Mastication, degluttition and speech

Mastication, Degluttition

and Speech

Presented by: Dr Sakshi

I yr PG

Department of Prosthodontics

MASTICATION

Digestive System

• Functions

Ingestion

– Mastication

– Deglutition

– Digestion

– Absorption of nutrients

– Elimination of indigestible/undigested

food products

From Mouth to Stomach

• Mastication (chewing):

– Mixes food with saliva -

• Amylase = enzyme that can catalyze the partial digestion of starch.

• Deglutition (swallowing):

– Involves 3 phases:

• Oral phase is voluntary.

• Pharyngeal and Esophageal phases are involuntary.

– Cannot be stopped.

– Larynx is raised.

– Epiglottis covers the entrance to respiratory tract

MASTICATION

Mastication of food is the initial stage in the process of digestion.

Large pieces of food are reduced to smaller for swallowing.

The food is broken apart and the surface area increased for the efficient action of digestive enzymes and to facilitate solubilisation of food substances in saliva to stimulate taste receptors.

Muscles of Mastication

Muscles of Mastication

Action of muscles during masticatory

movements

• Opening / Depressor jaw muscles

– mylohyoid

– digastric

– inferior lateral pterygoid

• Closing / elevator jaw muscles

– medial pterygoid

– superficial masseter

– temporalis

Chewing reflex

Presence of bolus causes inhibition of elevator muscles

of jaw ,causing lower jaw to drop.

The drop in turn initiates a stretch reflex of the jaw

muscles leading to rebound contraction.

This automatically raises the jaw to cause closure of the

teeth compressing the bolus against the linings of mouth.

This inhibits jaw muscles once again allowing the jaw to

drop and rebound another time ; this is repeated again

and again.

Chewing

Types of Jaw Reflexes:

• Jaw Closing Reflex / Jaw Jerk

Reflex

• Jaw Opening Reflex

• Jaw Unloading Reflex

• Tooth Contact Reflexes

Jaw Opening Reflex:

• It is a polysynaptic reflex.

• consists of reciprocal inhibition of antagonists, rather than direct excitation of opener

• occurs as a result of mechanical or electrical stimulation of the lips, oral mucosa or teeth.

• After stimulation, opening movement occurs due to inhibition of activity in the mandibularelevators without simultaneous contraction of the depressors .

Jaw Closing Reflex / Jaw

Jerk Reflex:

• monosynaptic reflex generated by stretching muscle spindles in the masseter muscle.

• Its latent time period is 6ms between the stimulus and the movement.

• Demonstration: A sharp downward tap on the chin when the mandible is held loosely in the rest position results in contraction of the elevator muscles to bring the teeth into occlusion.

Muscle spindle in the massetor suddenly stretched

Afferent nerve activity is generated in the spindles

afferent impulses passed to the mesencephalic nucleus in the brain stem

Afferent fibres synapse with the efferent motor neuron leading back to the fibres of the massetor

Muscle will contract

• This reflex also counteracts the force

of the gravity which would act to lower

the jaw and separate the articular

surface of the temporomandibular joint.

• As all the elevator muscles are

maintained in a mild state of the of

contraction called muscle tone.

Jaw Unloading Reflex

• protective reflex that occurs when the jaw is suddenly unloaded

e.g: When a stone comes inside mouth with food while mastication.

• On sudden encounter with the hard object, mastication is stopped. This is due to reflex inhibition of elevators & reflex excitement of jaw depressors due to receptors in periodontal ligament and protects teeth from damage.

Tooth Contact Reflex:

Reflex changes that occur in the elevator

muscles when the upper & lower teeth are

snapped together ( mechano-receptors in

the pdl , fire a burst of impulses ) .

the elevator muscles are stimulated.

Mastication : The crushing &

grinding

• opening stroke

• closing stroke / fast stroke

• power stroke

- puncture-crushing

- tooth-tooth contact

-buccal phase / phase I

-lingual phase / phase II

MASTICATORY

MOVEMENTS

– Movements

– Chewing stroke Tooth contact• Forces of

mastication

• Role of periodontal fibres

• Role of saliva

• Muscle activity

Chewing Stroke

Rhythmic

Opening and closing of the jaw is in cyclic movement.

Chewing stroke is divided into

Opening movement

Closing movementa) crushing phase

b) grinding phase

Management of temporomandibular disorders and occlusion- Jeffery P. Okeson (5

edition)

Opening phase

• During opening phase there is initial rotation of the mandible for the first 20-27mm of interincisal distance.

• Thereafter there is translatory or bodily shift of the mandible anteriorly and in downward direction.

Opening

• Start from static intercuspal position, where jaw movement pauses for 194 ms in chewing cycle,

• muscle activity begins in the ipsilateral inferior head of the lateral pterygoid muscle

• Follow closely by the action of the contralateral inferior lateral pterygoid muscles.

Opening

• Early in the opening phase,

digastric muscles become active and remain until maximum opening position.

• During the opening phase, masseter, temporalis, medial pterygoid, and superior head of lateral pterygoid muscles are inactive.

Closing Phase

1) Crushing phase

Starts when the mandible

starts closing.

At this point buccal cusp of

maxillary teeth are under

the buccal cusp of

mandibular teeth.

As the mandible closes, the

bolus of food is trapped.

Jeffery P .Okeson (5 edition)

2) Grinding phase

• Bolus gets trapped

between the cusps

and is ground

• Bolus is trapped by

the buccinator

buccally and by the

tongue lingually.

Mandibular movements in

frontal plane

A cyclic movement pattern

is seen when the

mandibular movements

are traced along the

frontal plane.

Management of temporomandibular disorders and occlusion- Jeffery P.Okeson (5 ed)

TOOTH CONTACT

• In final stages of mastication, just

before swallowing tooth contact

occurs during every stroke.

• Gliding contact

Centric contact

• Average length of time for tooth

contact during mastication is 194

msec.

Occlusal condition influences

the entire chewing stroke

Tall cusps and deep fossae promote a predominantly vertical chewing stroke .

– Flattened or worn teeth encourage a broader chewing stroke area.

Management of temporomandibular disorders and occlusion- Jeffery P.Okeson(5 edition)

FORCES OF MASTICATION

• Varies from individual to individual.

• Maximum amount of force applied to the molar is usually several times that can be applied to the incisors.

for the molars is 91-198lb

for the incisors is 29-51lb

• The individuals can increase their maximum biting force over time with practice and exercise.

• The force generated during routine

mastication of food is about 70 to

150 N

• The maximum biting force is around

500 to 700 N

• When the opposite teeth contact on inclines that is during the lateral movements , the horizontal forces are applied to the teeth ( as the periodontal fibres are not properly aligned to control them . so ,some areas are compressed and others are elongated.)

Role of periodontal fibres

• PDL, is a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone

• These fibers help the tooth withstand the naturally substantial compressiveforces which occur during chewing and remain embedded in the bone.

• The periodontal fibres have the

mechanoreceptors that respond to the forces

applied to the tooth and send impulses to the

brainstem.

• The alveolar crest fibers prevent extrusion of

tooth and resist lateral tooth movements.

ROLE OF SOFT TISSUE

• LIPS:

– Guide and controlintake.

– Seal off the oral cavity.

• TONGUE:

– Maneuvering the food within the oral cavity.

– Initiates the breaking of food.

– Pushes food to occlusal surfaces of teeth.

TONGUE

– During opening phase repositions the crushed food.

– Divides food into portions that require more chewing and portions that are to be swallowed .

– After eating ,the tongue sweeps the teeth to remove any food residue that has been trapped in the oral cavity.

Buccinator muscle

• It repositions food from buccal side.

• Forms a boundary and limits the food and brings it back on the occlusal table for further grinding.

• Gray’s Anatomy-38th edition

Muscle activity

The general pattern of muscle activity

during chewing cycle.

Closing muscles are inactive during jaw

opening.

Activity of the jaw closing muscles

increases slowly as the teeth begin to

interdigitate or as soon as food is

encountered between the teeth.

•The combined efforts of

the Lateral Pterygoid and

digastric muscles provide

jaw opening

The Lateral Pterygoids

advance the condyles,

thereby opening the mouth

(depressing the mandible),

with the assistance of the Digastric muscle.

SIDE TO SIDE GRINDING MOVEMENT

• In normal chewing function, the mandible opens, and then, while initiating closing, there is a shift slightly to the side of the bolus, due to the orientation of the masseterand medial pterygoid.

Medial and lateral pterygoid act together

to protrude the mandible

ELEVATION OF MANDIBLE BY

TEMPORALIS

Neurological control during mastication

• Coordination between

– sensory feed back from peripheral organ

– CPG :Central Pattern Generator neuron

in brain stem

– higher center

– jaw reflexes

Motoneuronal Excitation

• During the jaw-opening phase of mastication,

– rhythmic inhibition occurs to inhibit the stretch

reflex.

• This postsynaptic hyperpolarization appears to be

responsible for the phasic inhibition of the stretch reflex

during jaw-opening

• Moto-neuron pool is inhibited during chewing.

• The muscle spindle feedback is mainly controlled by

cyclical changes in the membrane potential of jaw-

closing motoneurons.

Reflex modulation

• neuron circuits are modulated at the level of primary afferent or interneurons.

• modulation of sensory transmission occur through neurons in the trigeminal main sensory nucleus in the sub-nucleus oralis, and in the inter-trigeminal area which lies between the sensory and motor nuclei.

Reflex modulation

• During the masticatory cycle the excitability of the jaw-opening reflex interneurons is inhibited– which receive inputs from low-threshold

mechano-sensitive fields in the face or oral cavity.

– most of the neuron with high threshold fields are very excitable during fast and slow jaw closing and relatively unexcitable during jaw opening.

• Modulation of sensory transmission through the subnucleus caudalis is not phase modulated.

Control of mastication -

Sensory

Control of mastication -

Motor

MASTICATION WITH COMPLETE

DENTURE

• The biting force of subjects with complete denture is only one fourth than that of subjects with natural teeth.

• Patient comfort and mastication may be impaired due to the elicited excess flow of the saliva for a few days after the placement of new complete denture.

COMPLETE DENTURE AND IMPLANT SUPPORTED DENTURES ZARB –BOLENBER -12TH EDITION

• Patient should begin chewing relatively soft

food that requires less mastication and also

ready for swallowing with a simple push of

the tongue against the palate. This will make

the patient confident in stabilising the denture

• when biting with the denture ,patients should

be instructed to place the food between their

teeth towards the corner of the mouth then

the food should be pushed inward and

upwards as this will tend to seat the denture .

• So , learning with new denture requires at

least 6-8 weeks as the memory patterns are

established for the muscle of mastication.

DEGLUTITION

Deglutition is the act of swallowing, through which a food or liquid bolus is transported from the mouth through the pharynx and esophagus into the stomach.

Normal deglutition is a smooth coordinated process that involves a complex series of voluntary and involuntary neuromuscular contractions and typically is divided into four distinct phases:

Preparatory phase

Oral

Pharyngeal

Esophageal

Preparatory phase

• The average tooth contact during swallowing

lasts about 683msec.

• It is more than three times longer than the

duration of mastication.

• Definition--It consists of a reflex

sequence of muscle contraction that

propels ingested materials and pooled

saliva from the mouth to the stomach.

PREPARATORY PHASE

Bolus is prepared

↓

Positioned on the dorsum of the tongue

↓

The tongue tip pressed against the palatal aspect of the maxillary incisors or against the anterior hard palate

↓

Bolus is located in depression of the tongue

↓

Tongue raised laterally against the buccal teeth and palatal mucosa

↓

Posteriorly the pharyngeal part of the tongue arches up to meet the soft palate

ORAL PHASE

It is a Voluntary

phase

It includes the

collection of

chewed food into

a bolus by tongue.

Chewed food goes

from mouth to

pharynx.

Gray’s Anatomy-38th edition

– collection of chewed food into a bolus by

tongue.

– bolus pressed against palate.

– lips sealed, teeth brought together.

– reflex contraction of tongue pushes food

backwards down into pharynx.

PHARYNGEAL PHASE

• Food goes from

pharynx to esophagus

– pharyngeal muscles

contract & push food

by peristalsis

– soft palate lifts & seals

off nasal passages

– epiglottis blocks

entrance to trachea

ESOPHAGEAL PHASE

• Food travels down esophagus to stomach.

• bolus moved through the esophagus. Smooth muscles contract behind the bolus to prevent it from being squeezed back into the mouth.

• Peristalsis refers to the symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube.

• which pushes the digested food forward. and take about 8 seconds to reach the lower esophageal sphincter which opens to admit the entry of the bolus into the stomach

Food propulsion

When the food is propelled from the oral cavity to the esophagus

Peristaltic wave starts in the whole esophagus

This propels the bolus towards the stomach

Due to pressure difference, the valve of lower esophageal sphincter opens and

food enters the stomach.

CONTROL OF SWALLOWING

• Preparatory and oral phases are under voluntary control.

• The pharyngeal and esophageal phases are involuntary.

• Organization of the swallowing motor sequence depends on the activity of brain stem neurons that belong to a functionally defined swallowing center

(Textbook of medical physiology- Guyton (10th edition)

Importance of swallowing

in prosthodontics

• As the process of swallowing completes, it brings the mandible to its most retruded position and therefore helpful in recording the centric relation in edentulous patients.

• Immediately after swallowing, mandible tends to come into maximal intercuspal position, therefore it is important in recording “vertical jaw relations”.

• COMPLETE DENTURE AND IMPLANT SUPPORTED DENTURES ZARB –BOLENBER -12TH EDITION

SPEECH

INTRODUCTION

Definition-"Speech is the use of

systematized vocalization to express

verbal symbols or words." (GPT-7)

• Speech in matured man is learned habitual

neuromuscular pattern which makes use

of anatomical structures designed primarily

for respiration and deglutition.

• speech as the basic and fundamental means

of communication became the cornerstone for

the establishment and organization of society.

Larynx

• The larynx is a respiratory organ, set in the respiratory tract between the pharynx and trachea.

• Although phonation is important in man, the main function of the larynx is to provide a protective sphincter for the air passages.

• The larynx lies below the hyoid bone in the midline of the neck at the level of C 4-6 vertebrae.

Grays Anatomy – 40th edition

Speech production

• Controlling the airstream that is

initiated in the lungs and passes

through the larynx and vocal cords

produces all speech sounds

• Subtle adjustments in the airflow

contribute to variations of pitch and

intensity of the voice

MECHANISM OF VOICE

PRODUCTION

• The pre-requisites for sound are a source of energy and a vibrator . The source of energy for the voice is air in the lungs. The vibrator for the voice are the vocal folds in the larynx.

• The larynx, pharynx, nasal cavity all act as cavity resonators to reinforce the original sound wave. This reinforcement is augmented by the change of shape and size of these cavities permitted by neuromuscular control.

lungs: filled with air

contraction of rib cage forces

air from the lungs into the

trachea

-trachea (windpipe): conveys

air to the vocal tract (the

volume of air determines the

amplitude of the sound )

Text book of medical physiology,

choudary-5th edition

Vocal cords tense, pressed together

air pressure cause the vibration of the

vocal ligament

phonation

Speech is composed of two mechanical

functions:

SPEECH

Phonation Articulation achieved by the larynx achieved by structures of

mouth

• During normal breathing, the folds are wide open to allow easy passage of air. During phonation, the folds move together so that passage of air between them will cause vibration.

The pitch of the vibration is determined mainly by the degree of stretch of the folds but also by how tightly the folds are approximated to one another and by the mass of their edges.

Human embrology-7th edition

• The three major organs of articulation are the lips, tongue, and soft palate .

• They alter the sound wave as it passes through the mouth and shapes the flow of air and voice into speech sounds, that is, vowels and consonants.

• The resonators include the mouth, the nose and associated nasal sinuses, the pharynx.

• Broca's responsible for producing speech.

• Broca's area is located in the lower portion of the left frontal lobe. This brain area controls motor functions involved with speech production.

Text book of medical physiology, choudary-5th edition

Neuromuscular control of speech

• Persons with damage

to Broca's area of the

brain can understand

language but cannot

properly form words or

produce speech.

• Broca's area is

connected to another

brain region known as

Wernicke's area.it

interprets and

understands the words.

COMPONENTS

OF SPEECHRESPIRATION

RESONATION

ARTICULATION

PHONATION

NEUROLOGIC

INTEGRATIONAUDITION

COMPLETE DENTURE AND IMPLANT SUPPORTE DENTURES

ZARB –BOLENBER -12TH EDITION

RESPIRATION

• The speech process is initiated by the energy inherent in a stream of air in normal speech

• During exhalation, a continuous stream of air with sufficient volume and pressure, under adequate voluntary control, for phonation.

• The stream of air is modified in its course from the lungs by the maxillofacial structures and gives rise to the sound symbols which we recognize as speech.

PHONATION

• When air leaves the lungs, it passes through the larynx, whose true vocal folds modify the stream.

• The true vocal folds, by opposing each other with different degrees of tension and space, create a slit like aperture of varying size and contour.

RESONATION

• It is the resonators that give the characteristic

quality to the voice.

• The resonating structures are the air

sinuses, organ surfaces and cavities, such as

the pharynx, oral cavity, nasal cavity, and

chest wall.

• The resonating structures contribute no

energy to the stream of air; they act to

conserve and concentrate the energy

already present in the laryngeal tone, rather

than to let it dissipate into the tissues.

ARTICULATION

• It is the function of the articulatorymechanism to break up and modify the laryngeal tones and to create new sounds within the oral cavity.

• So, the final action of the articulatoryapparatus is to articulate, that is to join in a sequence all the sounds which have been synthesized into symbols.

• Without the articulatory capacity, the

sounds produced would be only of

variable pitch, volume, and quality,

like a vowel sound.

NEURAL INTEGRATION

• Speech is a learned function, and adequate hearing and vision and a normal nervous system is required for its full development.

• When the speech function comes into conflict with other vital functions of the maxillofacial structures, it is speech that suffers.

AUDITION

• Audition, or the ability to receive acoustic signals, is vital for normal speech. Hearing permits receptions and interpretation of acoustic signals and allows the speaker to monitor and control speech output.

• Compromised hearing can preclude accurate feedback and hence, affect speech. Speech development and subsequent speech therapy is hampered in patient with hearing impairments.

SURD

• The surd is any voiceless sound and is produced by separation of the vocal folds (glottis open) with no marginal vibration.

• The sound is made by frictions of the air stream as it posses through the appropriate cavities;

• The initial 'h' sound as in huh and the voiceless

sibilants, z, sh and zh pronounced initially are

examples.

Charles M.Heartwell -5th edition

Sonants

• Sonants are voiced sounds and include all vowels and vowel like sounds.

• They are produced by vibration of some portions of vocal folds.

• The vowels require minimum articulation.

• The tip of the tongue lie on the floor of the mouth either in contact with or close to the lingual surface of the lower anterior teeth.

Consonants

• Consonants are articulated speech sounds, and require articulation to constrict, divert, or stop the air stream at the proper place and time to produce the desired sound.

• 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

• may be either voiced sounds or breathed sounds,which are produced without vocal cord vibration

Different valve positions from which consonants are produced

• Bilabial

• Labiodental

• Linguodental

• Lingeoalveolar

• Linguopalatal

• Linguovelar

Out of the above six valves, five valves are affected by teeth position

COMPLETE DENTURE AND IMPLANT SUPPORTED DENTURES

ZARB –BOLENBER -12TH EDITION

Bilabial Sounds

• Bilabial Sounds: -

The sounds b, p

and m are made

by contact of the

lips.

• Insufficient support of lips by teeth and / or denture base can cause these sounds to be defective.

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

• An incorrect vertical dimension of occlusion (VDO) or teeth positioning hindering proper lip closure, might influence these sounds.

Labio-dental Sounds

• Labio-dental

Sounds: - The

labio-dental

sounds f and v are

made between the

upper incisors and

the labio-lingual

center to the

posterior third of

the lower lip.

• If the upper anterior teeth are too short (set

too high up), the v sound will be more like an

f. If they are too long (set too far down), the f

will sound more like a v.

• If upper teeth touch the labial side of the

lower lip while these sounds are made, the

upper teeth are too far forward or the lower

teeth are too far back in the mouth.

If the upper anterior teeth are set too

far back in mouth, they will contact

the lingual side of the lower lip when

f and v sounds are made

This may also occur if the lower

anterior teeth are too far forward in

relation to the lower anterior teeth

Linguodental Sounds

Dental sounds (eg. Th in this)are made with the tip of the tongue extending slightly between the upper and lower anterior teeth.

This sound is actually made closer to the alveolus(the ridge) than to the tip of the teeth

• Careful observation of the amount of tongue that can be seen with the words this, that, these and those will provide information about the labiolingual position of the anterior teeth

• If about 3mm of the tip of tongue is not visible, the anterior teeth are probably too far forward or there may be an excessive vertical overlap

• If more than 6mm of the tongue extends out between the teeth when such thsounds are made, the teeth are probably too far lingual

Linguoalveolar Sounds:

Alveolar sounds

(eg. t, d, s, z, v &

1) 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 sides of the

anterior teeth.

• The sibilants (sharp sounds) s, z, sh, ch &

j (with ch & j ) are alveolar sounds,

because the tongue and alveolus forms

the controlling valve.

• The important observations 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

The ‘s’ Sound

From dental point of view, the ‘s’ sound

is the most interesting one because

its articulation is mainly influenced by

the teeth and palatal part of the

maxillary prosthesis

following are the phonetic properties of s

sound

Articulatory characteristics

• The tip of tongue is placed far forward,

coming close to but never touching the

upper front incisors

• A saggital groove is made in the upper front

part of the tongue ,with a small cross-

sectional area

• The tongue dorsum is flat

• Normally, the mandible will move forward

and upward, with the teeth almost in contact

Acoustic characteristics

• The comparatively strong sound

energy is concentrated to a high

frequency range, with a steep energy

cut-off at about 3-4kHz

Auditory characteristics

• The sound is fairly loud, with a light,

sibilant(sharp) quality

• The s sounds can be considered dental and

alveolar speech sounds because they are

produced equally well with two different tongue

positions

• Most people make the s sound with the tip of

tongue against the alveolus in the area of the

rugae, but with a small space for air to escape

between the tongue and alveolus

• A sharp s requires accuracy of the

neuromuscular control system for the

creation of the groove and directing

of the air jet

• If the opening is too small, a whistle will

result.

• If the space is too broad and thin, the S

sound will be developed as sh, somewhat

like a lisp.

• The frequent cause of undesired whistles

with dentures is a posterior arch form that

is too narrow.

Let ‘speech’ be your guide Earl

Pound

JPD 1977:38;482-489

• Establishing vertical dimension of occlusion

• While repeating (three thirty three) there should be enough space for the tip of the tongue to protrude between the anterior teeth

• While repeating fifty five , the incisal edge of the maxillary incisor should contact the vermillion border of the lower lip

• When the patient repeats the words MISSISIPPI and EMMA ,the teeth should not contact.

Spectral analysis of ‘s’ sound

with changing angulation of the

maxillary central incisor

Runte C, Tawana D,Dirksen D, Runte B,

Lamprecht-Dinnesen A, Bollmann F,

Seifert E,Danesh G IJP 2002;15: 254-258

• Concluded that the maxillary incisor

position influences /s/ sound production.

Displacement of the maxillary incisors

must be considered a cause of immediate

changes in /s/ sound distortion.

• Therefore, denture teeth should be

placed in the original tooth position

as accurately as possible. Results

also indicate that neuromuscular

reactions are more important for

initial speech sound distortions than

are aerodynamic changes in the

anterior speech sound producing

areas.

Linguopalatal and

linguovelar sounds

• The truly palatal sounds (e.g. those in

year,she,vision and onion) present less

problem for dentures

• The velar sounds (k,g and ng) have no

effect on dentures except when the

posterior palatal seal extension

encroaches on soft palate

FACTORS IN

DENTURE

DESIGN AFFECTING

SPEECH

CLINICAL DENTAL PROSTHETICS

Fenn, Liddelow, Ginisons 2nd edition

The vowel sounds

• The tip of the tongue, in all the vowel sounds, lies on the floor of the mouth either in contact with or close to the lingual surfaces of the lower anterior teeth and gums.

• The application of this in denture construction is that the lower anterior teeth should be set so that they do not impede the tongue positioning for these sounds.

• i.e. they should not be set lingual to the alveolar ridge. The upper denture base must be kept thin, and the posterior should merge into the soft tissue in order to avoid irritating the dorsum of the tongue, which might occur if this surface of the denture were allowed to remain thick and square edged

Denture thickness and

peripheral outline

• One of the reasons for loss of tone and incorrect articulation of speech is the decrease of air volume and loss of tongue space in the oral cavity resulting from unduly thick denture bases.

• Any interference with the freedom of tongue ,lips these movements may result in indistinct speech, especially if the function of the lips is in any way hindered.

• CLINICAL DENTAL PROSTHETICSFenn, Liddelow, Ginisons 2nd edition

• The production of the palatolingual (T, D) group of sounds involves contact between the tongue, and either the palate, the alveolar process, or the teeth.

• With the consonants T and D, the tongue makes firm contact with the anterior part of the hard palate, and is suddenly drawn downwards, producing an explosive sound; any thickening of the denture base in this region may cause incorrect formation of these sounds.

• In the case of the S, C (soft) and Z sounds, a slit like channel is formed between the tongue and palate.

• Through which the air hisses. If artificial rugae are too pronounced, or the denture base too thick in this area, the air channel will be obstructed and a noticeable lisp may occur as a result.

Vertical dimension

• The formation of the bilabials, P, B and

M requires that the lips make contact to

check the air stream.

• With P and B, the lips part quite forcibly

so that the resultant sound is produced

with an explosive effect, whereas in the

M sound lip contact is passive.

• For this reason M can be used as an

aid in obtaining the correct vertical

height since a strained appearance

during lip contact, or the inability to

make contact, indicates that the

record blocks are occluding

prematurely.

The speaking method in measuring

vertical dimension

Silverman JPD1953Meyer M ;3:193-199

• When the sounds like ch, s ,j are pronounced , the upper and the lower teeth reach their closest relation without contact. This minimum amount of space is

called the silverman”s speaking space.

This space is measured before the loss of the remaining natural teeth to give us the patient natural V.D. which can be recorded and used at later dates.

Closest speaking space should be reproduced in full dentures as in the natural dentition. This space is also the means of proving that , VD must not be increased.

Occlusal plane

• The labiodentals, F and V are produced by the air stream

being forced through a narrow gap between the lower lip

and the incisal edges of the upper anterior teeth.

If the occlusal plane is set too high the correct positioning

of the lower lip may be difficult. If, on the other hand, the

plane is too low, the lip will overlap the labial surfaces

of the upper teeth to a greater extent than is required for

normal phonation and the sound might be affected.

Anteroposterior position of

the incisors

• In setting the upper anterior teeth, consideration of their labio palatal position is necessary for the correct formation of the labiodentals F and V.

• If they are placed too far palatallythe contact of the lower lip with the incisal and labial surfaces may be difficult, so

• If the anterior teeth are placed too far

back some effect may be noticed on

the quality of the linguopalatals S, C

(soft) and Z, resulting in a lisp due to

the tongue making contact with the

teeth prematurely.

Post-dam area

• Errors of construction in this region involve the vowels and the palatolingual consonants K, NG, G and C(hard).

In the latter group the air blast is checked by the base of the tongue being raised upwards and backwards to make contact with the soft palate.

A denture which has a thick base in the post dam area, or a posterior edge finished square instead of chamfered, will probably irritate the dorsum of the tongue, impeding speech and possibly producing a feeling of nausea.

• Indirectly, the postdam seal

influences articulation of speech.

• If it is inadequate the denture may

become unseated during the

formation of those sounds that have

a explosive effect.

Width of dental arch

• If the teeth are set to an arch which is too narrow the tongue will be cramped, thus affecting the size and shape of the air channel

• this results in faulty articulation of consonants such as T, D, S, N, K, C, where the lateral margins of the tongue make contact with the palatal surfaces of the upper posterior teeth.

Relationship of the upper

and lower anterior teeth

• The chief concern is that of the S

sound which requires near contact of

the upper and lower incisors so that

the air stream is allowed to escape

through a slight opening between the

teeth.

• In abnormal protrusive and retrusive

jaw relationships, some difficulty may

be experienced in the formation of

this sound, and it will probably

necessitate adjustment of the upper

and lower anterior teeth

anteroposteriorly so that

approximation can be brought about

successfully. The consonants Ch, J

and Z require a similar air channel in

their formation.

POST –

INSERTION

SPEECH

DIFFICULTIES

• When complete dentures are worn for the first time there is always some temporary alteration in speech owing to the thickness of the denture covering the palate, necessitating slightly altered positions of the tongue.

Patients usually adapt readily to moderate changes in denture shape, and problems with speech which are apparent at the delivery stage are not often present at the review.

• Adaptation occurs rapidly over the first few

days, but if distortions of speech persist

after 30 days a change to the denture

has to be made.

• However, that adaptation of speech

patterns back to normal is prolonged when

the patient has a hearing impediment, and

not all patients will admit to such a

disability.

TONGUE SPACE

• Restriction of the tongue space may give rise to the following complaints:

(1) the patient feels that the dentures are a

'mouthful';

(2) the patient has difficulty in speaking;

(3) the lower denture feels loose all the time;

(4) the tip or sides of the tongue feel sore.

Tongue space is most likely to be

restricted anteriorly by the setting of the

upper incisors in the wrong relationship to

the incisive papilla, and posteriorly by

the setting of the upper posterior teeth 'on

the ridge' and the lower posterior teeth

lingual to the ridge.

• Difficulty with speech, is often associated with the placement of the anterior teeth on the ridge instead of in front of it.

• The anterior tooth position can be very quickly checked by measuring from the middle of the incisive papilla depression, on the fitting surface of the denture, to the labial surfaces of the incisors.

• The horizontal distance between these two points should be approximately 1 cm. If it is less than 7 mm it is safe to assume that there is restriction of the anterior part of the tongue space.

PATIENT’S COMPLAINT CAUSES OF

COMPLAINT

• Whistle on ‘s’ sounds Too narrow an air space on the

anterior part of the palate

• Lisp on ‘s’ sounds Too broad an air space on the

anterior part of the palate

• ‘Th’ and ‘t’ sounds Indistinct Inadequate interocclusal

distance

• ‘T’ sounds like ‘th’ Upper anterior teeth too far

lingual

• ‘F’ and ‘v’ sounds Indistinct Improper position of upper

anterior teeth either vertically

CLINICAL DENTAL PROSTHETICS Fenn, Liddelow, Ginisons 2nd edition

Special consideration in

implant prosthodontics

• Speech problems with maxillary fixed implant prostheses are frequently reported,mostly during the first several weeks after delivery but may persist over several months

• Sibilants specially s have been most commonly affected sound

• Space left between the alveolar ridge and a fixed maxillary prosthesis and air passing through it may be the cause of the higher error rate for linguoalveolar and linguopalatal stops and fricatives

• Patients who receive an immediate

loaded implant-supported prosthesis

after wearing a denture for a long

period,should be informed about the

possibility of a 3-6 month speech

adaptation period

References

• CLINICAL DENTAL PROSTHETICS Fenn, Liddelow, Ginisons

2nd edition.

• Runte C, Tawana D,Dirksen D, Runte B, Lamprecht-Dinnesen A,

Bollmann F, Seifert E,Danesh G

IJP 2002;15: 254-258

• Let ‘speech’ be your guide Earl Pound

JPD 1977:38;482-489

• COMPLETE DENTURE AND IMPLANT SUPPORTED DENTURES

ZARB –BOLENBER -12TH and 13th editions

• M. Heartwell 5th edition

Thank you