with masticatory performance in group C (P = .003) and group B (P = .047), but no significant relationship in group A. A decline of posterior occlusal contacts, occlusal force, and hyposalivation appear to be associated with masticatory performance with aging in older adults.
    The International journal of prosthodontics 19(5):475-81. · 1.38 Impact Factor
  • Article: Impact of masticatory performance on oral health-related quality of life for elderly Japanese.
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    ABSTRACT: This study aimed to investigate the association of masticatory performance with oral health-related quality of life in independently living elderly Japanese subjects. The study sample consisted of 1028 independently living people over the age of 60 years. Masticatory performance was determined by the concentration of dissolved glucose obtained from test gummy jellies, which are the standardized food developed for measuring masticatory performance. The short-form Oral Health Impact Profile (OHIP-14) and Geriatric Oral Health Assessment Index (GOHAI) were used to measure the impact of oral conditions on oral health-related quality of life. Subjects with lower masticatory performance had significantly higher total OHIP-14 and GOHAI scores (15.0 +/- 9.0 and 14.5 +/- 9.2, respectively) than their counterparts (10.0 +/- 7.5 and 11.3 +/- 7.1, respectively) (P < .01). Logistic regression analyses showed that after controlling for age, gender, self-perceived general health, satisfaction with financial status, and number of teeth, a higher GOHAI score was significantly related to lower masticatory performance (P = .001; odds ratio: 0.56; 95% CI: 0.40 to 0.79). A higher OHIP-14 score was associated with lower masticatory performance but at a level below statistical significance (P = .096; odds ratio: 0.75; 95% CI: 0.53 to 1.05). It is suggested that masticatory performance is an important factor influencing the quality of life in independently living, relatively healthy elderly Japanese subjects.
    The International journal of prosthodontics 20(5):478-85. · 1.38 Impact Factor
  • Article: Association between oral stereognostic ability and masticatory performance in aged complete denture wearers.
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    ABSTRACT: Clinically excellent dentures have shown a limited influence on the function of denture wearers, suggesting that patient factors, such as salivary flow or oral sensory ability, may play an important role in oral function. The purpose of this study was to examine the oral sensory ability of aged edentulous patients in relation to masticatory performance. Subjects were 30 edentulous elderly patients with no oral symptoms or pathologies. Oral stereognostic ability (OSA) tests were conducted with test pieces of 12 shaped forms. The duration time for recognition was noted and the answers were recorded using a 3-point scale. Masticatory performance was determined by the concentration of dissolved glucose obtained from test gummy jellies, which are a standardized food developed for measuring masticatory performance. Bilateral maximum occlusal force in the intercuspal position was measured with pressure-sensitive sheets. Stimulated whole saliva was collected using the mastication method. A multiple linear regression analysis for masticatory performance was carried out. Statistical significance was set at P < .05. The stepwise multiple linear regression analysis showed that masticatory performance was significantly associated with maximum occlusal force (beta = .65, P < .001), OSA score (beta = .51, P < .001), and hyposalivation (beta = -.26, P = .042). The R2 of the model was 0.67, indicating that about two thirds of the variation in masticatory performance could be statistically explained by this model. Reduced oral sensory function, low occlusal force, and hyposalivation appear to be associated with impairment of masticatory performance in aged complete denture wearers.
    The International journal of prosthodontics 20(3):245-50. · 1.38 Impact Factor
  • Article: Validation of the Eichner index in relation to occlusal force and masticatory performance.
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    ABSTRACT: Eichner Indices (A, B, and C), especially the Eichner subgroups (A1-A3, B1-B4, C1-C3), have not been validated in relation to oral functions. The purpose of this study was to investigate the association of posterior occlusal contact loss with occlusal force and masticatory performance in subjects who had a normal dentition or partially edentulous arches restored with removable prostheses. The study sample consisted of 1,288 independently living patients over the age of 60 years. Subjects were grouped into 10 subgroups by posterior occlusal contacts according to the Eichner Index. Bilateral maximum occlusal force in the intercuspal position was measured using pressure-sensitive sheets. Masticatory performance was determined by the concentration of dissolved glucose obtained from comminuted gummy jellies. Occlusal force and masticatory performance were significantly associated with posterior occlusal contacts. Occlusal force measured in subgroups A2 to B2 and B3 to C3 did not differ statistically, although overall occlusal force decreased significantly as the loss of occlusal contacts increased. Similarly, masticatory performance was reduced with decreasing occlusal contact, although the decline was more gradual. Masticatory performance among subgroups A1 to B1, A3 to B2, B2 to B3, B4 to C2, and C1 to C3 did not differ significantly. The Eichner Index subgroups were significantly associated with reduced oral functions, even if the teeth were restored with removable prostheses. Preservation of occlusal contacts of the bilateral (B2) and unilateral (B3) premolars was critical for occlusal force and masticatory performance, respectively.
    The International journal of prosthodontics 23(6):521-4. · 1.38 Impact Factor