Mujtaba Ashraf 1

Tongue, Speech &Its Prosthodontic

ConsiderationPresented by:

Dr MujtabaMDS-1st year

Dept. of Prosthodontics

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Contents Introduction Structure Papillae Taste buds Development Function Speech Conclusion References

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Introduction

The tongue is a muscular organ in the mouth of most vertebrates that manipulates food for mastication, and is used in the act of swallowing. It is of importance in the digestive system and is the primary organ of taste in the gustatory system.

A major function of the tongue is the enabling of speech in humans and vocalization in other animals.

The average length of the human tongue from the oropharynx to the tip is 10 cm. The average weight of the human tongue from adult males is 70g and for adult females 60g.

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Structure The human tongue is divided into two

parts:I. an oral part at the frontII. a pharyngeal part at the back.

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The left and right sides are also separated along most of its length by a vertical section of fibrous tissue (the lingual septum) that results in a groove, the median sulcus on the tongue's surface.

Its anterior part is in the oral cavity and is somewhat triangular in shape with a blunt apex of the tongue. The apex is directed anteriorly and sits immediately behind the incisor teeth. The root of the tongue is attached to the mandible and the hyoid bone.

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Tongue thrusting habit tend to displace mandibular denture and sometimes maxillary denture also.

Measurement of the tongue force and fatigue indicate that long span edentulous state effects the musculature of the tongue. The tongue becomes stronger and this increase in strength must be considered.

JPD 1963,,VOL 13,857-865, by Philip Rinaladi

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After the loss of teeth, tongue expands into the space created by loss of teeth, known as Proptosis Lingualis.The enlarged tongue creates problem during impression making, contributes to mandibular denture instability, is crowded by denture base resulting in difficulty in swallowing.

The crowded tongue always presses on the front part of palate causing soreness and tenderness.

It also causes excessive pressure on the mandibular denture which pushes it forward and outward every time the mouth is opened.

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Tongue Form

Class 1: Tongue is normal or ideal in development, size, and function. A sufficient number of natural or artificial teeth are properly distributed to maintain the normal form and function of the tongue.

Class 2: Natural teeth have been absent for a sufficient period to permit a change in the functional action and form of the tongue.

By M M House-1958

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Class 3: Tongue is excessively large. All, or practically all, of the teeth may have been absent for an extended period of time, or there may be an abnormal development of the size of the tongue.

Inefficient dentures sometimes create a Class 3 condition in the functional action and form of the tongue.

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Tongue Position Class 1 – Tongue lies

in the floor of mouth with the tip forward and slightly below the incisal edges of mandibular anterior teeth.

It has the most favorable prognosis as adequate border seal can be achieved because floor of the mouth will be high enough to cover the lingual flange.

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-By CR Wright

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Class 2 – The tip is in a normal position but the tongue is broadened and flattened.

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Class 3 – The tongue is retracted and depressed into the floor of the mouth with the tip curled upward, downward or assimilated into the body of tongue.Its very unfavorable position as an adequate border seal can’t be achieved. An attempt to extend the flange to gain border seal results in overextension during tongue movements that would dislodge the denture

Tongue position and the degree of freedom provided for tongue movements during border molding procedures also play an important role in positioning of the denture borders, design of the denture flange thus influencing stability of the mandibular denture.

Tongue Position and Occlusal plane

Tongue should be in resting position with the tip just passively touching the lingual surface of the mandibular anterior teeth and the lateral surface touching the mandibular posterior teeth.

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Muscles The eight muscles of the human tongue are classified

as either intrinsic or extrinsic.The four intrinsic muscles

superior longitudinal, inferior longitudinal,

transverse, and vertical muscles.

The intrinsic muscles of the tongue originate and insert within the substance of the tongue and they alter the shape of the tongue by:

• lengthening and shortening it,• curling and uncurling its apex and edges,

and• flattening and rounding its surface.

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Extrinsic muscles of the tongue originate from structures outside the tongue and insert into the tongue.

the genioglossus, hyoglossus, styloglossus, and palatoglossus.These muscles protrude, retract, depress, and elevate the tongue

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Genioglossus Thick fan-shaped Origin: superior mental spines on the

posterior surface of the mandibular symphysis Insertion: Body of hyoid, entire length of

tongue Function: Protrudes tongue, depress center of

tongue

It is a “lingual fixing muscle of the lower denture”.

The movements of the tongue esp. the contraction is in conjunction with the lingual vertical and the Genioglossus muscle that helps in the drawing of the tongue anteriorly towards the floor of the muscle.Hence, it increases the pressure which the tip of the tongue can exert on the floor of the oral cavity and the alveolar process.

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Hyoglossus Thin quadrangular muscles Origin: Greater horn and adjacent part of body of hyoid bone Insertion: Lateral surface of tongue Function: Depresses tongue

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Styloglossus Origin: Styloid process of temporal bone Insertion: Lateral surface of tongue Function: Elevates and retracts tongue

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Palatoglossus

Origin: Inferior surface of palatine aponeurosis

Insertion: Lateral margin of tongue

Function: Depresses soft palate and elevates back of the tongue.

• It helps tongue to touch the palate, thus preventing the bolus from coming out.

• It is also a lingual dislocating muscle.

• It is having the same action as that of the styloglossus muscles.

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Blood Supply The tongue receives its blood

supply primarily from the lingual artery, a branch of the external carotid artery.

There is also a secondary blood supply to the tongue from the tonsillar branch of the facial artery and the ascending pharyngeal artery.

The tongue is drained by dorsal lingual and deep lingual veins

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Nerve Supply

Innervation of the tongue consists of motor fibers, special sensory fibers for taste, and general sensory fibers for sensation.

Taste and general sensation from the pharyngeal part of the tongue are carried by the glossopharyngeal nerve [IX] .

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General sensory innervation from the anterior two-thirds or oral part of the tongue is carried by the lingual nerve, which is a major branch of the mandibular nerve [V 3] .

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Papillae The superior surface of the oral part of the tongue is

covered by hundreds of papillae. The papillae in general increase the area of contact

between the surface of the tongue and the contents of the oral cavity.

Types:FiliformFungiformVallateFoliate

All except the filiform papillae have taste buds on their surfaces.

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Filiform papillae are small cone-shaped projections

Fungiform papillae are rounder in shape and larger than the filiform papillae, and tend to be concentrated along the margins of the tongue.

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Vallate papillae The largest of the papillae are the, which are blunt-ended cylindrical papillae invaginations

only about 8 to 12 in number Foliate papillae are linear

folds of mucosa on the sides of the tongue near the terminal sulcus of tongue.

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Taste Bud The taste buds are the sensory

end organs for gustation. Each bud is flask-shaped, with a

wide base and a short neck opening at the taste pore.

The apical ends of the taste cells contain microvilli 2-3 μm in length that connect with the luminal surface through a porelike opening.

Taste buds have a life span of about 10-12 days.

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Taste bud are involved in detecting the five elements of taste perception:saltysourbittersweetumami

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A popular myth assigns these different tastes to different regions of the tongue; in reality these tastes can be detected by any area of the tongue.

Via small opening i.e. taste pores, parts of the food dissolved in saliva come into contact with the taste receptors. These are located on top of the taste receptor cells that constitute the taste buds. The taste receptor cells send information detected by clusters of various receptors and ion channels to the gustatory areas of the brain via nerve

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Development The tongue appears in embryo of approximately 4 weeks

in the form of two lateral lingual swellings and one medial swelling, the tuberculum impar.

These 3 swelling originate from the first pharyngeal arch.

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Development A second median swelling, the copula, or hypobranchial

eminence, is formed by 2nd , 3rd , and part of the 4th arch. Further lateral lingual swellings increases in size, they

over the tuberculum impar and merge, forming anterior 2/3rd (body) of tongue.

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Development A third median swelling, formed by the posterior part of

4th arch, marks development of epiglottis. Immediately behind this swelling is laryngeal orifice,

which is flanked by the arytenoid swelling

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Development The posterior part, or root of the tongue originates from

the 2nd, 3rd, and parts of the 4th pharyngeal arch. The body of the tongue is separated from posterior 3rd

by a ‘V’ shaped groove, the terminal sulcus.

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Developmental Anomalies

Macro-glossia Micro-glossia Ankylo-glossia Bifid tongue Fissured tongue Median rhomboid glossitis

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Macroglossia

too large tongue seen in Downs syndrome & Beckwith-Wiedemann syndromedue to an over development of

the musculatureEnlargement due to lymphangioma

gives the tongue pebbly appearance with multiple superficial dilated lymphatic channels

In case of patients with large sluggish tongue, proper designing of the lingual flange at the wax up stage helps increase the stability of mandibular denture providing adequate room for the tongue to perform its function of distributing the food during mastication and to relax when the mouth is at rest without disturbing the mandibular denture.

Impression making In Macroglossia

This can be achieved by adding as little as wax possible, behind the incisors in the anterior region while behind the premolars, a flat or slightly concave surface should be established In the molar and retromolar region, the polished surface is designed to be slightly concave facing inwards, upwards and forwards. Narrow posterior teeth should be selected for patients with macroglossia

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Microglossia Due to the failure of lingual swellings of the

first arch to develop the tongue which is present in the posterior

most part develops from the copula i.e. the hypobranchial eminence of third arch only.

Impression making for Microglossia

Though impression making is easy microglossia jeopardizes the lingual seal. In such cases, the mandibular denture should be planned to be made with thick lingual flanges with wider posterior teeth while retaining its characteristic shape.

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Ankyloglossia The apical part of the tongue may be

anchored to the floor of the mouth by an overdeveloped frenulum.

Tongue tie Causes

speech disorders deformities in dental occlusiondifficulties in swallowing

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Cleft Tongue/Bifid Tongue The tongue may be bifid because of non-

fusion of the two lingual swellings.

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Fissured tongue Its a malformation manifested clinically by numerous

small grooves on dorsal surface radiating out from central groove along the midline of tongue

Down syndrome & Melkersson-Rosenthal syndrome

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Median Rhomboid Glossitis It is an asymptomatic

elongated erythematous patch of atrophic mucosa on the mid-dorsal surface of the tongue

Presents in the posterior midline of the dorsum of the tongue ,just anterior to the V-shaped grouping of the circumvallate papilla. This is due to failure of fusion of lingual swellings with tuberculum impar.

1. It is a necessary part of the instrument of articulate speech.2. It acts like a reed in a wood-wind instrument to effect variations of sound qualities.3. It moistens lips to facilitate speech. This is an important, yet frequently overlook observation.

Function Of Tongue

An analysis of tongue factor and its functioning areas in dental prosthesis;B. Kessler JPD,1955

4. It acts as an improved conveyor belt to help complete the process of mastication by gathering, holding, and assisting food to the food table for complete mastication before deglutition.5. It also aids as a vehicle to direct the masticated bolus to the oropharynx.6. It helps control and guide the fluid intake to the pharynx.7. It contains the greatest number of the taste organs and mucin-secreting gland.

An analysis of tongue factor and its functioning areas in dental prosthesis;B. Kessler JPD,1955

8. It is a contributing factor in aiding normal positioning of erupting teeth in the dental arches as a counter-pressure to the facial muscles on the labial and buccal side of teeth.

9. It aids in depressing the soft palate to eliminate mucous, sinus, and lacrymal secretions.

An analysis of tongue factor and its functioning areas in dental prosthesis;B. Kessler JPD,1955

10. It aids in the retention of ill-fitting dentures.

11. It helps block the trachea in deglutition to keep food out of the bronchial tract.

12. It effects displacement and compression of air, thereby helping create suction in swallowing.

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Mastication: The tongue an important accessory organ in the digestive

system.

The tongue is used for crushing food against the hard palate, during mastication and manipulation of food for softening prior to swallowing.

The epithelium on the tongue’s upper, or dorsal surface is keratinized. Consequently, the tongue can grind against the hard palate without being itself damaged or irritated.

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Places food on occlusal table.

During mastication food after being adequately mixed with saliva and chewed ,is converted into bolus and is placed on tongue in its central depression, series of muscular waves travelling posteriorly along the tongue, passes the food over epiglottis into the oesophagus.

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Speech

Speech is the mechanical process of producing audible sounds to represent language.

The intrinsic muscles of the tongue enable the shaping of the tongue which facilitates speech.

Voice is mainly produced in larynx and modified by tongue by constantly altering its shape, position by contacting lips, teeth, alveolar processes, hard palate and soft palate.

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Mechanism Of Speech Production

Normal speech depends on proper functioning of 5 essential mechanism:

(1) The motor: consisting of the lungs and associated musculature which supply the breath (air)

(2) The vibrator: consisting of the vocal cords which give pitch to the tone

(3) The resonator: consisting of oral, nasal, and pharyngeal cavities and paranasal sinuses which

create overtones peculiar to each individualRobert Rothman; Phonetic consideration in denture prosthesis, J Prosthet Dent;1961;11:214-223)

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(4) The enunciators or articulators: consisting of the lips, tongue, soft palate, hard palate and teeth, which form musculoskeletal valves to obstruct the passage of air, breaking up the tones and producing the individual speech sounds

(5) The initiator: consisting of the motor speech area of the brain and the nerve pathways which convey the motor speech impulses to the speech organs.

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Articulation

Articulation, in phonetics, a configuration of the vocal tract resulting from the positioning of the mobile organs of the vocal tract (e.g., tongue) relative to other parts of the vocal tract that may be rigid (e.g., hard palate).

This configuration modifies an airstream to produce the sounds of speech.

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The main articulators are: tongue upper lip & the lower lip teeth alveolar ridge hard palate velum (soft palate) uvula pharyngeal wall and glottis (space between

the vocal cords)

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The primary concern in phonetics is with the changes in the stream of air as it passes through the oral cavity. Of these, the tongue plays a major role.

The tongue is the principal articulator and changes position and shape for the pronunciation of each of the vowels and consonant.

In pronouncing, the tongue contacts a specific part of the teeth, alveolar ridge, or hard palate.

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Vowels are voiced sounds, that is, the vocal cords are activated by vibration in their production.

They are the free emission of a speech sound through the mouth and require subglottic pressure for the production.

vowels in English: a, e, i, o, u

Consonants are produced as a result of the airstream being impeded, diverted, or interrupted before it is released,

such as p, g, m, b, s, t, r, and z.

Consonants may be either voiced sounds or breathed sounds, which are produced without vocal cord vibration.Zarb- Bolender:Speech consideration with complete dentures ;Prosthodontic treatment For Edentulous Patients

CLASSIFICATION OF SPEECH

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Consonants are divided into 6 groups:(depending on their characteristic production and use of different articulators and valves)

Plosives (Stops) Fricatives Affricatives Nasals Liquids Glides

CLASSIFICATION OF CONSONANTS

Zarb- Bolender:Speech consideration with complete dentures ;Prosthodontic treatment For Edentulous Patients

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Plosive consonants: These sounds are produced when overpressure of the air has been built up by consonants between the soft palate and pharyngeal wall and released in an explosive way.Ex: p, b, t, d

Fricatives: are also called sibilants and are characterized by their sharp and whistling sound quality created when air is squeezed through the nearly obstructed articulators.

Ex: s, z

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Affricative consonants: are a mix between plosive and fricative ones. Ex: c, j

Nasal consonants: are produced without oral exit of air. Production involves the coupling of nasal cavity as resonators. Ex: m, n, ngLiquid consonants(semi vowels): are , as the name implies , produced with out friction. Ex: r, lGlides: that is sounds characterized by a gradually changing articulator shape Ex: w, y

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CLASSIFICATION OF CONSONANTS BASED ON THE PLACE OF THEIR

PRODUCTION

Consonant sounds are most important from the dental point of view. They may be classified according to the anatomic parts involved in their formation:

(1) Palatolingual sounds: formed by tongue and hard or soft palate

(2) Linguodental sounds: formed by the tongue and teeth

(3) Labiodental sounds: formed by the lips and teeth

(4) Bilabial sounds: formed by the lips.Robert Rothman; Phonetic consideration in denture prosthesis, J Prosthet Dent;1961;11:214-223)

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PALATOLINGUAL SOUNDS

formed by tongue and hard or soft palate

T, D, N, and L.

S- the sound ‘s’ as in sixty six- is formed by a hiss of air as it escapes form the median groove of the tongue when the tongue is behind the upper incisor.

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The essential factor in the production of a correct s is the proper grooving of the tongue.

As the depth of this groove is decreased, s is softened toward sh, and as the groove is further decreased, toward th as a lisp.

Excessive thickness of the denture base in the anterior part of the palate is often the cause of lisping.

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T, D, N and L Rugae area is very important for

the production of these sounds. Tongue must be placed firmly

against the anterior part of the hard palate for the production of these words.

If teeth too lingual – T will sound like D

If teeth too forward - D will sound like T

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BILABIAL SOUNDS

Formed by contact of the lips. b, p, and m

In b and p, air pressure is built up behind the lips and released with or without a voice sound. Insufficient support of the lips by the teeth or the denture base can cause these sounds to be defective.

Therefore the antero-posterior position of the anterior teeth and thickness of the labial flange can affect the production of these sounds.

Used to asses the correct inter-arch space Labial fullness of the rims can be checked

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LABIODENTAL SOUNDS Formed between the upper incisors and the

labiolingual center to the posterior third of the lower lip.

f and v Upper anterior teeth are too short (set too high

up), V sound will be more like an F. If they are too long (set too far down), F will sound

more like a V.

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LINGUODENTAL SOUNDS

Consonant Th is representative of the linguodental group of sounds

Dental sounds are made with the tip of the tongue extending slightly between the upper and lower anterior teeth.

The words this, that, these, and those will provide information as to the labiolingual position of the anterior teeth.

If about 3mm of the tip of the tongue is not visible, the anterior teeth are probably too far forward.

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LINGUOALVEOLAR SOUNDS

Alveolar sounds (e.g., t, d, s, z, n, and l) are made with the valve formed by contact of the tip of the tongue with the most anterior part of the palate (the alveolus) or the lingual side of the anterior teeth.

The sibilants (sharp sounds) s, z, sh, ch, and j (with ch and j being affricatives) are alveolar sounds because the tongue and alveolus form the controlling valve.

The important observation when these sounds are produced is the relationship of the anterior teeth to each other. The upper and lower incisors should approach end to end but not touch.

Zarb- Bolender:Speech consideration with complete dentures ;Prosthodontic treatment For Edentulous Patients

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Conclusion

Knowledge of anatomy, physiology and functions of tongue is an essence to understand the complex morphological and functional changes in the tongue with aging or with complete and partial edentulism.

This knowledge will help us to reach optimal prosthetic success, as tongue plays significant and perhaps the dictating role in affecting stability and retention of prostheses.

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References

Langman’s medical embryology. — 12th ed. / T.W. Sadler. Orban’s Oral Histology and Embryology, 11/e Netter's head and neck anatomy for dentistry, 2nd ed. Gray's Anatomy For Students, Third Edition Zarb- Bolender:Speech consideration with complete

dentures; Prosthodontic treatment For Edentulous Patients 13th ed

Robert Rothman; Phonetic consideration in denture prosthesis, J Prosthet Dent;1961;11:214-223)

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