Functnal analysis

Cephalometric Evaluation of Tongue Posture
The clinical examination of the tongue and associated structures
enables only a subjective evaluation of its status.
Further complementary, exact, and reproducible study method are
available, and are of special interest if important decisions are to be
made, such as whether to perform a glossectomy.
The cephalometric analysis from a lateral roentgenogram is
exacting, reproducible, and simple and can be employed in private
practice.
The assessment is made on lateral cephalograms taken in postural
rest and habitual occlusion.
Exposure is adjusted to visualize the soft tissue. The size of the
tongue can be measured on the occlusion film.
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A successful analysis depends on the proper utilization of correct
measurable data.
A baseline or reference line for measurement should satisfy the
following criteria.
1. The greatest possible area of the tongue should lie above the
reference line, since the two dimensional radiographs do not show the
anatomical borders of the tongue and the transverse dimensions.
2. The baseline should be independent of variations in skeletal
structures
3. Its relation to the tongue should not change with changes in
position of the mandible.
4. Base line should remain constant in relation to changes in tongue
position.

5. It should relate to the anatomical and functional properties of
the tongue.
6. The measurement should be an easy one to make and to
replicate.

1 = the incisal margin of the lower incisors,
V = the most caudal point on the shadow of the soft palate or its
projections onto the reference line,
M = the tip of the distobuccal cusp of the lower first molar.
1 and M are connected by a straight line, which is extended to V to
form the reference line.
It has the following advantages.
1. A relatively large part of the tongue is seen on the cephalogram
normally lies superior to the line.
2. The line does not depend on skeletal relationships.
3. Changes in tongue position do not affect the reference line

After constructing the line, it is bisected between I and V.
This point is called O and a perpendicular is constructed from
it to the palatal contour. A transparent template has been
developed to make the necessary measurements. The baselines
of the template coincides with the constructed reference line,
whereas the vertical line intersects the reference line at O.
from O, at which point three lines now meet, our more lines
are constructed as shown by the illustration of the template.
These seven lines form six angles of 30 degrees each. The
lines can be marked in millimeters. Placing the template over
the constructed lines permits reading the exact measurements.

Assessment of tongue size from the
occlusion cephalogram requires measuring the
distance between the superior tongue surface and
the roof of the mouth. This is done along the
seven constructed lines. The measurements give
the relative size of the tongue, that is, the size in
relationship to the oral cavity. Only when the
entire oral cavity is filled can a diagnosis of
macroglossia be made. This, the course, must be
supported by clinical evidence.

The results of the measurements made from the tongue
template may be expressed by graphs. The palatal vault may
be represented by a horizontal line, and the seven single
measurements may be shown by a curve. The distances
between the references line and the seven points on the
constructed curve graphs the relationship of the superior
surface of the tongue with the palatal vault and soft palate to
the tip of the uvula.

The posture of the tongue may be similarly evaluated by measurements
taken from the postural rest lateral cephalogram.
In order to objectively assess the posture and mobility of the tongue,
the differences between the rest and occlusal positions can be calculated.
The occlusal position is taken as zero, with changes in rest position
given as positive or negative figures, that is, positive if the tongue is
higher in the rest position and negative if the tongue is lower
Changes in tongue position are predominantly reflected by the position
of the tip of the tongue.
The position of the other parts of the tongue also are subject to change,
though not relative to the mandible but in conjunction with it.
The changes in tongue tip position relate closely to the different types of
malocclusion.

In class II, the tip of the tongue is more retruded in the rest position, and
in Class III, it lies further forward in the rest position.
It may be assumed that changes in the position of the tongue tip relative
to tendencies in mandibular malformation.

Tongue Dysfunction.
The most common tongue dysfunctions are those involving
selective outer pressure – pressing and tongue biting. Tongue
thrusting can be anterior, posterior, or combined. The consequences
of the localization of aberrant pressures seen are dependent on the
area of applied pressure.
1. An anterior open bite is caused by anterior tongue thrust (and
posture)
2. A lateral open bite or deep over bite is the result of lateral
tongue thrust or postural spread, which causes infra occlusion of the
posterior teeth.
3. An edge to edge incisal relationship and cuspal relationship of
the teeth in the buccal segments may mean a combined thrust.
Anterior and posterior open bite can occur from what a complex
tongue thrust.

The recognition of areas of excessive tongue pressure is important
not only to determine the etiology of the associated malocclusion but
also to provide information for fabrication of the screening
appliance.
As pointed out earlier, depending on the dentoalveolar and skeletal
relationships, abnormal tongue function and posture can be a primary
etiological factor in malocclusion. These abnormal postures and
functions include anteriorly relocated flat tongues and 20
adaptive
and compensatory functions and positions resulting from skeletal
dysplasia.
In either case, the tongue dysfunction provides the anterior seal of
the oral cavity.
The dentoalveolar anterior and posterior open bite problems are
usually attributable to abnormal tongue posture and function and
usually respond successfully to functional appliance intervention in
mixed dentition.

This is also true for cases of deep over bite, in which lateral tongue
spread during function and posture has resulted in infra occlusion of
the posterior teeth.
The space is maintained by invagination of the peripheral portions
of the tongue into the inter occlusal space during postural rest of the
mandible.
In such cases, there is a large freeway space, and the deep over bite
is functional in nature.
A second type of overbite is caused by supra-occlusion of the
incisors.
In this instance, there is a small freeway space. This type of
problem is called a functional pseudo overbite.
Functional appliance intervention in these cases, particularly when
there are developmental disturbances, is not indicated.

Fixed appliances and orthopedic guidance are more likely to correct
the problem.
In skeletal open bite problems, there is a genetically determined
vertical growth pattern, which is often associated with marked
antegonial notching.
This type of case does not offer a favorable prognosis for orthodontic
therapy.
The inclination of the maxillary base should also be considered in
the evaluation of open bite problems.
An upward and forward inclination enhances the open bite
relationship, whereas a maxillary base can be influenced by both
functional factors, both good and bad habits.
.

The consequence of tongue posture and function abnormalities in the
dentoalveolar region also depends on the skeletal pattern.
In a horizontal growth pattern, the forward tongue thrust or posture
can result in a bimaxillary protrusion
With the tongue pressing against the lingual surfaces of both upper
and lower incisors simultaneously , there is often spacing in the
incisor segments.

In a vertical growth pattern, the tongue thrust can open the bite, and the
lower incisors may be tipped lingually.
During the abnormal functional and postural forward positioning, the
tip of the tongue lies between the dental arches and is in contact with
the lower lip, which the patient constantly sucks. Thus, the incisors are
tipped lingually.

Palatographic examination of the tongue
A complementary evaluation of tongue function is possible
using a palatographic examination.
This method enables the observation of tongue function during
swallowing and speaking and also allows the evaluation of the
influence of various functional orthodontic appliances on the tongue.
Originally, palatographic procedures were used only for speech
disorders.
There is a direct and indirect method.
In the direct method first described by Oakely Coles in 1872, gum
Arabic and flour were mixed and painted on the tongue. After going
through the selected functional exercises, the contacts on the palate
and teeth were transferred onto the cast of the upper jaw with redwww.indiandentalacademy.com

The indirect palatographic technique was first used by Kingsley.
He prepared an upper plate of black India rubber and covered the
tongue with a mixture of chalk and alcohol.
The contacts seen on the palatal rubber plate were then transferred
onto the cast as already described.
In the current direct method, the superior surface of the
tongue is covered with a precise impression material, for example,
Imprex.
A thin even layer is applied on the tongue with a spatula.
After functional exercises, a Polaroid print is made of the palatal
region, with the help of a surface mirror.
The evaluation of the palatogram is possible by direct
measurements.

TONGUE AND FINGER SUCKING EFFECTS
One specific kind of malocclusion, which is also a consequences of
abnormal function, requires a combined treatment (an active
mechanical appliances as well as a functional appliance in the mixed
dentition).
Finger sucking can cause an open bite, with simultaneously
narrowing of the maxillary arch.
The adaptive tongue function aggravates and prolongs the
malocclusion.
With bilateral narrowing the patient often compensates with a
lateral shift to one side or the other to gain maximal chewing surface
contact.
This functional type of cross bite, or convenience cross bite is not
skeletal, but adaptive, in the initial stages.www.indiandentalacademy.com

Before beginning functional appliance therapy, it is advisable to
expand the maxillary arch with a split palate, jackscrew type of
active plate.
Sometimes, a small wire crib can be incorporated to block the
tongue in the cross bite area, or at least set up an exteroceptive
engram that initiates tongue retraction.
In some severe dysfunction cases, treatment may begin with the oral
screen, with the active plate being used later.
This is especially the case in the deciduous dentition.
In a skeletal open bite, which gets progressively worse because of a
severe vertical growth pattern, successful causal therapy is not
possible.

Since the tongue dysfunction in these cases is secondary to the
primary morphogenetic basis, therapeutic demands are more
rigorous. Fixed appliances, often with tooth sacrifice, offer a more
effective corrective approach.
In extreme cases, orthognathic surgery is the only viable alternative
after completion of growth.
In the early mixed dentition, however, a partial improvement may
be achieved by elimination of some of the dysfunction, but this does
not materially alter the growth pattern, which will require other
therapeutic methods later.
Yet a vertical growth, pattern can be partly influenced by strong
orthopedic forces or a specially designed, activator.

Fixed orthopedics with a heavy vertical pull can alter the direction of
mandibular growth while restricting buccal segment eruption, whereas
the activator has the potential of affecting the inclination of the maxillary
base.
It is stressed again that an analysis of the growth pattern is needed in
addition to the functional study to determine the therapeutic approach
that is most likely to be successful.

Examination of the lips.
As part of the functional continuum, the lips must be examined
as carefully as the tongue.
The external balancing muscle factors are as important as those
working from inside.
The configuration of the lips should be studied in the relaxed position
to assess the competency.
If the lips are trained, any patient can achieve a lip seal, at least with
conscious effort.
HOWEVER, WHAT IS THE LIP RELATIONSHIP MOST OF
THE TIME?

1. If there is only a slight contact or a very small gap between the
upper and lower lips they are said to be competent.

2 If there is a wide gap, or if the lips (primarily the upper lip) are
too short, they can be considered incompetent. Improvement with
orthodontic treatment and exercise is possible only in the early stages.

3 If the lips seem normally developed, but the upper incisors are
labially tipped making closure difficult, Ballard(1965) and
Tulley(1956) called this potential lip incompetency.
The incisal margins interpose between the lips, resting on the lower
lip and preventing the normal lips seal.The lower lip trap then
enhances the already excessive overjet, tipping the incisors further
forward into a more dangerous zone in which any trauma may result
in breakage.
Hypermobility is even possible in the incisors area with the lower lip
pushing the upper incisors labially while often retroclining and
crowding the lower incisors. Early treatment of these problems is an
important preventive measure.

4. If the lower lip is hypertrophic, everted, redundant, and has
an excessive amount of tissue, little can be done to improve the
situation with orthodontic therapy.

Various methods for evaluating the lip profile.
Photographs and lateral cephalograms can be used effectively
The Schwarz Analysis (1961)
Martin Schwarz devised an analysis on a lateral cephalogram
that is quite useful. Three reference lines are constructed for this
method.
1. The H line, which corresponds to the Frankfort Horizontal
2. The PN line, which is perpendicular to the H line (Frankfort
Horizontal) at soft tissue Na.
3. The PO line, which is a perpendicular from orbitale to the H line.

Between the two constructed
perpendicular lines is what Schwarz
terms the GPF or gnathic profile field.
In normal proportions, the upper lip
touches the *PO line, whereas the lower
lip lies one third the width of the GPF
posterior to it.
The oblique tangential line T is
constructed by joining sub nasale (Sn), at
the junction of the upper lip and nose, to
soft tissue Pog, the most anterior point
on the profile curvature of the
symphysis. In the ideal case, the T line
bisects the vermilion border of the upper
lip and touches the anterior vermilion
curvature of the lower lip.

The Rickets lip Analysis
The reference line used by Ricketts is similar to the
Schwarz T line but is drawn from the tip of the nose to soft tissue
Pog. In a normal relationship, the upper lip is 2 mm to 3mm.
behind this line, and the lower lip is 1 mm to 2mm behind it.

The Steiner lip Analysis
The upper reference point for the Steiner analysis is at the
center of the S-shaped curve between the tip of the nose and Sn. Soft
tissue Pog is the lower terminus. If the lips lie behind the reference
line, they are too flat, and lips lying in front this line are too
prominent.

The Holdaway lip analysis
Holdaway describes a H-line (Harmony Line) which is a
tangent of the chin point and upper lip
The H – line angle : is the angle formed between the H – line and
soft tissue N’ – Pog’

Holdaway defines the ideal profile as follows :
1. The ANB angle should be 2 degrees, and the H angle should be 7
degree to 8 degrees.
2. The lower lip should touch the soft tissue line that connects Pog
and the upper lip and extends to Sn.
3. The relative proportions of the nose and upper lip should be
balanced (the soft tissue line bisects the Sn s-shaped curve).
4. The tip of the nose should be 9 mm anterior to the soft tissue line
(normal at age 13 years).
5. There should be no lip tension on closure.www.indiandentalacademy.com

Dysfunctions of the lips
The most common lip muscle abnormalities are sucking or
biting of the lower lip.
This has also been called a mentalis habit because of the crinkling,
“Golf ball” appearance of the symphyseal tissue with excessive
mentalis muscle activity.
In this type of dysfunction, there is usually contact between the
tongue and the lower lip, which can be observed during swallowing.
This combined muscle abnormality can result is not only the opening
of the bite anteriorly but also the lingual tipping of the lower incisors
with crowding, together with the labial malposition of the upper
incisors. www.indiandentalacademy.com

The pernicious “Lip trap” thus works against the integrity of both
the upper and lower dentitions.
There can actually be a retraction or dehiscence of the labial
gingival tissue overlying the lower incisors.
Lip biting is a habit frequently seen in school children, similar to
nailbiting or pencil biting.
All are a stress and strain relief syndrome. The tongue function can
be normal in these cases, with the hyperkinetic behavioral activity
and abnormal lip habit the main factors.
Of course, an inherent morphogenetic pattern type of Class II
malocclusion can provide the over jet that requires lip
compensations, which, in turn, exacerbate the original overjet.

As with tongue habits, lip sucking can be either a primary or secondary
factor, as mentioned earlier.
The symptoms of a primary causative nature are over jet with labial
tipping of upper incisors and lingual tipping of lower incisors with only
a slight skeletal sagittal discrepancy.
The lip habit enhances the original slight to moderate over jet. In the
case of a secondary role, the original over jet is due to a significant
sagittal discrepancy, usually with mandibular underdevelopment.
The inclination of the incisors can be normal.
The lower lip cushions in the gap between the upper and lower incisors
primarily as an adaptation to the morphological mal-relations. Lip
activity may not be as intensive but more adaptive.
As with tongue problems functional therapy is successful only in cases
of primary dysfunction. In the case of a secondary role for the lip,
functional therapy is subservient to other orthopedic and orthodontic (or
surgical) methods.

RESPIRATION:
The mode of respiration is of interest for several reasons.
I Mouth-breathing and disturbed nasal breathing can be considered
etiological factors or at least predisposing causes for some malocclusion
symptoms.
In 1968, Ricketts described the respiratory obstruction syndrome,
which had the following symptoms; a visceral type of swallowing, a
predisposition to open bite, a unilateral or bilateral cross bite, and a
slight deflection of the head.
Graber in his examinations, observed in patients with disturbed nasal
respiration - Class II, Division I malocclusion, narrowness of the upper
arch, crowding of the upper and lower arches, vertical growth pattern.

II It is not possible to carry out treatment with some functional
appliances if the patient has disturbed nasal breathing.
If the tonsils and adenoids are enlarged, with a compensatory anterior
tongue posture, the patient cannot tolerate a bulky acrylic appliance in
the oral cavity.
There are other appliances that can be used in cases of habitual mouth
breathing. Eg: Clark’s Twin Block, Hamilton Expansion Activator

III. In mouth breathing patients, the lip seal is usually inadequate.
The tongue usually has a low posture and disturbed function.
If this condition persists after treatment is finished, the result is likely to
be unstable, with relapse as a consequence.
If at all possible, it is advantageous to establish normal nasal respiration
prior to orthodontic therapy.
Unfortunately, it is not possible to do this during the growth period in a
patient with allergies or a deviated nasal septum.

The assessment of disturbed nasal function is not always easy.
The case history data can give some idea of the frequency of ear, nose,
and throat disease and the mode of sleeping, as well as habits, allergies
and so forth.
The clinical examination should determine whether the lips are
competent or not.
Lip incompetency does not necessarily mean mouth breathing, but it
suggests that this might be the case.
Further clinical examination with a mirror or cotton swab is possible but
is not really reliable.
It can be helpful to have the patient hold a sheet of cardboard between
the lips, or some water in the mouth, to see whether it is possible to
breathe through the nose without difficulty.

The presence and size of the adenoids and tonsils can also be estimated
on the lateral head film.
This indicates whether the nasopharyngeal passage in free or partially or
totally obstructed.
The work of Moyers, Linder-Aronson(1992), Woodside and
Lowe(1995) in this field shows the potential effect of epipharyngeal
lymphoid tissue blockage, with resultant tongue posture compensation
and mouth breathing, so this part of the examination is important.
There are various ways of assessing the size of adenoids and tonsils. An
arbitrary scale of small, medium, or large can be used, both from clinical
examination and from the lateral cephalogram.
It should be remembered that there is spontaneous regression of
epipharyngeal lymphoid tissue with development. At 10 years of age,
180 per cent of the lymphoid tissue is present as compared to what will
still be there at 18 years of age. Obstructive adenoids usually regress
without surgical intervention.www.indiandentalacademy.com

The nasal respiratory resistance can also be measured using an indirect
plethysmographic approach.
In habitual mouth breathing, the respiration resistance is low, whereas
in structurally conditioned mouth breathing, it is high.
The use of a small piece of paper held under the nose while the patient
is breathing will also determine if respiratory air is escaping form the
nostrils.
If the paper does not flutter at all, at least some obstruction is likely.
Visualization of the nasal turbinates by looking through the nostrils is
also of some help.
The diagnosis of mouth breathint is probably best determined by the ear,
nose, and throat specialist, however, and a consultation is to be
recommended if there is a problem.

The scope of functional therapy with respiratory problems can be
summarized as follows :
1. In habitual mouth breathing with small respiratory resistance, a
functional therapy is indicated. Exercises can be prescribed. Holding
a sheet of cardboard between the lips is a good means of enhancing
the lip seal.
2. When there are structural problems, with excessive adenoid tissue,
allergies, and so forth, it advisable to seek an ear, nose, and throat
consultation and possible treatment, if such treatment is successful,
orthodontics can subsequently be carried out.
3. If the structural conditions cannot be altered, functional appliance
therapy cannot be instituted. In such cases, only active fixed
appliance mechanotherapy is likely to produce the changes desired.
Even then, the stability of the results is open to question, unless
autonomous improvement occurs.www.indiandentalacademy.com

CEPHALOMETRIC DIAGNOSIS FOR
FUNCTIONAL APPLIANCE THERAPY
Thomas Rakosi (1992)
Germany
Consist of 3 subdivisions.
1. Analysis of facial skeleton
2. Analysis of jaw bases
3. Analysis of dento alveolar relationship

Analysis of facial skeleton:-
It includes 3 angles and 4 liner measurements.
1.Saddle angle (N-S-Ar)
- Formed by joining N-S-Ar
- It provides a parameter for assessment of the relationship between
anterior and postero lateral cranial bases.
- Mean value is 123 ± 5.
- It is large in retrognathic faces and small in prognathic faces
- A large saddle angle signifies posterior condyle position and
mandible that is posteriorly positioned with respect to the cranial base
and maxilla (unless an increase in saddle angle compensated by decrease
in articular angle and increase in renal length. A non compensated
posterior positioning of mandible caused by a large saddle angle is very
difficult to influence with M.F.T.www.indiandentalacademy.com

2. Articular angle
• Formed by joining S-Ar-Go
• Size of this angle depends an mandibular position
• Mean value is 1430
± 6
• It is large in retrognathic face and small in prognathic face
It can be influenced by orthopedic and orthodontic treatment

• Anterior positioning of mandible
• Closing of the bite decreases
articular angle
• Mesial migration of the posterior segments (Favours MFT)
Posterior relocution of mandible
• Opening of the bite increases the articular angle
Distal driving of posteriors
Articular angle is slightly less for individuals with horizontal growth
pattern (139.500
at 9 yrs) when compared to ‘V’ growers (142.40
).
Between 9 and 15 yrs.
Articular angle decreased by 2.890
for ‘H’ growth pattern and 2.490
for
‘V’ growers www.indiandentalacademy.com

3. Gonial angle
Angle between ramal plane and mandibular plane formed by
joining Ar-Go-Me. It gives information on the form of the mandible
and its growth direction. If this angle is small especially in the lower
component (G02
), the direction of the growth is horizontal favourable
for anterior positioning of the mandible using MFT.

In patients with large gonial angle MFT (activator) is generally
contraindicated.
Upper Go angle - Ar-Go-N 52-550
Lower gonial angle - N-Go- Me 70- 750
Mean Go.Value is - 128 ± 70
At 9yrs of age
In ‘H’ growth pattern average gontal angle -125.50
with Go2
is 69.50
In ‘V’ growth pattern average gonial angle -113.40
with Go2
78.30
Between 9th
and 11th
yrs of growth, the growth increment was
- 2.890
for the ‘H’ growth pattern and
- 2.420
for the ‘V’ growth pattern
decrease of gonial angle is more for ‘H’ patternwww.indiandentalacademy.com

Linear measurement
Facial height
Linear millimetric assessment
S- Go = PFH, N- Me = AFH”
In a ‘H’ growing individual AFH < PFH is for ‘H’ pattern – 69.5mm
with increment of 1.5mm between 9-15yrs.
For ‘V’ pattern – 64.1mm with increment of 10.8mm between 9-
15yrs
AFH at 9yrs
For ‘H’ pattern – 103mm with increment of 12.18mm
For ‘V’ pattern – 106mm with increment of 12.71mm

To compare AFH and PFH and to estimate direction of growth clinically
Jaraback’s ratio is used
Jaraback’ s ratio (1972)
PFH X 100 = 62-65%
AFH
<62% indicates ‘H’ growth pattern
Between 9 and 15yrs, averge Jaraback’s ratio increases
‘H’ growers – 67.5% at 9 yrs to 69.9% at 15 yrs
‘V’ growers – 60.1% at 9yrs to 62.7% at 15 yrs

Anterior cranial base length
• Distance between the center of superior entrance to Sella (Se) to
the Nasion (N)
• Useful in comparing the length of jaw base
• At 9yrs of age, average length of anterior cranial base length for
‘H’ pattern. 68.8mm with increment of 3.52mm between 9 –15 yrs.
• Ideally anterior cranial base length is slightly less than the
mandibular base length.

Posterior (Lateral) cranial base length
Distance between S – Ar.
Short posterior cranial base length occurs in vertical growth
pattern and skeletal open bites and would give poor prognosis for MFT.
In 9 yrs old, average length of posterior- cranial base length for ‘H’
pattern 32.2mm with increment of 9.16mm (for 6yrs, 9 –15yrs) cranial
base length. For ‘V’ pattern – 30mm increment of 4.4mm.

Analysis of Jaw Bases
The angle between the vertical ref: lines represent the sagittal
relationship of the parts (Eg: SNA, SNB) where as angles between the
Horizontal lines assist in the evaluation of the vertical relationship (Eg:
Base plane angle and inclination angle)
Linear measurement indicates the length of the maxillary and mandibular
bases and ascending ramus.
A morphologic assessment, especially of mandible is important in
forcecasting growth direction only selected measurements (both angular
and linear) that are applicable in treatment planning for MFT

SNA angle represent the sagittal relationship of the anterior limit of the
maxillary apical base as related to the anterior cranial base.
It express the horizontal relationship of the maxillary base in relation
to the cranial base.
Mean value is 810
. It is larger in prognathic and small in retruded
maxilla. In class II division I (Prognathic Maxilla) with large SNA,
MFT is generally contra indicated
McNamara (1981) SNA angle does not change much with MFT.
But a moderate decrease of SNA angle is possible through the
use of conventional activator therapy. A large decrease of SNA is
possible by using Clark’s Twin Block

SNB angle
It expresses the sagittal relationship between the anterior extent of the
mandibular apical base and anterior cranial base.
Horizontal position of the mandibular base in relation to the cranial base
Large in prognathic mandible and small in retrognathic madible
MFT is indicated if the mandible is retrognathic and has a small SNB
SNB gives information of the anterior posterior position of th mandible,
and not its morphology or its growth direction
A posteriorly located mandible can be large / small. If it is small the
prognosis for anterior repositioning of the mandible during mixed
dentition is good because a large growth increment can be expected

The favourable growth direction and greater increments of mandible in
horizontal pattern (that is increased anterior translation of mandible)
makes successful treatment of these patients possible through MFT.
The average SNB angle is 790
The average angle and growth increments in horizontal patter
(77.20
at 9 yrs and 80.50
at 15 yrs)are much larger than in ‘V’ growers.
That is 74.30
at 9yrs and 75.90
at 15 yrs)

Base plane angle
This is the angle between the palatal plane and the mandibular
plane. Average value is 2.50
. B.P angle is small with ‘H’ growth pattern
but large with a vertical growth pattern. In horizontal growth 23.40
at 9
and 20.5 at 15 yrs . In V. growth 32.90 at 9yrs and 30.90
at 15 yrs.
Growth increments of BP angle shows it decrease more in ‘H’ growing
faces.
The age dependent decrease of BP angle corresponds to the
general trend toward a more ‘H’ growth pattern and expresses the
logarithmic spiral type of growth desired by Moss, Graber and other.

Inclination angle
The angle formed by the Pn lines and the palatal plae (Pn line is a
perpendicular line is a dropped from N-se line at N’) it gives an
assessment of the inclination of the maxillary base.
Mean value is 850
Large angle indicated upward and forward inclinations where as
small angles indicated downward and backward tipping of the anterior
end of the palatal plane and maxillary base.
This angle does not co-relate with growth pattern or facial type.

Growth Increments
Terminal growth appears to increase this angle in horizontal
growing faces. The angle remains constant in vertical pattern. Functional
and therapeutic influences can alter the inclination of the maxillary base.

Rotation of the jaw bases
Base plane angle and inclination angle are used to evaluate the
rotation of the upper and lower jaw bases.
These rotations are of special interest in treatment with functional
appliances because they show whether such appliances are indicated and
provide the criteria for appliances constructions. If the posterior condylar
growth of the mandible proceeds greater than the anterior (sutural and
alveolar) facial skeleton – Horizontal rotation results. If growth
increments are balanced, parallel growth down the Y axis results.
Bjork (1962) – 2 process involved in rotational growth of mandible

1. Intermatrix rotation:- Remodeling of mandible in the symphyseal
and gonial areas. It is a function of periosteal matrix (Moss) and often
results in subsequent rotations. More apposition in gonial area and
resorption in symphyseal area lead to ‘H’ rotation while greater
apposition in symphyseal area and resorption in gonial area causes
vertical rotation.
2. Matrix rotation :- Vertical or horizontal rotation of mandile in its
neuromuscular envelop is called matrix rotation or relocation of the
functional matrix, according to Moss and Enlow (1962).
Total rotation :- Rotation observed cephalometrically. It consists of
both matrix rotation and intermatrix rotation. Mandibular rotation is
caused by both growth dependent and functional influences. Functional
orthodontic and orthopedic methods alter the functions and guide the
growth process. For this reason the rotation of the mandible is
moderately influenced by M.F.T.

The pattern of Maxillary base rotation can be observed by sequential
measurement of the inclination angle.
Generally maxillary base inclination is stable and no growth
dependent changes are seen. But according to Linder Anderson, Lowe,
and Wood Side (1986) environmental influences such as neuromuscular
dysfunction, occlusal forces, gravity, naso respiratory malfunction can
modify this inclination.
Eg :- An upward and forward tipping of the anterior part of the
maxillar is seen in mouth breathers increase inclination angle. A
downward and backward tipping of the anterior part of the maxilla is
observed as a natural compensation in patients with vertical growing
faces. Maxillary inclination is influenced by both fixed orthopedic and
functional therapeutic techniques.

Mutual relationship of the rotatory jaw bases
Rotation of the mandible can establish vertical proporation of the
facial skeleton. Horizontal rotation predisposes to deep over bite and
excess vertical rotation indicates open bite tendency. The inclination of
the maxillary base is also important to the occlusal relationship.
Dentalveolar malocculsion depends on combination of these rotations.
Mutual relationship of rotating law bases
Human implant studies by Lavergri and Gasson (1982)
differentiates the following type of rotation.
1. Convergent rotations of the jaw bases
Maxillary base rotates downwards and mandible rotates upwards-
results in deep overbite that is difficult to manage using functional
methods.

2. Divergent rotation
Here maxilla rotates upwards and mandible rotates downwards,
results in marked open bite, requires orthognathic surgery for correction.
3. Cranial rotation of both bases
In this ‘H’ growth pattern harmonious rotation of both jaws
occurs in upward and forward direction. The rotation of maxillar
compensates for upward and forward rotation of the mandible offsetting
a deep bite and results in normal bite.

4. Caudal or down and back rotations of both bases
Here the down and back maxillary rotation offsets the open the created
by down and back mandibular rotation.
Convergent rotation - Deep bite
Divergent rotation - Open bite
Cranial rotation - Normal bite
Caudal rotation - Normal bite
Therapeutic control of vertical diamension is usually difficult
than control of the sagittal diamension. Orthodontic surgery is the
ultimate corrective procedure if the magnitude of the malreltionship
transcends orthodontic and orthopedic growth guidance procedure.

Linear measurement of the jaw bases
When the indication for functional appliance therapy (MFT) is
being determined not only the position but also the length of the jaw
bases must be assessed. This is important in considering the etiology
and therapy for each patient. The length of the maxillary base,
mandibular base and ascending ramus is measured relative to se-N.
Mean Se-N value is 71mm
The ideal dimension relative to Se-N is calculated using the ratio put
forward by Schwartz(1958).
N-Se: Mandibular Base=20:21
Ascending ramus: Mandibular Base=5:7
Maxillary Base: Mandibular Base=2:3

The evolution results in 2 ideal dimension
1.Length of Se-N(2)Extent of Mandibular Base
Extent of mandibular base
Linear distance between Go and Pog projected perpendicular to
mandibular
Plane-Ideally the mandibular base should be 3 mm larger than Se-N until
12th
Year and 3.5mm larger after 12th
year. Average length and growth
increments
Larger after 12th
year. Average length and growth increments larger in
‘H’ pattern than in ‘V’ average length :In 67.59 at 9 and 77.35mm at
15yrs. In ‘V’ pattern, average length:65.23mm at 9yrs. And 73.5mm at
15yrs. A length of 5mm less than average is considered WNL up to 7
yrs and a length of >5mm is normal up to 15 yrs.www.indiandentalacademy.com

EXTENT OF MAXILLARY BASE
Distance between the PNS and point A projected ** on to the palatal
plane. Growth increments in ‘H’ pattern. Average length of the
maxillary base in ‘H’pattern is slightly higher than vertical growth
pattern.
Average length of maxillary base.
In ‘H’ pattern 44.56 at 9 and 48.6 mm at 15 yrs. IN ‘v’ pattern,44mm at
9yrs and 47.16 mm at 15yrs. Growth potential of the mandible
base>maxillary base. Hence mandible is less retronathetic after 12 yrs.
The recognition that the mandible out grows the maxilla by as 5mm is
especially important to functional appliances proponents and to the
skeletal class ii patients being treated.

Length of the ascending ramus (R.asc.)
Linear distance between Go and condylon (cd). The length of ramus is
important in determination of PFH and its relations to AFH.
Ramus tends to be longer in ‘H’ growing pattern
Average remal length is
In ‘H’ pattern 48.9mm at 9 and 58.67mm st 15yrs.
Ain ‘av’pattern 44.47 mm at 9 yrs and 51.7mm at 15 yrs.
Greater growth increments seen in ‘H’ pattern.

Evaluation of the length of the jaw bases
Mandibular base:- If the length of the mandibular base corresponds to
the distance N-Se (mandible base: N-Se +3mm) it indicates an age
related normal mandibular length and an average growth increment can
be expected. If the mandibular base is shorter, growth increment is
larger. If the mandibular base is larger, growth increment is smaller.
The correlation between the length and position of the Mandibular base
also should be examined. A retrognathic mandible with short base (due
to growth deficiency) with favourable growth direction, prognosis is
good with MFT.

. A mandibular base that is both long and retrognathic can result from 2
reasons.
1. Functionally retruded (forced A) position of mandible due to over
closure and occlusal guidance –Here treatment consists of eleimination
of forced guidance and up and back path of closer in either mixed or
permanent dentition
2. Mandible is morphogenetically built into the facial skeleton in a
posterior position. Fossa is posterior and superior. Discrepancy not
compensated in spite of long mandibular base. Prognosis is poor with
MFT.

Evaluation of maxillary base and ascending ramus.
Assessment of the length of the maxillary base and ascending
ramus is by relating to 2 ideal values.
1. N –Se distance (2) Mandibular base length using Schwartz ratio.
A deviation from the mandibular base related norm indicated that
maxillary base or ramau length is too long or too short. If the ramus is
too short in relation to other proportions, a large amount of growth can
be expected because the growth pattern is not vertical.
In ‘V’ growth pattern – Ramus remains short.

Morphology of the mandible:- (orthognathic, prognathic, retrognathic)
is important to enhance the differential diagnosis.
Prognathic mandible grows horizontally, even if an average or a
slight vertical growth direction is evident in mixed dentition, shifting or
mandible in a horizontal direction can be expected in the coming years.
In a retrognathic mandible, shifting of growth pattern in opposite
direction is less likely and produces less expressively.
Orthognathic mandile well developed in ideal proportions
Morphology of mandible is important in determination, indication and
management of myofunctional appliances.

Analysis of dento alveolar relationship
The inclination and position of the incisor with respect to amount
cranial base, their apical bases and each other.
1. Axial inclination of incisors. Upper incisors ( perpendicular to SN)
Angle between the long axis of the upper incisor and S-N plane. Average
value up to 6th
yr 940
- 1000
. Average value after 12 yrs of age 1020
.
increased angle shows increased incisor procumbency.

Lower incisors (T to MP, IMPA)
Angle between long axis of the lower incisor and the mandibular
plane. Ideal plane is 900
. Average value from 6 – 12 yrs varies from 880
-
940
. If IMPA is small (Lingually tipped lower incisor) – advantageous
for MFT increased IMPA MFT – is difficult, labially flared lower
incisors. If IMPA is small, mandible and lower incisors can be moved in
same direction. If IMPA is large – mandible and lower incisor moved in
opposite directions.

Position of the incisors (Linear) perpendicular to N Pog
Upper incisor edge to N- Pog line upper incisors 2-4mm anterior
to (mean) N-Pog line.
T to N- Pg
Lower incisors can be 2mm ahead or 2mm behind N-Pog line ±
2mm. During growth Pog drifts forward. This should be considered in
planning the position of incisors in treatment planning

Summary and Conclusion
Cephalometrics allows anomalies to be located and
differentiation made between skeletal and dentoalveolar malocclusions.
If the problem has both skeletal and dentoalveolar components
cephalometric assessments helps to determine 10
and 20
dysplastic
structure and possible autonomous compensatory response before
treatment begins.
Cephalometrics allows the determinations of whether jaw bases
are anteriorly or posteriorly placed, short or long, rotations of maxillary
and mandibular bases and the growth pattern delineated.

While bio mechanical factors of planned therapy considered the axial
inclination and position of upper and lower incisors are important.
Cephalometrics enhances the assessment of the influences of
neuromuscular dysfunction on the dentition. This accurate assessment is
vital for diagnosis and treatment planning with functional appliances.
Growth forecasting for early mixed dentition treatment with MFT
should be done by comparing angular and linear measurements and
morphologic characteristics of facial skeleton. The assessment of growth
direction is important in MFT.

Functnal analysis

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