Myofunctional appliances -BASIC PRINCIPLES

MYOFUNCTIONAL APPLIANCES
PART 1- BASIC PRINCIPLES OF
MYOFUNCTIONAL THERAPY
Dr.Tinet Mary Augustine. BDS,MDS
Pediatric Dentist
Dr.Tinet’s Pedorayz, Pediatric And Early Age
Orthodontic Dental Clinic
DR.TINET MARY AUGUSTINE.BDS.MDS 1

CONTENTS
• NORMAL GROWTH AND DEVELOPMENT
BONES
TMJ
MUSCLES
HORMONES
FUNCTIONAL MATRIX HYPOTHESIS
ASSESSMENT AND PREDICTION

• PRINCIPLES OF FUNCTIONAL APPLIANCE
• FUNCTIONAL DIAGNOSIS
• ROLE OF MUSCLES IN FUNCTIONAL
APPLIANCE THERAPY
• ROLE OF FUNCTIONAL APPLIANCE IN
CORRECTION OF MALOCCLUSION

DIFFERENT FUNCTIONAL APPLIANCES
1. ACTIVATOR
2. BIONATOR
3.FUNCTIONAL REGULATORS
4. SCREENS
5.TWIN BLOCK APPLIANCES
6.MYOBRACES

• BONDING IN ORTHODONTICS
DIFFERENT BRACKET SYSTEMS
BRACKET PLACEMENT
BONDING PROCEDURES

GROWTH AND DEVELOPMENT

DEFENITIONS
• GROWTH
It is a process that leads to increase in the
physical size of cells ,tissues,organs and
organism as a whole(STEWART 1982)
Growth refers to increase in size or
number(PROFIT 1986)
Growth may be defined as the normal
changes in the amount of living substances
(moyer 1988)

Growth is an increase in the size of a living
being or any of its parts, occurring in the
process of development (STEDMAN 1990)
Growth refers to increase in size ( TODD)
Growth signifies an increase ,expansion or
extension of any given tissue (PINKHAM )

DEVELOPMENT
Development is increase in complexity (TODD
1931)
 Development is used to indicate an increase
in skill and complexity of functions( Lowrey
1951)
Development is in complexity (Profitt 1986)
Development addresses the progressive
evolution of a tissue(PIKNHAM)

The act or process of natural progression from
a previous, lower, or embryonic stage to a
later , more complex or adult stage(STEDMAN
1990)

• DIFFERENTIATION:It is the change from
generalised cells or tissues to more specialized
kinds during development
• TRANSLOCATION:It is the change in position
• MATURATION:It is the qualitative changes
which occur with aging

•DEVELOPMENT=GROWTH+
DIFFERENTIATION+TRANSL
OCATION+MATURATION

DIFFERENT PRINCIPLES AND THEORIES OF
GROWTH AND DEVELOPMENTCEPHALOCAUDAL
GRADIENT

SCAMMONS CURVE

GROWTH FIELD ,SITE, CENTER

BONE REMODELLING

CRANIUM
• neural mass translation
tension at suture edges bone
deposition growth

SYNCHONDROSIS
• Inter sphenoidal(at birth)
• Inter occipital(5yr)
• Spenoethmoidal(5-10yrs)
• Spheno occipital/basioccipita(13-15yrs)
• Thilander and ingervall 1973 showed that there is a
growth catrilage in the sella turcica which is patent till 3
years of life

SPHENO OCCIPITAL SYNCHONDROSIS
MAJOR CONTRIBUTOR IN POSTNATAL
GROWTH
FUSE AT 12-13 IN GIRLS
14-15 IN BOYS
OSSIFIES AT 20 YEARS

DRIFT
• The term coined by ENLOW(1963)
• Drift is the growth movement (relocation or
shifting) of an enlarging portion of a bone by
the remodelling action of its osteogenic tissue

BONE DISPLACEMENT
• Displacement is the movement of the whole
bone as a unit
• The entire bone is carried away from its
articular interface (suture, synchondroses
,condyle) with adjascent bones

PRIMARY DISPLACEMENT

SECONDARY DISPLACEMENT

MAXILLA

ZYGOMATIC BONE

PALATE
• Intermaxillary suture is smooth and open in
children(6-8)
• Overlapping in adolescence(10-12)
• Interdigitated in late adolescence(14-16)DR.TINET MARY AUGUSTINE.BDS.MDS 28

ORBIT
• Lateral wall-resorption-lateral movemenmt of eyeball
• Floor-deposition in superior lateral and anterior
direction

OVERALL GROWTH

MANDIBLE

V PRINCIPLE

CONDYLE

ROTATION

• INTRA MEMBRANEOUS OSSIFICATION

TMJ

ZONES
• Articular zone
• Proliferating zone
• Hypertrophic zone
• Zone of endochondral ossification
• Active proliferation till 13-15yrs. And most
evident in pubertal age

ORAL CAVITY

RELOCATION
• When new bone is added
onto an existing surface,
the relative positions of all
the old levels of bone becomes
shifted into new positions
& this process is termed
as relocation

Posterior growth and anterior
displacement

HOW THEY REMODEL
“ FORM FOLLOWS FUNCTION”

The origin ,growth and maintanence of all skeltal
tissues and organs are always secondary
compensatory and obligatory response to
temporally and operationally prior events or
processes that occur in specifically related
nonskeltal tissues ,organs or functioning spaces
(functional matrices)

FUNCTIONAL CRANIAL COMPONENT
SKELTAL UNIT
MICRO
SKELATAL
MACRO
SKELETAL
FUNCTIONAL MATRICES
CAPSULAR
MATRICES
PERIOSTEAL
MATRICES

ORGANIZATION OF FMH
Periosteal
matrix microskelton transformation
Capsular matrix macroskelton translation
+
GROWTH

Transformation (remodelling)
• change in size and shape
• Ossoeus deposition and
resorption
Translation(displacement)
• Change in spatial position
• Without ossoeus deposition and resorption

FUNCTIONAL CAPSULE

FUNCTIONAL ANALYSIS OF MANDIBLE
Matrix consist of
• All muscles with mandibular attachments
• Neurovascular triad
• Associated salivary glands
• Teeth
• The tongue
• Fat,skin and connective tissue
• The oral and pharyngeal spaces

• Mandible consist of a group of microskeltal
unit and a basal core part(Moss)
Functions include
• Articulation(condyle)
• Muscle attachment(coronoid)
• Occlusion(alveolar process)
• Holding the dentition(corpus)
• Compensation(ramus)

Protected nerve concept
• The basal tubular portion serves as protection
for mand.canal and follows downward and
forward movement from beneath the cranium

• The most constant portion of mandible is the
arc that forms from foramen ovale to the
mandibular foramen and mental foramen

• Orthodontic tooth movement( periosteal
matrix) – alveolar bone transformation( micro
skeletal unit)
• Orofacial orthopedics( capsular matrix) – jaw
bones translation ( macro skeletal unit)

NORMAL ANATOMY
MUSCLES

MUSCLES OF FACIAL EXPRESSION

INNERVATIONS

MUSCLES OF MASTICATION

MASSETER
• Origin: inferior border and medial surface of
zygomatic arch.
• Insertion: lateral surface of ramus of mandible
and its coronoid process.
• Innervation: mandibular nerve via masseteric
nerve that enters its deep surface.
• Action: It elevates and protrudes the
mandible, closes the jaws and the deep fibres
retrude it.

TEMPORALIS
• Origin: floor of temporal fossa and deep surface
of temporal fascia.
• Insertion: tip and medial surface of coronoid
process and anterior border of ramus of
mandible.
• Innervation: deep temporal branches of
mandibular nerve (CN V3).
• Action: The temporalis muscle elevates the
mandible, closes the jaws; and its posterior fibres
retrude the mandible after protrusion.

LATERAL PTERYGOID
• Origin:
superior head—infratemporal surface and
infratemporal crest of the greater wing of the
sphenoid bone,
inferior head—lateral surface of lateral pterygoid
plate.
• Insertion: neck of mandible, articular disc, and
capsule of temporomandibular joint.
• Innervation: mandibular nerve via lateral
pterygoid nerve from anterior trunk, which enters
it deep surface.

• Acting together, these muscles protrude the
mandible and depress the chin. Acting alone
and alternately, they produce side-toside
movements of the mandible.

MEDIAL PTERYGOID
• Origin: deep head—medial surface of lateral
pterygoid plate and pyramidal process of
palatine bone, superficial head—tuberosity of
maxilla.
• Insertion: medial surface of ramus of
mandible, inferior to mandibular foramen.
• Innervation: mandibular nerve via medial
pterygoid nerve. It helps to elevate the
mandible and closes the jaws.

• Action: Acting together, they help to protrude
the mandible. Acting alone, it protrudes the
side of the jaw. Acting alternately, they
produce a grinding motion.

62
BUCCINATOR MECHANISM
DR.TINET MARY AUGUSTINE.BDS.MDS

EFFECT OF MUSCULAR FORCE

EVOLUTIONARY CHANGES DUE TO
FUNCTIONAL CHANGES
• DIET CHANGE
• SURVIVAL RESPONSE

EVOLUTION OF HUMAN TEETH

66
• A muscular functional component seems to have an important
influence on mandibular growth, both natural and induced by
functional appliance.
• This concept was formulated as “ muscular hypothesis “ to
provide theoretical basis for mode of action of activator.
• According to this hypothesis, myotatic reflex activity of
protractor muscles, especially lateral pterygoid, keep mandible
in forward direction, stimulating the growth of mandible.
Muscular Hypothesis

67
• Any response of the skeletal muscle for the
stimuli is through the contractility.
• It can be :
Isotonic
contraction
Isometric
contraction

68
Isotonic Contraction
•Is a contraction in which the tone or
tension within the muscle remains the
same, but length of the muscle changes.
•The term isotonic literally means same
tension. Since there is a little or no
resistance (load) placed on the muscle
in an isotonic contraction, all of the
energy is used to pull on the thin
filaments and decrease the length of a
fiber’s sarcomere.

69
• Is a contraction in which muscle
length remains the same, but in
which the muscle tension increases.
The term isometric means same
length.
 The isometric contractions can
do work by tightening to resist a
force, but they do not produce
movements.
Isometric Contraction

70
When the overall length
of a muscle increases during
contraction, it is called an
eccentric contraction.
• E.g. As you lower the
book to place it back on the
table, the previously
shortened biceps gradually
lengthens while it continues
to contract.
Muscle shortens and pulls
on another structure, such
as bone, to produce
movement and to reduce
the angle at a joint
• E.g. Picking up a book
involved concentric
contractions of the biceps
brachii muscle in the arm.
CONCENTRIC CONTRACTION ECCENTRIC CONTRACTION

MUSCLE REFLEX

MYOTACTIC REFLEX
• Functional significance :
- Serves as a mechanism for upright posture/ standing
- Postural rest position of mandible DR.TINET MARY AUGUSTINE.BDS.MDS 72

HORMONES

FUNCTIONS

Functions of Growth
Hormone
 G.H. stimulates the growth of skeleton. It has specific
action on the epiphysis, cartilages and promote
chondrgenesis, consequent mineralization causes
linear growth of bones.
 It stimulate growth of viscera e.g. Liver, Kidney,
Thymus and alimentary canal.
 It increase skeletal muscle mass.
75DR.TINET MARY AUGUSTINE.BDS.MDS

Timing of growth hormone release
• Growth hormone is released primarily during
the evening time.
• New bone at the epiphyseal plates occur
during the night time.

• It becomes important to stress to the patient
to wear head gear right from the evening time
rather than waiting for the bed time.
• It is more likely that the tooth movement
occur more faster at this period of time.

GROWTH HORMONE&
SOMATOMEDINS
• Although growth hormone stimulates increased deposition of
proteins, and increased growth in almost all tissues of the body,
its most obvious effect is to increase growth of the skeletal
frame.
• Growth hormone is therefore indicated for the long- term
therapy of children who have growth failure due to inadequate
growth hormone secretion.

 Somatomedin may have arised from degradation of growth
hormone itself.
 A substance called as somatomedin must be atleast to
some extent under the control of GH, be insulin like in its
actions and stimulate cell growth in one or more

• Generally , GH and somatomedins interact in
such a way that growth results.
• However, in cartilage the mode of action is
different
80
GH acts on
the cartilage
cells
cartilage cells alter and now
become responsive to the SMs
SMs acts
growth of cartilages
(hence growth in
height etc ) results

CYBERNETIC THEORY
• Craniofacial growth is an extremely complex process.
• The concept of Cybernetics was put forth by Petrovic
to describe craniofacial growth mechanisms and
method of operation of functional and orthopedic
appliances.
• Cybernetics is based on communication of
information.

Cibernetically organized biologic
features
INPUT
Orthodontic
functional ,
and
orthopaedic
appliances
BLACK BOX
oMaxillary
lengthening and
widening,
o mandibular
lengthening and
widening,
oTeeth movements
OUTPU
T
Correction of
malocclusion
and
intermaxillary
relation

 Any cybernetically organised system operates through
signals that transmit information
 According to this theory the influence of STH-
somatomedin complex on the growth of primary cartilages
has the cybernetic form of a command and the influence
on the growth of secondary cartilages comprises direct
and indirect effects on cell multiplication.
83
INPUT PROCESS OUTPUT

Growth in Length:
growth of
Nasal
Septum
Increased
size
Of Tongue
Labio
narinary
Muscles
Protrusion
of
Upper
Incisors
Protrusion
of
Lower
Incisors
Post-ant shift
of premaxillary
bones
Growth of
Pre
Maxillary
extremity
Growth of
Pre
Maxillary
Suture,
Growth of
Maxillo
Palatine
suture
Release of
STH
Somatomedin
Septo-
Premaxillary
ligament
Biomechanical
Induction
Traction
ThrustThrust
Thrust
Direct Action

Growth in Width
Release
of
STH
Somato
medin
Growth of
Lateral cartilaginous
masses of Ethmoid
Increased size
Of Tongue
Growth of cartilage
B/w greater wings
& body of sphenoid
Outward
growth
Of maxillary
bones
Outward
shift of
Alveolus and
molars
Transverse
Separation
of
premaxillae
Transverse
Seperation of
Horizontal
Maxilla and
Palatine plates
Growth of
mid
Palatine
suture
Outward
Appositiona
l
Bone
growth

• Primary cartilages are subjected to general extrinsic
factors and the effects of STH- somatomedin.
Therefore, orthopedic devices can modify the
direction but not the amount of growth.
• Secondary cartilages are subjected to local extrinsic
(epigenetic) factors and the effects of STH-
somatomedin.
Therefore, orthopedic devices may modify the
direction as well as amount of growth.

• There is no negative feed back of excessive
mandibular growth on growth hormone secretion.
This has been termed as “OPEN LOOP” by Petrovic.
• This is the reason that even though there is
excessive mandibular growth in acromegaly GH
secretion continues in the same excessive manner .

Effects of growth hormone on craniofacial
skeleton
AO 2006;76: 970 -977
• 57 patients with GHD were investigated and divided
into 3 groups: Untreated group, Short term therapy
group and Long term therapy group.
• In the untreated group, the anterior cranial base,
total facial height, maxillary length, mandibular total
length, and ramus height were smaller than the
standard values.

 Long term therapy group had a significantly large
upper facial height (N- ANS) , maxillary length (A’-
Ptm’) and ramus height (Cd- Go)
 Body height at puberty is reported to be correlated
with final body height.
 Therefore, to succeed with GH therapy, we need to
promote growth before puberty so that the body
height is similar to that of a normal child before
puberty.

Cephalometric study of children with
various endocrine diseases
AJO 1971; 59: 362-375
• 106 pediatric patients with various
endocrinopathies
• Generalised growth retardation
Anterior pituitary insufficiency
Idiopathic short stature
Delayed puberty
Hypothyroidism
• Greatest retardation seen in PFH

• Most growth occurs during the evening hours when
growth hormone is being secreted.
• Active eruption of teeth occurs during the same
time period, typically between 8 PM to 1 AM.
• The condylar cartilages and alveolar bones of
growing children exhibit a higher percentage of cells
in the DNA synthesis phase during the night than
during the day.

• To take advantage of this time period, it is suggested
that children wear functional appliances from after the
evening meal until they awake in the morning, which
should be approximately 12 hours per day.
• Waiting until bed time to insert the appliance misses
part of the period of active growth.

TESTOSTERONE
Testosterone increases the total quantity of bone
matrix, and it also causes calcium retention.
When great quantities of testosterone (or any other
androgen) are secreted in the growing child, the rate
of bone growth increases markedly, causing a spurt
in total body height as well.

• However, testosterone also causes the epiphyses of
the long bones to unite with the shafts of the bones
at an early age in life.
• Therefore, despite the rapidity of growth this early
uniting of the epiphyses prevents the person from
growing as tall as he would have grown had
testosterone not been secreted at all.

Corticosteroids Effects on bone
and tooth movement
• Corticosteroids are immunosuppressive and
antiinflammatory agents, widely used to treat
pathological processes in medical and dental
practice, in such a way that patients under
orthodontic treatment may present variations
in normal bone remodeling due to the use of
these drugs.

• Evidence indicates that the main effect of
corticosteroids on bone tissue is direct
inhibition of osteoblastic function and thus the
decrease of total bone formation. Decrease in
bone formation is due to elevated parathyroid
hormone levels caused by inhibition of
intestinal calcium absorption which are
induced by corticosteroids.

Effect of menstrual cycle on tooth
movement
• Relationships between ovarian hormones and
serum markers of bone metabolism
• Since mechanically induced bone modeling
and remodeling are essential for orthodontic
tooth movement, the responses to
orthodontic force may vary depending on the
phase of the menstrual cycle.
DR.TINET MARY
AUGUSTINE.BDS.MDS
97

Effect of menstrual cycle on tooth
movement
• Initial studies (1954)
– cyclic variation in the rate of tooth movement in
relation to the menstrual cycle
– rate increased during the second half of the cycle
– fell before or at menstruation.
• Recent studies
– higher levels of bone-resorptive markers around
menstruation.
DR.TINET MARY
AUGUSTINE.BDS.MDS
98

ADOLESCENCE
• Adolescence is a sexual
phenomenon.
• It can be defined as the
period of life when sexual
maturity is attained .

• It is the transitional period between the juvenile stage
and adult hood during which the secondary sexual
characteristics appear, the adolescent growth spurt
takes place, fertility is attained and profound
physiologic changes occur .
• All these developments are associated with
accompanying urge in secretion of sex hormones.
• This is the period when functional appliances are most
commonly used.

• There is a great deal of individual variation, but
puberty and the adolescent growth spurt occur on
the average nearly 2 years earlier in girls than in
boys.
• But the phenomenon has an important impact on
the timing of orthodontic treatment, which must be
done earlier in girls than in boys to take advantage of
the adolescent growth spurt.

• Because of the considerable individual variation,
early maturing boys will reach puberty ahead of slow
maturing girls
Chronologic age has very little to do with where an
individual stands developmentally
• The stage of development of secondary sexual
characteristics provides a physiologic calendar of
adolescence that correlates with the individual's
physical growth status.

• Girls have a “juvenile acceleration” in jaw growth
that occurs 1- 2 years before the adolescent growth
spurt.
• In boys ,if a juvenile spurt occurs ,it is nearly always
less intense than the growth acceleration at puberty.
• This juvenile acceleration can equal or even exceed
jaw growth which accompanies secondary sexual
maturation.

• Sex hormones produced by the adrenal glands first
appear at age 6 in both the sexes.
• This activation of adrenal component of system is
called as Adrenarche.
• It is likely that juvenile acceleration in growth is
related to intensity of adrenarche and therefore is
more prominent in girls because of greater adrenal
component of their early sexual development.

• This tendency for a clinically useful acceleration in
jaw growth to precede the adolescent spurt,
particularly in girls, is a major reason for careful
assessment of physiologic age in planning
orthodontic treatment.
• The presence of juvenile growth spurt in girls
accentuates this tendency for significant acceleration
of jaw growth in mixed dentition.

• So if most girls are to receive orthodontic treatment
while they are growing rapidly, it must begin during
the mixed dentition rather than after all
succedaneous teeth have erupted.
• However, in slow maturing boys, the dentition can be
relatively complete while a considerable amount of
physical growth remains.

107
Event Factors Stimulating Factors Inhibiting
Bone Formation Gh
Calcitonin
Insulin
Testosterone
Estrogen
Igf- I & Ii
Tgf-beta
Skeletal Growth Factor
Bone Derived Growth Factor
Platelet Derived Growth Factor
Cortisol
Mineralization Calcitonin
Insulin
Vitamin D
Cortisol
Bone Resorption Parathormone
Thyroxine
Cortisol
Pgs
Il- I
Testosterone

ASSESSMENT OF
GROWTH

SKELTAL AGE
SKELTAL AGE
ASSESMENT
CERVICAL
VERTEBRAE
FRONTAL
SINUSHAND WRIST
RADIOGRAPH
MID PALATINE
SUTURE

HANDWRIST RADIOGRAPH
Fishman Method
Greulich and Pyle
Method
Bejork Grave and
Brown Method
Hagg and Taranger
Method
Tanner and
Whitehouse Method

FISHMAN SKELTAL MATURITY
INDICATOR(1982)
• Thumb
• Middle Finger (Proximal, Middle and Distal
Phalanges)
• Little Finger
• Radius

4.OssificationAdductor
Sesamoid
No
1. Width
Proximal
Phalanx III
2. Width Middle
Phalanx III
3. Width Middle
Phalanx V
Yes
8. Fusion Distal
Phalanx III
No
5. Capping Distal
Phalanx III
6. Capping
Middle Phalanx
III
7. Capping Of
middle phalanx
of vth
Yes
9. Fusion
Proximal
Phalanx III
10. Fusion
Middle Phalanx
III
11. Fusion in
radius

CERVICAL VERTEBRAE AS SKELTAL
MATURITY INDICATOR
• Suggested by Lamparski in 1972.

HASSEL AND FARMAN(1995)
STAGE 1 (INITIATION) STAGE 2(ACCELERATION)
(PEAK IN MAND. AFTER 2 YEARS) (MAX.EXPANSION,MAND-WITHIN 1 YEAR)
Brent Hassel and Allan Farman. Skeletal maturation evaluation using cervical vertebrae,
AJODO 1995:107:58-66

STAGE 3(TRANSITION) STAGE 4(DECCELERATION)
(IDEAL FOR JAW ORTHOPEDICS AND VER.CORRECTION) (PEAK)
AJODO 1995:107:58-66

STAGE 5(MATURATION) STAGE 6 (COMPLETION)
AJODO 1995:107:58-66

Modified by Mc Namara,Bacetti,and
Franchi(2005)

STAGES AND APPROXIMATE AGES

CO-RELATION OF HAND WRIST AND
CERVICAL VERTEBRAE MATURATION
STAGES
(Garcia fernandez. The cervical vertebrae as maturational indicators, JCO APRIL
1998) DR.TINET MARY AUGUSTINE.BDS.MDS 119

Reliability of cervical maturation for
assessing mandibular growth
• Billie Jean Rainey et al concluded that the CVM stage
influence the reliability of the CVM method for the
assessment of mandibular growth.
(Reliability of cervical vertibral maturation staging – Billie et al - AJODO July 2016)

Assessment of Optimal Treatment
Timing in DentofacialOrthopedics
• Skeletal effects of rapid maxillary expansion for the correction of
transverse maxillary deficiency are greater at prepubertal stages,
while pubertal or postpubertal use of the rapid maxillary
expander entails more dentoalveolar effects.
(The Cervical Vertebral Maturation (CVM) Method for the Assessment
of Optimal Treatment Timing in
DentofacialOrthopedics,TizianoBaccetti, Lorenzo Franchi, and James
A. McNamara, Jr.)

FRONTAL SINUS
• Ruf and Pancherz (1996)
• Sabine Ruf, Hans Pancherz. Frontal Sinus Development as an indicator
for somatic maturity at puberty?, AJODO 1996;110:476-82

• Frontal sinus growth velocity at puberty is closely
related to body height growth velocity.
• Frontal sinus growth shows a well-defined pubertal
peak (Sp) which on the average occurs 1.4 yr after
body ht. peak
• 1year=1.3mm:2year=1.2mm:peak in 15.1year

MID PALATINE SUTURE
• Amount of approximation of the midpalatal suture
compared with stages of ossification of the hand-wrist
according to the Fishman’s system
• Bernal Revalo, Fishman. Maturational evaluation of ossification of the mid palatal suture,
AJO MARCH 1994

• Increase in sutural approximation as SMI stages progressed.
• SMI 1&2- decreased sutural approx.
• After SMI 9- significant increase in the sutural approx.
• No significant difference b/n sexes.
• Conclusion-ideal time is between SMI-SM4,Less orthopedic
force required

Stages
• Stage A- straight high density suture line
with no or little interdigitation
• Stage B-scalloped appearance
• Stage C-two parallel scalloped high density
lines seperated in some areas by
small low density spaces
• Stage D-fusion completed in palatine bone with no
evidence of a suture
• Stage E-complete anterior fusion in the maxilla
(Angelina et al, Diagnostic performance of skeltal maturity for assesment of mid
palatal suture maturation(AJODO Dec 2015)

Using CVM method
Prepubertal
• CS1 and CS2-midpalatal maturational stages A and
B.
• CS3 in CVM -stage C in maturation of the
midpalatal suture.
• CS5 in CVM -stages D and E in midpalatal suture
• CS4 and CS5, -assessment of the mid palatal
suture with CBCT should be undertaken, since
13.5% of patients at CS5 presumably could be
treated with conventional RME.
(Diagnostic performance of skeltal maturity for assesment of mid palatal suture
maturation(AJODO dec 2015)DR.TINET MARY AUGUSTINE.BDS.MDS 128

PRINCIPLES OF
FUNCTIONAL
THERAPY

130
"Form-function" Principal
- Emphasizes the role of Biological Purpose, Behavior, And The Environment, i.e.
"Function," in the production of form.
It is also useful in accounting for the results of grossly abnormal function, such as
The Effects Of Muscle Paralysis On Skeletal Growth And Form
The Appearance Of Muscle Attachments On Bones
The Effects Of Digit Sucking On Incisor Inclination
Growth Modification : From Molecules to Mandibles
David S CarlsonDR.TINET MARY AUGUSTINE.BDS.MDS

131
• "Intrinsic" often is used to refer to Genetically Predetermined Factors Within The
Differentiated Cells and their Local Effects On Associated Tissues.
• “Extrinsic” Refers To Systemic Influences That Are Remote From The Cells And Tissue Being
Considered, Such As Hormones, As Well As Influences From The External Environment And
Behavior, Such As Muscle Activity/Function, Mechanical Force.
Intrinsic Vs. Extrinsic Factors
Growth Modification : From Molecules to Mandibles
David S Carlson

132
 1930s : Remodeling Theory of Craniofacial Growth (Brash)
 Beginnings of Developmental Genetics
 1940s : The Sutural Theory (Weinmann and Sicher)
 1950s : The Nasal Septum Theory (Scott)
 Paradigm Shift in Craniofacial Biology (1960-1980)
 Genomic paradigm to functional paradigm
 1960s : Functional Matrix Hypothesis (Moss)
 1970s : Servosystem Theory of Craniofacial Growth (Petrovic)
l
Seminar in ortho 2005

133
• 2 treatment principles can be differentiated :
– Force application
– Force elimination
Principles Of Functional Appliance
Therapy
In force application :- compressive stress and strain act on
the structures involved, resulting in a primary alteration in
form with a secondary adaptation in function.
In force elimination :- abnormal and restrictive
environmental influences eliminated, allowing optimal
development.
( lip bumper & Frankel buccal shields employ force
elimination )

135
• Claims that the origin, growth (i.e., changes in size, shape, and
location), and maintenance of all skeletal tissues and organs (i.e.,
skeletal units) are always secondary, compensatory,
mechanically obligatory responses to temporally and
operationally prior events or processes occurring in specifically
related non skeletal tissues, organs, or functioning spaces (i.e., in
functional matrices, either capsular or periosteal).
Functional Matrix Hypothesis

136
Functional cranial component
Skeletal unit
Functional matrices
Macro-
skeletal unit
Micro-
Skeletal unit
Periosteal
matrices
Capsular
matrices
• Condyle
• Coronoid
• Ramus
• Body
• Zygoma
• palate
• Mandible
• Maxilla
• calvarium
• Influences the
bone directly &
actively
• Bone dep &
resorp
• Affects size &
shape of micro
sk units
• Eg: BV,nreves,
muscles
• Acts indirectly &
passively
• Produces
translation
• Which causes
gth of whole
bone
• Eg: neuro cranial
capsule
• Oro facial
capsule

137
• Melvin L Moss ( 1962, 1969, 1997 ), emphasize that length of
mandible depends upon the size of oral capsule.
• Any increase in size of oral capsule will result in secondary
bone deposition in TMJ region to keep unchanged
relationship between temporal bone & mandible. ( ‘carry
away’ phenomenon ).
• Prof. Rolf Frankel, from east Germany used this hypothesis in
his functional regulator appliance.
• Both design of appliance and its use are based on functional
matrix hypothesis.

138
• Enlow, Moffet, Graber and others confirm the Frankel’s
findings that periosteal pull, which is a type of viscoelastic
stretch has the potential to stimulate bone growth.
• In short, FR uses all the logical means for growth modification
namely :
– Active muscular involvement ( proprioception )
– Viscoelastic hypothesis ( periosteal stretch by lip pads/
buccal shields)
– Screening deleterious forces ( lip pads/ buccal shields)
But poor patient cooperation associated with FR favored development of fixed bite jumping
appliance.

139
• After extensive study, Johnston (1970s) concluded that the LPM
hyperactivity hypothesis is incorrect.
• His statement shattered notions of how functional appliances
produces skeletal or condylar modifications which was
established 30 years earlier by Andersen & Haupl.
Viscoelastic Hypothesis

140
• Support for this theory of ‘ viscoelastic force’ came from work of Herren, Havold, &
Woodside (1973 ).
• They do not accept the theory that myotatic reflex activity with isometric muscle
contractions induces skeletal adaptation.
• It was claimed that viscoelastic properties of muscle & the stretching of soft tissues are
decisive for action of functional appliances.
• During each application of force, secondary forces arise in the tissues, introducing a
bioelastic process for induction of bone.
According to proponents of viscoelastic theory, its not the LPM
but the retrodiscal tissue which is responsible for bony
deposition of glenoid fossa or increase in length of condylar
cartilage.

141
• Hence, any appliance which keeps the mandible
forward ( irrespective of how, actively or passively ) will
induce bone formation & subsequent increase in
mandibular length.
• This hypothesis formed the basis for mode of action of
most of the existing bite jumping appliances including
fixed appliances.

142
The Servosystemis a part of the Cybernetic Theory which
describes The Craniofacial Growth Mechanism Systematically And Also Explains
The Functioning Of The Various Appliance System.
Servosystem

143
Cybernetically Organized Biologic Features
Orthodontic
Functional And
Orthopedic
Appliances
Genetically determined and
cybernetically organized
biologic features of
phenomenon characterizing.
Inducing, Or Controlling
Sponteneous And Appliace-
modulated Growth.
• Maxillary lengthening and
widening
• Mandible lengthening and
widening
• Teeth movements
Correction Of
Malocclusion And
Intermaxillary
Relation
INPUT BLACK BOX OUTPUT

144
The Face as a Servosystem
Release of
Hormones (Command)
Position of
Maxillary
Dental arch
(Ref Input)
Occlusion
(Comparator)
Periodontium
Teeth
Musculature
Joint
Mastication
(Performance)
Deviation Signal
Brain
(sensory engram)
(controller)
Motor Cortex (Actuator)
Output
Actuating
signal
LPM & RDP
(Coupling
system)
Growth At
Condyle
(Controlled
System)
Cartilage, Bone, Muscles
Ref Input element

145
Role of Lateral Pterygoid and RDP on Condylar growth
• Lateral pterygoid muscle and RDP are involved in 2 important aspect ( Stutzman
& Petrovic 1990 ).
 Blood Circulation
LPM acts as a direct and RDP as a indirect blood supply to the Condyle.
an Increase Blood flow and Increases Lymph flow
Increase in Open Loop Nutritive and Growth Stimulating factors like STH-
somatomedin, Testosteron, Insulin, PG, Mitogenic peptides
Decrease in locally produced cell catabolites and Negative feedback factors like
cAMP, Restraining signals and Somatostatin like substances
Supplementary Growth Of Condylar CartilageDR.TINET MARY AUGUSTINE.BDS.MDS

The Biomechanical Effect:Electric charge due to pressure
PIEZOELECTRIC Mechanism

147
• Charlier et al 1968, 1969, Petrovic et al, 1975: distribution of dividing cells in the
sagittal section of condylar cartilage of juvenile rats.
• Histologic and radiographic study.
• Results : treatment with both postural hyper propulsor and growth hormone, STH,
produced increase in growth rate of condylar cartilage as compared to controls.
• Location of increase of dividing cells :
– More posterior in hyperpropulsor
– More anterior in STH
CHARLES ERT AL 1968,PETROVIC ET AL
1975

148
Proposed 4lines of evidence suggesting that the LPM plays a role in the physiologic control
of the condylar cartilage growth rate:
1. After surgical resection of the LPM in the growing rat, untreated or treated with a
functional appliance, a relative decrease in the growth of the condylar cartilage was
observed.
2. Electromyographic record of the LPM in the monkey treated with a functional
appliance shows increased electrical activity.
AJODO 1990

149
3. The LPM was directly stimulated by means of intermittent electric shocks ( frequency,
5times /sec; duration, 10ms; potential, 0.55v ).
This microelectronic stimulation of the LPM produced an increased rate of condylar
cartilage growth.
4. After treatment with the postural hyperrpropulsor, there is a significant increase in
the proportion of fast non-fatigable fibres in the young rat’s LPM
These authors suggested that increased activity of the LPM will
result tension in the posterior part of condylar capsule because of
its attachment to the articular disc.

150
• McNamara & Petrovic noticed one peculiar phenomenon where patient
experienced pain when mandible was retracted.
PTERYGOID RESPONSE(petrovic 1980)
This was due to altered muscular balance resulting in ‘tension zone’ distal to
condyle.(harvold and wood side)Two possible means of filling the so called tension zones are :
• Growth of condylar cartilage
• Remodeling of glenoid fossa

151
• Prototypes of fixed appliances are Twin Block, Herbst And Jasper
Jumper.
• Recently, ‘ viscoelastic’ hypothesis revisited to ensure survival of
these fixed bite jumping appliances because their role in growth
enhancement can not be explained by muscle activation.
• Based on basic viscoelastic hypothesis, Voudouris and Kuftinec
(2000) advanced GROWTH RELATIVITY HYPOTHESIS to explain
mode of action of these fixed functional appliance.
Improved clinical use of twin block & Herbst as a result of radiating viscoelastic
tissue forces on the condyle & fossa in the treatment & long term retention :
Growth relativity; Voudouris and Kuftinec
AJO 2000;117: 247- 66.DR.TINET MARY AUGUSTINE.BDS.MDS

152
• Refers to growth that is relative to the displaced condyles from actively
relocating fossae.
• According to authors, there is no role of muscles for growth modification.
• Basis for this non muscular theory came from following two observations:
– Attachments of the LPM to the condylar head or articular disc may be
expected to cause condylar growth, but anatomic research has not
found evidence that significant attachments actually exist.
Growth Relativity Hypothesis

153
3D illustration of unadvanced human TMJ shows minimal attachment of superior
head of the LPM to articular disk & retrodiscal tissue complexDR.TINET MARY AUGUSTINE.BDS.MDS

154
• Permanently implanted longitudinal muscle
monitoring techniques have found that the
condylar growth is actually related to decreased
postural and functional LPM activity.
Effect Of Functional Appliances On Jaw Muscle Activity.
Sessle, Woodside, Gurza, Powell, Voudoris and Metaxas
AJO 1990; sept, 222-230.DR.TINET MARY AUGUSTINE.BDS.MDS

155
• Three growth stimuli in growth relativity
Displacement + viscoelasticity + referred force
1) The concept that viscoelastic tissue forces can effect growth of the condyle
suggests that modification first occurs as a result of the action of anterior
orthopedic displacement. (Displacement).
2) The condyle is affected by the posterior viscoelastic tissues anchored
between the glenoid fossa and the condyle, inserting directly into the condylar
fibrocartilage. ( viscoelasticity)
3) New bone formation – some distance from the actual retrodiscal
attachments in the fossa by the transduction of forces over the fibrocartilage
cap of the condylar head.

156
3D prospective illustrates the growth relativity hypothesis in the orthopedically
advanced condyle. The posterior, anterior & lateral attachments of the
retrodiscal- articular disc complex are shown. This guides the condyle upward
& backward. The retrodiscal- articular disk complex are pulled in the opposite
direction of the arrows for glenoid fossa modification.DR.TINET MARY AUGUSTINE.BDS.MDS

157
Growth relativity hypothesis for condylar & glenoid fossa growth with
continuous orthopedic displacement.
3 factors influence growth modification : A) displacement B)viscoelastic
tissue pull (arrows) C) transduction with fibrocartilage.
Viscoelastic tissues include :
B1 – superior & inferior bands of retrodiscal fibres
B2 – fibrous capsule (fine white lines )
B3 – synovial fluid perfusion in a posterior direction
The pull of the retrodiscal fibres, capsule & the flow of the synovial fluids
on the condyle relative to glenoid fossa are in a posterosuperior direction.
The forces are translated to the condyle with the articular disks ( blue
region) posterior, anterior, lateral & medial attachments.

158
• Condyle acts as a light bulb on a
dimmer switch.
• When condylar growth is
continuously advanced, it lights up
like a bulb.
• When condyle is released from the
anterior displacement, the reactivated
muscle activity dims the light bulb &
returns it close to normal growth
activity.
In the boxed area, the upper open coil
shows the potential of the anterior
digastric muscle & other peri mandibular
connective tissues to reactivate & return
the condyle back into the fossa once the
advancement is released.
The lower coil in the box represents the
shortened inferior LPM.
Condylar Light Bulb Analogy

159
• Hence this growth relativity theory totally discard any role of muscles in
growth modification of mandible.
• Authors claim that there is decreased muscle activity, even not normal.
• After considering all these hypothesis/ theories ( muscular, viscoelastic,
functional, growth relativity ) the obvious question arise –
Which one is best to explain mandibular growth??

160
• Enlow & Hans (1996,2001 ) presented an excellent
overall perspective suggesting that mandibular growth
is a composite of regional forces and functional
agents of growth control that interact in response to
specific extracondylar activating signals.
• In other words, mandible grow under the influence of
all these variables and therefore, its growth cannot be
attributed to any one particular variable.

161
• Functional appliances obtain the average 6-7mm of correction needed for
the resolution of class II malocclusion through a combination of orthopedic
(30% to 40%) & dentoalveolar (60% to 70%) effects.
Where the functional appliances stand
today !!!
Frankel aplliance therapy. Creekmore, Radney & Righellis
AJO 1983; feb 89-108.

162
• The originators of functional appliance had their own philosophies to
explain how their functional appliances achieved the correction of class II
malocclusion.
• There are 6 possible structural mechanisms through which functional
appliances obtain a class II correction.
• { Forsberg & Odenrick( 1981), Cohen ( 1983 ), Frankel ( 1984 ) }.

163
• These include :
1. Retardation or redirection of the mesial and vertical growth of maxilla.
2. Encouragement of mandibular growth ( including condylar growth) as a
secondary response to its anterior dislocation from the articular fossa.
3. Retardation of the mesial and vertical maxillary dentoalveolar growth.
4. Mesial and vertical mandibular dentoalveolar growth.
5. Overjet correction through a combined maxillary and mandibular
orthopedic effect with maxillary incisor lingual tipping and mandibular
incisor labial tipping.
6. Remodelling changes in the TMJ.

164
• McNamara, Petrovic, Eirew, Joho think that functional appliance therapy results
primarily in orthopedic changes, particularly increase in mandibular length &
limited tooth movement.
• Gianelly, Bernstein, Gottfried, Schmuth, Graber & Newmann believe that the
changes are primarily dentoalveolar.
• Baumrind, Harvold, Vargervik, Hiniker Ramfjord believe that the changes are
primarily dentoalveolar with some maxillary orthopedic effects.

165
Growth Hypothesis
His 1874- Physiology of the plasticity of bone (biologic
structures may be altered)
Moss 1960,1962,1997- Regional and local factors play a
role in cranio-facial morphogenesis- Functional Matrix
Theory
Voudouris 2000- Factors of displacement, viscoelasticity,
transduction- Growth Relativity
Mao &Nah 2004- Growth and development is the net
result of environmental modulation of genetic
inheritance

166
Role Of Muscles
 Study by McNamara with primates 1975
Masticatory muscles and appropriate orthopedic
appliances can modify the rate and amount of condylar
growth
LPM activity may induce condylar deposition
 Study by Voudouris- AJO March 2000
Growth Relativity Hypothesis- Three factors of
displacement, several direct viscoelastic connections,
and transduction of forcesDR.TINET MARY AUGUSTINE.BDS.MDS

167
Role Of Glenoid Fossa
 Voudauris 1988
Fossa is altered and brought forward by mandibular
advancement
 Ruf et al- AJO 1999
The increase in mandibular prognathism to be a result of
condylar and glenoid fossa remodeling
 Rabie et al –AJO 2002
Forward mandibular positioning causes significant
increases in vascularization and new bone formation in
the glenoid fossa DR.TINET MARY AUGUSTINE.BDS.MDS

168
Factors influencing mandibular growth
Cranium positioning
Condylar cartilage
Muscles (LPM ?)
TMJ disc
STH (Somatomedin)

THANK YOU

References
1. Graber’s text book of orthodontics,5th edition
2. Text of craniofacial growth, Sridhar Premkumar
3. Lill DJ et al. Importance of pumice prophylaxis for bonding with self
etch primer. Am J Orthod Dentofacial Orthop. 2008:133;423-6.
4. Lindauer et al. Effect of pumice prophylaxis on the bond strength of
orthodontic brackets. Am J Orthod Dentofacial Orthop 1997;111:599-
605.
5. Lehman et al. Loss of surface enamel after acid etching procedures and
its relation to fluoride content. Am J Orthod. 1981 Jul;80(1):73-82.
6. Ching et al. Bond strength with APF applied after acid etching. Am J
Orthod Dent Facial Orthop. 1988;114:510–13.
7. W.P Rock et al, Comparison of three light curing units. Journal of
Orthodontics 2004:31;243-247.
8. Ramkumar Gandhi. Shear bond strength of stainless steel brackets with
moisture insensitive brackets; AJODO 2001: 119: 251-255.
9. Crystal growth theory: Jon Arton in AJO-DO Study by Leonardo
Foresti et al Angle.

Myofunctional appliances -BASIC PRINCIPLES

More Related Content

What's hot

Similar to Myofunctional appliances -BASIC PRINCIPLES

More from Dr.Tinet Mary Augustine

Recently uploaded

Myofunctional appliances -BASIC PRINCIPLES