The technology of tongue and hard palate contact detection: a review.

The tongue and hard palate play an essential role in the production of sound during continuous speech. Appropriate tongue and hard palate contacts will ensure proper sound production. Electropalatography, also known as EPG, is a device that can be used to identify the location of the tongue and hard palate contact. It can also be used by a speech therapist to help patients who have a speech disorder. Among the group with the disease are cleft palate, Down syndrome, glossectomy, and autism patients. Besides identifying the contact location, EPG is a useful medical device that has been continuously developed based on the patient's needs and treatment advancement. This article reviews the technology of electropalatography since the early introduction of the device. It also discusses the development process and the drawbacks of the previous EPG systems, resulting in the EPG's upgraded system and technology. This review suggests additional features that can be useful for the future development of the EPG. The latest technology can be incorporated into the EPG system to provide a more convenient method. There are some elements to be considered in the development of EPG's new technology that were discussed in this study. The elements are essential to provide more convenience for the patient during speech therapy. New technology can accelerate the growth of medical devices, particularly on the development of speech therapy equipment that should be based on the latest technological advancements available. Thus, the advanced EPG system suggested in this article may expand the usage of the EPG and serve as a tool to provide speech therapy treatment services and not limited to monitoring only.

Tongue pressure distribution of individual normal occlusions and exploration of related factors.

BACKGROUND: Tongue plays an important part in oral and maxillofacial system. Measurement of tongue pressure helps to evaluate the performance of tongue movement. OBJECTIVES: To establish a system for measuring tongue pressure against hard palate and to preliminarily explore pressure distribution of individual normal occlusions and the relationship with dental arch form. METHODS: A total of 19 volunteers of individual normal occlusions out of 189 dental students met inclusion criteria (nine males, ten females, aged 25.53 ± 0.96 years). A force-sensing resistor device was used to measure tongue pressure at rest and functional state (swallowing). We observed tongue pressure of four channel (anterior, posterior and lateral sides of hard palate) in sitting, supine position and swallowing. We analysed pressure differences according to gender and explored correlation relationship between tongue pressure and dental arch width and length using 3D digital maxillary image. RESULTS: In rest, tongue pressure against hard palate increased from front to back in both sitting and supine position, without gender differences. When swallowing saliva, the pressure at lateral sides of females was found significantly higher than that of males. Bivariate correlation analysis revealed duration of swallowing was positively correlated with BMI and weight at posterior region and positively correlated with palatal length at anterior palate. The greater the dental arch width, the smaller the pressure of swallowing in the anterior and lateral region. CONCLUSION: In rest, there was consistent pressure of tongue against hard palate. The pressure increased significantly during swallowing, especially in females. Tongue pressure was related to dental arch length, width, BMI and weight.

Tongue pressure measurement in children with mouth-breathing behaviour.

The tongue plays an important role in oral functions. Reduced tongue strength is often noted among children with mouth-breathing behaviour. The purposes of this study were to measure the tongue pressure in children with mouth-breathing behaviour, to compare these values to those of children with nasal-breathing behaviour and to analyse the relationship between age and tongue pressure in children with a mouth-breathing pattern and in children with a nasal-breathing pattern. In this cross-sectional analytical observational study, we enroled 40 children aged 5-12 years who either exhibited mouth-breathing behaviour (n = 20) or nasal-breathing behaviour (gender- and age-matched [±2 years] controls; n = 20). Tongue pressure was evaluated using the Iowa Oral Performance Instrument; 3 measurements were recorded for each participant, with a 30-seconds rest interval. The average tongue pressure in the mouth-breathing group was lower than that in the nasal-breathing group. There was no difference in tongue pressure between genders. There was a strong and direct correlation between tongue pressure and age in the nasal-breathing group. The breathing pattern impacts tongue pressure development.

Effect of tongue-palate contact mode on food transport during mastication.

The physiological mechanisms underlying Stage II transport (STII), during which comminuted solid food is transported from the oral cavity into the meso-pharynx for aggregation into a pre-swallow bolus, have yet to be clarified. The purpose of the present study was to investigate relationships between tongue-palate contact during mastication and incidence of STII by synchronised analysis of tongue pressure production on a hard palate and video-endoscopic (VE) images during mastication. Tongue pressure at 5 measuring points with an ultra-thin sensor sheet attached to the hard palate and trans-nasal VE images while masticating corned beef was recorded for 12 healthy subjects. All recordings were divided into 2 groups: mastication with STII and without STII. Tongue pressure duration was longer at the anterior-median part in the group with STII than in the group without STII. Integrated values of tongue pressure were greater at the anterior-median parts and posterior circumferential part in the group with STII. Integrated values of tongue pressure per second were greater in late-stage mastication than in early-stage mastication in the group with STII. These results suggest that the tongue-palate contacting at the anterior-median and post-circumferential parts of the hard palate is related with the incidence of STII.

Effects of water viscosity and tongue ingestion site on tongue pressure during food bolus propulsion.

The purpose of this study was to help provide data to help to implement effective rehabilitation following surgery for oral cancer by comparing tongue pressure production for water and thickened water from the anterior and posterior parts of the tongue during swallowing. Ten healthy volunteers (7 men, 3 women; age 27.6 ± 1.5 years) participated in the experiments. Tongue pressure during 3 mL water and 3 mL thickened water at the anterior and posterior tongue during swallowing was measured using a sensor sheet system with five measuring points on the hard palate. The sequential order of the points, maximal magnitude and duration of tongue pressure at each point were compared based on water viscosity and tongue ingestion site. There was a common pattern in the sequential order of tongue pressure generation among the two swallowing conditions. The maximal magnitude of tongue pressure was significantly higher when swallowing thickened water than when swallowing water at all points except for the anterior-median and mid-median part. Moreover, the pressure at all sites during posterior ingestions was significantly lower than that during anterior ingestion. The present results provide mean values of tongue pressure during voluntarily triggered swallowing in anterior ingestion and posterior ingestion in young, healthy dentate individuals; these values can be clinically referenced for tongue pressure measurement in the evaluation of patients with dysphagia. The use of reference values may help streamline the diagnosis, treatment and rehabilitation of dysphagia.

Relationships between dysphagia and tongue pressure during swallowing in Parkinson's disease patients.

Although dysphagia is a life-threatening problem in patients with Parkinson's disease (PD), the pathophysiology of oropharyngeal dysphagia is yet to be understood. This study investigated the tongue motor function during swallowing in relation to dysphagia and the severity of PD. Thirty patients with PD (14 males and 16 females; average age, 69.4 years), Hoehn and Yahr stage II-IV, in Osaka University Hospital are participated in this study. During swallowing 5 ml of water, tongue pressure on the hard palate was measured using a sensor sheet with 5 measuring points. The maximal tongue pressure at each measuring point during swallowing was compared between patients with PD and healthy controls. Subjective assessment of oropharyngeal dysphagia was performed using Swallowing Disturbance Questionnaire-Japanese. The maximal tongue pressure at each measuring point was significantly lower in patients with PD than in healthy controls (8 males and 12 females; average age, 71.6 years). Furthermore, the maximal tongue pressure was significantly lower in dysphagic PD patients than non-dysphagic PD patients. Loss of tongue pressure production at the anterior part of the hard palate was strongly related to dysphagia in the oral phase as well as in the pharyngeal phase. An abnormal pattern of tongue pressure production was more frequently observed in dysphagic PD patients than in non-dysphagic PD patients. The results suggest that tongue pressure measurement might be useful for early and quantitative detection of tongue motor disability during swallowing in patients with PD.

Simulating alveolar trills using a two-mass model of the tongue tip.

This paper investigates the possibility of reproducing the self-sustained oscillation of the tongue tip in alveolar trills. The interest is to study the articulatory and phonatory configurations that are required to produce alveolar trills. Using a realistic geometry of the vocal tract, derived from cineMRI data of a real speaker, the paper studies the mechanical behavior of a lumped two-mass model of the tongue tip. Then, the paper proposes a solution to simulate the incomplete occlusion of the vocal tract during linguopalatal contacts by adding a lateral acoustic waveguide. Finally, the simulation framework is used to study the impact of a set of parameters on the characteristic features of the produced alveolar trills. It shows that the production of trills is favored when the distance between the equilibrium position of the tongue tip and the hard palate in the alveolar zone is less than 1 mm, but without linguopalatal contact, and when the glottis is fully adducted.

Application of a barometer for assessment of oral functions: Donders space.

We developed a barometer applicable to a small space, to assess oral and pharyngeal functions. Negative oral pressure during rest and pressure changes during swallowing were measured in a space between the palate and tongue (STP). Twenty volunteers were asked to sit in a chair in a relaxed upright position. A sensor was placed on the posterior midline of hard palate. Recording commenced just before subjects closed their lips and continued. Subjects were asked to swallow saliva and keep the apposition. Finally, subjects were asked to open their mouth. Recordings were performed five times, and 5 s of continuous data in each phase was averaged. To verify the reliability of the system, the same procedure was accomplished with twin sensors. When the jaw and lips were closed, the pressure slightly decreased from atmospheric pressure (-0·17 ± 0·24-kPa). After swallowing, the pressure in STP showed more negative value (-0·50 ± 0·59-kPa). There is a significant difference between the values in open condition and after swallowing (P < 0·001) and between values after swallowing and final open condition (P < 0·05). Twin sensor showed almost the same trajectories of pressure changes for all the recordings. Obtained negative pressure might generate about 0·71-N of force and would be enough to keep the tongue in the palatal fossa at rest. The system detected large negative/positive pressure changes during swallowing. We conclude this system may be a tool to evaluate oral functions.

New method of neck surface electromyography for the evaluation of tongue-lifting activity.

Elevation of the posterior part of the tongue is important for normal deglutition and speech. The purpose of this study was to develop a new surface electromyography (EMG) method to non-invasively and objectively evaluate activity in the muscles that control lifting movement in the posterior tongue. Neck surface EMG (N-EMG) was recorded using differential surface electrodes placed on the neck, 1 cm posterior to the posterior border of the mylohyoid muscle on a line orthogonal to the lower border of the mandible. Experiment 1: Three healthy volunteers (three men, mean age 37·7 years) participated in an evaluation of detection method of the posterior tongue lifting up movement. EMG recordings from the masseter, temporalis and submental muscles and N-EMG revealed that i) N-EMG was not affected by masseter muscle EMG and ii) N-EMG activity was not observed during simple jaw opening and tongue protrusion, revealing the functional difference between submental surface EMG and N-EMG. Experiment 2: Seven healthy volunteers (six men and one woman, mean age 27·9 years) participated in a quantitative evaluation of muscle activity. Tongue-lifting tasks were perfor-med, exerting a prescribed force of 20, 50, 100 and 150 gf with visual feedback. For all subjects, a significant linear relationship was observed bet-ween the tongue-lifting force and N-EMG activity (P < 0·01). These findings indicate that N-EMG can be used to quantify the force of posterior tongue lifting and could be useful to evaluate the effect of tongue rehabilitation in future studies.

Effect of an intraoral appliance on tongue pressure measured by force exerted during swallowing.

INTRODUCTION: The goal of this study was to modify the transpalatal arch design that is used for vertical control of the molars, based on individual muscle strength and morphology features of the tongue during swallowing. METHODS: Individual Silastic (Müller-Omicron, Cologne, Germany) swallowing tongue records were created and measured for 32 healthy volunteers. The transpalatal arches were modified by adding acrylic pads, based on the swallowing tongue records. Tongue pressure exerted on the hard palate and the acrylic pads at 3 distances to the palatal mucosa during swallowing was measured by pressure sensors for 18 subjects. RESULTS: The intraclass correlation coefficient of the thickness of swallowing tongue records taken by 2 researchers was 0.977, indicating good consistency between these researchers. A significant negative correlation was found between the thickness of the swallowing tongue records and individual tongue pressure (r = -0.511; P <0.01). Tongue pressure exerted on the fabricated pads consistent with swallowing tongue records was significantly higher than on the hard palate, yet not significantly higher than tongue pressure exerted on the pads positioned 3 mm closer to the palatal mucosa. In contrast, increasing the distance of the pad 3 mm away from the mucosa led to significant augmentation of tongue pressure. CONCLUSIONS: Creating patient swallowing tongue records is a repeatable and reliable method to reflect individual differences in morphologic features and muscle strengths of the tongue. Decreasing the distance of the pads to the mucosa is preferable if a high force to intrude molars will not be used. On the premise of a patient's tolerance, increasing the distance of the pads away from the mucosa leads to augmentation of tongue force.

Neural network pattern recognition of lingual-palatal pressure for automated detection of swallow.

We describe a novel device and method for real-time measurement of lingual-palatal pressure and automatic identification of the oral transfer phase of deglutition. Clinical measurement of the oral transport phase of swallowing is a complicated process requiring either placement of obstructive sensors or sitting within a fluoroscope or articulograph for recording. Existing detection algorithms distinguish oral events with EMG, sound, and pressure signals from the head and neck, but are imprecise and frequently result in false detection. We placed seven pressure sensors on a molded mouthpiece fitting over the upper teeth and hard palate and recorded pressure during a variety of swallow and non-swallow activities. Pressure measures and swallow times from 12 healthy and 7 Parkinson's subjects provided training data for a time-delay artificial neural network to categorize the recordings as swallow or non-swallow events. User-specific neural networks properly categorized 96 % of swallow and non-swallow events, while a generalized population-trained network was able to properly categorize 93 % of swallow and non-swallow events across all recordings. Lingual-palatal pressure signals are sufficient to selectively and specifically recognize the initiation of swallowing in healthy and dysphagic patients.

Three speech sounds, one motor action: evidence for speech-motor disparity from English flap production.

The assumption that units of speech production bear a one-to-one relationship to speech motor actions pervades otherwise widely varying theories of speech motor behavior. This speech production and simulation study demonstrates that commonly occurring flap sequences may violate this assumption. In the word "Saturday," a sequence of three sounds may be produced using a single, cyclic motor action. Under this view, the initial upward tongue tip motion, starting with the first vowel and moving to contact the hard palate on the way to a retroflex position, is under active muscular control, while the downward movement of the tongue tip, including the second contact with the hard palate, results from gravity and elasticity during tongue muscle relaxation. This sequence is reproduced using a three-dimensional computer simulation of human vocal tract biomechanics and differs greatly from other observed sequences for the same word, which employ multiple targeted speech motor actions. This outcome suggests that a goal of a speaker is to produce an entire sequence in a biomechanically efficient way at the expense of maintaining parity within the individual parts of the sequence.

Training effects of the effortful swallow under three exercise conditions.

The effortful swallow achieves overload through high effort. It was predicted that both immediate effects on biomechanics and long-term neuromuscular adaptations would be facilitated by maximal overload during this exercise. This study examined how high-effort sips from small-diameter straws influenced linguapalatal swallow pressures. Additionally, training effects of effortful swallows preceded by high-effort sips were compared to two other exercise conditions: effortful swallows preceded by maximum effort lingual elevation and effortful swallows performed in isolation. Training outcomes included linguapalatal pressures produced during effortful and noneffortful swallows, and maximum isometric pressure (MIP) produced during tongue elevation and interlabial compression. Forty healthy adults participated in the experiment. Lingual-palatal swallowing pressure during non effortful and effortful swallows and MIPs were measured prior to and after 4 weeks of training. Prior to training, anterior linguapalatal pressures were significantly higher during effortful compared to noneffortful swallows. Anterior linguapalatal pressures did not significantly differ during swallows preceded by sips from high-resistance straws. Weak correlations were observed between tongue MIP and linguapalatal pressures during effortful swallows. After training, anterior linguapalatal pressures significantly increased, with training effects more dramatic for effortful swallows. Anterior tongue MIP also significantly increased. Gains in anterior linguapalatal pressure were not correlated with gains in tongue MIP. Training effects did not vary across exercise condition. The study failed to find a training advantage of pairing the effortful swallow with a precursor movement. The results demonstrated specificity of training, with more dramatic benefits observed for effortful swallows relative to noneffortful swallows. Further investigation is needed to characterize training effects in older adults and patients with dysphagia.

Tongue kinematics in palate relative coordinate spaces for electro-magnetic articulography.

This paper describes a method for constructing a three-dimensional model of the hard palate using electro-magnetic articulography, and defines two algorithms to derive constriction degree and constriction location values from the trajectories of tongue coils using this model. The kinematics of tongue motion that have been transformed into constriction degree and constriction location values are investigated in detail to determine whether this type of representation obeys the constraints theorized to operate over higher level motor control. Results show that palate-relative coordinate spaces decouple mechanical dependencies present in the tongue, while maintaining low-level kinematic properties. They additionally preserve the 1/3 power law for speed and curvature observed across many motor systems. Finally, it is shown that tongue movements in a palate relative coordinate space more closely correspond to their optimal, jerk-minimized trajectories. These results suggest that this type of coordinate space provides a closer match to higher level motor-planning, in line with production models that specify control units in terms of vocal tract constriction parameters.

Duration of action of bupivacaine hydrochloride used for palatal sensory nerve block in infant pigs.

Bupivacaine hydrochloride is frequently used in veterinary dental procedures to reduce the amount of general anesthesia needed and to reduce post-procedural pain. The aim of this study was to develop a novel method to test local anesthetic duration in mammals. Six infant pigs were placed under deep/surgical anesthesia with 3 % isoflurane and oxygen while 0.5 ml of 0.5% bupivacaine hydrochloride was injected to block the two greater palatine and the nasopalatine nerves. They were then maintained under light anesthesia with 0.5-1.0% isoflurane. Beginning 15-minutes after the injection, 7 sites in the oral cavity were stimulated using a pointed dental waxing instrument, including 3 sites on the hard palate. The response, or lack of response, to the stimulus was recorded on video and in written record The bupivacaine hydrochloride injections lasted 1 to 3-hours before the animals responded to the sensory stimulation with a reflexive movement This study provides evidence that bupivacaine used to anesthetize the hard palate has a relatively short and variable duration of action far below what is expected based on its pharmacokinetic properties.

Optimization of parameter settings in cine-MR imaging for diagnosis of swallowing.

Videofluorography is frequently used to evaluate swallowing and is considered the "gold standard" among imaging modalities. This modality, however, has several disadvantages, including radiation exposure and limitations in the detection of soft tissues. Conversely, magnetic resonance imaging (MRI) offers excellent contrast resolution in soft tissue without radiation exposure. A major drawback of MRI in evaluating swallowing, however, is that temporal resolution is poor. The aim of this study was to investigate a new cine-MRI modality. Imaging parameters were optimized and the efficacy of this new technique is discussed. Three techniques for speeding up MRI were combined: true fast imaging with steady state precession, generalized auto-calibrating partially parallel acquisition, and key-hole imaging. The effects of the receiver coils used, receiving bandwidth, slice thickness, and flip angle on each image were determined. The optimal imaging parameters obtained comprised a reduction factor of 2, receiving bandwidth of 1,000 Hz/pixel (repetition time of 151.7 milliseconds and echo time of 1.4 milliseconds), flip angle of 50°, and slice thickness of 6 mm. Neck and spine coils were used. Under these conditions, the new cine-MR imaging technique investigated showed a temporal resolution of 0.1 sec/slice (10 frames/sec). Even with optimized parameter settings, this technique did not allow a true temporal resolution of 30 frames/sec by a large margin. Motion artifacts persisted. Further study is needed on how to speed up this technique.

Comparison of the Effects of Different Palatal Morphology on Maxillary Expansion via RME and MSE: A Finite Element Analysis.

OBJECTIVES: This study aims to compare and analyze the biomechanical effect and the displacement trend of RME and MSE on the maxillofacial complex under different palatal shapes by using finite element analysis. METHODS: The three-dimensional model of maxillofacial complex was obtained from a computed tomography image of a person with a normal palate. Then, we modified the shape of the palate to obtain the model with a high palate. Additionally, two expander devices were considered. MSE and RME were created and four models were made: Model 1: Normal-palate craniomaxillofacial complex with RME expander; Model 2: Normal-palate craniomaxillofacial complex with MSE expander; Model 3: High-palate craniomaxillofacial complex with RME expander; Model 4: High-palate craniomaxillofacial complex with MSE expander. Then, lateral forced displacement was applied and the analysis results were obtained. RESULTS: The lateral displacement of the palatal suture of Model 3 is greater than that of Model 1, and the maxilla has more rotation. The crown/root ratio of Model 1 is significantly greater than that of the other three groups. Compared with Model 1, Model 3 has greater stress concentration in the superstructure of the craniomaxillofacial complex. Both of them have greater stress in the anchorage area than Model 2 and Model 4. CONCLUSION: Different shapes of the palate interfere with the effects of RME and MSE, and its influence on the stress distribution and displacement of the craniomaxillary complex when using RME is greater than MSE. The lateral displacement of the palatal suture of MSE is significantly larger than that of RME. It is more prone to tipping movement of the anchor teeth using RME under normal palate, and MSE may manage the vertical control better due to the smaller crown/root ratio than RME and intrusive movement of molars.

Alteration of functional loads after tongue volume reduction.

OBJECTIVES: An earlier study revealed that the patterns of biomechanical loads on bones around the tongue altered significantly right after tongue volume reduction surgery. The current study was to examine whether these alterations persist or vanish over time post-surgery. DESIGN: Five sibling pairs of 12-week-old Yucatan minipigs were used. For each pair, one had surgery reducing tongue volume by about 15% (reduction) while the other had same incisions without tissue removal (sham). All animals were raised for 4 weeks after surgery. Three rosette strain gauges were placed on the bone surfaces of pre-maxilla (PM), mandibular incisor (MI), and mandibular molar (MM); two single-element gauges were placed across the pre-maxilla-maxillar suture (PMS) and mandibular symphysis (MSP), and two pressure transducers were placed on the bone surfaces of hard palate (PAL) and mandibular body (MAN). These bone strains and pressures were recorded during natural mastication. RESULTS: Overall amount of all loads increased significantly as compared to those in previous study in all animals. Instead of decreased loads in reduction animals as seen in that study, shear strains at PM, MI, and MM, tensile strains at PMS, and pressure at MAN were significantly higher in reduction than sham animals. Compared to the sham, strain dominance shifted at PM, MI, and MM and orientation of tensile strain altered at MI in reduction animals. CONCLUSION: A healed volume-reduced tongue may change loading regime significantly by elevating loading and altering strain-dominant pattern and orientation on its surrounding structures, and these changes are more remarkable in mandibular than maxillary sites.

Essentials of standard chinese phonetics for prosthetic dentistry.

Speech adaptation after oral rehabilitation is based on a complex interaction of articulatory and myofunctional factors. The knowledge of basic phonetic principles may help clinicians identify phonetic problems associated with prosthodontic treatment. The purpose of this article is to illustrate basic phonetic terminology, standard Chinese (Putonghua) phonetics, and the anatomic structures relevant for dentistry. In cooperation with a Chinese linguistic specialist, Chinese articulators were selected and are described and compared with English phonetics. Established test words and sentences aid the identification of mispronounced articulators and their related dental structures. The pronunciation of most consonants and vowels in standard Chinese is similar to English, but some of them, such as the retropalatals (/zh/ [tʂ], /ch/ [thʂ], /sh/ [ʂ]), have notable differences. Palatal consonants (/j/ [tɕ], /q/ [tɕh], /x/ [ɕ]) are unique to the Chinese phonetic system and are not found in English phonetics. The comprehension of the basic anatomic regions involved in Chinese phonetics may help prosthodontists treat patients whose native language is standard Chinese.

Positional targets for lingual consonants defined using electromagnetic articulography.

The study examined the positional targets for lingual consonants defined using a point-parameterized approach with Wave (NDI, Waterloo, ON, Canada). The overall goal was to determine which consonants had unique tongue positions with respect to other consonants. Nineteen talkers repeated vowel-consonant-vowel (VCV) syllables that included consonants /t, d, s, z, , k, g/ in symmetrical vowel contexts /i, u, a/, embedded in a carrier phrase. Target regions for each consonant, characterized in terms of x,y,z tongue positions at the point of maximum tongue elevation, were extracted. Distances and overlaps were computed between all consonant pairs and compared to the distances and overlaps of their contextual targets. Cognates and postalveolar homorganics were found to share the location of their target regions. On average, alveolar stops showed distinctively different target regions than alveolar fricatives, which in turn showed different target region locations than the postalveolar consonants. Across talker variability in target locations was partially explained by differences in habitual speaking rate and hard palate characteristics.