CEPHALOMETRICS

AS A DIAGNOSTIC AID

Introduction

Definition

Types of cephalogram

Uses

Anatomic landmarks

Lines and planes of lateral cephalometrics

Cephalostat

Steiner analysis

Downs analysis

Tweed’s analysis

Wits appraisal

Sassouni analysis

McNamara analysis

Ricketts analysis

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INTRODUCTION

‘Beauty is the finest expression of human emotion. The art that

was produced in the past has survived because it was expressed in the

highest, finest and most sensitive manner possible. The beauty that

survives knows no limits either of time or place’.

- Wuerpel

Ever since God created man in his image, man has been trying to

change man into his image. Orthodontists, in their attempts to treatment

planning with brought various analysis into being.

In 1922, Pacini introduced a method for standardized head

radiography and failed due to large fixed distance from X-ray source to

the cassette.

Dr. Herbert Hofrath of Germany and Dr. B. Holly Broadbent of

U.S. published a new X-ray technique and its application in orthodontia.

In 1946, Dr. Charles Tweed developed Tweeds diagnostic

triangle. First true classic full scale cephalometric analysis developed by

William B. Downs in 1948.

In 1953, Dr. C.C. Steiner presented his famous Steiner’s

analysis. Riedel in 1952 developed SNA and SNB angle. Sassouni

(1995) described total archial analysis.

Rickets (1960) give dynamic analysis to study morphology of a

patient at different stages of development or treatment. Jacobson’s

‘Wits’ appraisal (1975) was used for assessing horizontal disharmony of

the jaw.

For surgical correction quadrilateral analysis Dipaolo (1970) and

an analysis by McNamara (1984) developed.

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DEFINITION

Cephalometrics includes measurements, description and appraisal

of the morphologic configuration and growth changes in the skull by

ascertaining the dimensions of lines, angles and planes between

anthropometric landmarks established by physical anthropologists and

point selected by orthodontists.

TYPES OF CEPHALOGRAM

1) Lateral cephalogram

2) Frontal cephalogram

USES

1) Helps in orthodontic diagnosis, by enabling study of skeletal,

dental and soft tissue structures of the craniofacial region.

2) Helps in classification of malocclusion.

3) Helps in treatment planning.

4) Evaluation of treatment results.

5) Helps in predicting growth related change.

6) It is also valuable aid in research work.

ANATOMIC LANDMARKS

1) Nasion – Most anterior patient on naso frontal suture.

2) Sella – Midpoint of hypophyseal fossa.

3) Si – Most inferior patient of lower contour of sella turcica.

4) SP – Most posterior patient on posterior contour of sella turcica.

5) Se – Midpoint of the entrance of sella. At the same level of jugum

sphenoidal.

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6) Point A (subspinale) – Deepest midline patient in the curved bony

outline from the base of alveolar proceeds of the maxilla. i.e.

between ANS and Prosthion.

Donovan - Junction of maxillary basal bone and alveolar bone.

Higley – Deepest midline point between ANS and Prosthion on the

premaxilla.

Jacobson – Anterior limit of maxillary denture base.

7) Prosthion – Alveolar rim of maxilla or the lower most anterior

point on the alveolar portion of the premaxilla in the median plane

between upper central incisors.

8) Is (Incisor spurious) – Tip of crown of most anterior maxillary

central incisor.

9) AP 1 (Apicale 1) - Root apex of the most anterior mandibular

central incisor.

10) Ii (Incisor inferius) - Tip of crown of most anterior mandibular

incisor.

11) AP 1 – Root apex of most anterior maxillary incisor.

12) Intradental – Alveolar rim of mandibular.

13) Point B (Supramentale) – Most anterior part of mandibular base

or it is the most posterior point in the outer contour of the

mandibular alveolar process, in the median plane.

Donovan – Junction of mandibular basal bone and alveolar

process.

Jacobson – Anterior limit of mandible

14) Pog - Most anterior point on bony chin in median plane.

15) Gn

Brodie – Located by taking the midpoint between most anterior

and inferior points on the bony chin.

Craig – Patient of intersection of facial and mandibular plane.

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16) Go – Constructed point at the intersect of lines tangent to posterior

margin of ascending ramus and mandibular base.

Hingley – Intersection of posterior ramal and mandibular plane.

17) Me –

Sassouni - Most caudal point in the outline of the symphysis or the

inferior most point on mandible.

18) Ar (Articulare) -

Bjork – Point of intersection of the posterior margin of ascending

ramus and outer margin of cranial base.

19) Cd (Condylion) – Most superior point on the head of the condyle.

20) Or (Orbitale) – Lower most point of the orbit in radiograph.

21) ANS – Tip of bony anterior nasal spine in the median plane.

22) PNS – The intersection of continuation of anterior wall of

pterygopalatine fossa and the floor of nose.

23) Basion – Lowest point on the anterior margin of foramen magnum

in the median plane.

24) Ptm (Pterygomaxillary fissure) – Anterior wall represents

maxillary tuberosity outline, posterior wall represents anterior

curve of pterygoid process.

25) Po (Porion) –

Tweed – 4.5mm above geometric center of ear rod.

Craig – Uppermost point on the soft tissues overlying the external

auditory meatus.

Ricketts – True Porion, located directly over that of basion and

downward and forward from internal auditory canal.

Moorrees – Center of ear rods.

Higley – Highest point on the root of the left external auditory

meatus.

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26) BO (Bolton point) –

Broadbent – Highest point in the upward curvature of the

retrocondylar fossa.

Higley – Highest point in the concavity behind the occipital bone.

27) D point – Center of symphysis given by Steiner.

28) Op (Opisthion) – Most posterior point of the bony margin of the

foramen magnum.

29) AC (Acanthion) – Tip of ANS.

30) J point – Located at the junction of the anterior border of ramus

and the corpus of mandible.

31) DS (Dorsam selae) – Square bone forms posterior boundary of

sella turcica.

32) Broadbent registration patient (R) – Perpendicular from sella on

Nasion – Bolton plane.

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LINES AND PLANES OF LATERAL CEPHALOMETRICS

1) Blumenbach’s plane (Resting horizontal plane) - It is the plane

formed as the skull, minus the mandible rest on a flat horizontal

surface. Entails the skull resting anterior on maxillary teeth and

posterior either on occipital condyles or on the mastoid process.

2) Broadbent’s line (S-N reference line) – From sella to nasion.

3) Broadbent Bolton line – Line from Bolton patient to nasion.

4) Broca’s line – Extends from true anatomic prosthion to the lower

most point of the occipital condyle. When skull is resting on

horizontal surface.

5) Camper’s line – Line extending from tip of ANS to the centre of

external auditory meatus. Camper’s plane is a triangular plane

formed by two lines from tip of ANS to each external auditory

meatus.

6) Decoster’s line – This is the only line that is not linear connection

of two points. It represents an actual anatomical contour of the

planoethmoidal line from internal plate of frontal bone down

through roof of cribriform plate to the anterior portion of sella

turcica.

7) Frankfort horizontal plane) – Its origins date back to the

international congress on prehistoric anthropology and

archaeology, held in Frankfort in 1882. The line runs from

orbitale to porion. It is supposed to represent the ideal horizontal

position of the head when the patient stands erect.

8) Palatal plane – Line running from ANS to PNS.

9) His plane – Runs from acanthion to opisthion.

10) Hold way line – Also referred as harmony line was developed by

R.A. Holdaway and is strictly a soft tissue profile assessment

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reference line. Runs from soft tissue pogonion to vermilion border

of upper lip.

11) Huxley’s line – Runs from nasion to basion and referred as nasion

– basion line. It would be the near perfect base reference line for

research purposes on growth and development.

12) Mandibular plane – Four different mandibular planes.

Steiner – Line joining Go and Gn

Downs – Line joining Go and Me

Tweed and Ricketts – Straight line tangent to the lower most

border of mandible.

Bimpler’s line – Line from menton to antigonial notch.

13) Margolis line – Line runs from nasion to spheno-occipital-

synchondrosis.

14) Occlusal plane – 3 occlusal planes.

First plane – Line joining midpoint of overlap of M-B cusps of

upper and lower first molars with point bisecting overbite of

incisions. Used by Downs and Steiner.

Second plane – Used by Ricketts and in Wits analysis called as

functional occlusal plane and is line joining the midpoint of the

overlap of M-B cusp of Ist molars and buccal cusps of premolars or

deciduous molars.

Third plane – Line joining midsection of molar cusps to the tip of

upper incisors.

15) Orbital plane – Plane perpendicular to FH plane at orbitale.

16) Ramal plane – Line tangent to posterior border of ramus of

mandibular.

17) Rickett’s esthetic line –Extends from soft tissue tip of nose to the

most anterior portion o profile of soft tissue chin.

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18) Von Ihering’s line – Orbitale to center of external auditory

meatus.

19) Y-axis – Given by Downs and extends from sella to gnathion.

CEPHALOSTAT

An 8 10 inches film cassette equipped with approximate film

and intensifying screen is placed either horizontally or vertically in the

cephalostat cassette holder.

A distance of 15 cm from midsagittal plane of the cephalostat to

the film cassette is often used. The patients head is fixed by two ear-rods

that are inserted into ear holes so that upper border of ear holes rest on

upper part of ear rods. The head is oriented with the FH plane parallel to

the floor and midsagittal plane vertical and parallel to the cassette. The

standardized FH plane is achieved by placing the infra-orbital pointer at

the patients orbit and adjusting the head vertically until the infra-orbital

pointer and two ear rods are at same level. The upper part of face is

supported by forehead clamp positioned at nasion.

Projection is taken when teeth are in centric occlusion and the lips

relaxed. The focus film distance is usually 5 feet i.e. 152.4cm.

Milliamperage should be 10MA, KVP is about 60-90Kv and

exposure time is not longer than 3 seconds.

STEINER ANALYSIS (1953)

C. C. Steiner selected what he considered to be the most

meaningful parameters and evolved a composite analysis. He proposed a

appraisal of skeletal, dental and soft tissue analysis. He considered SN

plane as a reference plane.

L – Project the most anterior point of the body of the mandible to the line

SN.

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E – Erect the line from the most distal point of head of condyle,

perpendicular to the line SN.

Skeletal analysis

1) SNA angle - 820

2) SNB angle - 800

3) ANB angle - 20

a. Class- I – ANB - 0-50

b. Class-II – ANB - ≥ 60

c. Class-III – ANB - < 00

4) SND angle - 760

5) Mandibular plane to SN - 320

6) Occlusal plane to SN - 14.50

Dental analysis

1) UI to NA (angle) - 220

2) UI to NA (linear) - 4mm

3) LI to NB (angle) - 250

4) LI to NB (linear) - 4mm

5) Interincisal angle - 1300

6) Holdaway ratio - 1:1

SL - 51mm

SE - 22mm

Steiner analysis for Indian population

Sidhu S.S. in 1970 gave the Indian (Maharashtrian) norms. Sample

size was 25 and all were male with the age group of 13-16 years.

1) SNA - 82.7 ± 7.42

2) SNB - 79.4 ± 7.84

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3) ANB - 3.3 ± 3.64

4) UI to NA - 25 ± 9.42

5) LI to NB - 32 ± 7.22

6) SL (mm) - 53 ± 11.78

7) UI to NA (mm) - 6.7 ± 3.74

8) LI to NB (mm) - 7.6 ± 2.68

9) FH to SN - 6 ± 5.86

10) Distance of U6 to NA - 23.3 ± 2.56

11) Distance of L6 to NB - 17.9 ± 2.96

Gamm and Gianelly in 1970 gave S.D. to the values of Steiners

analysis.

Parameters Mean S.D.

SNA 80.60 3.3

SNB 780 3.1

ANB 2.50 1.7

SND 75.20 2.8

Pg to NB 2.5mm 1.5mm

I/I 125.40 7.9

OP 17.30 4.1

MP 32.80 3.5

UI/NA 5.2mm 1.2mm

UI/NA 230 6.1

LI/NB 4.7mm 1.5mm

LI/NB 27.50 4.5

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Comparison of Steiners values with Gamm and Gianelly’s value

and Maharashtrian norms (Indian)

ParametersSteiner’s

values

Gamm &

Gianelly

Maharashtrian

norms

SNA 820 80.60 ± 3.3 82.70± 7.42

SNB 800 780 ± 3.1 79.40± 7.84

ANB 20 2.50 ± 1.7 3.30±3.64

SND 760 75.20 ± 2.8 -

MP 320 32.80 ± 3.5 -

OP 14.50 17.30 ± 4.1 -

UI to NA 220 230 ± 6.1 250±9.42

UI to NA 4mm 5.2 ± 1.2mm 6.7 ± 3.74mm

LI to NB 250 27.50±4.5mm 32 ± 7.22

LI to NB 4mm 4.7 ± 1.5mm 7.6 ± 2.68

I/I 1300 125.40±7.9 -

Holdaways ratio 1:1 - -

SL 51mm - 53 ± 11.78

SE 22mm - -

DOWN ANALYSIS (1948)

Downs observed following four basic facial types.

1) Retrognathic – A recessive lower jaw

2) Mesognathic – An ideal o average lower jaw

3) Prognathic – A protrusive lower jaw

4) True prognathism – Pronounced protrusion of lower face.

Downs elected to use FH plane as a reference base from which to

determine the degree of retrognathism, prognathism or orthognathism.Sample – 20 children, 12 to 17 years of age with excellent occlusion with a

mean age of 14.5 ± 2.5 years were taken.

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Measurements Range Mean

A) Skeletal measurements

1) Facial angle

2) Angle of convexity

3) A-B plane angle

4) Mandibular plane

angle

5) Y-axis

820±920

100±-8.50

-90±0

280 to 170

660 to 530

87.80

00

-4.60

21.90

59.40

B) Dental measurements

1) Cant of occlusal

plane

2) Interincisal angle

3) LI to mandibular

plane

4) LI to occlusal plane

5) Distance UI to A-

Pog

1.5-140

130-150.50

-8.5-70

3.50-200

-1mm to 5mm

9.30

135.40

1.40

14.50

2.7mm

Vorrhies and Adams (1951) made a graphic portryal of 10 values

calculated by Downs.

But later on in 1952 it was modified by Wylie and his polygon

shows not only mean but the maximum and minimum range for each

measurement.

Downs analysis for Maharashtrian

This study was done by Kotak V.B. (1960)

Not mentioned any sample size.

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Measurements Mean Range

1) Facial angle 84.980 79-91

2) Angle of convexity 3.75 -14 to 13

3) A-B plane angle -4.85 -10 to 3.5

4) Mandibular plane 22.73 11-34

5) Y-axis 61.85 54.5-68.5

6) Cant of occlusal plane 11.55 0-18

7) Interincisal angle 119.6 105.5-134.5

8) LI to mandibular plane 17.13 5-29

9) LI to occlusal plane 29.22 21-41

10) UI to A-Pog (mm) 7.5 3.5-11

TWEED’S ANALYSIS – 1946

Tweed has focused on how cephalometrics might be applied in

diagnosis and treatment planning for daily clinical orthodontics. It

consists of a triangle formed by FH plane, mandibular plane and axis of

lower incisor.

A sample of 95 was taken and average values seen were

FMPA – 24.570

IMPA – 86.930

FMIA – 68.200

Hence FMPA of 240, IMPA of 900 and FMIA of 650 were workable

figures ad still used.

Tweeds projected scale (FMIA formula)

1) When FMPA is 300 or more – FMIA should be 650 or more upto

700.

2) If FMPA is 250±40 – FMIA should be 680 or 700.

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3) If FMPA is 200 or less – IMPA should not exceed 940.

Tweeds head plate correction

If FMPA ore than 250 then IMPA should not be 900 or more.

e.g. If FMPA showed 280, then IMPA would have to be positioned

at 870. This is termed as Tweed’s head plate correct.

Cephalogram correction

To achieve the FMIA requirements of 650 we require tipping of

mandibular incisors lingually and will require shortening both the side of

dental arch.

According to Tweed’s head plate correction for every 20 correction

1mm of space is required. For both side of arch it will become 2mm.

The measurement taken from cephalogram combined with actual

arch length discrepancy and this is the total discrepancy in millimeters.

WIT APPRAISAL (1975)

Wits appraisal of jaw disharmony given by Jacobson is measure of

the extent to which the jaws or related to each other anteroposteriorly. As

a measurement from the cranial base do not necessarily provide are liable

expression of A-P Jaw relationship in the dentofacial complex.

Reference plane common is both dentures is that of occlusion,

hence the effects of rotation of jaw are not affecting the overall

assessment of the jaw.

Sample of 46 adults with excellent occlusion were taken. (21 M & 25 F)

Construction - Draw perpendicular from point A & B on the maxilla and

mandible on to the occlusal plane.

The points of contacts of the perpendicular onto the occlusal plane

are labeled AO and BO respectively.

Wits reading

Males – 1 mm

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Females – 0 mm

The more the wits reading deviates from -1 mm in males and 0 mm

in females the greater the horizontal jaw disharmony

Class-II - Positive wits reading

Class-III - Negative wits reading

If AO ahead of BO then wits appraisal positive

SASSOUNI ANALYSIS (1955)

Sassouni wanted a system based on relationships of anatomical

structures to each other with in the frame work of the individual patients

i.e. he wanted to let the patients own amatory serve as the clue to what is

none al of abnormal to himself.

Thus he developed a system that utilizes a series of portions of

circles in the form of arcs, that have a common center formed by

intersection of composite of anatomical planes to form what has become

known as the Sassouni archial analysis.

This analysis is 3-dimensional and inclusive of all the important

structures of facial skeletal.

Sample – 50 children with normal occlusion

Point O – It is the center of the focal area where the four horizontal

planes of the face i.e. cranial base, palatal, occlusal and mandibular

converge.

Planes

Draw a plane parallel to supraorbital plane tangent to Si. Four

planes converge toward focal area called center or point O. Generally 3 of

the 4 planes meet, while the fourth is divergent. This shows the plane,

which is not integrated in the facial balance. Occasionally only two

planes meet at the same point two others are parallel or meeting in front

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or beyond point O. In these cases the junction of the cranial base &

mandible planes should be taken as the center O.

Arcs- From O as of center, draw arcs from N, ANS, A, Te & Sp.

Norms

1. Planes – Four planes are converging toward a focal center O.

2. Facial angles – Cranial base plane to palatal plane angle is equal to the

palato-mandibular angle.

3. Arcs-

a. The arc – from N should pass through ANS, tip of UI,

pogonion. If whole lower face is anterior or posterior to the arc

from N, draw a second are from ANS down. This should pass

through tip of UI and pogonion.

b. The arc from point A down should pass through point B.

c. The arc from Sp (Dorsam Sella) should pass through gonion.

d. The arc from Te (Temporale) should be tangent to the mesial

contour of U6.

Vertical proportions

1) Anterior vertical proportions

Put the point of compass on ANS & open compass to supraorbitale,

then transfer this dimension by rotating the compass until it intersects

anterior arc at the menton. Distance from ANS to supraorbitale should be

equal to that from ANS to Me.

2) Post vertical proportions

From PNS to cranial base plane & then from PNS to Go.

Both distances should be equal.

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Anteroposterior evaluation of profile

In normal profile ANS, IS, and Pog should be located on anterior arc

It ANS & Pog both posterior to anterior arc then the profile is

retroarchial which essentially is normal. This situation may be due to the

fact that nasion is to far anterior.

It ANS is on anterior arc Pog is not there are two possibilities.

1. Pog is anterior to arc

2. Pog is post to arc

It Pog is on anterior arc & ANS is not, there are also two possibilities

1. ANS is anterior to arc

2.ANS is posterior to arc

Any combination of maxillary protrusion and/or mandibular

retrusion called as skeletal Class II.

Any combination of maxillary retrusion and/or mandibular

protrusion called as skeletal Class II.

Size of corpus of mandible

It Go located on posterior arc and Pog is on anterior arc then

corpus length is equal to the cranial base (Sp to N). This is for 12 year of

age.

Before 12 years corpus of mandibular is small and after 12 year

corpus is larger than cranial base.

Vertical balance

The anterior upper and lower face heights should be equal. The

posterior upper and lower face heights should be equal.

ANS to cranial base = ANS to mandibular plane and

PNS to cranial base = ANS to mandibular plane

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The tip of UI is situated at the midpoint between ANS and Pog.

The tip of LI is situated at the midpoint between A and B.

Interpretation

Skeletal deep bile cases

4 bony planes of face are not steep to each other and center O is

away from profile.

Cranial base angle (supraorbital to clivus angle) is small.

Upper and lower incisors have long axis nearly parallel and are

vertically extruded while molars are intruded.

Total post height is nearly equal to ant facial height

Skeletal open bile cases

4 bony planes are steep to each other bringing the

center O close to the profile.

Cranial base angle and genial angle are obtuse. PFH

half the AFH.

Skeletal Class II cases

Large cranial base angle, small gonial angle with short

ramus.

Palate is tipped down word and backward

Skeletal Class III cases

Small cranial base angle

Large genial angle and palate is tipped upward at PNS

and downward at ANS.

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SASSOUNI PLUS

After Sassouni’s death in 1983, a new champion of archial

analysis, Dr. Richard Beistle arose to continue work of teaching and

promoting this great analysis.

Beistle represents 11 points now called as Sassouni plus.

The first eight components are from original Sassouni, the last

three which form the plus form of the last three which form the plus form

of the analysis.

1. Skeletal AP alignment

2. Skeletal vertical dimension

3. Maxillary incisor position

4. Maxillary AP length

5. Maxillary AP position

6. Maxillary 6 position

7. Mandibular AP length

8. Mandibular AP position

9. Mandibular incisor position

10.Growth direction indicator

11.Upper lip angle

1. Skeletal AP length

It ANS and Pog both post to anterior arc profile is retroarchial

It may be due to

- N too for anteriorly

- Entire lower face too far posteriorly.

- Combination of both.

If ANS to Pog both anterior to anterior arc profile considered

prearchial.

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It may be due to

- N positioned too far posteriorly

- Entire lower face too far anteriorly

- Combination of both.

A point and B point ideally showed be on basal arc.

2) Skeletal vertical dimension

At age 4 years AUFH = ALFH

At age 12 years ALFH is more by 6mm and

At adulthood ALFH is more by 10mm

3) Maxillary incisor position

Tip of UI should be on anterior arc or within range of 0 to 3 mm

ahead of anterior arc.

4) Maxillary AP length

Drop cribriform perpendicular on PNS

It PNS is on cribriform perpendicular and ANS on anterior arc then

maxilla is normal.

5) Maxillary AP position

If ANS and PNS both back of anterior arc and cr perpendicular by

the same amount – maxillary retruded.

If ANS and PNS ahead of there respective reference line – maxilla

is protruded.

6) U6 position

Mesial surface should be tangent to midfacial arc.

7) Mandibular AP length

Measured from anterior and posterior arc at Go and Pog.

8) Mandibular AP position

If Go and Pog displaced in opposite direction an abnormally large

mandible or abnormally small mandible is indicated.

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9) LI position

IMPA angle is seen in this.

It is 950 50.

10) Growth direction indicator

Beistle split the gonial angle and uses the upper and lower portions

of it to evaluate growth direction.

The upper position of split gonial angle represents slant of ramus.

Lower portion of angle represents slant of the body of mandibular corpus.

Total gonial angle 120-1320

Upper gonial - 52-550

Lower gonial - 70-750

If upper gonial angle is large and lower is small indicating strong

horizontal growth pattern.

If upper gonial angle is small and lower is large indicating strong

downward and backward grower.

11) Upper lip angle

Constructed by drawing a line tangent to anterior most tip of upper

lip i.e. soft tissue subnasale and extending it upward to intersect the optic

plane, which is parallel to FH.

Angle is measured inferiorly and posterior at the intersection

If 900 or less Retruded

91-990 Flat

100-1150- Normal

116 or more Protruded

McNAMARA’S ANALYSIS (1984)

The analysis proposed by McNamara is an effort to relate teeth to

teeth, teeth to jaws, each jaw to the other and the jaws to the cranial base.

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Sample - 277 children 8 to 10 years of age with Class II

malocclusion were selected.

Effective maxillary length – Condylion to point A

Effective mandibular length – Condylion to Gn

Lower face height – ANS to Me

Anatomic portion is used

Measurements

a) Relating maxilla to cranial base – Determine by measuring

distance of point A to Nasion perpendicular.

b) Relating mandible to cranial base – Determined by measuring

distance from Pog to Nasion perpendicular.

Age Point A-NP Pog – NP

9 years 0mm -8mm to –6mm

Adult 1mm in front -2 to +2mm

c) Relating maxillary and mandibular height

9 years Adult male Adult Female

Effective maxillary length- 85mm 100mm 94mm

Effective mandibular length- 105mm 130mm 120mm

LFH - 60mm 70mm 66mm

d) Mandibular plane angle

FH to Go – M = 230

Low mandibular plane angle – Adequate ramus height

High mandibular plane angle – Short vertical height

e) Relating upper incisors to maxilla

Horizontal position

- Distance between point A perpendicular to the

facial surface of upper incisors = 4 mm

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Vertical position

- Incisal edge of upper incisors lies 2-3 mm below

the upper lip at rest.

f) Relating the lower incisor to mandible

Horizontal position

- Distance between A-Pog line and facial surface of

lower incisor = 2 mm

Vertical position

- Vertical position of lower incisors is evaluated on

the basis of existing anterior facial height.

RICKETS ANALYSIS (1960)

In this analysis mean value are given that change with growth and

those that remain stable.

Points

Pt- Located at lower border of foramen rotendum.

CC – Intersection of facial axis and cranial axis i.e. N to Ba.

Xi – Centroid of ramus

Pm – Protrubrance menti between point B and Pog.

Variables norms S.D. For 9 years old+age adjust

1) Facial axis 900 3 No adjustment

2) Facial angle 870 3 +10 Every 3 years

3) Mandibular plane 260 4 –10 every 3 years

4) Lower facial height 470 4 No adjustment

5) Palatal plane to PH 00 (1-2.5)0

6) Convexity of point A 2 2mm –1mm for every 3 years

7) LI to Apog 1mm 2 No adjustment

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8) U6 to Ptv Age 3 increase 1mm/year upto

maturity

9) Interincisal 1220 50

10) Lower lip to E line –2 2mm Less protrusive with growth

Interpretation

1. Facial axis

Indicate chin is upward and forward or down ward and backward.

2. Facial angle

Indicate mandibular prognathism or retrognathism.

3. Mandibular plane angle

Low mandibular plane angle – Adequate ramus height

High mandibular plane angle – Short vertical height of ramus

4. Palatal plane to FH

Indicate position of nasal floor and it is a objective in orthodontic

treatment to bring palatal plane parallel to the FH plane.

5. Maxillary convexity or convexity of point A

Helps in locating the position of maxilla with relation to cranial

base and it can be change with age and with mandibular growth.

6. Denture height

Angle made by connecting ANS, Xi and Pm points. Its

effectiveness represents the denture heights or lower facial height or

vertical relation between maxillary and chin.

7. LI to A Pog line

Helps in assessing lower incisor position in relation to existing

skeleton.

8. Upper molar to PTV

It is the indicator of upper denture position in the arch

anteroposteriorly.

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9. Interincisal angle

Helps in assessing degree of proclination or retroclination of

maxillary and mandibular incisors.

10. Lower lip and E line

Protrusion or retrusion of lower lip.

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