Dr. Kazem AL-Nimri BDS, Ph.D, M.Orth.R.C.S

Cephalometrics introduced for use by orthodontists in 1931 by Dr. Broadbent in the USA and Hofrath in Germany independently of one another.

Cephalo: head Metric: measurments

Cephalometry: is the analysis and the interpretation of standardized radiographs of the facial bones.

It is a standardized and reproducible

form of skull radiography used extensively in orthodontics to asses the relationships of the teeth to the jaws, and the jaws to the rest of the facial skeleton.

Head position: the patient’s head is oriented in the same position relative to the x-ray beam every time a film is taken, with the use of a cephalostat.

Ear rods: in the ear canals (external auditory meatus).

Frankfort plane: horizontal. Teeth: in centric occlusion. Lips: in their habitual position.

Assess facial and dentoskeletal relationships.

To study growth and growth patterns Evaluation of post treatment

changes. Research purposes and long term

follow-up studies.

The cranial base. The facial skeleton. Soft tissues.

The midpoint of the sella turcica

The most inferior anterior point on the margin of the orbit

• Sella Turcica (S)

• Orbitale (Or)

The most anterior point of the frontonasal suture

The most posterior inferior point on the clivus (basiocciput). It represents the posterior limit of the midline cranial base.It lies on the anterior margin of foramen magnum.

• Nasion (N)

• Basion (Ba)

The tip of the anterior nasal spine

The tip of theposterior nasal spine

• Anterior Nasal Spine (ANS)

• Posterior Nasal Spine (PNS)

The most posterior point on the profile of the maxilla between theanterior nasal spine and the alveolar crest

The most posterior point on the profile of the mandible between the chin point and the alveolar crest

• A point

• B point

The most anterior point on the bony chin

The lowermost point of the mandibular symphysis in the midline

• Pogonion (Pog)

• Menton (Me)

The most inferior point on the mandibular symphysis in the midline

The most posterior inferior point on the angle of the mandible

• Gnathion (Gn)

• Gonion (Go)

The uppermost, outermost point on the bony external auditory meatus

• Porion (Po): superior point of external auditory meatus

• Machine Porion: landmark created by ear post of cephalostat

The intersection of the posterior border of the neck of the mandibular condyle and the lower margin of the posterior cranial base

The most superior posterior point on the head of the mandibular condyle

The tip of the crown of the most prominent upper incisor

The tip of the crown of the most prominent lower incisor (E-lower incisor edge)

• 1: most anterior upper central incisor __• 1: most anterior lower central incisor • 6: upper permanent first molar __• 6: lower permanent first molar

Sella - Nasion plane:S – N Represent the cranial base

De Coster’s line:Follows the floor of the anterior cranial base from the anterior margin of the ethmoid bone to sella turcica

Maxillary line:ANS - PNS

Mandibular plane:Me - Go

Line drawn from Menton (Me) to Gonion (Go)

Occlusal plane:Cusp tips of molars – tip of lower incisor

Functional occlusal plane (FOP):Passes through the occlusion of the premolars or deciduous molars and the first permanent molars

The Line from point A to pogonion:A – PogFor best aesthetic results: -lower incisor edges lay on A-Pog line (Willians, 1969)

Measurement:

Skeletal relationships : Sagittal basal relationships Vertical basal relationships

Dentoalvealar relationships

Soft tissues analysis

Angle SNA (82 ± 3)

Prognathism of maxillary apical base

Angle SNB (79 ± 3)

Mandibular prognathism

Angle ANB (3 ± 1)The

anteroposterior apical base relationship (skeletal pattern)

Jaw discrepancies (maxillary and mandibular).

Anteroposterior position of the Nasion Inclination of S-N line to the Frankfort

plane. Lower anterior facial height.

Wits analysis (Jacobson, 1975)

Compares the relationships of the maxilla and mandible with the occlusal plane (FOP)

S-N-POG (87 ± 3)

Indicate the anteroposterior

position of the chin

Maxillary-mandibular planes angle (Mx-Mn or MM angle) (27 ± 5)

Frankfort-mandibular planes angle (FM angle) (27 ± 5)

If the SN line inclination from the True horizontal or from Frankfort plane deviates more than 6 degrees, and less than 11 degrees, measurements based on the SN line should be corrected by this difference.

Face height ratio

(Me-Mx / N-Me) (50 - 55 %)

To estimate the anterior intermaxillary height

Gonial angle (Ar-TGp / TGi-

Me)(126 ± 5)

Upper incisor to maxillary plane angle (UI / Mx) (108 ± 5) Lower incisor to mandibular plane

angle (LI / Mn) (92 ± 5) Interincisor angle (UI / LI) (133 ± 10) Lower incisor edge to A-Pog distance

(E↓ A-Pog) (0-2 mm)

UI / Mx plane angle (108 ± 5)

LI / Mn plane angle (92 ± 5)

Interincisal angle (133 ± 10)

E↓ A-Pog (0-2 mm)E↓ C↑ (0-2 mm)FOP / Mx (10 ± 4)

Cephalometric superimpositions involve the evaluation of:Changes in the overall face.Changes in the maxilla and its dentition.Changes in the mandible and its

dentition.Amount and direction of condylar

growth, and mandibular rotation.

(Kristensen, 1989)

The most accurate superimposition is obtained by tracing the first radiograph and superimposing that tracing on the second film, registering the appropriate cranial base structures. (Ekstrom, 1982)

Reliable picture of overall facial growth. Superimposition on: S-N line with registration at sella

(reliable) De Coster’s line (more reliable).

Maxilla is subject to extensive periosteal remodelling.

Superimposition on: The anterior surface of the zygomatic

process – little periosteal remodelling with growth (Bjork and Skieller, 1979) (not easily seen and too short).

Anterior surface of the palatal vault. The maxillary plane (at PNS)(contour of

the palate at the alveolar process base).

The mandible undergoes rather complex remodeling changes (anterior / posterior growth rotations.

(Bjork and Skieller,

1972)

Superimposition on: The inner contour of the cortex of

the mandibular symphysis (most useful).To evaluate remodeling in the mandible with

growth.To evaluate changes in the lower incisor

position. The contour of the mandibular canal. The crypt of the developing third

permanent molars (from the time of commencement of mineralization until root formation begins).

A digitizer comprises an illuminated radiographic viewing screen connected to a computer.

Information from a lateral cephalometric radiograph is entered into the computer by means of a cursor which records the horizontal and vertical (x,y) co-ordinates of cephalometric points or bony or soft tissue outlines.

Specialized software employed to utilize the information entered to produce a tracing and/or the analysis of choice.

Research purposes.

Digora scanner.

Studies have shown digitizers to be as accurate as tracing a radiograph by hand.

There was no difference in the regional superimpositions of the mandible, the maxilla, and the cranial base, manually vs digitally with Quick Ceph 2000.

(Roden-Johnson et al., 2008)