Relationship between two pressure-sensitive films for testing reduced occlusal force in diagnostic criteria for oral hypofunction

Improvement of oral function and its impact on oral food intake in subacute stroke patients: A prospective study with dental intervention

BACKGROUND

The association between oral food intake and oral function during the subacute stage of stroke is not well known.

OBJECTIVE

To investigate (1) oral function changes in subacute stroke patients and (2) association between oral function and oral intake status at several time points.

METHODS

In a prospective study involving 324 stroke patients at a convalescent rehabilitation unit, four oral function parameters (maximum tongue pressure, MTP; lip-tongue motor function, LTMF; maximum occlusal force, MOF and oral health assessment tool, OHAT) were quantitatively measured upon admission (T0), at 1 month (T1) and 2 months (T2). Oral feeding status was assessed using the Functional Oral Intake Scale (FOIS) and divided based on the FOIS score into the dysphagic and regular diet groups. The changes in oral functions at the three time points were tested using generalized estimating equation analysis. The association between FOIS groups and oral functions at T1 and T2 was analysed by means of logistic regression analysis.

RESULTS

All oral function parameters improved significantly over time during the hospital stay (mean differences: 4.9 for MTP, 0.6 for LTMF, 1.1 for MOF and -1.8 for OHAT). The FOIS groups were significantly associated with MTP (p < .05) and OHAT (p < .05) at both T1 and T2.

CONCLUSION

Our findings suggest that oral function significantly improves in patients during subacute stroke rehabilitation and better oral health can be associated with better oral intake. Improved oral function through dental intervention and oral rehabilitation may contribute to gains in oral food intake.

Association between oral health status and occlusal bite force in young adults

Background/purpose

Oral health is related to general health and a person's overall well-being. The aim of the present study was to explore the association between oral health status and bite force among young adults.

Materials and methods

Maximum bite force (MBF) was measured using Dental Prescale II in conjunction with a pressure-sensitive film and bite force analyzer in 40 young adults aged 20 to 40. Supragingival dental plaque was collected and cultured. Plaque weight, pH, and colony counts were assessed. The decayed, missing, and filled teeth index (DMFT) and body mass index (BMI) were recorded.

Results

Bite force was negatively correlated with the number of missing teeth and the sum of missing and filled teeth. When the filled-to-remaining-teeth ratio (F/R ratio) was less than 8%, the bite force was significantly higher compared to an F/R ratio of 8-25%. Additionally, the amount of total bacteria was positively correlated with total bite force, and the quantity of Streptococcus mutans (S. mutans) along with total bacteria was positively correlated with bite force in the molar region (∗P < 0.05). The molar region predominantly contributed to bite force.

Conclusion

Elevated levels of cariogenic bacteria may increase the risk of tooth loss, subsequently leading to reduced bite force. This reduction in bite force can further impact the efficiency of chewing function and, consequently, the quality of life. An F/R ratio above 8% could be easily calculated clinically and could serve as a guide to identify patients, particularly young adults, at risk of reduced bite force.

A Study on the Contact Characteristics of Tires-Roads Based on Pressure-Sensitive Film Technology

Tire-road characteristics are a critical focus of research in the automotive and transportation industries. On the one hand, the research can help optimize tires' structural design; on the other hand, it can analyze the mechanical response of the pavement structure under the vehicle load. In addition, the non-uniformity distribution of the tire ground stress will also have a direct impact on the skid resistance, which determines the driving safety. Due to the limitation of testing technology, the measurement of tire ground pressure was mainly carried out on a flat test platform, ignoring the roughness of the actual pavement surface texture. The tire-road contact characteristics research on the macro-texture and micro-texture of asphalt pavement needs to be broken through. A high-precision pressure-sensitive film measurement system is utilized to examine the actual contact characteristics between two types of automobile tires and three types of asphalt pavement in this paper. The influence law of pavement texture and patterned tires on the contact area and stress was explored, and the concentration effect of tire-road contact stress was evaluated. The results indicate that the contact area of grounding tires exhibits a nearly linear relationship with tire inflation pressure and load. Notably, the change in load has a more significant influence on the contact area than tire inflation pressure. On asphalt pavement, the contact reduction rate decreases by approximately 5-10% for block pattern tires and 10-15% for longitudinal pattern tires. Furthermore, as the texture depth of the pavement increases, the contact area between tires and the pavement texture decreases. The actual tire-road interface experiences significant stress concentration due to the embedding and meshing effects between the tire and road surface. Even on a flat steel surface, the peak stress at the edge of the tread block exceeds the 0.7 MPa design load, which is about 2.5-3 times higher than the design uniform load. The peak stress between the tire and asphalt pavement reaches 4-10 times the design uniform load, with a rising trend as the pavement texture depth increases. This study can provide relevant experimental technical support for tire design and functional design of asphalt pavement.

Evaluating the effect of management on patients with oral hypofunction: A longitudinal study

INTRODUCTION

Declining oral function may affect subsequent physical frailty in the older population. The aim of this longitudinal study was to summarise data on patients who underwent functional oral examination and evaluate the impact of management on patients with oral hypofunction (OHF).

METHODS

Dental outpatients aged over 65 years at their initial visit to the Niigata University Hospital received detailed assessment of seven oral function items to diagnose oral hypofunction using diagnostic criteria defined by the Japanese Society of Gerodontology. Patients with OHF at the first assessment received management including oral health guidance for low function and dental treatment. They were re-evaluated approximately 6 months later and the two assessments were compared. According to the results of the second assessment, the patients were divided into two groups: OHF improved and OHF re-diagnosed.

RESULTS

Of the 273 patients who underwent the first assessment, 86 (31.5%) were diagnosed with OHF and received management. Of those, 42 (48.8%) completed the second assessment. Comparing the first and second assessment, significant improvement was observed in oral hygiene, occlusal force, tongue-lip motor function of /pa/, mastication and swallowing. The change in values from the first assessment demonstrated a significant difference between the OHF improved and re-diagnosed groups only in occlusal force.

CONCLUSION

Management for patients with OHF can contribute to the improvement of poor oral function, and an increase in occlusal force was notable in the recovery from OHF.

Evaluation of automatic cleaning in analysis of occlusal force

This study aimed to clarify the usefulness of automatic cleaning in analysis of occlusal force. The maximum occlusal force was calculated in 151 healthy adults before cleaning (B), after manual cleaning (M), and after automatic cleaning (A) and compared among the three conditions. The absolute value of the error rate of A, based on M, was calculated. The occlusal forces in M and A were similar and significantly smaller than the occlusal force in B. The absolute error rate of A was 2.4%. These results suggest that automatic cleaning has a similar effect to manual cleaning and can be applied clinically.

The correlation between two occlusal analyzers for the measurement of bite force

Background

Occlusal force represents masticatory function. Using quantifiable occlusal indicators provides a more objective occlusal force evaluation. In the recent dental practice, digital methods such as the Dental Prescale II (DP2, GC Corp., Tokyo, Japan) and T-scan (T-Scan III v8; Tekscan Inc.) are commonly used in clinics to evaluate treatment outcomes. The T-scan provides the relative bite force (%) compared to the maximal bite force on individual teeth or the unilateral arch. The DP2 can quantify occlusal force, measured in newtons (N), on the half arch or the overall bite, but it is difficult to identify the bite force on an individual tooth. It is difficult to select a device that fulfils all the requirements to record occlusal force. This study aimed to investigate the association between the bite measured by the DPS2 and T-scan to determine whether the measured bite force is comparable through calculation.

Methods

A total of 80 healthy adults, including 41 women and 39 men with a mean age of 38.2, were requested to bite pressure sensitive film sheets ten minutes apart. Linear regression analysis was used to estimate the measured bite force by the DP2 and T-scan.

Results

There was a significant positive correlation between the occlusal force measured by the DP2 and T-scan (P < 0.01) when intercept was equal to zero as confounders were adjused. These results provided the comparability of the measured occlusal forces determined by the DP2 and T-scan.

Conclusion

The estimated bite force determined by DP2 and T-Scan is convertible using the linear equation from this study to increase the value for clinical applications. The estimated bite force from the two quantifiable occlusal indicators are comparable. The two commercially available quantifiable occlusal indicators can be fully adapted to all clinical requirements according to this result.

Effects of Interval Walking Training on Oral Health Status in Middle-Aged and Older Adults: A Case-Control Study

The purpose of this study was to determine the effect of walking training "Interval Walking Training (IWT)" on oral health status. Participants were divided into two groups: an exercise intervention group and a non-intervention group (control). The intervention group consisted of 59 subjects (20 males, 39 females) aged 50 years or older who participated in the IWT program in Matsumoto from 2019 to April 2022. The control group consisted of 33 subjects (14 males and 19 females) aged 50 years or older who have visited Niigata University Medical and Dental Hospital and agreed to participate in the study. The intervention group underwent walking training (interval walking training) for at least 5-6 months. The walking training consisted of five sets of fast walking above 70% peak aerobic capacity for walking (VO₂peak) for 3 min, followed by 3 min of slow walking at ~40% VO₂ peak per day for more than four days/week. The oral health status was evaluated for the number of teeth, occlusal force, salivary occult blood, masticatory performance, and tongue pressure. A total of 57 participants were analyzed in the intervention group (18 males and 39 females, age: 66.7 ± 0.8 (mean ± S.E.) years) and 33 participants in the control group (14 males and 19 females, age: 74.5 ± 1.1 (mean ± S.E.) years). There were no significant differences in gender, salivary occult blood, tongue pressure, masticatory performance, or occlusal force between the two groups at the start of the intervention (p = 0.36, p = 0.48, p = 0.42, p = 0.58, and p = 0.08, respectively by unpaired t-test or χ² test). On the other hand, there were significant differences in age and BMI, with a trend toward lower age and higher BMI in the intervention group (p < 0.001 and p < 0.001, respectively, by unpaired t-test). In terms of rate of change, the intervention group showed a significant increase in occlusal force (F = 4.5, p = 0.04, ANCOVA) and a significant decrease in BMI (F = 7.3, p = 0.009, ANCOVA). No significant differences were observed in the other measured items. It was found that walking training in both middle-aged and older people does not only affect the physical aspect of weight loss but may help maintain and improve the occlusal force.

Periodontal status is associated with oral function in community-dwelling older adults, independent of dentition status

OBJECTIVE

To determine whether periodontal status is associated with oral function, including masticatory performance and occlusal force, among community-dwelling older adults.

BACKGROUND

Although a potential association between periodontal status and oral function has been reported, variations in the root surface area (RSA) of each tooth have not been considered.

METHODS

We used data from a population-based study involving community-dwelling older adults. The RSA with periodontal ligament (RSA-PL), which quantifies the RSA attached to the periodontal ligament and alveolar bone, was calculated based on full-mouth periodontal examination. Masticatory performance was assessed using spectrophotometric measurement of the color (a* value) of color-changing chewing gum. The bilateral maximal occlusal force (MOF) was measured using a pressure-sensitive sheet and dedicated software. The associations of the RSA-PL, a quantitative marker of periodontal tissue support, with the a* value and MOF were assessed using linear regression models.

RESULTS

The analyses included data from 250 adults [60.8% women; age, mean (standard deviation) 82.5 (5.0) years]. On average, the study participants had an RSA-PL of 26.3 cm² , a* value of 25.0, and an MOF value of 555.1 N. After adjustments for potential confounders, including dentition status, age, sex, dental visit regularity, smoking status, physical activity level, depressive symptoms, a history of stroke or diabetes mellitus, and body mass index, the RSA-PL was found to be associated with the a* value [coefficient (per 1 cm² increase): 0.16, 95% confidence interval (CI) 0.10-0.22)] and MOF (coefficient: 9.2, 95% CI 5.3-13.1).

CONCLUSION

This study demonstrated that greater amounts of remaining tooth-supporting structures, indicated by higher RSA-PL values, were associated with better masticatory performance and a higher occlusal force among community-dwelling older adults.

Comparison of oral hypofunction tests and determination of reference values for a subjective masticatory function test

Background

In Japan, oral hypofunction has been recognized as a disease since 2018. An alternative to occlusal force testing for assessing oral hypofunction is the evaluation of the number of natural teeth. Subjective masticatory function testing, which evaluates the ease or difficulty in chewing foods, is an effective alternative to occlusal force testing. However, no reference values have been established for this test. We determined the reference values of the subjective masticatory function test and evaluated its potential as a substitute for the number of natural teeth for assessing oral hypofunction.

Methods

The sample consisted of 184 older adults who visited the Department of Geriatric Dentistry, Showa University Dental Hospital, from July 2018 to January 2020. The subjective masticatory function test (table for evaluation of chewing function in complete denture wearers [Chewing Score 20]) was performed using 20 foods. The occlusal force test and a receiver operating characteristic curve were used to determine the reference values for Chewing Score 20. The sensitivity, specificity, and positive and negative predictive values were calculated and compared with the occlusal force test and the number of natural teeth.

Results

A significant correlation (r) was found between the occlusal force test and the Chewing Score 20 (r = 0.526, p < 0.001). The reference value for Chewing Score 20 was < 85. Although the Chewing Score 20 was less sensitive than the number of natural teeth, it demonstrated a higher specificity and a positive predictive value.

Conclusion

Herein, a score of < 85 on the subjective masticatory function test was determined to be the optimal quantitative reference. The subjective masticatory function test may be used as an alternative for assessing oral hypofunction.

Standard Values and Concurrent Validity of a Newly Developed Occlusal Force-Measuring Device among Community-Dwelling Older Adults: The Otassha Study

Recently, an occlusal force-measuring device with a capacitive-type pressure-mapping sensor (OFMD-CPS) was developed. We aimed to establish age- and sex-specific standard values for OFMD-CPS-measured occlusal force (OF) and to assess the concurrent validity of the OFMD against another OF measuring system with a pressure-sensitive sheet (Dental Prescale II). Using data from a population-based study, we calculated the OFMD-CPS-measured OF means and deciles in 5-year age groups for each sex. The OFMD-CPS-measured OF was validated against the Dental Prescale II-measured OF with Spearman correlation coefficients. Furthermore, we calculated the area under the receiver operating characteristic curve (AUC) against the preexisting Dental Prescale II-measured OF cutoff value of 350 N. In total, 596 individuals (236 men and 360 women) with a mean (standard deviation (SD)) age of 73.7 (6.7) years were included in the analyses. The mean (SD) OFMD-CPS-measured OFs were 581.6 (284.6) N in men and 446.9 (209.9) N in women. There was a strong positive correlation (Spearman's Rho = 0.73) between OFMD-CPS-measured and Dental Prescale II-measured OF. The diagnostic accuracy of the OFMD-CPS-measured OF for the Dental Prescale II-measured OF cutoff value was high (AUC = 0.88). In conclusion, we demonstrated standard values and concurrent validity of OFMD-CPS-measured OF in community-dwelling older adults.

Effect of masticatory training using confectioneries on oral function in elderly patients – A randomized controlled trial

Background/purpose

Materials and methods

Results

Conclusion

Regular Oral Health Management Improved Oral Function of Outpatients with Oral Hypofunction in Dental Hospital: A Longitudinal Study

This longitudinal study aimed to clarify the impact of regular oral health management for oral hypofunction on the oral function of older dental outpatients. The 68 participants enrolled in this study were older dental outpatients (mean age 78.5 ± 8.1 years). According to the number of declined oral examinations after the first exam, participants were assigned to the oral hypofunction group (Hypo group, ≥3), receiving regular oral health management with a leaflet at the dental clinic, or the pre-oral hypofunction group (Pre-hypo group, ≤2), which served as a control. At the second oral examination, after approximately 6 months to 1 year, the Hypo group showed significant improvement in the tongue-lip motor function (Oral diadochokinesis, ODK) /pa/, /ta/, and masticatory function, while the Pre-hypo group showed significant worsening in oral hygiene and oral wetness. Temporal changes in ODK /pa/, /ta/, and the number of declined examination items were significantly different between the groups. Multiple analysis revealed that the number of improved oral examination items were associated with presence of regular oral health management after adjusting for age, sex, number of visits, measuring period, and dental treatment. Regular comprehensive oral health management for oral hypofunction improves and maintains oral function among older dental outpatients.

Effect of scan delay on measurements of an occlusal pressure sensitive film: An in-vitro study

Background/purpose

While scan delay may affect the measurements of an occlusal pressure-sensitive film, Dental Prescale II (DPS2), the duration of scan delay was rarely reported in previous studies. This study aimed to clarify the effect of scan delay on DPS2 measurements.

Materials and methods

Two experiments were performed to clarify the effect of 0- to 10-min scan delay after DPS2 force registration. In both experiments, 11 loads were applied separately on a DPS2 film at 1-min interval between loads. Scanning was performed immediately after the 11th load in the 1-scan experiment and immediately after each load in the 11-scan experiment. A 300-N load was applied with a universal testing machine on 10 DPS2 films in each experiment and the DPS2 film was scanned with Bite Force Analyzer. Load measured, contact area, mean pressure, and maximum pressure were reported. ANOVA and Scheffé test were performed to compare the effect of number of scans and delay scan duration on these measurements with the critical value set at P ≤ 0.05.

Results

Number of scans had no significant effect on the four measurements studied. However, all measurements, except contact area, were significantly affected by scan delay; the longer the scan delay, the greater the increase in measurements. The load measured showed a rapid increase (13%) in the first 2 min, followed by a gradual increase from 2 min to 10 min (10%).

Conclusion

Scan delay does affect DPS2 measurements, and it is important to standardize and report scan delay duration in clinical studies.

Associations between Oral Hypofunction Tests, Age, and Sex

Oral function declines in older individuals due to disease and age-related changes, making them vulnerable to oral and physical frailty. Therefore, it is important to manage the decline in oral function in older outpatients. Oral hypofunction is diagnosed by seven tests related to oral function, oral hygiene, oral moisture, occlusal force, oral diadochokinesis, tongue pressure, masticatory function, and swallowing function. However, sex or age were not factored into the current reference values of these tests. We included subjects attending the dental hospital clinic for maintenance, and recorded and analyzed oral hypofunction and the factors associated with its diagnosis. Of the 134 outpatients (53 males and 81 females, mean age 75.2 ± 11.2 years), 63% were diagnosed with oral hypofunction. Oral hypofunction prevalence increased significantly with age, and significant variations were observed in all tests. Furthermore, oral hygiene and swallowing function were not associated with oral hypofunction diagnosis. All examined factors decreased with increasing age, even after adjusting sex, except for oral hygiene and moisture. Occlusal force and masticatory function were higher in men after adjusting age. This study suggested that older outpatients were likely to be diagnosed with oral hypofunction, and that the test reference value and their selection for oral hypofunction should be reconsidered.

Association between oral health status and oral food intake level in subacute stroke patients admitted to a convalescent rehabilitation unit

BACKGROUND

Stroke patients often suffer from dysphagia during their recovery. We hypothesised that subacute stroke patients with dysphagia had more deteriorated oral health status including muscle strength and motor function.

OBJECTIVE

Quantitatively investigate oral health status and identify associations with oral feeding status in stroke patients admitted to a convalescent rehabilitation unit.

METHODS

We prospectively recruited 187 stroke patients admitted to a convalescent rehabilitation unit. Oral feeding status was examined using the Functional Oral Intake Scale (FOIS), and the cohort was divided into three groups based on FOIS score as non-oral feeding (FOIS-123; 22 patients), dysphagic diet (FOIS-45; 74 patients), and regular diet (FOIS-67; 91 patients) groups. Activities of daily living (ADL) were assessed with the Functional Independence Measure (FIM). Oral health status was measured quantitatively in six oral function parameters and Oral Health Assessment Tool (OHAT), and differences according to the FOIS, age and FIM were statistically tested.

RESULTS

In bivariate analysis, two parameters, tongue pressure and tongue-lip motor functions were significantly higher in the regular diet group than in the other groups (P < .01). Gross OHAT score was also significantly better in the regular diet group than in the other groups (P < .01). These significant associations mostly remained in the multiple model after adjusting for age and FIM.

CONCLUSION

This study suggests that, amongst oral health status, tongue strength and motor function, as well as OHAT score, may have strong associations with oral feeding status in subacute stroke patients at convalescent rehabilitation units regardless of ADL levels.