Stomatognathic

STOMATOGNATHIC
SYSTEM
www.indiandentalacademy.com

FORMAT
• INTRODUCTION
• FUNCTIONAL OSTEOLOGY
• MYOLOGY
• TMJ
• FUNCTIONS OF STOMATOGNATHIC
SYSTEM
• CLINICAL IMPLICATIONS
• CONCLUSIONS

INTRODUCTION
• STOMA- mouth
• GNATHIA- jaws
- Taber’s dictionary
• Force linked closed functional unit
- Salzmann 1948
Synonymous with masticatory system

TOOLS
• Active muscles guided by nerve impulses
• Passive jaws, TMJ, ligaments and teeth
ACTIVE + PASSIVE = HARMONY

• STATIC ANALYSIS
• DYNAMIC APPRECIATION
- Mastication
- Deglutition
- Respiration
- Speech
- Maintenance of head posture
SIMULTANEOUS

HIGHLIGHTING POINTS
• Tongue free at one end
• Mandible only movable bone in the
craniofacial region
• TMJ maximum movements
• Teeth deciduous and permanent
• Functions simultaneous

FUNCTIONAL OSTEOLOGY
BONE
• Calcified connective tissue forming
framework
• One of the hardest material
• Plastic
• Most responsive to functional forces
• FORM AND FUNCTION ARE INTIMATELY
RELATED

CONCEPT OF FUNCTIONAL MATRIX
• Given by MELVIN MOSS
• Original concept of FUNCTIONAL CRANIAL
component Van der Klaaus
• Control for growth- soft tissues
• Growth of face  response of functional
needs  mediated by soft tissues
CONCEPT BONE & CARTILAGE react
SOFT TISSUE GROWTH AND
FUNCTIONAL SPACESwww.indiandentalacademy.com

Origin, form, position, growth and
maintenance of all skeletal tissues and
organs are always secondary,
compensatory and morphologically prior
events or processes, that occur in
specifically related non skeletal tissues,
organs or functioning spaces
FUNCTIONAL MATRIX HYPOTHESIS

EXAMPLES
• Growth of CRANIAL VAULT direct
response to growth of BRAIN
• Pressure growing brain separates the
cranial bone at sutures  new bone
passively fills these sites
• Eye and orbital cavity

MICROCEPHALY

HYDROCEPHALY

SCAPHOCEPHALYwww.indiandentalacademy.com

• MOSS  genetic coding for craniofacial
growth  outside the bony skeleton 
FUNCTIONAL MATRICES
• Functional matrices specific function
• Skeletal tissues  support and protect

Periosteal matrices capsular matrices
• Affects the deposition and
resorption
• Thus matrices control
REMODELING
Eg:- interaction between
temporalis and coronoid
Cerebral Facial
• capsular matrices have
specific tissues, structures and
spaces
FUNCTIONAL MATRICES

APPLIED ASPECT
• 75 - 85 % who suffer condylar fractures do
not have impeded mandibular growth because
of non interference with function, while the
rest 20 % have growth deficiency because of
interference of function
• ANKYLOSIS TMJ infections / injury
destruction of the tissues scarring
functional insufficiency impedes
mandibular growthwww.indiandentalacademy.com

CLASSIFICATION OF BONE
• WOVEN BONE
• LAMELLAR BONE
• COMPOSITE BONE
ROBERT’S et al 1987

WOVEN BONE
• Weak, disorganized & poorly mineralized
• Not present in adult skeleton
IMPORTANCE
1. Rapidly fills osseous defect
2. First bone formed in response to orthodontic
loading
3. Provides initial continuity for fractures
4. Strengthens the bone weakened by surgery or
trauma www.indiandentalacademy.com

LAMELLAR BONE
• Strong, highly mineralized, comprises
99 % of skeleton
• Two types-New lamellar bone
Mature lamellar bone
• Primary mineralization - Osteoblasts
• Secondary mineralization - Crystal
growth

• Within physiologic limits strength of the bone
is directly related to mineral content- Currey
1984
• Woven < new lamellar < mature lamellar-
Roberts et al 1991
IMPORTANCE
Orthodontic retention is required
full strength of lamellar bone 1yr

COMPOSITE BONE
• Lamellar bone within a woven bone
lattice
• Most rapid means of producing relatively
strong bone
IMPORTANCE
1. Intermediary type of bone in response to
orthodontic loading
2. Predominant osseous tissue for
stabilization during early retention and
post operative healingwww.indiandentalacademy.com

BUNDLE BONE
• Functional adaptation of lamellar
structure for attachment of tendons and
ligaments
• SHARPEY’S FIBRES

HISTOLOGIC CLASSIFICATION
EMBRYONIC  No functional stresses
CANCELLOUS Appears at centers of ossification
Often replaced by compact bone
COMPACT  Dense and solid
Outer layer of all bones

METHOD OF FORMATION
• ENDOCHONDRAL
• INTRAMEMBRANOUS
BONE METABOLISM
- Kidney
- Gut
- Bone www.indiandentalacademy.com

CELLS OF BONE TISSUE
• OSTEOBLASTS
• OSTEOCYTES
• OSTEOCLASTS

OSTEOBLASTS
• Bone forming cells
• Location surface of forming bone
• Shape cuboidal or pear shaped
• Cytoplasm filled with large amount of
rER, golgi bodies, mitochondria and
secretory granules
• areas in cytoplasm
 Ergastoplasmwww.indiandentalacademy.com

OSTEOCYTES
• Location  within the lacuna of the
bone
• Shape  stellate with processes
extending from the body
• Relatively quiescent
• OSMIOPHILIC LAMINA
• Can bring about lysis of the bone
osteocytic osteolysis

OSTEOCLASTS
• Bone resorbing cells
• Formed by the fusion of monocytes derived
from blood
• When active rests on the surface of bone
• HOWSHIP’S LACUNA
• RUFFLED BORDER
• Gives strong reaction for acid phosphatase

MODELING AND REMODELING
• BONE ADAPTATION  Alterations in
Mass
Geometric distribution
Matrix organization
Lamellar collagen orientation
• Bone Adapts 2 mechanisms
Modeling
Remodeling

• Independent sites of resorption and deposition
MODELING
• Specific coupled sequence to replace
previously existing bone REMODELING
• DOMINANT PROCESS
• TRUE REMODELING  not usually imaged
on radiographs  ROBERTS 1990

Mechanism for internal remodeling is via axially
oriented CUTTING AND FILLING CONES

• REGIONAL ACCELARATORY PHENOMENON
Gradient localized remodeling  post operative
healing (FROST 1983)
CLINICAL IMPORTANCE
• Orthopedically position the maxilla  few weeks
following osteotomy
• Rapid alignment of the dentition after orthognathic
surgery

CONTROL FACTORS FOR MODELING
• FROST’S MECHANOSTAT THEORY
• Mechanical
Disuse atrophy  < 200 µE
Bone maintenance  200 – 2500 µE
Physiologic hypertrophy  2500 -
4000 µE
Pathologic over load  > 4000 µE

• Endocrine
Bone metabolic hormones  PTH, Vit D,
Calcitonin
Growth hormones  Somatotropin, IGF I, IGF II
Sex steroids  Testosterone & Estrogen
• Paracrine & autocrine
Wide variety of local agents

CONTROL FACTOR FOR REMODELING
• Metabolic
PTH  ↑ activation frequency
Estrogen ↓ activation frequency
• Mechanical
< 1000 µE, more remodeling
> 2000 µE, less remodeling

MECHANICAL PROPERTIES OF
BONE
• Effect of function on bonefemur
• Meyer & Cullman-1867
-Alignment of bony trabaculae 
definite engineering principles
-Trajectories on the condyle of femur
crossed  right angles  resist
stresses

JULIUS WOLFF – 1870
Trabecular alignment  primarily due to
functional forces
Change in intensity & direction of force 
change in internal architecture & external form
LAW OF ORTHOGONALITY

WOLFF’S LAW - 1892
Every change in the form & function of
bone or of their function alone is followed
by certain definite changes in their
internal architecture and equally definite
alterations in their external configuration
in accordance with mathematical law.

DRAWBACKS OF WOLFF’S LAW
• It is a statement of relevance.
• Biased functional interpretation  static
requirement or constraints.
• Refused concept of remodeling.
• Did not consider dynamic interaction capable
of modifying form.
• Bias in interstitial bone growth
• Bias in heredity

ROUX
• Loading and unloading generate information
for the developing bone.
• Functional stimulus  affects the bone.
Eg. Thickening of fibula in the absence of
tibia.
• Provided scientific approach for the dynamic
form-function interaction.

SUBSEQUENT RESEARCH
• All trabeculae do not cross at right angles &
do not form straight lines.
• Trajectories  irregular, wavy, vary from
bone to bone & depending on the stresses.
• Functional forces  changes in bony
architecture within limits of inherited
morphogenetic pattern.www.indiandentalacademy.com

• Lack of function bone density ↓ses
(osteoporosis).
• ↑sed function  greater density
(osteosclerosis).
eg. Kyphosis.
Teeth without antagonist.

CONLUSION
• WOLFF’S LAW:
 Accepted phenomenon.
But the biological aspects were
wrong.
• ROUX:
 contributor of our present day
knowledge www.indiandentalacademy.com

BENNINGHOFF
• Architecture and stress trajectories of cranial
& facial skeleton.
• Stress trajectories:
 compact & spongy bone.
 obey no individual bone limits but
rather demand of functional forces.
• Head Craniofacial
 Mandible

STRESS TRAJECTORIES-MAXILLA
• Arise from maxillary teeth  Zygomatic
butress.
• Vertical pillars:
canine zygomatic pterygoid
Curve around sinuses, nasal, orbital cavities.
• Horizontal members:
supraorbital infraorbital zygomatic
hard palate wall of orbit lesser wing

STRESS TRAJECTORIES-MANDIBLE
• Radiate from mandibular teeth  common
stress pillar  terminate in mandibular
condyle.
• UNLOADED NERVE CONCEPT.
• Thick cortical layer & lower border of
mandible  resistance to bending forces.

• ACCESSORY STRESS TRAJECTORIES 
due to muscle attachment.
• Symphysis region
• Gonial angle
• Coronoid processwww.indiandentalacademy.com

CONCLUSIONS
• Basic structure is designed  demands of
the life time of varied functional activity.
• Osseous skeleton  well qualified to adapt
to the stresses applied

• ORTHODONTIC MOVEMENT OF
TEETH  REMODELING
• ORTHOPAEDIC LOADING 
MODELING
• DISTRACTION OSTEOGENESIS

MYOLOGY
• TYPES OF MUSCLES
Skeletal  striated  voluntary
Plain  smooth muscle involuntary
Cardiac  involuntary
• PHYSICAL PROPERTIES:
Elasticity
Contractility

ELASTICITY
• Related to  Length
 Cross section
 Force being exerted
 Constant co-efficient
FΔ = AEL
HOOK’S LAW:
Muscle returns to the exact original
shape after being stretched.
Valid & linear only at initial stage.www.indiandentalacademy.com

CONTRACTILITY
• Ability of an muscle to shorten its length
under innervational impulse
• Prevents the muscle from following an
arithmetical proportion

MECHANISM OF CONTRACTION
• CONTRACTILE PROTEINS
1. MYOSIN  Thick filament
2. ACTIN  Thin filament
3. TROPOMYOSIN
4. TROPONIN

AT REST CONTRACTION

SHERINGTON
• Individual fibers have no variable contraction
status, but are either relaxed or going into
maximum contraction by the virtue of
adequate stimulus – ALL OR NONE LAW
• Strength of contraction  no. of fibers
• Rest  peripheral fibers maintenance of
posture www.indiandentalacademy.com

• Maximum contraction action of all the
available muscle fibers
• As long as the AP is adequate  each fiber
contracts with same amount of force
Eg. Pulling the trigger of a pistol

• Muscle contraction depends on
 striatedsmooth  no. of fibers
 cross section  frequency of
 muscle fiber length discharge
• Some muscles 50 – 70% contraction
• Eg. Temporalis  longer fibers  greater
contraction length than masseter
• Muscle  work & stabilization

• Isometric contraction resist external force
without shortening
• Isotonic  with shortening eg. Flexing of
biceps
• Greater strength of contraction  muscle
approximates its resting length
• Strength ↓ses  muscle shortens or lengthens
beyond optimal length
Eg. Mandible

• YILDIRIM-1971 studied open & closed bite
cases using gnathodynamometer
 opposite results were seen
G.D.M propped opened the mouth 2½ - 3cm
anteriorly
 This prevented the over closure of closed
bite & further opening of open bite to a greater
distance from postural position

STUDY- DR.SHRIKANTH SHENDRE
• AIMS AND OBJECTIVES
1. To assess and compare the activity of
TEMPORALIS and MASSETER in
subjects with different mandibular plane
angles
2. To assess the activity of muscles during
various positions of the mandible rest
chewing and maximum clenching.
3. To explore the possibilities of developing
guidelines in orthodontic treatment

SAMPLE GROUP
• 30 SUBJECTS
1. NORMAL ANGLE 10 SUBJECTS
2. HIGH ANGLE  10 SUBJECTS
3. LOW ANGLE  10 SUBJECTS

16-35
BELOW 16 ABOVE 35

MATERIALS AND METHOD
• Ceph apparatus  villa sistemi medicali (CR-
820 88000)
• ELECTROMYOGRAPHIC MACHINE
 2- CHANNEL MEDELAC II
• Needle electrodes
 0.46 mm dia
 0.07 mm sq area
 25 mm lengthwww.indiandentalacademy.com

ELECTROMYOGRAM
• Derived from ECG & EEG
• ROBERT MOYERS pioneer of EMG inv.
• EINTHOVEN(1918)  muscle in
contraction gives off a current referred to as
ACTION CURRENT
• Current  amplified
• Muscle activity under diverse functional
conditions

RESULTS
• Activity of ant. temporalis, middle temporalis,
post. temporalis and masseter during chewing
and maximum clenching was significantly higher
in low mandibular plane angle when compared
with other groups
• No definite pattern of activity of middle
temporalis, post. temporalis and masseter during
rest position could be found in subjects with low,
normal and high Mb plane angles

RESULTS
• Significant difference in the activity of ant.
temporalis when comparison is made
between low and high Mb plane angles
groups and normal and high Mb plane
angles groups

BUCCINATOR MECHANISM
• Bone  most responsive to changes 
alterations in the environmental balance
• Environmental balance  musculature
• Teeth & supporting structure  influence of
musculature

• Environmental factors
contact relation occlusal integrity
bone building-resorption balance in
PDL
shape & size of roots
total amount of PDL fibers

STABILITY  SUM TOTAL OF
• GENETIC
• EPIGENETIC
• ENVIRONMENTAL
• MORPHOLOGIC
• PHYSIOLOGIC

C.S. TOMES - 1873
• Related arch shape to muscle activity
• Muscles outside the dental arch (lips &
cheeks) apply symmetrical pressure to that
by inside (tongue)
Eg. Plastic material between tongue & lips
• Lingual & labiobuccal muscles forces
determine dental arch form

WINDERS – 1958
• Mastication & deglutition  tongue exerts 2-
3times > force on dentition than the lips &
cheeks
• Net effect balanced tonal contractions,
peripheral fiber recruitment of buccal & labial
muscles & atmospheric pressure  offset the
momentarily greater functional force of the
tongue

MEYER – 1966
• Pressure from inside & outside is
balanced teeth position secured
• Not been universally accepted

SCOTT
• Studied dental arches in human fetus,
3yr old child & adult
• Found no great variation except for size
• Conclusion form of dental lamina or
the arch not determined by postural
or functional activity of the
musculature

GRABER
• Beware of important role of musculature
in maintaining the stability of treated
teeth

BUCCINATOR
• Quadrilateral between maxilla & the
mandible
Upper fibers Middle fibers Lower fibers
Origin Opposite
maxillary
molars
Pterygo –
mandibular
raphe
Opposite
mandibular
molars
Insertion Upper lip Decussate Lower lip
Actions Compresses the cheeks
Mastication & Blowing

ORBICULARIS ORIS
Intrinsic part Extrinsic part
Origin Sup. Incisivus 
maxilla
Inf. mandible
Middle strata
buccinator
Superficiallips
Insertion Angle of mouth Lips & angle of
mouth
Action Closes & purses the mouth

BUCCINATOR MECHANISM
• Decussating fibers of orbicularis oris
laterally & posteriorly join other fibers of
buccinator insert into pterygo mandibular
raphe intermingle with Superior constrictor
fibers  posteriorly & medially anchor to
the pharyngeal tubercle

TONGUE
Solid muscular
organ covered
partially by MM,
lies partly in the
mouth & partly
in the pharynx

MUSCLES OF TONGUE
• Extrinsic  alter position
• Intrinsic  alter shape
• The extrinsic group
• Genioglossus
• Hyoglossus
• Chondroglossus
• Styloglossus
• palatoglossus
The intrinsic group
•Superior longitudinal
•Inferior longitudinal
• transverse linguale
•Verticalis linguale

• DORSUM CONCAVE:
Genioglossus  Superior longitudinal
Verticalis Styloglossus
• DORSUM CONVEX:
Hyoglossus Inferior longitudinal

• SHORTEN THE TONGUE:
Superior longitudinal  Verticalis
Inferior longitudinal
• ELONGATING TONGUE:
Transverse linguale

ORTHODONTIC IMPLICATION
• Tongue anchored at one end  Abnormal
function deform the dental arches
• Malocclusion & perverted perioral muscle
function  state of balance reached
• Malocclusion represents nature’s attempt to
establish a balance between morphogenetic,
functional & environmental componentswww.indiandentalacademy.com

FUNCTIONAL MOVEMENTS

TEMPOROMANDIBULAR
JOINT
• ANATOMIC CONSIDERATIONS
Mandibular condyle shape
Glenoid fossa
Articular eminence  temporal bone
Capsular ligament
Fibrous disk

FIBROUS DISK
• Divides the articular cavity

• LOWER COMPARTMENT
 Extent
 Movement HINGE or ROTATORY
Mandible  slight opening

• UPPER COMPARTMENT
 Extent
 GLIDINGTRANSLATORY
Mandible  Moved beyond the rest
position

HIGHLIGHTING POINTS
• Therefore TMJ DUAL FUNCTIONAL
ACTIVITIES
• GINGLYMOARTHROIDAL JOINT
• ARTICULAR SURFACES  Fibro cartilage
rather than hyaline cartilage
• CONDYLAR CARTILAGE Mandibular
growth

EXTENT OF THE CAPSULAR
LIGAMENT

CAPSULE
• Forms thin fibrous connective tissue sleeve
• Collagenous fibres  vertically oriented
• Within the capsule, all the non articulating
surfaces forms SYNOVIAL MEMBRANE,
the surface area of which is increased by dev
of folds or villi

LIGAMENTS OF TMJ
• CAPSULE  DELICATE
• LIGAMENTS  STABILITY
• TYPES
INTRINSIC EXTRINSIC
TEMPOROMANDIBULAR
COLLATERAL
CAPSULAR
SPHENOMANDIBULAR
STYLOMANDIBULAR
PTERYGOMANDIBULAR

MUSCLES OF MASTICATION
•

IMPORTANCE
• MOSS
 Muscles play a major role in the growth of
the mandible
Temporalis coronoid process
Masseter , med pterygoid gonial region
Lat pterygoid  condylar region

FUNCTIONAL MOVEMENTS
• MANDIBLE 
ONLY MOVABLE
BONE
• 13 ATTACHMENTS
• PROVIDES
STABILITY
POSTURAL REST
POSITION

• TEETH IN OCCLUSION
Mandible  opened what
happens to:
- CONDYLES
- CHIN
- HYOID BONE

• MUSCLE RESPONSIBLE FOR
 Opening
Stabilizing adjusting activity
Controlled relaxation
Paralysis of relaxing muscles

IMPORTANT CONSIDERATION
• UPPER FIBRES OF LP moves the disk
anteriorly
• LOWER FIBRES  Stabilizes the disk during
function
• NO ARTICULAR DISK RETRACTING
MUSCLE
• INTEGRITY OF LIGAMENTS,CAPSULE

CLOSING OF MANDIBLE
• MORE POWER IS ELICITED.
• BILATERAL ACTIVITY OF
MUSCLES
• CONTROLLED RELAXATION

PROTRUSION OF MANDIBLE
• Muscle responsible
• Stabilizing activity
• Mandible  retracted
• Ligaments restrict the retruding action

WORKING BITE
• Mandible  left
• Muscle  contraction
• Muscle  relaxation
• Teeth  end to end relation
• Further movement of the teeth

BENNET MOVEMENT
• Lateral shift of the mandible
articular disk moves towards the side
of the working bite
• Working side  condyle
• Balancing side  condyle

SYMMETRICAL MOVEMENT

CLINICAL IMPLICATION
• CLASS II ROTATORY movement of the
condyle predominates
• Class III  TRANSLATORY
• ABNORMAL OVERJET AND OVERBITE
 LARGE SHIFT of the condyles on
CLOSING
• SHORE CLICK is due to jumping forward
of the condyle a fraction second ahead of the
disk www.indiandentalacademy.com

CONCLUSION
• MUSCLES WORK AS A TEAM
• ADJUSTING OR COMPENSATORY
Activity is available
• Certain adaptive muscle functions may arise
EITHER TO RESTRAIN THE
MALOCCLUSION OR TO ACTUALLY
INCREASE THE DISCREPANCYwww.indiandentalacademy.com

FUNCTIONS OF STOMATOGNATHIC
SYSTEM
• MASTICATION
• DEGLUTITION
• RESPIRATION
• SPEECH

MASTICATION
• Mastication requires practice but is probably built
upon underlying innate co-ordinating pattern,
which once established does not require
concentrated attention.
AHLGREN(1976)
• Variations in mastication
Particular occlusion of teeth
Relation of the jaws
Form of articular surfaces of the TMJ

• AT BIRTH  Mouth sole avenue of
communication
• TACTILE CAPABILITIES  HIGH
• In the infant the food is first taken by
SUCKLING

SUCKLING
• Rhythmic caving in of the cheeks
• Bobbing of the hyoid bone
• Snake like movement of the tongue
• Anterior mandibular thrust
• Sphincter like activity of the lips
• Actual nodding like movement of the entire head

• As the infant learns to take the solid food
 Less activity of the lips
 Tongue primarily used to mix the food
Bolus- forced between the gum pads or occlusal
surfaces of the erupting teeth
Mandible is depressed – LP with a simultaneous
deflection to the working side
Mandible closed- muscles

PHASES OF MASTICATION
• SIX PHASES  MURPHY
1. PREPARATORY PHASE
2. FOOD CONTACT
3. CRUSHING PHASE
4. TOOTH CONTACT
5. GRINDING PHASE
6. CENTRIC OCCLUSION

PREPARATORY PHASE
• TONGUE  positions the food in the oral
cavity
• MANDIBLE  moves towards the
chewing side
• PRECISE BEGINNING OF THE PHASE

FOOD CONTACT
• Momentary hesitation in movement
Pause triggered by sensory receptors
concerning the apparent viscosity of
The food

CRUSHING PHASE
• Starts with high velocity
• GIBBS(1969)
CI approx 0.24 inches from closure
Jaw motion is stabilized at the condyle of the
working side and the final closing stroke is
guided by this braced condyle.

TOOTH CONTACT
• ALL REFLEX ADJUSTMENTS OF
MUSCULATURE OF TOOTH CONTACT
ARE COMPLETED IN CRUSHING
PHASE MURPHY
• Conversely, DISTINCT AND DISCRETE
MOTOR PAUSE is elicited in temporalis
and masseter following tooth contact
BEAUDREAU
DAUGHTERY
MARLAND(1969)

GRINDING PHASE
• COINCIDES TRANSGRESSION of
mandibular molars across their maxillary
counterparts
• MASSERMANTERMINAL FUNCTIONAL
ORBIT
• AHLGREN  Bilateral muscular discharge
becomes UNEQUALwww.indiandentalacademy.com

CENTRIC OCCLUSION
• Movement of the teeth comes to definite
stop at a single terminal point
• JAWS  NORMAL OCCLUSION
REMAINED IN THIS POSITION FOR A
CONSIDERABLE TIME
GIBBS(1969)

DEGLUTITION
• INFANTILE SWALLOW
• MATURE SWALLOW
• MOYER
1. Jaws are apart and tongue between the gum
pads
2. Mandible is stabilized  Muscles (VII C.N)
3. Swallow is guided by sensory interchange
between lips and tonguewww.indiandentalacademy.com

• MOYERCHARECTERISES
MATURE SWALLOW(18 MONTHS OF
AGE)
• TRANSITIONAL PERIOD
1. Teeth are together
2. Mandible  stabilized by the elevator
muscles (V C.N)
3. Tongue tip  held against palate, above
and behind the incisor
4. Minimal contractions of the lip

PHASES OF DEGLUTITION
• FLETCHER
1. PREPARATORY PHASE
2. ORAL PHASE
3. PHARYNGEAL PHASE
4. ESOPHAGEAL PHASEwww.indiandentalacademy.com

PREPARATORY PHASE
• Starts As soon as bolus has been
masticated or liquid is taken
• Bolus  on the tongue ready to be
swallowed
• Oral cavity sealed  lips and tongue

ORAL PHASE
• Soft palate  upwards
• Tongue  downwards and backward
• Hyoid and larynx  upwards
• Oral cavity  stabilized by muscles of
mastication
• Rippling activity  tongue  smooth path
for bolus movement

PHARYNGEAL PHASE
• Begins as the bolus passes through the
fauces
• Pharyngeal tube  raised upward
• Nasopharynx  sealed off by closure of
soft palate against the posterior pharyngeal
wall (PASSAVANT’S RIDGE)
• Hyoid and base of the tongue moves
forward

ESOPHAGEAL PHASE
• Food enters the esophagus
• Hyoid, tongue, soft palate original
position

FREQUENCY OF
SWALLOWING
• BETWEEN MEALS ONCE A MINUTE
• EATING  9 TIMES/ MIN
• EVEN DURING SLEEP
• LEAR, FLANAGAN,MOORREES
studied 20 young adults using visual
observation and acoustic apparatus

RESULTS
MEAN SWALLOWS/Hr7.5
RANGE(2.8-15.6)
MEAN SWALLOWS/Hr DURING EATING  296
RANGE (202-578)
TOTAL No. OF SWALLOWS/DAY585
RANGE  (233-1008)

RESPIRATION
• INHERENT REFLEX ACTIVITY
• Split second opening of epiglottis, keeping
out the food but permitting the entry of air
• BOSMA analyzed respiration in infants
and concluded  NASAL BREATHER
with tongue in proximity to palate
obturating the oral passage

• Both larynx and pharynx are active 
infant differentiates between respiration and
other associated activities such as grunt,
cough, sneeze and cry.
• Development of respiratory spaces and
maintainence of airway  significant factor
in orofacial growth

• Co-ordination achieved early in life
More mature and discriminate neuromuscular demands
SPEECH

SPEECH
• LEARNED ACTIVITY
• Comes later in the evolution of man
• Speech is a complicated process involving
the basic notes in the larynx, known as
phonation and the modifications of these by
changing the shape of the cavities in mouth
and nose.

• SPEECH makes use of muscles which have
many other functions
• WEST  OTHER THAN SPEECH
FUNCTIONS.
1. INNATE AUTOMATIC VEGETATIVE
2. LEARNED AUTOMATIC VEGETATIVE
3. LEARNED AUTOMATIC EMOTIONAL
4. INNATE AUTOMATIC EMOTIONAL
5. LEARNED NON AUTOMATIC VOLUNTARY
6. LEARNED AUTOMATIC PRACTICAL

MUSCLES
• Muscles of the respiratory tract
• Pharynx
• Soft palate
• Tongue, lips & face
• Nasal passage
SIMULTANEOUS BREATHING TO PROVIDE A
COLUMN OF AIR IS ESSENTIAL TO PRODUCE
VIBRATIONS NECESSARY FOR SOUND

• AT BIRTH tongue is large  fills the entire oral
cavity
• Extrinsic muscles  well dev suckle
• Intrinsic muscles needed for speech  poorly dev
• First sound make no demand on the lips
• Bilabial
• Tongue tip consonants
• Sibiliant
• Last speech sound is  r (after 5 yrs)

• The transition from gross movements of the
tongue to precise and finely controlled,
extend over first few years
• SPEECH THERAPIST IS CONCERNED
WITH RESIDUAL INFANTILE TONGUE
POSTURE AND FUNCTION

CLINICAL IMPLICATIONS
• Speech mechanism acts on the breath
stream in controlling the
AIR FLOW
AIR RELEASE
AIR PRESSURE
• DEFORMITIES  CLEFT PALATE 
NORMAL SPEECH IS NOT POSSIBLE

• CLEFT PALATE
PALATAL INSUFFICIENCY
INABILITY TO CONTROL THE AIR
PATH
DIRECTION
ENLARGEMENT OF TURBINATES
CHANGE IN Mb POSTURAL POSITION
CONTRACTION OF NARES

SPEECH AND MALOCCLUSION
• LISP ANTERIOR OPEN BITE
 LARGE GAP BETWEEN INCISORS
• DISTORTION (LABIODENTAL)
 SKELETAL CL III
• DISTORTION (LINGUODENTAL)
 ANTERIOR OPEN BITE
• DIFFICULTY IN PROD.(LINGUOALVEOLAR)
 LINGUAL POSITIONING OF Mx
INCISORS www.indiandentalacademy.com

• DYSLALIAS  common speech disorders
influenced by abnormalities of teeth and
jaws
• Sounds are either produced incorrectly ,
omitted or replaced by other

• CLARK STARR
Mx ARCH IS NARROWER THAN Mb ARCH
ARTICULATION PROBLEMS
CORRECTION OF SEVERE DENTAL DEVIATION
RESULTIG IN IMPROVEMENT IN COSMETIC
APPEARANCE MOTIVATE PATIENTS TO
GREATER SPEECH IMPROVEMENT,EVEN
THOUGH POTENTIAL FOR ADEQUATE SPEECH
EXISTED BEFORE THE CORRECTIVE WORK

REFERENCES
• T.M GRABER- ORTHODONTICS:PRINCIPLES
AND PRACTICE III Ed.
• BONE BIODYNAMICS IN ORTHODONTIC
AND ORTHOPAEDIC TREATMENTVOL 27
CRANIOFACIAL GROWTH SERIES
• PROFFIT- CONTEMPORARY
ORTHODONTICS III Ed.
• STRANG- TEXTBOOK OF ORTHODONTIA
• MICHAEL.H.ROSS, EDWARD.J.REITH-
HISTOLOGY, A TEXT AND ATLAS

• WILLIAM.F.GANONG-REVIEW OF MEDICAL
PHYSIOLOGY 20TH
Ed.
• GRANT’S ANATOMY- ATLAS
• GRAY’S ANATOMY
• SALZMANN-ORTHODONTICS IN DAILY
PRACTICE
• HOUSTON,STEPHAN,TULLEY-TEXTBOOK OF
ORTHODONTICS
• ANGLE ORTHODONTIST(1994)-WOLFF’S
LAW
• DR.SHENDRE SHRIKANTH- M.D.S
DESSERTATION MARCH(2000)- PATTERNS
OF EMG ACTIVITY OF MASSETER AND
TEMPORALIS IN SUBJECTS WITH HIGH AND

Tooth eruption
• Definition
• Tooth eruption can be defined as the axial
or occlusal movement of the tooth from the
developmental position within the jaw to
the functional position in the occlusal plane.

Types
active passive

Active Eruption
• Pre-functional
Eruption from the
developmental position
inside the jaw to the
functional position of
functional occlusion inside
the oral cavity relative to
its environment.
• Real movement of the
tooth
• Functional
Minor eruptive
movements which occur
after the tooth has
reached occlusion due
to wear of
incisal/occlusal surface
to maintain occlusal
contact.

Passive eruption
• Age
• Gingival recession leads to exposure of
more of tooth structure
• Actual movement of gingiva
• Tooth remains in same position

Tooth movement
» Pre-eruptive Eruptive

Tooth movements
• Pre –eruptive
• Decidous and
permanent tooth germ
within the tissue of
jaw before they begin
to erupt
• Eruptive
• Tooth moves from its
position within the
bone to its functional
position in occlusal
plane
• Axial or occlusal
movement

Pattern of tooth eruption
• These movements occur in association with growth of jaw and helps in
placement of tooth germ to its correct position of eruption
• Decidous tooth germ aer very small during early stages of differentiation
and lot space is present between them,this space is utilized with growth of
the tooth germ, more than the bone leading to crowding in insicors and
canineregion which relieved by growth of the jaw due to which anterior
tooth germ moves forward and decidous molar tooth germ move
backwards.
• Tooth germ moves outward, upward or downward with growth of jaw in
length, width and height.
• Bodily movements are seen by permanent tooth

pre-eruptive tooth movements can be
described as the movement to adjust and
position the tooth with its crypt within
growing jaw.
Two types of movements are seen
1 total bodily movement
2 eccentric growth.

Histological features
• Alveolar bone remodelling
• Bone resorption by osteoclasts in direction
of tooth movement and bone deposition
opposite side

Eruption time
Deciduous teeth
Tooth Maxilla (months) mandible
(months)
Central incisor 10 8
Lateral incisor 11 13
Canine 19 20
First molar 16 2 ½
Second molar 29 27

Permanent dentition
tooth Maxilla(months) Mandible(month
)
Central incisors 7 ¼ 6 ¼
Lateral incisor 8 ¼ 7 ¼
Canine 11 ¼ 10 ¼
First premolar 10 ¼ 10 ½
Second premolar 11
First molar 6 ¼ 6
Second molar 12 ½ 12
Third molar 20 20www.indiandentalacademy.com

Hitological features
• Formation of root
• Formation of periodontal ligament
• Formation of dentogingival junction

eruption
• Its only a part of the total pattern of
physiologic tooth movement
• Tooth movement occur because teeth
undergo complex movements in order to
maintain their position in growing jaw and
compansate for masticatory wear.

Physiologic tooth movement
• Axial or verticle
• Drifting
• Torsion
• tipping

Post eruptive tooth movement
• It maintains the position of erupted tooth
while the jaws continue to grow
• Compensate for occlusal and proximal wear
• 14-15 yrs
• Tooth has aquired its functional position

1. Primary eruptive movement is the axial or verticle
movement.
• Functional movements to move to occlusal plane.
2. Movements to compansate for occlusal and
interproximal wear
axial movement are made when apices of lower
permanent are formed and of sceond premolar and
second molar are almost complete this indicates the root
growth is not responsible for axial eruptive movement

Histological features
• Tooth movement to accommodate condylar
growth and growth of the jaws
• Between 14and 15 yrs-
• Rapid condylar growth
• Remodelling of socket
• Increase in alveolar bone ht

Investigation of tooth eruption
• Clinical studies
• Histological studies
• radiocraphs

Clinical studies
• Mucogingival junction is a reference point
to measure the rate of eruption
• Measurements
1. Enlarged oriented radiographs
2. Direct measurement of the dental cast
3. Occlusal plane as a reference pt

Histological studies
• Detailed picture of tooth movement during
eruption
• Slow drift of tooth follicle before apparent
eruptive tooth movement begin and slow
mesio-occlusal movement or drift of adult
teeth

radiographs
• Facilitates the analysis of human tooth
eruption
• Image analysis and substraction
radiography may soon provide a detailed
data

Stages of tooth eruption
• Based on orthopantomographic studies of children and
adult,there are 6 stages of tooth eruption
1. Follicular growth
2. Pre-emergent eruptive spurts
3. Post-emergent eruptive spurt
4. Juvenile occlusal equilibrium
5. Circumpubertal occlusal eruptive spurt
6. Adult occlusal equilibrium

Follicular growth
• Permanent tooth germ bud from the deciduous teeth
assumes a lingual position relative to their precurssors
• As the deciduous teeth develop and erupt,the permanent
tooth follicle undergoes complex migrations from their
intial to pre-eruptive position.
• As the crown formation begins the follicle of posterior
teeth move buccally with little or any radiographic
evidence of occlusal or mesio-distal movement

• The tooth crypt analogous to a cyst at this
stage,expanding vertically and mesio-
distally
• Eruptive movements per se begin soon after
the root begins to form
• This supports the motion that metabolic
activity within the pdl ligament provides a
major componant of tooth eruption.

Pre-eruptive spurts
• Rapid movements of tooth begins in the occlusal
direction while the roots formation continues.
Two processes are involved
• Resorption of overlying bone and overlying
deciduous roots in case of permanent tooth
The eruption mech itself must move the tooth where
the path is cleared.

Post-emergent spurt
• Rate of tooth eruption is greatest at the time
of gingival emergence.
• The rates begins to slow down as the tooth
approaches the occlusal plane and comes
under the influence of both masticatory and
intra-oral forces.

Juvenile occlusal equilibrim
• Once the permanent teeth,reaches
occlusion,occlusal movements stop or is
incredibly slow for several years.
• This period ends at the beginning of puberty
and the second active phase of eruption
begins.

Circumpubertal occlusal spurt
• 11 and 16 yrs of age
• Teeth in occlusion begins a second active
eruption phase lasting 2-3 yrs.
• Increase lower facial ht through additions of
alveolar bone.
• Not same in maxilla and mandible..

features
• Facial tissue undergoes a period of
accerlated growth with lengthening of facial
and masticatory ms and lowering of
mandible and associated soft tissues.
• This eruptive spurt slow as the tooth
reaches maturity and a state of relative
equilibrim establishes itself again by 18 yr
of age

Adult occlusal equlibrim
• Vertical movements of the tooth does not stop
abruptly, once physical maturity is reached.
• Throught life small increases in lower facial and
continued eruptin occurs.
• Lower facial ht increases at rate as
1. 2nd
decade-o.3mm/yr
2. 3rd
decade-0.1mm/yr
3. 7th
decade-.07mm/yr

• As a result of continued eruption with interproximal and
occlusal wearand mesio-distal movement are the
predominant aetiologic factors.
• However continued tooth eruption can be overshadowed
by
1. Tooth loss
2. Marked occlusal abrasion
3. Pdl breakdown
• Leads to decrease in facial ht.
• If antagonist is lostthe tooth erupts rapidly

Mechanism of tooth eruption
• Theories
• Root elongation theory
• Pulp growth theory
• Periodontal ligament theory
• Hydrostatic theory
• Alveolar bone remodelling
• Follicular theory
• Shrinkage of collagen
• Gubernacular cord
• Constriction of pulp

Root elongation theory
• It causes overall increase in length of the tooth
with the crown moving occlussaly
• Simplest theory is that the growth of root pushing
against the alveolar bone forces the crown through
the gums
• Drawbacks
• The eruptive movements of some teeth exceeds
the total length if root eg; upper canine

• Rootless teeth are known to erupt
1. Detin dysplasia type 1
2. Irradiation
• Some teeth erupt to a greater distance and
continue o erupt even after completion of root or
when the tissues forming the root ie;apical
papilla, hertwigs epithelial root sheath,and
periapical tissues are surgically removed.

• Eruption –roots are failed to form or fractured in accident
• Occasionally incisors are erupting in a new born child
although roots r not yet formed
• Mark and cahil
• Young dogs
• Teeth were extracted beforeeruption, pulp was`removed
and cells of pdl were killed by freez thawing. Rootless
teeth were reimplanted and still managed to erupt by
compansatory bone growth

Pulp growth theory
• Malcolm harris-
• Propulsive force is genrated by three mechanism
1. Growth of dentin
2. Interstitial pulp growth
3. Hydraulic pressure genrated by pulp vasculature.
• Drawbacks
• Evidence against theory is work of herzbergand schour –removed
the pulp of rat incisor and found that the eruption rate was
uneffected.
• Schroeder-force exerted by the growth of cells is the result of
multication f ceels analogous to the root of growing plant forcing
the pebbles aside,which causes eruption

• Drawback- the develping tooth is surgically removed and
replaced by silicone replica,erupts provided the dental
follicle remains unaffected.
• Sichers (1942)-growth of the pulp which must normally
keeps pacewith growth of root may provide at least part of
eruptive force in certain teeth. Zone at apical end of
pulp,cells are in active state of division new collgen fibers
are being formed.
• Ness and Smale (1959)-injected antimitotic drug and
measured the rate of eruption,reduce rate of eruption.

• Cluba et al(1968)-injected an antimitotic
drug demecolcine which had an immediate
effect on tooth eruption,although these
drugs inhibited cell proliferation in pulp,
they had other effect elsewhere which might
have affected the rate of eruption so results
were unconclusive.

PDL traction theory
• Most accepted and proven theory
• Tooth is pulled into occlusion by the tension developing in
connective tissue of PDL, brought about by the contractile
locomotive properties of PDL fibroblasts acting upon the
collagen fibres attached to the tooth.

• Similar to sailors climbing and pulling the rope while
getting on to ship
• For:
• Follicular tissue – imp role in eruption
• Normal PDL disturbed by interfering with collagen
synthesis
By Vit.C deficient diet
Injecting lathyritic agents – prevent cross linkages b/n
fibres
The eruptive movement stopped

• Berkovitz and thomas(1969)-resected or trasected
the roots of rat incisors and measured the effect on
unimpeded eruption rate
• Result-resection-5 out of 16 animals,eruption
vertually ceased wheras in other 11 it slowed
down at first,reached control level by 4-7 days
,remained theie for 12 days ,decreased when tooth
reached the alveolar crest

• Trasected-similar result
• Excluded –root elongation,pulp and detin
proliferation and tissue fluid pressure
theory(since walls are not closed vessel
• Most obvious cause of eruption is
associated with pdl.

• Evidence against theory –lathyritic
agents(β-aminoprpionitrile),inhibit the
collagen cross-linkage of polypeptide
chains on collagen molecules,therefore
inhibit teeth from erupting,despite of these
drugs rat insicors continue to erupt.

Hydrostatic theory
• Dental papilla is highly vascular.
• Vascular(arterial) pressure in BV of papilla
and fluid pressure due to retained water in
pdl causes teth to erupt.
• Teeth move in socket acc to arterial pulse
,local volume change,swelling of ground
substance 30 to 50% leads to eruption.

drawbacks
• Tooth continue to erupt
1. Root removal
2. Periapical vasculature
• Not recommended theory as in absence of
BV periapical region also,tooth continue
to erupt.

Follicular theory
• Critical role in tooth eruption.
• Loose CT of dental follicle is rich source of
factors responsible for bone formation and
resorption.
• Follicles produce
1. Ecosanoids
2. Cytokines
3. Growth factors

functions
• Resorption of overluing deciduous roots
and alveolar bone
• Induce bone formation at base of follicle.
• Conduit and chemoattracttant for
osteoclasts
• Bone remodelling.

• In osteopetrotic animals(lack factor to
stimulate differentiation of osteoclasts)
eruption is prevented as no mechanism for
bone removal exists.infection of colony
stimulating factor permit differentiation of
osteoclast and eruption occurs.

drawbacks
• Fails to explain the reason of the production
of force which causes tooth movement.
• Deposition of bone does not always occurs
at the base of the crypt ,when occurs its
presence cab be effect than cause.

Shrinkage of collagen as a sourse of
eruption
• Thomas (1964)-course of development and
maturation of collagen and formation of
cross linkage results in shrinkage of collgen
fibers in pdl which would exert the force for
eruption.
• AAN(aminoacetonitrile) was given to rats
which produces lathyrism.

• Eruption of molars wwa greatly reduced
although root growth normally continued.
• Berkovitz et al(1972)and T .Ssurvtta(1974)
repeated the exp of thomas as an effect of
AAN,although teeth becomes easier to
extract indicating some effect on pdl
eruption rate was virtually unchanged

• It cannot be implicated once the tooth has
breached the oral mucosa
• Surgical removal of CT may lead to
eruption.

Gubernacular cord
• Fibrous CT strands connect the follicle of the
permanent teeth to oral mucosa,imp role in
controlling movements of developing teeth
through the growing jaw.
• Gubernacular cord decreases in length,increases in
thickness,less dense.
• Provides a duct,path of least resistance or engaged
in pulling the tooth from underlying tissue yet to
establish.

Alveolar bone remodelling
• Growth of alveolar bone pulls the tooth
outward by pdl fibers.
• Selective deposition and resorption of
bone,pre-eruptive and eruptive phase of
movement.
• Strongest evidence –bone remodelling

• When premolars were removed without
disturbing dental follicle or eruption is
prevented by wiring the tooth germ down to
lower border of mb an eruptive pathway
still forms within the bone overlying the
enucleated tooth as osteoclast.

Constriction of pulp
• Odontoblasts increases in thickness of
dentin in root of tooth and as the pulp
cavity becomes smaller,increased pressure
within is sufficient to erupt the tooth.
• Drawbacks
1. Eruption of rootless teeth and teeth with
extirpated pulp does not support theory.

• Bryer –`protein and calorie def in rats produces
thinner dentin and wider pulps,eruption rates
either unchanged or in creased and not decreased
as pulp constriction theory.
• More shrinkage evidence against theory is
provided by hypophysectomy exp great
constriction of pulp occurs with marked eruption
rates

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