Evaluation of tongue motor biomechanics during swallowing—From oral feeding models to quantitative sensing methods

In today's aging society, dentists are more likely to treat patients with dysphagia and are required to select an optimal treatment option based on a complete understanding of the swallowing function. Although the tongue plays an important role in mastication and swallowing as described in human oral feeding models developed in 1990s, physiological significances of tongue function has been poorly understood due to the difficulty in monitoring and analyzing it. This review summarizes recent approaches used to evaluate tongue function during swallowing quantitatively mainly focusing on modern sensing methods such as manofluorography, sensing probes, pressure sensors installed in the palatal plates and ultrasound imaging of tongue movement. Basic understanding on the kinematics and biomechanics of tongue movement during swallowing in normal subjects was provided by the series of studies. There have been few studies, however, on the pathological change of tongue function in dysphagic patients. Therefore further improvement in measurement devices and technologies and additional multidisciplinary studies are needed to establish therapeutic evidence regarding tongue movement, as well as the best prosthodontic approach for dysphagia rehabilitation

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

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

Tongue pressure modulation for initial gel consistency in a different oral strategy.

In the recent hyper-aged societies of developed countries, the market for soft diets for patients with dysphagia has been growing and numerous jelly-type foods have become available. However, interrelationships between the biomechanics of oral strategies and jelly texture remain unclear. The present study investigated the influence of the initial consistency of jelly on tongue motor kinetics in different oral strategies by measuring tongue pressure against the hard palate.Jellies created as a mixture of deacylated gellan gum and psyllium seed gum with different initial consistencies (hard, medium or soft) were prepared as test foods. Tongue pressure production while ingesting 5 ml of jelly using different oral strategies (Squeezing or Mastication) was recorded in eight healthy volunteers using an ultra-thin sensor sheet system. Maximal magnitude, duration and total integrated values (tongue work) of tongue pressure for size reduction and swallowing in each strategy were compared among initial consistencies of jelly, and between Squeezing and Mastication.In Squeezing, the tongue performed more work for size reduction with increasing initial consistency of jelly by modulating both the magnitude and duration of tongue pressure over a wide area of hard palate, but tongue work for swallowing increased at the posterior-median and circumferential parts by modulating only the magnitude of tongue pressure. Conversely, in Mastication, the tongue performed more work for size reduction with increasing initial consistency of jelly by modulating both magnitude and duration of tongue pressure mainly at the posterior part of the hard palate, but tongue work as well as other tongue pressure parameters for swallowing showed no differences by type of jelly.These results reveal fine modulations in tongue-palate contact according to the initial consistency of jelly and oral strategies

The system for measuring tongue pressure.

<p>A) Swallow scan; Nitta, Osaka, Japan, B) Sensor sheet with five measuring points (Chs.1–5) attached to the hard palate.</p

Comparisons of maximal magnitude of tongue pressure among the three hardnesses of jelly, and between oral strategies.

<p>A) Squeezing; B) Mastication. *P<0.05. ¶: Maximal magnitude of tongue pressure for size reduction was smaller in Mastication than in Squeezing (P<0.05), ‡: Maximal magnitude of tongue pressure for swallowing was smaller in Mastication than in Squeezing (P<0.05).</p

Comparisons of duration of tongue pressure among the three hardnesses of jelly, and between oral strategies.

<p>A) Squeezing; B) Mastication. *P<0.05. ¶: Duration of tongue pressure for size reduction was shorter in Mastication than in Squeezing (P<0.05). : Duration of tongue pressure was longer in Mastication than in Squeezing (P<0.05).</p

Instrumental texture properties of gel samples.

<p>The three mechanical parameters (hardness, adhesiveness, and cohesiveness) were determined by two-bite compression of jelly samples (diameter, 40 mm; height, 15 mm) at a table speed of 10 mm/s using a 20-mm-diameter flat aluminum plunger, and values are given as mean ±SD.</p

Representative waves of tongue pressure during oral processing and final swallow.

<p>A) Squeezing; B) Mastication.</p