Relationship between maximal isometric tongue pressure and limit of fracture force of gels in tongue squeezing

BACKGROUND

There is no clear objective indicator for selecting soft foods that are required for food bolus formation in older people with impaired oral function.

OBJECTIVE

This study aimed to investigate the relationship between maximal isometric tongue pressure (MITP) and the mechanical properties of gels that can be crushed by the tongue.

METHODS

This study included 65 healthy participants aged 22-96 (young group; 15 males, 15 females; older dentate group; 7 males, 8 females; older edentulous group; 10 males, 10 females). MITP was measured by the balloon-probe device. Agar gel with 10 different kinds of fracture force from 10N to 100N was used. The limit of fracture force of gels (LFFG) that were crushed by the tongue was measured by the up-and-down method. In the older edentulous group, two items were measured with and without dentures. Spearman's rank correlation coefficient was used to evaluate the relationship between MITP and LFFG in each group (p < .05).

RESULTS

There were positive correlations between MITP and LFFG in all groups (overall groups: rs  = .66, young group: rs  = .46, older dentate group: rs  = .61, older edentulous group with dentures: rs  = .60, older edentulous group without dentures: rs  = .47).

CONCLUSION

MITP and LFFG were positively correlated in young, older dentate and older edentulous groups, suggesting that MITP has the potential to be an objective indicator of the range of mechanical properties of soft food that can be crushed by the tongue.

A Novel Tongue Pressure Measurement Instrument with Wireless Mobile Application Control Function and Disposable Positioning Mouthpiece

This study developed a novel chair-side tongue pressure (TP) measuring instrument with a disposable positioning mouthpiece controlled using a smartphone application (APP), denoted as the TP wireless application (TPWA). The mouthpiece was designed with a palate-shaped air balloon containing a tongue contact bump and a plastic bite positioning tube. Fatigue load testing was performed to evaluate mouthpiece durability by applying 700 displacement cycles (50 times a day for one week during training, with twice the safety factor) on the air balloon. The main component used in developing this instrument was a silicon pressure sensor equipped with wireless Bluetooth connection. Young (52 adults; mean age = 20.23 ± 2.17) and elderly (40 adults; mean age = 72.60 ± 7.03) individuals participated in the test with the new instrument, with the results compared to those of a commercial device. The TPWA mouthpiece fatigue test showed that mean response pressures were maintained at 12 kPa. No significant (p > 0.05) differences were found during testing repetitions 0–10 and 701–710. There were no significant differences in the maximum TP values presented between the test sequences using different instruments for young and elderly participants. The TPWA results showed that TP values gradually decreased with increasing age (40.77 kPa for young and 16.55 kPa for elderly participants). The maximum TP for males (43.51 kPa) was significantly larger than that for females (35.14 kPa) in the young group, but an opposite trend was seen in the elderly group (12.97 for males and 17.59 for females). Thus, this study developed a novel chair-side TP measurement instrument with Bluetooth wireless mobile application control. A durable positioning oral mouthpiece was approved for measuring pressure sufficiently, reliably, and precisely for TP screening.

Tongue Rehabilitation Device for Dysphagic Patients

Dysphagia refers to difficulty in swallowing often associated with syndromic disorders. In dysphagic patients’ rehabilitation, tongue motility is usually treated and monitored via simple exercises, in which the tongue is pushed against a depressor held by the speech therapist in different directions. In this study, we developed and tested a simple pressure/force sensor device, named “Tonic Tongue (ToTo)”, intended to support training and monitoring tasks for the rehabilitation of tongue musculature. It consists of a metallic frame holding a ball bearing support equipped with a sterile disposable depressor, whose angular displacements are counterbalanced by extensional springs. The conversion from angular displacement to force is managed using a simple mechanical model of ToTo operation. Since the force exerted by the tongue in various directions can be estimated, quantitative assessment of the outcome of a given training program is possible. A first prototype of ToTo was tested on 26 healthy adults, who were trained for one month. After the treatment, we observed a statistically significant improvement with a force up to 2.2 N (median value) in all tested directions of pushing, except in the downward direction, in which the improvement was slightly higher than 5 N (median value). ToTo promises to be an innovative and reliable device that can be used for the rehabilitation of dysphagic patients. Moreover, since it is a self-standing device, it could be used as a point-of-care solution for in-home rehabilitation management of dysphasia.

Tongue pressure production during swallowing in patients with mandibular prognathism

Abnormalities of swallowing in patients with mandibular prognathism have not been evaluated quantitatively. The aim of this study was to compare tongue pressure production for bolus transfer between volunteers with normal occlusion and patients with mandibular prognathism. The control group had 10 female volunteers with normal occlusion, and the patient group had 10 women with mandibular prognathism. Tongue pressure was measured by a palatal sensor sheet at five sites on swallowing 4 mL of a tasteless and odourless jelly.

RESULTS

The tongue pressure waveform differed between the control and patient groups. The incidence of a double-peak tongue pressure waveform was more frequent in the patient group. In both groups, the exertion of tongue pressure began at the anterior point of the sensor sheet, followed by the peripheral parts. Although the order of expression of tongue pressure was the same for the two groups, maximum tongue pressure at all parts of the sensor sheet was lower in the patient group than in the control group. Furthermore, swallowing time was longer in the patient group than in the control group at the peripheral parts of the palate. These results clearly show the difference in tongue pressure production during swallowing between patients with mandibular prognathism and volunteers with normal occlusion. The current findings suggest that maxillofacial morphology may affect tongue movement during swallowing.

Tongue pressure in patients with tongue cancer resection and reconstruction

OBJECTIVE

Assessment of tongue function following tongue reconstruction is important to evaluate patient status. To assess tongue function in patients who had undergone tongue reconstruction, the surgical team used a simple, hand-held tongue pressure measurement device to measure tongue power.

METHODS

Tongue power of 30 patients (25 males, 5 females; average age: 53.6±15.0 years) was calculated using a hand-held tongue pressure measurement device, six months postoperation. The defects were classified into minimal glossectomy (MG) (n=8), near-half partial glossectomy of the mobile tongue (PG) (n=5), hemi-glossectomy (HG) (n=4), more than half partial glossectomy of the mobile tongue (SG-MT) (n=7), and subtotal glossectomy (SG) (n=6). As seen in other tongue assessments, a simple articulatory test, food evaluation, and speech intelligibility assessment were also performed; resulting correlations were statistically calculated using tongue pressure values.

RESULTS

The tongue pressure values were 94.0±14.5% in MG, 48.5±13.2(a) % in PG, 40.4±18.7(a) % in HG, 19.3±7.7(a,b) % in SG-MT, and 15.3±5.6(a,b) % in SG (a: <0.05 vs. MG, b: <0.05 vs. PG). The Pearson r was 0.77, 0.67, and 0.74 when correlated with simple articulatory test, food evaluation, and speech intelligibility assessment, respectively.

CONCLUSION

Tongue pressure measurement in patients with tongue cancer resection and reconstruction facilitated determination of patients' tongue function status.

Effect of supraglottic and super-supraglottic swallows on tongue pressure production against hard palate

The objectives of this study were to evaluate the state of tongue pressure production during supraglottic swallow (SS) and super-supraglottic swallow (SSS) performed by healthy adults, and to investigate the effects of these swallowing maneuvers on the oral stage of swallowing. The participants were 19 healthy individuals. Tongue pressure against the hard palate during swallowing was measured using a tongue pressure sensor sheet system with five pressure-sensitive points. The tasks comprised swallowing 5 mL of water by normal wet swallow, SS, and SSS, and the parameters for analysis were the duration, the maximal magnitude, and the integrated value of tongue pressure during swallowing. The duration of tongue pressure was significantly longer at the anterior-median part of the hard palate during both SS and SSS than with normal wet swallow. The maximal magnitude increased significantly only at the posterior part of the hard palate during SS, but at all points during SSS. The integrated value increased significantly only at the posterior-median part of the hard palate during SS, but at all points except the mid-median part of the hard palate during SSS. The maximal magnitude and integrated value were also significantly higher at the anterior-median and posterior circumferential parts during SSS than during SS. These results show that these two swallowing maneuvers, which are known primarily as techniques to protect the airway, also function to strengthen the tongue pressure produced by the contact between the tongue and the hard palate during swallowing and this effect is more pronounced during SSS.

Effect of lingual plates on generating intra-oral pressure during swallowing: an experimental study in healthy subjects

Background

Although palatal augmentation prostheses (PAPs) can improve dysphagia, their application is compromised in the absence of maxillary abutment teeth. Experimental lingual plates (ELPs) used for raising the tongue may be employed as alternative to PAPs.

Methods

Influence of different ELP designs, plateau (P–type) and drop-shaped (D–type), on the intra–oral pressure during swallowing were tested. Eleven healthy dentate volunteers, with a mean age of 35.5±10.5 years, participated in this study. Tongue pressure on the hard palate was measured using an ultra-thin sensor sheet with five measuring points, whilst performing dry, 5–ml and 15–ml water swallows, with and without the ELPs in situ. Additional pressure sensors were installed in the lingual aspects of the ELPs, and on the vestibular aspect of the lower molars for measuring sublingual and oral vestibule pressures, respectively. Each measurement was recorded thrice. A repeated measures ANOVA was employed to verify differences in duration, maximal magnitude and integrated value for the different experimental situations. Tukey’s post hoc test was performed for comparison testing. Statistical significance was set at p<0.05.

Results

The sequence of tongue–palate contact on the median line of the hard palate without ELPs was maintained, except for the 15 ml P–type swallow. Tongue pressure started earlier with the D–type but reached its peak nearly at the same time as without ELPs. The peak magnitude and cumulative tongue pressure against the hard palate decreased by wearing ELPs (p<0.05), but was inconsistent between the two types of ELPs and for the different swallowing volumes. Both, maximum and cumulative vestibular pressures were mostly similar or larger with P–type than that with D–type.

Conclusion

D-type and P-type ELPs seem to have the inverse effect of PAPs on the palatal tongue pressure during swallowing. These first counterintuitive findings do not yet justify rejecting the basic rationale of using ELPs for the treatment of dysphagia; hence a rather biologically designed piezographic lingual plate may be more appropriate.

Repeated adjustment of new dentures for dysphagia

When multiple tooth loss causes loss of occlusal-masticatory function, functional recovery is normally obtained with the help of removable dentures. After resection of the jawbone or tongue because of tumors, the movement of the tongue and its surrounding tissues is limited, and patients exhibit a more pronounced loss of chewing and swallowing than that observed in other cases of multiple tooth loss. In such cases, it is necessary to take extra care in determining the position of the mandible, arrangement of artificial teeth, and morphology of the palate. In the present case, the left lower jawbone was resected because of a gingival tumor, and when the new denture was manufactured, the intercuspal position was based on the resting position of the mandible. The stability of the lower complete denture was a priority and the artificial teeth were partially arranged on the lingual side. The new denture, however, caused insufficient closing of the mouth aperture and insufficient impact between tongue and palate, resulting in dysphagia. Therefore, the vertical dimension of occlusion was reduced multiple times to improve chewing and swallowing function.

Impact of lingual plates on the interocclusal free way space: a pilot study

Palatal augmentation prostheses are commonly used in the treatment for dysphagia. By lowering the palatal contours, the tongue contact is increased and thus the bolus propulsion facilitated. However, the unfavourable weight of such appliances may be avoided when using lingual plates. Hence, the aim of this study is to investigate the effect of two different types of lingual plates on the vertical dimension in rest position. Eleven healthy dentate subjects with an average age of 35.5 years (26-60 years) volunteered in this pilot study. The vertical overbites were measured on plaster models. Two different designs of the experimental lingual plates were tested in this pilot study (P-type & D-type). The inter-occlusal freeway space was measured using the electromagnetic K7 jaw-tracking system (Myotronics, U.S.A.), while the subjects were seated in an upright position. They were asked to close from rest position into maximum intercuspation for about 2 s. Recordings were performed without the plates and subsequently with each of the two plate designs in situ. All recordings were performed three times and the second closing movement of each recording was used for the analysis. After averaging the repetitions without experimental lingual plates, with P-type and D-type plates, the differences were analysed using a Kruskall-Wallis test. The results showed no significantly increased freeway space while using both types of lingual plates. Hence, it can be concluded that any altered tongue pressure during swallowing with lingual plates is not related to an increase in vertical dimension.

Recent advances in sensing oropharyngeal swallowing function in Japan

Dysphagia (difficulty in swallowing) is an important issue in the elderly because it causes aspiration pneumonia, which is the second largest cause of death in this group. It also causes decline in activities of daily living and quality of life. The oral phase of swallowing has been neglected, despite its importance in the evaluation of dysphagia, because adequate protocols and measuring devices are unavailable. However, recent advances in sensor technology have enabled straightforward, non-invasive measurement of the movement of important swallowing-related organs such as the lips and tongue, as well as the larynx. In this article, we report the present state and possibility of clinical application of such systems developed in Japan.

Role of the artificial tooth arch during swallowing in edentates

PURPOSE

This study aimed to clarify the role of the artificial tooth arch (ATA) during swallowing in edentates.

METHODS

The tongue pressures, activities of the masseter and suprahyoid muscles, and laryngeal and mandibular movements when swallowing saliva, water, pudding, and corned beef were measured simultaneously using experimental dentures with and without an ATA. We analysed the maximum magnitudes of muscle activities and tongue pressures (MAmax and TPmax, respectively), the times from reaching MAmax and TPmax to laryngeal movement (TLM-MAmax and TLM-TPmax, respectively), and the vertical mandibular position.

RESULTS

The MAmax of the masseter muscle and TPmax were significantly greater with the ATA than without the ATA (p<0.05). However, MAmax of the suprahyoid muscles was not significantly different in the conditions with and without the ATA. TLM-TPmax was significantly longer without the ATA than with the ATA (p<0.05) but the TLM-MAmax of the suprahyoid and masseter muscles were not significantly different with and without the ATA. The MAmax of both suprahyoid and masseter muscles and the TPmax were significantly greater, and TLM-TPmax was significantly longer when swallowing corned beef than other materials (p<0.05). The intermaxillar distance and the range of measured mandibular position at the time of swallowing were shorter and wider in the absence of the ATA than with it.

CONCLUSION

The present study shows that during swallowing the ATA supports the function of the tongue to perform skillful movements for the smooth passage of food to the oropharynx and the elevation of the larynx by maintaining the mandible position constant near the intercuspal position.

Decreased tongue pressure reflects symptom of dysphagia

The tongue plays a key role in oropharyngeal swallowing. It has been reported that maximum isometric tongue pressure decreases with age. The risk for dysphagia resulting from low tongue strength remains unclear. This study was designed to reveal the relationship between tongue pressure and clinical signs of dysphagic tongue movement and cough and to demonstrate the clinical value of tongue pressure measurement in the evaluation of swallowing function. One hundred forty-five institutionalized elderly in five nursing homes participated. Evaluation of physical activity with self-standing up capability and mental condition with Mini Mental Status Examination (MMSE) were recorded. Maximum tongue pressure was determined using a newly developed tongue pressure measurement device. Voluntary tongue movement and signs of dysphagic cough at mealtime were inspected and evaluated by one clinically experienced dentist and speech therapist. The relationship between level of tongue pressure and incidence of cough was evaluated using logistic regression analysis with physical and mental conditions as covariates. Tongue pressure as measured by the newly developed device was significantly related to the voluntary tongue movement and incidence of cough (p < 0.05). The results of this study suggest that tongue pressure measurement reflects clinical signs of dysphagic tongue movement and cough and that measurement of tongue pressure is useful for the bedside evaluation of swallowing.

Influence of bite force and tongue pressure on oro-pharyngeal residue in the elderly

OBJECTIVE

To investigate the influence of maximal bite force, maximal tongue pressure, number of mastications and swallowing on the oro-pharyngeal residue in the elderly.

BACKGROUND

Oro-pharyngeal residue in the elderly is an indication of dysphagia. Pharyngeal residue is especially critical as it may cause aspiration pneumonia, which is one of the major causes of death in elderly.

MATERIALS AND METHODS

Videofluorographic recordings were performed on 14 elderly volunteers (six males, eight females, age range 65-93 years) without any history or symptoms of dysphagia. The subjects were instructed to consume 9 g of barium containing bread in two manners; free mastication and swallow (FMS: masticate and swallow freely), and limited mastication and swallow (LMS: swallow once after 30 chewing actions). The amount of oral and pharyngeal residue was evaluated using a 4-point rating scale. Maximal occlusal force was measured by a pressure sensitive sheet, and maximal tongue pressure using a handy probe. Multiple regression analysis was performed to examine the influence of these items on the amount of oral and pharyngeal residue in FMS and LMS.

RESULTS

In FMS, age was found to be a factor which increased oral residue (p = 0.053), and the number of swallowing (p = 0.017) and the state of the prosthesis (p = 0.030) reduced the pharyngeal residue. In LMS, tongue pressure was a factor which reduced oral residue (p = 0.015) and increased pharyngeal residue (p = 0.008).

CONCLUSION

It is suggested that in the elderly tongue pressure contributed to propulsion of the food bolus from oral cavity into the pharynx, and multiple swallowing contributed to the reduction in the amount of pharyngeal residue.

Tongue pressure against hard palate during swallowing in post-stroke patients

OBJECTIVES

The tongue plays an important role in swallowing by contacting the palate. The aim of the present study was to investigate the characteristics of tongue pressure production during swallowing in post-stroke patients using a newly developed sensor sheet.

MATERIALS AND METHODS

Ten post-stroke inpatients with hemiplegia and five healthy volunteers participated in this study. Magnitude of tongue pressure during a dry swallow was measured using a newly developed sensor sheet comprising five sensors applied directly to the palate or to the palatal surface of a maxillary denture using denture adhesive. Swallowing ability was evaluated by measuring the time taken to swallow 30 ml of water. The magnitude of tongue pressure was compared between the post-stroke patients and healthy subjects as well as between each measuring point in both groups. The relationship between tongue pressure and swallowing ability and that between tongue pressure and state of occlusal support were also examined.

RESULTS

The magnitude of tongue pressure in the post-stroke patients was smaller than that of the healthy subjects at the measuring points along the median line (Welch test, p < 0.05), larger in the non-paralysed side than in the paralysed side (two-way ANOVA, p < 0.05), and was influenced by swallowing ability and occlusal support (Welch test, p < 0.05).

CONCLUSIONS

Measurement of the magnitude of tongue pressure shows promise as a simple, non-invasive and quantitative method by which tongue activity in post-stroke patients, in whom swallowing ability is a concern, could be evaluated.