Association of symptomless TMJ sounds with occlusal force and masticatory performance in older adults

Summary  This study investigated associations between temporomandibular joint (TMJ) sounds and occlusal force or masticatory performance stratified by posterior occlusal supports in older Japanese adults. The subjects consisted of 1646 independently living people over 60 years. Masticatory performance, occlusal force, TMJ sounds and maximal mouth opening were examined. Posterior occlusal supports were classified by the Eichner Index. The prevalence of TMJ sounds was 27·7%, limitation of mouth opening (<40 mm) was 7·9% and TMJ pain was only 1·5%. In the Eichner C group, TMJ sounds were significantly associated with lower occlusal force (OR = 3·20, P  = 0·046) and lower masticatory performance (OR = 3·18, P  = 0·041) after controlling for gender and age. These associations were not found in the Eichner A and B groups. Within the limitations of this study, the presence of TMJ sounds, even if they were symptomless, was associated with impairment of masticatory function in older adults with reduced occlusal support.     

Discrepancy between satisfaction with mastication, food acceptability, and masticatory performance in older adults

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: The subjective masticatory function was associated not only with objective masticatory performance, but also with an individual's posterior occlusal contacts.     

Association between oral stereognostic ability and masticatory performance in aged complete denture wearers

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: Reduced oral sensory function, low occlusal force, and hyposalivation appear to be associated with impairment of masticatory performance in aged complete denture wearers.     

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.     

Relationship between oral function and occlusal support in denture wearers

Patients with removable partial dentures or complete dentures do not demonstrate masticatory function to the same level as patients with a full set of natural teeth. The purpose of this study was to characterize the relationship between reduction of masticatory function, in terms of masticatory performance and bite force, and the existence of remaining natural occlusal supports as assessed by the Eichner index. One hundred and eighteen removable partial denture and complete denture wearers were selected for analyses. These subjects were divided into four groups depending upon the number of occlusal supports. Seventy dentate subjects with full occlusal support were designated as a comparison group. Bilateral bite force was measured at the first molar region in all subjects. Masticatory performance was assessed using the modified Masticatory Performance Index. Peanuts were used as the test food. Both bite force and masticatory performance were significantly associated with group classification. Moreover, both bite force and masticatory performance of the four denture groups were significantly reduced compared to the comparison group and this tendency was remarkable for the denture groups without occlusal support. These results suggest that the existence of functional tooth units may be a key factor in preservation of masticatory function.     

Association of bite force with ageing and occlusal support in older adults

OBJECTIVES: The purpose of this study was to investigate the effect of ageing, occlusal support and TMJ condition and general health status on bite force in older adults. METHODS: The study sample consisted of 850 independently-living people over the age of 60 years. Bilateral maximal bite force in the intercuspal position was measured with pressure sensitive sheets. TMJ noise by palpation and limitation of mouth opening (less than 40 mm) were assessed. Subjects were grouped into three categories by occlusal support according to the Eichner Index. RESULTS: A multiple logistic regression analysis showed that whether participants had low bite force or not was significantly associated with gender, age, self-rated general health and occlusal support, but not TMJ noise or mouth opening limitation. Overall bite force showed a statistically significant but weak negative Spearman's correlation with age (r=-0.24, p<0.001). However, there was no significant correlation between age and bite force in the Eichner C group for males or in any of the Eichner classification for females. CONCLUSIONS: Decline of occlusal support and general health might translate into reduction of bite force with ageing in older adults. Since tooth loss is not physiological ageing but pathological ageing, it cannot be shown that reduction of bite force is a natural effect of ageing.     

Masticatory performance in postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses

PURPOSE: Oral cancer develops frequently in older populations. In Japan, the incidence of oral and pharyngeal cancer is 9,201 per year, with such tumors accounting for 1.74% of all cancers. Although obturator prostheses play an important role in the rehabilitation of postmaxillectomy patients, clinicians sometimes experience difficulty in placing obturator prostheses in edentulous maxillae, and criteria for the objective evaluation of treatment outcome have yet to be established. The present study aimed to investigate postsurgical factors influencing the masticatory performance of postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses. MATERIALS AND METHODS: The extent of the hard palate defect, status of the mandibular dentition, mouth-opening distance, and maximum occlusal force were investigated, and masticatory performance was measured using a testing gummy jelly in 27 postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses. The influence of these items was evaluated quantitatively, and theoretical masticatory performance for each subject was calculated using multiple-regression analysis (quantification method type 1). RESULTS: Although average masticatory performance was almost equivalent to that of healthy, independent older patients with occlusal support classified as Eichner C, considerable individual variation was noted among subjects. The order of strength of influence on masticatory performance was identified by category weight: extent of hard palate defect > status of posterior mandibular teeth > maximum occlusal force > mouth-opening distance. A relatively high correlation (R2 = 0.78, P < .01, Pearson correlation coefficient) was evident between theoretical and actual values. CONCLUSION: Masticatory performance could be predicted by evaluating postsurgical factors in patients with edentulous maxillae fitted with obturator prostheses.     

A multifactorial model of masticatory performance: the Suita study

Previous studies have identified various factors related to masticatory performance. This study was aimed to investigate variations and impacts of factors related to masticatory performance among different occlusal support areas in general urban population in Japan. A total of 1875 Japanese subjects (mean age: 66·7 years) were included in the Suita study. Periodontal status was evaluated using the Community Periodontal Index (CPI). The number of functional teeth and occlusal support areas (OSA) were recorded, and the latter divided into three categories of perfect, decreased and lost OSA based on the Eichner Index. Masticatory performance was determined by means of test gummy jelly. For denture wearers, masticatory performance was measured with the dentures in place. The multiple linear regression analysis showed that, when controlling for other variables, masticatory performance was significantly associated with sex, number of functional teeth, maximum bite force and periodontal status in perfect OSA. Masticatory performance was significantly associated with number of functional teeth, maximum bite force and periodontal status in decreased OSA. In lost OSA, masticatory performance was significantly associated with maximum bite force. Maximum bite force was a factor significantly influencing masticatory performance that was common to all OSA groups. After controlling for possible confounding factors, the number of functional teeth and periodontal status were common factors in the perfect and decreased OSA groups, and only sex was significant in the perfect OSA group. These findings may help in providing dietary guidance to elderly people with tooth loss or periodontal disease.     

Relationship among malocclusion, number of occlusal pairs and mastication

This study evaluated the relationship among malocclusion, number of occlusal pairs, masticatory performance, masticatory time and masticatory ability in completely dentate subjects. Eighty healthy subjects (mean age = 19.40 ± 4.14 years) were grouped according to malocclusion diagnosis (n = 16): Class I, Class Class II-2, Class III and Normocclusion (control). Number of occlusal pairs was determined clinically. Masticatory performance was evaluated by the sieving method, and the time used for the comminute test food was registered as the masticatory time. Masticatory ability was measured by a dichotomic self-perception questionnaire. Statistical analysis was done by one-way ANOVA, ANOVA on ranks, Chi-Square and Spearman tests. Class II-1 and III malocclusion groups presented a smaller number of occlusal pairs than Normocclusion (p < 0.0001), Class I (p < 0.001) and II-2 (p < 0.0001) malocclusion groups. Class I, and III malocclusion groups showed lower masticatory performance values compared to Normocclusion (p < 0.05) and Class II-2 (p < 0.05) malocclusion groups. There were no differences in masticatory time (p = 0.156) and ability (χ2 = 3.58/p= 0.465) among groups. Occlusal pairs were associated with malocclusion (rho = 0.444/p < 0.0001) and masticatory performance (rho = 0.393/p < 0.0001), but malocclusion was not correlated with masticatory performance (rho = 0.116/p= 0.306). In conclusion, masticatory performance and ability were not related to malocclusion, and subjects with Class I, II-1 and III malocclusions presented lower masticatory performance because of their smaller number of occlusal pairs.     

Oral motor function and masticatory performance in the community-dwelling elderly

This study was performed to ascertain the relationships between oral motor functions, such as those of the tongue and lips, and age in the community-dwelling elderly, as well as to investigate the effects of these factors on masticatory performance. The subjects were 268 healthy elderly Japanese living in Kyoto. They were divided into four age groups and further classified into the following two groups by the presence or absence of posterior occlusal support: Eichner A or B1-B3 (group A), and Eichner B4 or C (group B). They were wearing removable or fixed dentures if they had missing teeth. Oral function evaluation items included (1) masticatory performance and (2) oral motor skills. Significant differences were noted among the age groups in tongue pressure within group A (P < 0.01) and group B (P < 0.05), and in the number of repetitions of the syllables /ta/ and /ka/ in group B (/ta/: P < 0.05, /ka/; P < 0.01). The number of natural teeth (β = 0.463, P < 0.001) in group A and tongue pressure (β = 0.436, P < 0.001) in group B were the only predictors of masticatory performance when the data were analyzed by multiple regression analysis. The tongue may compensate for the missing teeth in masticatory performance of those elderly who have lost their natural teeth. The results of this study highlight the importance of tongue function in masticatory performance.     

The relationship between oral function and body mass index among independently living older Japanese people

PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.     

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 (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).

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.     

Clinical assessment of chewing function of obturator prosthesis wearers by objective measurement of masticatory performance and maximum occlusal force

PURPOSE: Eating, which includes chewing and swallowing, is an oral function that influences quality of life. Though the swallowing ability of maxillectomy patients was reported in our previous study, the chewing function has not been fully reported to date. Thus, the purpose of this study was to evaluate the chewing function of obturator prosthesis wearers by measurement of masticatory performance and occlusal force. The relationship of these 2 measurements was also investigated. MATERIALS AND METHODS: Twenty maxillofacial obturator prosthesis wearers undergoing periodic checkup at the maxillofacial rehabilitation clinic in Kyushu University Hospital were recruited for this study. Additionally, 20 young, healthy individuals were recruited as controls. Data on masticatory performance, which was measured by a sieve method using hydrocolloid material, and maximum occlusal force, which was measured by the Dental Prescale System (Fuji Film), were obtained for each participant. RESULTS: The mean of masticatory performance was 2.6 (SD 1.2) on a 1.40-mm mesh. There was no significant difference in masticatory performance between the patient group and the controls. The mean maximum occlusal force of the patient group was 625.9 N (SD 299.1 N), which was significantly lower than that of the control group. There was no significant correlation between masticatory performance and maximum occlusal force for the patient group in this study (P = .3726). CONCLUSION: Masticatory performance of obturator prosthesis wearers with dentate or partially edentulous maxillae was not different from that of young, healthy individuals, though maximum occlusal force of these patients was lower than that of controls.     

Electromyographic evaluation of masticatory function in denture wearers in related to existing occlusal support

The aim of this study was to clarify the relationship between partially edentulous pattern and the masticatory function in removable partial denture wearers. Eighty eight removable partial denture wearers and 7 subjects with intact dentition volunteered for this study. Using the Eichner's index, all subjects were divided into 6 groups. Electromyographic (EMG) activities of the masticatory muscle were recorded during chewing a piece of raw carrot. The masticatory function was analyzed by using the variation coefficient (VC) of the time parameter of EMG interval recorded during mastication. The association of the VC with group classification based on Eichner's index was analyzed using analysis of covariance with gender and age as the covariates. The result of the analysis revealed that the VC was significantly associated with group classification and the patients in groups without posterior occlusal supports exhibited significantly higher VC values than those in groups with posterior occlusal supports. These findings suggested that the reduced function in patients without the posterior occlusal contacts was difficult to attain improved and satisfactory outcome with removable partial dentures and that there is a significant need for posterior occlusal support for the preservation of masticatory function.     

Effect of experimental jaw muscle pain on occlusal contacts

The aim of the study was measuring the effect of experimental jaw muscle pain on number and position of posterior occlusal contacts. Eleven adult voluntary subjects were enrolled. A lower impression was taken for each subject and two dental casts were obtained from each impression. The study was carried out in a randomised cross-over fashion. Each subject participated in two experimental sessions (30-day interval) in which he/she received an injection in the central part of the right masseter muscle consisting of 0·5 mL of either hypertonic or isotonic saline. Each subject was asked to rate pain intensity on a visual analogue scale. Three occlusal bite checks (polyvinylsiloxane) at the maximal intercuspal position were obtained during the experimental session: the first before the injection, the second between 60 and 90 s after the injection and the third 15 min after the injection. Evaluation of contacts was performed on dental casts with the use of different colours (black for baseline, red for intermediate and green for final contacts). Repeated-measures analysis of variance was used to compare the overall number of contacts among groups and the number of contacts of different colours. No significant difference was found between the overall number of occlusal contacts (P>0·05), but significant differences were found between contacts according to different colours: confirmed (P=0·006), disappeared (P=0·007) and new (P<0·001). Assuming different colours as change in contact position, the overall number of contacts did not change, but the position did. Experimentally induced jaw muscle pain affected the pattern of posterior occlusal contacts.     

Masticatory muscle thickness, bite force, and occlusal contacts in young children with unilateral posterior crossbite

Few investigations have evaluated the characteristics of functional and structural malocclusion in young children. Thus, the aim of this study was to assess the ultrasonographic thickness of the masseter and anterior portion of the temporalis muscles, the maximum bite force, and the number of occlusal contacts in children with normal occlusion and unilateral crossbite, in the primary and early mixed dentition. Forty-nine children (26 males and 23 females) was divided into four groups: primary-normal occlusion (PNO), mean (PNO) age 58.67 months; primary-crossbite (PCB), mean age 60.50 months; mixed-normal occlusion (MNO), mean age 72.85 months; and mixed-crossbite (MCB), mean age 71.91 months. Thickness was evaluated with the muscles at rest and during maximal clenching, and comparison was made between the right and left side (normal occlusion), and between the normal and crossbite side (crossbite). The results were analysed using Pearson's correlation, paired and unpaired t-test, and Mann-Whitney ranked sum test. The anterior temporalis thickness at rest was statistically thicker for the crossbite side than the normal side in the MCB group (P = 0.0106). A statistical difference in bite force and the number of occlusal contacts was observed between the MNO and MCB groups, with greater values for the MNO subjects (P < 0.05). Masseter muscle thickness showed a positive correlation with bite force, but the anterior temporalis thickness in the PCB and MCB groups was not related to bite force. Masticatory muscle thickness and bite force did not present a significant correlation with occlusal contacts, weight, or height. It was concluded that functional and anatomical variables differ in the early mixed dentition in the presence of a malocclusion and early diagnosis and treatment planning should be considered.     

Relationship between the number of occlusal contacts and masticatory muscle activity in healthy young adults

The electromyographic (EMG) potentials of left and right masseter and temporalis anterior muscles were recorded in 23 healthy young adults during: 1. a 3-second maximum voluntary clench (MVC) on cotton rolls positioned on the posterior teeth (standardized recording); and 2. a 3-second MVC in intercuspal position. EMG potentials recorded in intercuspal position were standardized as a percentage of the mean potentials of the standardized recording, and the EMG muscle activity was calculated. The number of occlusal contacts in intercuspal position was assessed by using eight microm thick shim stocks. Two groups of subjects with either 1. Less than ten occlusal contacts (11 subjects with "few contacts"); or 2. At least ten occlusal contacts (12 subjects with "many contacts") were selected. The MVC muscle activity in the "few contacts" group was significantly lower than that recorded in the "many contacts" group (p<0.005). In conclusion, the number of occlusal contacts and masticatory muscular function are significantly related, at least in young adults with a sound stomatognathic apparatus.     

Masticatory performance of the elderly as seen from differences in occlusal support of residual teeth

Purpose

To clarify whether the occlusal state affects the masticatory performance of elderly adults.

正常(牙合)牙尖交错位咬合平衡的定量研究

目的　对正常（牙合）牙尖交错位（ICP）最大（牙合）力咬合进行定量研究，初步探讨ICP咬合平衡的生理范围。方法　应用T－Scan　Ⅱ系统记录123名正常骀者ICP最大（牙合）力的咬合情况，测量并计算力的中心点（COF）、（牙合）力百分比值、胎接触点数目。结果　正常胎者ICP最大（牙合）力时力的中心点相对位置、（牙合）力百分比差值以及不对称系数均服从正态分布，95％参考值范围分别为：－6．60～6．68mm，－15．50％～12．10％，0．65～1．39；98．4％的正常（牙合）者ICP最大（牙合）力咬合时力的中心点分布于后牙区。结论　正常（牙合）者最大（牙合）力时ICP咬合是稳定、平衡的咬合。     

Assessment of swallowing and masticatory performance in obturator wearers: a clinical study

PURPOSE

To assess function by identifying changes in swallowing and masticatory performance in maxillary obturator prosthesis wearers.

MATERIALS AND METHODS

Sixty subjects were recruited for the study, of which 20 were obturator wearers, 20 were completely dentulous and 20 had removable partial/complete dentures with similar Eichner''s Index. Swallowing ability was evaluated with and without obturator using the "Water Drinking Test"; Masticatory performance was evaluated with the Sieve test; and maximum occlusal force was recorded with the help of a digital bite sensor. The data was analyzed using the Statistical Package for Social Science version 15.0 with a confidence level at 95%.

RESULTS

Profile, behavior of drinking and time taken to drink were significantly improved (P<.001) in subjects after wearing obturator. Masticatory performance was not significantly different (P=.252) in obturator wearer when compared with dentulous or removable partial/complete denture wearer, but significantly (P<.001) high inter group difference in maximum occlusal force existed. Correlation between masticatory performance and maximum occlusal force was not significant (P=.124).

CONCLUSION

Swallowing ability was significantly improved after wearing obturator but masticatory performance was not significantly different from those having similar occlusal support zone in their dentition.