Masticatory Performance Test Using a Gummy Jelly for Older People with Low Masticatory Ability.

Evaluation of masticatory ability has become more important in an aging society because decreased masticatory ability has the potential to affect the general health of older people. A new masticatory performance test, intended for older people with low masticatory ability, has been developed using gummy jelly half the size of that used in the conventional masticatory performance test. This study aimed to investigate the compatibility between the new and conventional tests and the adaptation of the new test. The new test using the 8-grade visual score with half-size gummy jelly was performed among 137 removable denture wearers (mean age 75.8 ± 9.0 years) with low masticatory performance (a score of ≤4 on a conventional test). The correlation between the scores of half-size gummy jelly (VS-H) in the new test and those of full-size gummy jelly (VS) in the conventional test was evaluated. VS-H among the groups divided by VS were also compared. A strong positive correlation was detected between VS-H and VS (rs = 0.70). In groups with VS of 0 and 1, VS-H values were widely distributed from 0 to 7. There were significant differences in VS-H between the groups with VS of 0-2 but no significant differences in VS-H between the groups with VS of 2-4. Therefore, the masticatory performance test using half-size gummy jelly is suitable for a detailed evaluation of masticatory ability in older people with low masticatory ability when their visual score of full-size gummy jelly in the conventional test is 2 or less.

Corrigendum: Lower Masticatory Performance Is a Risk for the Development of the Metabolic Syndrome: The Suita Study.

[This corrects the article DOI: 10.3389/fcvm.2021.752667.].

Compatibility of two types of gummy jelly tests for detecting decreased masticatory function.

OBJECTIVE: This study aimed to verify the compatibility of masticatory performance tests using different two types of gummy jellies. BACKGROUND DATA DISCUSSING THE PRESENT STATUS OF THE FIELD: Compatibility between the glucose concentration measuring method (GC) and 10-steps visual scoring method (VS), which are masticatory performance tests for diagnosing decreased masticatory function (DMF) in oral hypofunction and the use of different types of gummy jelly, has yet to be confirmed. MATERIALS AND METHODS: The participants consisted of 134 Japanese older people (51 men and 83 women). GC, VS and the increased surface area measuring method (ISA), as an alternative analysis method for VS, were conducted to evaluate masticatory performance. Cohen's Kappa coefficient was used to verify the consistency for detecting DMF between GC and VS. Pearson's correlation coefficient was used to analyse the relationship between GC and ISA. Each masticatory performance was compared among three different groups for the number of residual teeth. Cut-off values of VS and ISA for DMF that were consistent with GC were identified. RESULTS: Glucose concentration measuring method and VS showed an excellent consistency (Kappa coefficient = 0.86). There was a high positive correlation between GC and ISA (r = .70). However, the change in masticatory performance according to the number of teeth was different between GC and VS/ISA. The cut-off values of VS and ISA were a Score of 2 and 1687 mm2 , respectively. CONCLUSION: Glucose concentration measuring method and VS/ISA remained fairly consistent for detecting DMF, which might be useful information to interconnect the various studies on masticatory performance.

Lower Masticatory Performance Is a Risk for the Development of the Metabolic Syndrome: The Suita Study.

Objectives: Declined masticatory function has recently been receiving attention as a risk factor for poor general health. The present longitudinal analysis was conducted to clarify the relationship between decreased masticatory performance and the development of the metabolic syndrome (MetS) in a general urban cohort in Japan. Methods: We surveyed 599 participants (254 men, 345 women; mean age at baseline, 65.8 ± 7.8 years) who underwent physical health checkups in the Suita study. We evaluated masticatory performance at baseline using test gummy jelly and divided participants into two groups: a "Lower group," comprising participants in the lower 25% of the masticatory performance at baseline; and a "Normal group," comprising all others. We estimated hazard ratios (HRs) for the Lower group by using Cox proportional hazard regression analysis to develop the MetS and the components of the MetS at follow-up, adjusting for age, smoking status, and periodontal status. Results: On Cox proportional hazard regression analysis, the multivariable adjusted hazard ratio for the development of the MetS in the Lower group was 2.24 (95% confidence interval, 1.12-4.50) in men. The multivariable adjusted hazard ratio for the development of high blood pressure was 3.12 (1.42-6.87), for high triglycerides was 2.82 (1.18-6.76), and for high fasting plasma glucose was 2.65 (1.00-7.00) in men. Conclusions: Lower masticatory performance suggested to be a risk factor for the development of the MetS as well as MetS components such as high blood pressure, high triglycerides, and high fasting plasma glucose in Japanese men.

Deterioration of periodontal status affects declines in masticatory performance: The Suita study.

AIM: We aimed to clarify the association between deterioration of periodontal status and masticatory performance in a longitudinal follow-up study of a general urban population. MATERIALS AND METHODS: This study investigated 663 participants in the Suita study with no changes in the number of functional teeth or occlusal support areas during a 5-year follow-up period. Participants were classified into three groups according to changes in periodontal status during the survey period: a recovered group; a stable group; and a deteriorated group. Rate of masticatory performance change was calculated by subtracting the value at baseline from the value at follow-up and dividing the resulting value by the baseline value. RESULTS: Median rates of masticatory performance change were -11.7% in the recovered group, -19.2% in the stable group, and -30.8% in the deteriorated group, and these values were significantly different (p < .001). Multiple regression analysis revealed periodontal status group (recovered group: reference; stable group: p = .029; deteriorated group: p = .006) as an independent variable was significantly associated with the rate of masticatory performance change. CONCLUSION: The present results suggest that deterioration of periodontal status increases the risk of age-related declines in masticatory performance.

Association between declines in objective masticatory performance and salivary stress markers: The Suita study.

Dentists often encounter patients suffering from psychological and social stress due to declines in masticatory performance, making this a critical issue to manage. We aimed to clarify the relationships between salivary stress markers as objective indices of chronic stress and objective masticatory performance in a general urban Japanese population. Data from 880 participants (mean age, 65.8 years) in the Suita study were used. Salivary interleukin (IL)-6 and cortisol concentrations were measured by enzyme-linked immunosorbent assay. Objective masticatory performance was determined by measuring the increase in surface area test gummy jelly after 30 times chewing. Participants were divided into two groups based on masticatory performance: a decreased group (lowest quartile) and a non-decreased group (second to fourth quartiles). Odds ratios (ORs) of higher salivary levels of stress markers (highest quartile) according to masticatory performance were estimated using logistic regression analysis adjusting for age, sex, periodontal status, salivary flow rate and smoking habit. Salivary IL-6 level was significantly higher in the decreased group than in the non-decreased group. Logistic regression analysis showed the adjusted OR for higher salivary IL-6 was significantly higher in the decreased group than in the non-decreased group (OR = 1.92; 95% confidence interval = 1.33-2.76; P < .001). No significant associations were found between salivary cortisol and decreased masticatory performance in any analyses. Declines in objective masticatory performance may correlate with higher salivary IL-6 level as an objective index of chronic stress.

A prediction model of masticatory performance change in 50- to 70-year-old Japanese: The Suita study.

OBJECTIVES: Declines in masticatory performance might be a risk factor for worsening nutritional intake and result in general frailty. The present study constructed and investigated a method to predict the extent to which objective masticatory performance declines with age in cases with poor oral health status. METHODS: Participants comprised 1201 participants in the Suita study with dental checkup at both baseline and follow-up (500 men and 701 women; age at baseline, 65.6 ± 7.8 years; mean follow-up, 5.1 ± 1.1 years). First, multiple linear regression analysis was performed with masticatory performance at follow-up as the dependent variable and sex as well as baseline age, number of functional teeth, maximum bite force, occlusal support, periodontal status, salivary flow rate, and masticatory performance as independent variables. Scores were assigned to each factor based on the standardized partial regression coefficient obtained from multiple linear regression analysis. Participants were divided into quintile groups (Q1-Q5) based on total scores for factors, and rates of masticatory performance change for each group were calculated and compared. RESULTS: Mean rates of masticatory performance change in groups Q1-Q5 from the model to predict declining masticatory performance were: Q1, -9.7%; Q2, -12.7%; Q3, -18.0%; Q4, -19.9%; and Q5, -29.8%.Thus there was a trend for masticatory performance to decrease with decreasing score. CONCLUSIONS: The model developed in this study quantitatively predicted declines in masticatory performance after approximately 5 years. CLINICAL SIGNIFICANCE: We developed a model for predicting the extent to which masticatory performance will change over the next 5 years. This model may offer a useful tool when taking measures to prevent declines in masticatory performance with aging.

The impact of a newly constructed removable denture on the objective and subjective masticatory function.

Purpose This study investigated the impact of the renewal of a removable prosthesis on the masticatory function by subjective and objective measures and its variation among the types of occlusal support.Methods Seventy-eight patients who received newly fabricated removable denture patients participated in this study. For the objective assessment, masticatory performance was measured using test gummy jelly. For the subjective assessment, standardized questionnaires about food acceptability and the oral health-related quality of life (OHRQoL) were used. Pre- and post-insertion assessments were performed for each subject. Subjects were divided into three groups according to their posterior occlusion: with posterior occlusion (w/PO), without posterior occlusion (w/o PO) and edentulous. Wilcoxon's signed rank test was used to compare the pre- and post-treatment measurements of each assessment. The analysis of covariance and a multiple comparison were used to assess the effect of new dentures and differences due to occlusal support.Results The masticatory performance, OHRQoL and food acceptability following prosthodontic treatment were significantly improved by new denture insertion. The masticatory performance among groups varied to a relative degree. The rate of masticatory performance improvement for edentulous subjects was twice that in w/PO subjects. The OHRQoL was significantly lower in the w/o PO and edentulous groups with old denture than patients w/PO. The food acceptability improved most markedly in the edentulous group.Conclusions The improvement in the masticatory performance by new denture insertion varied among types of occlusal support. Re-establishing the occlusal support of edentulous patients may help restore their OHRQoL and improve food acceptability.

Periodical utilization of dental services is an effective breakthrough for declining masticatory performance: the Suita study.

Masticatory performance of subjects from a general urban population was examined by measurement at baseline and again at follow-up, to clarify whether periodical utilization of dental services (PUDS) is effective in maintaining masticatory performance. Subjects comprised 1010 people (414 males, 596 females; mean age at baseline, 65.7 ± 7.8 years) who participated in the Suita study with dental checkups at both baseline and follow-up (mean follow-up, 5.2 ± 1.5 years). Number of functional teeth, occlusal support, periodontal status, masticatory performance, maximum bite force, and salivary flow rate were surveyed. Subjects were divided into a with-PUDS group (n = 430), who responded at both baseline and follow-up that they regularly utilized dental services, and a without-PUDS group (n = 580), who responded otherwise. To evaluate longitudinal changes in masticatory performance over the study period, the rate of masticatory performance change was calculated by dividing the difference in masticatory performance between follow-up and baseline by the masticatory performance at baseline. The relationship between the presence of PUDS and the rate of masticatory performance change was investigated by multiple linear regression analysis. Analysis was performed using a model with number of functional teeth as an independent variable (number of functional teeth model), and a model with occlusal support as an independent variable (occlusal support model). Multiple linear regression analysis identified PUDS as significantly associated with the rate of masticatory performance change in both the number of functional teeth model and the occlusal support model. PUDS is likely to prove effective in ameliorating reductions in masticatory performance over time.

Decreased masticatory performance is related to increased intima-media thickness in a general urban Japanese population: The Suita study.

PURPOSE: The association between periodontal disease and carotid atherosclerosis has been widely discussed, but to our knowledge, no population-based studies have been conducted on the association between masticatory ability and carotid atherosclerosis. We aimed to clarify the hypothesis that objectively accessed masticatory performance is related to increased intima-media thickness (IMT) in a general urban population. METHODS: We studied 1,484 Japanese (mean age: 66.9 y) from the Suita study. Masticatory performance was measured using test gummy jelly, and periodontal status was evaluated using the Community Periodontal Index (CPI). Carotid ultrasonography was performed to measure maximum IMT (max-IMT) in the entire area of the carotid arteries. Analysis of covariance was used to compare max-IMT according to quartiles of masticatory performance adjusted by cardiovascular risk factors and periodontal status. RESULTS: Multivariable-adjusted max-IMT (standard error) was significantly higher in the lowest masticatory performance quartile group (decreased group) (1.58 ± 0.03 and 1.44 ± 0.03 mm) than in the 2nd to 4th quartiles combined (non-decreased groups) in both sexes (1.48 ± 0.02 mm, trend P = 0.038) and in women (1.34 ± 0.02 mm, trend P = 0.013), respectively. In participants without cardiovascular risk factors (n = 250), multivariable-adjusted max-IMT was significantly higher in the decreased (1.54 ± 0.06, 2.08 ± 0.22, and 1.42 ± 0.06 mm) than in the non-decreased groups in both sexes (1.31 ± 0.04 mm, trend P = 0.006), in men (1.41 ± 0.12 mm, trend P = 0.028), and in women (1.28 ± 0.04 mm, trend P = 0.073). CONCLUSIONS: These findings suggest that decreased masticatory performance may be related to carotid IMT progression in the general urban Japanese population.

Masticatory performance analysis using photographic image of gummy jelly.

PURPOSE: Masticatory performance can be measured through elution of glucose or beta-carotene from comminuted gummy jelly. However, these methods require special devices. Additionally, occasional/unintentional swallowing or inadequate collection of comminuted particles of gummy jelly in the oral cavity may cause measurement errors. Therefore, we devised a new photographic method to estimate the increase in surface area and weight of comminuted gummy jelly. This study aimed to verify the accuracy of this method. METHODS: Initially, fifty images depicting the comminuted pieces in a special box were prepared. Then, the increase in surface area was measured using a fully-automated method, and the weight was measured. The size and angle of each image were adjusted based on markers located at the four corners of the box. From these photographic images, the area, perimeter, color average, color deviation, side area, and amount of surface roughness for each particle was calculated, and multiple regression analysis was performed to estimate the surface area and weight. The relationship between the estimated values and the values measured with the fully-automated device and by weight were analyzed. RESULTS: The intra-class correlation coefficient between the estimated value and the value from the fully-automated method was r = 0.956. This high correlation was also obtained under different photographic conditions. Furthermore, for determining whether 80% or less gummy jelly was collected, the sensitivity was 100% and the specificity was 91%. CONCLUSIONS: The newly developed photographic method is valuable because it is accessible and may assist in achieving reliable evaluation of masticatory performance.

Relationship between metabolic syndrome and objective masticatory performance in a Japanese general population: The Suita study.

OBJECTIVES: An association between metabolic syndrome (MetS) and periodontal status has recently been focused on. However, no study has investigated the relationship between the prevalence of MetS and the decline of masticatory performance. We aimed to clarify the relationship between MetS and objective masticatory performance using the standardized test food in a general urban Japanese population. METHODS: We studied 1780 Japanese men and women (mean age, 66.5 years) using the Suita study. MetS was defined using the uniform definition proposed in the 2009 Joint Interim Statement. Masticatory performance was evaluated by a chewing test using gummy jelly. Prevalence of MetS among quartiles of masticatory performance was compared using multiple logistic regression analysis adjusting for sex, age, drinking and smoking status, and periodontal status evaluated by the Community Periodontal Index. RESULTS: Compared to the highest quartile of masticatory performance, the 2nd quartile showed a 1.46-fold increase in the prevalence of MetS (trend P=0.159). In addition, Analysis by age showed 1.67-, 1.90- and 1.74-fold increases in the prevalence of MetS in the 3rd, 2nd and 1st quartiles among individuals in their 70s, respectively (trend P=0.094). However, individuals in their 50s and 60s showed no significant relationship between masticatory performance and MetS. CONCLUSIONS: These findings suggested that masticatory performance are inversely associated with the prevalence of MetS independent of periodontal disease, especially in the elderly. CLINICAL SIGNIFICANCE: Declines in objective masticatory performance might be associated with the prevalence of MetS, independent of periodontitis. Given our results, treatments aimed at maintaining and recovering masticatory performance may represent important dental care to mitigate the risk of MetS.

Does the utilization of dental services associate with masticatory performance in a Japanese urban population?: the Suita study.

There are numerous reports on the relationship between regular utilization of dental care services and oral health, but most are based on questionnaires and subjective evaluation. Few have objectively evaluated masticatory performance and its relationship to utilization of dental care services. The purpose of this study was to identify the effect of regular utilization of dental services on masticatory performance. The subjects consisted of 1804 general residents of Suita City, Osaka Prefecture (760 men and 1044 women, mean age 66.5 ± 7.9 years). Regular utilization of dental services and oral hygiene habits (frequency of toothbrushing and use of interdental aids) was surveyed, and periodontal status, occlusal support, and masticatory performance were measured. Masticatory performance was evaluated by a chewing test using gummy jelly. The correlation between age, sex, regular dental utilization, oral hygiene habits, periodontal status or occlusal support, and masticatory performance was analyzed using Spearman's correlation test and t-test. In addition, multiple linear regression analysis was carried out to investigate the relationship of regular dental utilization with masticatory performance after controlling for other factors. Masticatory performance was significantly correlated to age when using Spearman's correlation test, and to regular dental utilization, periodontal status, or occlusal support with t-test. Multiple linear regression analysis showed that regular utilization of dental services was significantly related to masticatory performance even after adjusting for age, sex, oral hygiene habits, periodontal status, and occlusal support (standardized partial regression coefficient ß = 0.055). These findings suggested that the regular utilization of dental care services is an important factor influencing masticatory performance in a Japanese urban population.

The effect of periodontal status and occlusal support on masticatory performance: the Suita study.

AIM: In this study, we investigated the effect of differences in periodontal status in the masticatory performance of dentate subjects with the same occlusal supporting area. MATERIALS AND METHODS: The subjects of the analysis were classified into those of Eichner A1-3 (n = 1094) and Eichner B1-4 (n = 529). Subjects' periodontal status was evaluated on the basis of the Community Periodontal Index (CPI). The number of functional teeth and occlusal support were investigated, the latter on the basis of the Eichner Index. Furthermore, masticatory performance was investigated by means of test gummy jelly. For each group, periodontal status was classified in two different ways, either with/without moderate periodontitis (CPI Code ≤2/≥3) or with/without severe periodontitis (CPI Code ≤3/4), and masticatory performance was compared between the various groups. RESULTS: In subjects who were Eichner A1 and B3, masticatory performance was significantly lower in subjects with moderate periodontitis compared with those without, and in subjects with severe periodontitis compared with those without. CONCLUSION: Periodontal disease affects masticatory performance not only if occlusion is established by natural dentition with no tooth loss but also if occlusal support has decreased.

Validity and reliability of a visual scoring method for masticatory ability using test gummy jelly.

BACKGROUND: For quantitative evaluation of masticatory ability of the elderly patients, there should be a simple and reliable method without special techniques and instruments. OBJECTIVE: The purpose of this study was to examine the validity and reliability of a visual scoring method for assessing masticatory performance. MATERIALS AND METHODS: A 10-stage scale for visually scoring was rated based on the range of the glucose concentration dissolved from comminuted jelly. Photographic images of comminuted jellies were produced as a standard material for each score. Fifty subjects were recruited as raters who graded the visual score for 50 photographic images of comminuted jellies on the screen of a lap-top three times in random order. RESULTS: There were strong correlations (rs = 0.911- 0.981, Spearman's rank coefficient) between the actual scores determined from the glucose concentration and the visual scores graded by subjects in all three measurements. The intraclass correlation coefficients (ICCs) of the inter-rater reliability and the ICCs of the intra-rater reliability of the visual scoring ranged from 0.946 to 0.947 and from 0.860 to 0.987 in three measurements, respectively. CONCLUSIONS: These results indicated that the visual scoring method was valid and reliable for evaluation of masticatory performance.

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.

Influence of voluntary control of masticatory side and rhythm on cerebral hemodynamics.

The aim of this study was to investigate the influence on cerebral hemodynamics of voluntary control of masticatory side and rhythm during gum chewing. Blood flow velocity in the middle cerebral artery was measured using transcranial Doppler ultrasonography to evaluate cerebral circulation in healthy volunteers. Heart rate and masseter muscle activity were recorded simultaneously. Volunteers performed three tasks: (1) free gum chewing, (2) gum chewing in which mastication was limited to the right side, and (3) gum chewing in which mastication was limited to the right side and rhythm was set at 1.0 Hz. Changes in cerebral circulation during pre-task, on-task, and post-task periods were analyzed using random effects model, and differences in cerebral circulation and muscle activity between tasks were analyzed using the Friedman test. In all tasks, on-task cerebral circulation was greater than pre-task. Muscle activity and masticatory rhythm varied between tasks, whereas the rate of increase in cerebral circulation did not differ significantly among tasks. These results suggest that cerebral circulation is activated during gum chewing, irrespective of voluntary control of masticatory side and rhythm.

Validation of the Eichner index in relation to occlusal force and masticatory performance.

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Association of salivary Streptococcus mutans levels determined by rapid detection system using monoclonal antibodies with prevalence of root surface caries.

PURPOSE: 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. METHODS: 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. RESULTS: 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.

Differential columnar processing in local circuits of barrel and insular cortices.

The columnar organization is most apparent in the whisker barrel cortex but seems less apparent in the gustatory insular cortex. We addressed here whether there are any differences between the two cortices in columnar information processing by comparing the spatiotemporal patterns of excitation spread in the two cortices using voltage-sensitive dye imaging. In contrast to the well known excitation spread in the horizontal direction in layer II/III induced in the barrel cortex by layer IV stimulation, the excitation caused in the insular cortex by stimulation of layer IV spread bidirectionally in the vertical direction into layers II/III and V/VI, displaying a columnar image pattern. Bicuculline or picrotoxin markedly extended the horizontal excitation spread in layer II/III in the barrel cortex, leading to a generation of excitation in the underlying layer V/VI, whereas those markedly increased the amplitude of optical responses throughout the whole column in the insular cortex, subsequently widening the columnar image pattern. Such synchronous activities as revealed by the horizontal and vertical excitation spreads were consistently induced in the barrel and insular cortices, respectively, even by stimulation of different layers with varying intensities. Thus, a unique functional column existed in the insular cortex, in which intracolumnar communication between the superficial and deep layers was prominent, and GABA(A) action is involved in the inhibition of the intracolumnar communication in contrast to its involvement in intercolumnar lateral inhibition in the barrel cortex. These results suggest that the columnar information processing may not be universal across the different cortical areas.