Investigation of hydrated smectite microstructure through wet environmental transmission electron microscopy.

Water is an essential constituent of all biological materials as well as many non-biological materials. Not only the removal of water may result in undesirable morphological and structure change, the inability to sustain the hydrated conditions in the microscope also prevents the study of reactions which take place in aqueous environment. In order to overcome these problems we used wet environmental-cell transmission electron microscopy TEM (WETEM). Conventional TEM of dry smectite showed well-defined particle outlines (but without a specific shape) and typical smectite aggregates. Selected area electron diffraction (SAD) of dry particles showed stacking of smectite particles (i.e., aggregate) in very clear dot and ring patterns. In contrast, WETEM depicted well-dispersed clay particles showing a variety of different particle shapes. Analysis of SAD patterns obtained from dry and hydrated states illustrated a lattice change in different environments. The small lattice expansion in (h k 0) resulted from the expansion of the (0 0 l) plane resulting from the addition of water molecules in the crystal along the c-axis.

Lower Protein Intake Mediates Association Between Lower Occlusal Force and Slower Walking Speed: From the Septuagenarians, Octogenarians, Nonagenarians Investigation with Centenarians Study.

OBJECTIVES: To investigate the association between lower extremity motor function and occlusion in older adults and to examine the possibility of dietary intake of protein mediating the association. DESIGN: Cross-sectional, population-based study. SETTING: Urban and rural area in Japan. PARTICIPANTS: Community-dwelling septuagenarians (N = 655) and octogenarians (N = 629). MEASUREMENTS: Information was collected on occlusal force, protein intake, grip strength, walking speed, sociodemographic characteristics, and medical history. Multivariable logistic regression analysis was used to investigate the association between walking speed, occlusal force, and protein intake, and structural equation modeling analysis and mediation analysis were performed to investigate the validity of the hypothesized model and identify the indirect effect of protein intake in occlusal force and walking speed. RESULTS: The proportion of participants whose walking speed was 0.8 m/s or slower (slow walking speed) was 27.7%. Logistic regression analyses showed that slower walking speed was associated with occlusal force (odds ratio = 1.57, P = .001) after adjusting for medical history, body mass index, grip strength, and protein intake. The fit of the hypothesized model that walking speed was associated with occlusal force through protein intake was good, and the indirect effect was significant. CONCLUSION: Slower walking speed was associated with lower occlusal force. Lower protein intake mediated the association between walking speed and occlusal force. Maintaining occlusal force might prevent insufficient nutrition intake and further deterioration of motor function in older people.

Association of personality traits with oral health-related quality of life independently of objective oral health status: a study of community-dwelling elderly Japanese.

OBJECTIVES: Oral health-related quality of life (OHRQoL) is being increasingly used in epidemiologic studies of dentistry. However, patient-reported OHRQoL does not always coincide with clinical measures. Previous studies have shown a relationship between OHRQoL and personality, but did not concomitantly investigate oral function. We aimed to examine the association among personality traits, oral function, and OHRQoL using a large sample of community-dwelling Japanese elderly. METHODS: The participants (n = 938; age, 69-71 years) were drawn from a complete enumeration of an urban area and a rural area of both the Tokyo metropolitan area and Hyogo Prefecture. The self-perceived impact of OHRQoL was measured using the Geriatric Oral Health Assessment Index (GOHAI). The oral status and socioeconomic characteristics were recorded in each participant, and personality traits (neuroticism, extraversion, openness to experience, agreeableness, and conscientiousness) were assessed with the NEO-five-factor inventory. Multiple linear regression analysis was performed to examine the relationships between OHRQoL and other factors, with p < 0.05 considered to be statistically significant. RESULTS: Neuroticism was negatively associated with the GOHAI score in bivariate analyses (Spearman rank-order correlation coefficient (rs )= -0.20), whereas extraversion was positively associated (rs = 0.17). In the regression analyses, neuroticism (standardized partial regression coefficient (ß) = -0.179) and extraversion (ß=0.094) were significantly associated with the GOHAI scores independently of the number of teeth, maximal occlusal force, and financial status. CONCLUSIONS: Personality traits are associated with OHRQoL independently of objective measures of oral health status in community-dwelling elderly Japanese. CLINICAL SIGNIFICANCE: This study showed personality traits are associated with OHRQoL independently of dental status and oral function in old Japanese people. As elderly patients undergo increasingly complex dental treatments, there is a need to evaluate patient personality traits prior to dental treatment and predict patient expectations and responses to planned treatment. This is advantageous in determining the most appropriate therapy.

Significance of occlusal force for dietary fibre and vitamin intakes in independently living 70-year-old Japanese: from SONIC Study.

OBJECTIVES: The number of teeth has frequently been used as an indicator of oral health in investigations of food intake; however, this measure does not represent the efficacy of the masticatory performance. Masticatory performance may be more important for food selection and avoidance than number of remaining teeth. The aim of this study was to investigate the association of occlusal force with habitual dietary intakes in independently living older Japanese. METHODS: The study population was 757 community-dwelling people aged 69-71 years old. Bilateral maximal occlusal force in the intercuspal position was measured with pressure-sensitive sheets. Removable denture wearers kept their dentures in place during the measurements. Dietary habits during the preceding month were assessed using a brief-type self-administered diet history questionnaire that measures consumption frequencies of selected food commonly consumed and calculates energy-adjusted dietary intakes. Linear trends of food and nutrient intakes with decreasing occlusal force were tested after adjusting for gender and socioeconomic factors. RESULTS: After adjusting for socioeconomic status and the number of remaining teeth, decline of occlusal force was significantly associated with lower intakes of vegetables, vitamins A, C, B6, folate, and dietary fibre (P for trend<0.05). In contrast, number of teeth was significantly associated only with calcium and zinc, controlling for occlusal force. CONCLUSIONS: It is concluded that occlusal force was significantly associated with intakes of vitamins and dietary fibre rather than number of remaining teeth in independently living older Japanese.

Chronological histological changes during bone regeneration on a non-crosslinked atelocollagen matrix.

Cleavage of the antigenic telopeptide region from type I collagen yields atelocollagen, and this is widely used as a scaffold for bone regeneration combined with cells, growth factors, etc. However, neither the biological effect of atelocollagen alone or its contribution to bone regeneration has been well studied. We evaluated the chronological histological changes during bone regeneration following implantation of non-crosslinked atelocollagen (Koken Co., Ltd.) in rat calvarial defects. One week after implantation, osteogenic cells positive for runt-related transcription factor 2 (Runx2) and osteoclasts positive for tartrate-resistant acid phosphatase (TRAP) were present in the atelocollagen implant in the absence of bone formation. The number of Runx2-positive osteogenic cells and Osterix-positive osteoblasts increased 2 weeks after implantation, and bone matrix proteins (osteopontin, OPN; osteocalcin, OC; dentin matrix protein 1, DMP1) were distributed in newly formed bone in a way comparable to normal bone. Some resorption cavities containing osteoclasts were also present. By 3 weeks after implantation, most of the implanted atelocollagen was replaced by new bone containing many resorption cavities, and OPN, OC, and DMP1 were deposited in the residual collagenous matrix. After 4 weeks, nearly all of the atelocollagen implant was replaced with new bone including hematopoietic marrow. Immunohistochemistry for the telopeptide region of type I collagen (TeloCOL1) during these processes demonstrated that the TeloCOL1-negative atelocollagen implant was replaced by TeloCOL1-positive collagenous matrix and new bone, indicating that new bone was mostly composed of endogenous type I collagen. These findings suggest that the atelocollagen itself can support bone regeneration by promoting osteoblast differentiation and type I collagen production.

Effect of dental status and masticatory ability on decreased frequency of fruit and vegetable intake in elderly Japanese subjects.

PURPOSE: The aim of this study was to investigate the association of masticatory ability and dental status with intake of fruits and vegetables after adjusting for other factors in independently living elderly Japanese subjects. MATERIALS AND METHODS: The study population consisted of 1,535 community-dwelling, independent elderly subjects over the age of 60 years. Self-assessed general health, financial status, dental status, self-assessed masticatory ability by food acceptance, and frequency of food intake were evaluated from responses to a questionnaire. Multiple logistic regression analysis for shortage of food intake was carried out. RESULTS: Of the participants, 29% had natural dentitions in both the maxilla and mandible and 15% were edentulous in at least one arch and wearing a complete denture. Percentages of participants with nutrient shortages of meat, fish and seafood, green and yellow vegetables, other vegetables, and fruits were 44%, 17%, 30%, 33%, and 12%, respectively. Multiple logistic regression analysis showed that men and subjects with a poor financial status had significant associations with shortages of dietary intake. In addition, shortages of meat, green and yellow vegetables, other vegetables, and fruit were significantly related to poor masticatory ability but not to dental status. Masticatory ability was significantly associated with shortages of green and yellow vegetables. CONCLUSION: Multivariate analyses showed that after adjusting for age, sex, and financial status, self-assessed masticatory ability rather than dental status by itself was significantly associated with shortages in vegetable and fruit intake in independently living elderly Japanese subjects.

Comparison of GOHAI and OHIP-14 measures in relation to objective values of oral function in elderly Japanese.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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 [ß] = -0.164, P = 0.004) and masticatory performance (ß = -0.125, P = 0.019) had significant associations with the GOHAI score, whereas this association was not found with the OHIP score. CONCLUSIONS: 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.

Masticatory performance in older subjects with varying degrees of tooth loss.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

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?

OBJECTIVE: 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. DESIGN: 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. RESULTS: 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 (ß=0.456, P<0.001), occlusal force (ß=0.244, P<0.001) and stimulated salivary flow rate (ß=0.069, P=0.003). Age was not related to masticatory performance (ß=-0.007, P=0.753). CONCLUSIONS: 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.

Subjective values of different age groups in Japan regarding treatment for missing molars.

OBJECTIVE: To determine how patients and dentists in Japan value the outcomes of different treatment options for missing molars. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Increase of salivary flow rate along with improved occlusal force after the replacement of complete dentures.

OBJECTIVE: 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. STUDY DESIGN: 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. RESULTS: 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. CONCLUSIONS: These results suggest that proper prosthetic treatment can increase not only maximal occlusal force but also salivary flow rate.

Relationship between bite force and salivary flow in older adults.

OBJECTIVE: To examine the relationship between bite force and stimulated salivary flow rate in older adults. STUDY DESIGN: The study sample consisted of 934 independent-living, cognitively healthy Japanese older adults 60 to 84 years of age. The maximal bite force was measured with pressure-sensitive sheets, and stimulated whole saliva was collected using the mastication method. RESULTS: The mean stimulated salivary flow rate was 1.36 +/- 0.97 mL/min. In bivariate analysis, the stimulated salivary flow rate was significantly lower in females and subjects with daily multiple medications (P < .01). Multiple linear regression analysis showed that the stimulated salivary flow rate was significantly associated with sex (standardized partial regression coefficient: partial beta = .22; P < .001), bite force (partial beta = .18; P < .001), and multiple daily medications (partial beta = -.12; P < .001). CONCLUSIONS: It is suggested that reduced bite force is associated with a decline in stimulated whole salivary flow rate independent of sex and medication in older adults.