CEPHALOMETRICS

ByShameel ahmed shariffGUIDED BY:

DR. SHASHIKALA Professor and H.O.D., Dept. Of orthodontics.DR. APARNA.DR. ROSHAN.DR. SHEELA.

Introduction History Equipment Technical aspect Positioning of the patient Exposure parameters Types Uses Landmarks and planes Analysis

CONTENTS

Assessment of cranio-facial structures forms a part of orthodontic diagnosis.

Craniometry can be said to be the forerunner of cephalometry.

Craniometry involved measurements of cranio facial dimensions of skulls of dead persons.

This method was not practical in living individual due to soft tissue envelope that made direct measurement difficult and far reliable.

Introduction

Cephalometry was a modification of anthropological studies and craniometry.

PACINI in 1922 published the first paper on cephalometry.

But it was BROADENT(USA) and HOFRATH(Germany) who introduced and popularized in 1931.

Clinical application of cephalometry was introduced by DOWNS.

History

Broadent bolton type: Uses two x ray sources and two film

holders. Lateral and AP cephalograms can be

taken without moving the subject. More precise results can be obtained..

EQUIPMENT

Broadent bolton type

Uses one x ray source and one film holder

Patient is repositioned for various projections..

Less reliable results as there is movement of subject.

HIGHLEYS TYPE

Other type of cephalometers of historical interest

HOFRATH TYPE Korkhaus, 1938

Bjork, 1951Thurow, 1951

Marcolis, 1940Waldo, 1938

Cephalometric radiographs are taken using an apparatus that consist of an x ray source and an head holding device called cephalostat.

Cephalostat consists of two ear rods preventing movement of head.

Vertical stabilisation of head is by orbital pointer contacting lower border of orbit.

Technical aspect

Upper part of face is supported by forehead clamp positioned above the region of nasal bridge.

The distance between the x ray source and mid saggital plane of the patient is fixed at 5 feet.

Thus the equipment helps in standardising the radiographs.

F.H. plane should be parallel to floor. Ear rods stabilize the patient on the horizontal plane.

Patient is made to close the mouth in centric occlusion.

Orbital pointer should be fixed for vertical plane stabilization of patient.

POSITIONING OF THE PATIENT

75 – 80 Kvp7 – 8 ma0.8 sec

Exposure parameters

Lateral cephalogram; provides lateral view of skull.

Frontal cephalogram; provides anteroposterior view of skull.

Types

Helps in orthodontic diagnosis. Helps in classification of skeletal and dental

abnormalities. Helps in planning treatment of an individual. Helps in evaluation of treatment results. Helps in predicting growth related changes.

Uses

LANDMARKS

S Sella: the midpoint of Sella Turcica N Nasion: the extreme anterior point on the

frontonasal suture sna Spina nasalis anterior: the extreme anterior

point on the maxilla snp Spina nasalis posterior: the extreme

posterior point on the maxilla Pt Pterygoid point: the extreme superior point

of the pterygopalatine fossa

A Point A: the deepest point in the curvature of

the maxillary alveolar process B Point B: the deepest point in the curvature of

the mandibular alveolar process Pg Pogonion: the extreme anterior point of the

chin Me Menton: the extreme inferior point of the chin Gn Gnathion: the midpoint between pogonion and

menton

Go Gonion: the midpoint of the mandibular angle between ramus

and corpus mandibulae

O Opisthion: the posterior border of foramen magnum

Ba Basion: the anterior border of foramen magnum

Cd Condylion: the extreme superior point of the condyle

Fc Fossa cranialis: the intersection between the sphenoidal plane

and the larger wing of the sphenoid

L Lambda: the midpoint of the lambdoid suture on the external

cranial contour

Horizontal planes: S.N. Plane – sella to nasion. F.H. Plane – orbitale to porion. Occlusal plane – plane bisecting posterior

occlusion. Palatal plane – ANS to PNS of palatine

bone. Mandibular plane – gonion to gnathion.

Planes used in cephalometrics

VERTICAL PLANES: A-Pog line – point A on maxilla to pogonion

on mandible. Facial plane – nasion to pogonion, Facial axis – ptm point to gnathion. E-plane – esthethic plane is a line between

the most anterior point of soft tissue nose to soft tissue chin.

It is one of the most frequently used cephalometric analysis.

Downs analysis consists of ten parameters of which five are skeletal and five are dental.

Downs analysis;

Facial angle; it is the inside inferior angle formed by

intersection of nasion-pogonion plane and F.H. plane.

average value; 87.8’ ( 82 – 95’) significance; indication of antero-

posterior positioning of mandible in relation to upper face. Angle is increased in skeletal class III with prominent chin while decreased in skeletal class II.

Skeletal parameters;

Angle of convexity; Nasion-point A to point A – pogonion. Average value; 0’ ( -8.5 to 10’). Significance; A positive angle suggest a

prominent maxillary denture bace in relation to mandible.

Negative angle is indicative of prognathic profile.

A-B plane angle; point A – point B to nasion – pogonion. Average value; -4.6’ ( -9 to 0’) Significance; indicative of maxillo

mandibular relationship in relation to facial plane.

Negative since point B is positioned behind point A.

Positive in class III malocclusion.

Mandibular plane angle; Intersection of mandibular plane with F.H.

Plane. Average value; 21.9’ ( 17 to 28’)

Y-Axis; Sella gnathion to F.H. plane. Average value; 59’ ( 53’ to 66’) Angle is larger in class II facial patterns.

Indicates growth pattern of a individual.

Cant of occlusal plane; OCCLUSAL PLANE TO F.H. Plane Average value; 9.3 ( 1.5 to 14’) Gives a measure of slope of occlusal plane

relative to F.H. Plane.

Inter incisal angle; Angle between long axes of upper and lower

incisors. Average value: 135.4’ ( 130 to 150.5’) increased in class I bimaxillary protrusion.

DENTAL PARAMETERS

Incisor occlusal plane angle; This is the inside inferior angle formed by the

intersection between the long axis of lover central incisor and the occlusal plane and is read as a plus or minus deviation from a right angle

Average value: 14.5” ( 3.5 to 20’) An increase in this angle is suggestive of

increased lover incisor proclination.

• Incisor mandibular plane angle: This angel is formed by intersection of the long

axis of the lower incisor and the mandibular plane. Average value: 1.4’(-8.2 to 7’) An increase in this angle is suggestive of

increased lower incisor proclination.

Upper incisor to A-pog line: This is a linear measurement between

the incisal edge of the maxillary central incisor and the line joining point A to pogonion. This distance is on an average 2.7 mm(rang-1 to 5 mm)

The measurement is more in patients presenting with upper incisor proclination.

SNA (Maxillary position)  82.0

SNB (Mandibular position)  80

ANB (Maxillary/Mandibular relation)  2

l to NA (Upper incisors to NA mm) 4mm

l to NA (Upper incisors to NA degree)  22

l to NB (Lower incisors to NB mm)  4mm

l to NB (Lower incisors to NB degree) 25

l to l (lnter-incisal angle)  131

SN to GoGn (Mandibular plane angle 32

SN to occlusal plane  14

Steiners analysis

FMA (Frankfurt plane to mandibular plane) 

25.0 25.8 +- 5.19

FMIA (Frankfurt plane to lower incisor angulation) 

65.0 62.7 +- 6,97

IMPA (Lower incisor to mandibular plane) 

90.0 91.5 +- 5.97

TWEED ANALYSIS

TWEEDS TRIANGLE

"Wits" Male mm -----------------------------------------

1.0 -2.9 +- 2.45

"Wits" Female mm --------------------------------------

0.0 -2.5 +- 2.54

THE WITS APPRAISAL

It determines the extent to which mandible and maxilla are related to each other.

Wits appraisal is used in cases where the ANB angle is considered not so reliable due to factors such as position of nasion or rotation of jaws.

The method includes drawing an occlusal plane through overlapping cusps of first premolars and molars.

Then perpendiculars are drawn to occlusal plane from point A and point B.

The point of contact are termed as AO and BO.

Distance between AO and BO gives antero posterior relationship between two jaws.

Method

WITS APPRAISAL

Beggs techniques, Bishara, Graber, modern principles, M.S.Rani, Balaji, Internet,

References

Dr. Shashikala madam, My Parents, My Sister, Dr.Ayesha, My brother, Dr.Suhail Mr. Sadakath, Librarian sir,

Acknowledgements