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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