2. ❏Skeletal
Land Marks
● A Point
● ANS
● BA(Basion)
● PT Point(The intersection of the inferior
border of the foramen rotundum with the
posterior wall of the pterygomaxillary fissure)
● CC(Centre of Cranium-Cephalometric
landmark formed by the intersection of the two
lines BA-NA and PT-GN)
● CF(Centre of Face- intersection of the line
connecting Porion and orbitale and
perpendicular through Pt)
● DC(Centre of neck of Condyle coinciding with
Basion Nasion Plane)
● GO(Point formed by intersection of Ramus And
Mandibular Plane)
● PM Point(A point selected at the anterior
border of the symphysis between point B and
pogonion where the curvature changes from
concave to convex)
● PO Point(Pogonion)
● Xi Point
3. ❏Dental
Landmarks
● A 6 (Upper molar). A point on the
occlusal plane located perpendicular
to the distal surface of the crown of the
upper first molar.
● B 6 (Lower molar). A point on the
occlusal plane located perpendicular
to the distal surface of the crown of the
lower first molar.
● TI point. The point of intersection of
the occlusal and the facial planes.
6. ❏ Deriving Xi Point (A Point located at the Geometric Centre of the Ramus)
● R1. Mandible. The deepest point on
the curve of the anterior border of the
ramus, one-half the distance between
the inferior and superior curves.
● R2. Mandible. A point located on the
posterior border of the ramus of the
mandible.
● R3. Mandible. A point located at the
centre and most inferior aspect of the
sigmoid notch of the ramus of the
Mandible.
● R4. Mandible. A point on the border
of the mandible directly inferior to the
centre of the sigmoid notch of the
ramus.
Xi Point is located in the centre of the rectangle at the intersection of diagonals.
7. ❏ Basic Reference Planes
● Horizontal reference plane
Frankfort horizontal (FH) plane is constructed by connecting the porion and the orbitale.
● Vertical reference plane
Pterygoid vertical (PTV) is constructed by drawing a line perpendicular to the Frankfort plane at the
posterior margin of the pterygopalatine fossa.The intersection of FH and PTV has been found to be
stable, i.e. the change in the location of this point as a result of patient growth is minimal. Therefore,
serial cephalometric tracings of a patient superimposed at this point are recommended.
● Facial Axis
It is a line from PT point through cephalometric Gnathion which normally interacts BA-NA at Right
Angles.
● Cranial Base Plane
It is a line formed by connecting BA-NA,in normal Caucasians it forms 30° with FH plane.
● Occlusal plane
It is a line bisecting the overbite of the molars and passing through the overbite of the first bicuspids.
The occlusal plane is nearly parallel to the Frankfort horizontal and palatal plane.
● Maxillomandibular relationship
Horizontally, the maxilla and mandible of the normal face are in alignment, both falling along the facial
plane. Vertically,the relation of the maxilla to the mandible is described by the lower facial height and
the intersection of two planes,ANS-Xi and Xi-PM. The norm for this measurement is 45° The maxillary
first molar normally is 21 mm anterior to the pterygoid vertical. The relationship of the maxillary to the
mandibular first molars is such that the maxillary molar is 3mm distal to the mandibular molar.
9. ❏ Eleven factor summary analysis
Provides an overview of the patient's craniofacial and dental growth direction.
1. Facial axis angle. This angle is formed by the intersection of BA-NA line and the facial axis. The angle describes the
direction of growth of mandible at chin. A larger angle indicates horizontal direction of mandibular growth while a smaller
angle is suggestive of more vertical growth. Facial axis angle remains stable in a normally growing child or reduce a little.
2. Facial depth angle. This angle is formed by the intersection of the facial plane and the Frankfort horizontal plane. This
angle gives the clinician an indication mandible (pogonion) in sagittal direction. This facial depth angle increases 1° every
3 years as the mandible grows forward and downward. In adulthood, the mean measurement is 90°.
3. Mandibular plane angle. The mandibular plane angle is formed by the intersection of mandibular plane and the Frankfort
horizontal plane. High mandibular plane angle indicates Leptoprosopic and low angle Euryprosopic.
4. Lower facial height. This is the angle formed by the intersection of a line from anterior nasal spine (ANS) to Xi-point and
the corpus axis (Xi-PM). A larger angle indicates a divergence of mandible and maxilla or vertical growth trend. Lower
facial height angle does not usually change significantly with age. However,this angle would be affected by treatment
mechanics,i.e. it may open or close the bite. Low values of angle are suggestive of horizontal facial pattern.
5. Mandibular arc. The mandibular arc is the angle formed by the intersection of the condylar axis (DC-Xi) and the distal
extrapolation of the corpus axis. It describes the configuration of the mandible whereby a large angle is indicative of a
'strong' and 'square mandible; a small angle represents a lower jaw with a short ramus and vertical growth pattern. Smaller
angles suggest a short romus and vertical growth trend. The norm for a 9-year-old child is 26° + or - 4º. It decreases
approximately 0.5° per year with growth.
➔ Measurements to locate the chin in space
10. 6. Convexity of point A. Facial convexity is the distance in millimeters from A point to the facial
plane, when measured perpendicular to that plane.The normal growth trend shows more anterior
growth of the mandible than the maxilla.Thereby a decrease in its measurement with age.At
maturity, the norm is 9 mm, indicating that A point lies along the facial plane a high convexity
indicates a Class II skeletal pattern; negative convexity, a skeletal Class III.
➔ Measurements to determine convexity
11. ➔ Measurements to locate denture in face
7. Lower incisor protrusion. This linear measurement relates the position of the tip of the lower central
incisor to the maxillomandibular relationship. The plane used to describe this relationship intersects
both A point and pogonion (A-PO). The distance from the tip of the incisor is measured perpendicular to
this plane. The position of the lower incisor has been associated both with aesthetics and stability as
suggested by Tweed. Labial or lingual movement of lower incisors affects archlength.
8.Mandibular incisor inclination. The angular measurement formed by the intersection of the long axis of
the lower central incisor and the A-PO plane is called the lower incisor inclination. The measurement also
relates the lower incisor to the maxillomandibular relationship.
9. Upper molar position. Upper molar position is the linear distance between the most distal point of the
maxillary first permanent molar, and the pterygoid vertical (PTV) measured parallel to the occlusal
plane.This measurement indicates mesial or distal position of the upper denture. It is also indicative of
whether or not the upper molar can be moved distally without impacting the maxillary second and third
molars. Norm is the patient's age (in years) plus 3 mm. At least 21 mm of maxilla (+/- 3 mm) is generally
needed in later years for proper eruption of the second and third molars.
10. Interincisal angle. The angle depicts cumulative proclination of the upper and lower incisors. It does
not quantify the proclination of maxillary/mandibular tooth.
12. ➔ Measurements to determine the profile
11. Lower lip to E-plane. The lower lip protrusion is evaluated by measuring the lower lip from an
aesthetic line constructed by joining the tip of the nose and the tip of the chin.
12. Maxillary depth. This angle is formed by intersection of FHP to a line from Nasion to A point. The
maxillary depth angle relates horizontal position of maxilla at point A to cranium (NA).
14. ❏ Summary
Ricketts cephalometric analysis essentially tries to orient face and
mandible to the cranium. His analysis was fundamental to this treatment
approach whereby he gave great emphasis to the growth and facial growth
pattern. The ultimate objective was to integrate growth to work out best
possible treatment plan.
