dipaolos analysis and point a revisited orthodontics cephalometry

2. AJO,1984
The quadrilateral analysis concerns primarily with the skeletal
configurations of the individual dentofacial complex in both the
horizontal and the vertical dimensions regardless of dentoalveolar
relationships.

3. COMPARISON WITH STANDARD METHODS
• The standard method of anteroposterior jaw measurement was the
ANB angle. But this proved to be varied as the positions of the
anatomical landmarks greatly influenced the readings. eg-The
horizontal and vertical shift of the nasion affected the readings and
also the rotation of the jaws.
• The WITS appraisal was a more effective means to measure this
relationship as it was unaffected by the shift in the position of the
nasion or the rotation of the jaws.
• But the problem with the wits appraisal was that it was unable to
determine which jaw was affected or the extent of the variation

4. • Model surgery gives the clinician only an approximate,
dimensional, and visual rendition of what the jaw-to-jaw
relationship would look like after surgery.
• It does not locate or indicate the extent of the skeletal dysplasia;
nor does it permit the surgeon to position the incisors accurately
as related to the soft-tissue profile of the patient.

5. MATERIAL AND METHOD
• equally divided male and female patients with a mean
age of 12.6 yrs were studied.
• In order to group the patients into the different skeletal
patterns, the palatal plane angle was used.
• patients with a palatal plane angle of 22o to 25o were
considered normal,
• while those below 21o were classified as hypodivergent,
• those above 29o as hyperdivergent.

6. MAXILLARY BASE LENGTH
• The maxillary base length is determined
horizontally between two points
projected on the palatal plane.
• The anterior limit : perpendicular from
point A upward to the palatal plane
• posterior limit :a perpendicular from the
most inferior portion of the
pterygomaxillary fissure down to the
palatal plane.

7. MANDIBULAR BASE LENGTH
• The mandibular base length is
measured horizontally between two
points projected on the mandibular
plane.
• The anterior limit : project a
perpendicular from point B downward
to the mandibular plane
• posterior limit : project a
perpendicular from point J downward
to the mandibular plane.

8. • ANTERIOR LOWER FACIAL HEIGHT is measured from the projection
of point A onto the palatal plane to the projection of point B onto
the mandibular plane.
• POSTERIOR LOWER FACIAL HEIGHT is measured from the
projection of PTM onto the palatal plane to the projection of point
J onto the mandibular plane.
• ANTERIOR UPPER FACIAL HEIGHT is measured from the projection
of point A onto the palatal plane to the nasion on the cranial base
plane.
• A proportional relationship exists between the anterior upper facial
height and anterior lower facial height of 45:55

10. QUADRILATERAL ANALYSIS
The concept of lower facial proportionality states that in a balanced
facial pattern :
• there is a 1:1 proportionality that exists between the maxillary
base length and the mandibular base length,
• the average of the anterior lower facial height (ALFH) and
posterior lower facial height(PLFH) equals these denture base
lengths. Therefore max length =mandibular length=ALFH+PLFH
2

11. DENTAL ANALYSIS(QUADRILATERAL)
1: pogonion line
2: point A line
3: point B line
4: anterior lower facial
hieght

12. SAGITTAL RATIO
• The sagittal ratio is important in assesing the relative
anteroposterior position of the maxillary and the mandibular bony
bases.
• Skeletal malformations of the jaws may be either in the bony bases
or located posteriorly. Therefore pinpointing the area of the
deformity will have a significant impact on whether or not certain
surgical procedures are indicated.
• for eg- In a case of mandibular prognathism it would be necessary
to determine whether the reduction of the bony base length is
required or the mandibular surgery posterior to the bony base
area.

13. • The lines that are used to measure the bony base lengths in the
quadrilateral pattern are extended posteriorly to a point X. This
forms the sagittal angle.
• The ratio of A to B and C to D is called the sagittal ratio.
• In balanced skeletal patterns the sagittal ratio :
• in adoloscents is 1.0:1.50
• In adults it is 1.0:1.45 ± 0.05

14. ANGLE OF FACIAL CONVEXITY
• Anterior lower facial height and anterior upper facial height
intersect at a point A on the palatal plane.
• The intersection forms an angle of facial convexity.
• This angle relates the quadrilateral to the cranial base and
upper face and is a means of establishing a skeletal profile
assessment

15. • this angle of facial convexity may be the same with different skeletal
patterns.
• Various rotations of the lower facial complex result in different
profiles yet lower “balanced” relationship of the dental arches.
• This is the result of:
1. Relative size differences of the maxillary and mandibular bony
bases.
The maxillary base
length = 45mm
mandibular base
length = 39mm

16. 2. Relative position of the maxillary and mandibular
bony bases.
Maxillary and mandibular base length =49mm
posterior legs are 125mm and 118mm respectively

17. 3.Vertical dysplasia of lower face:
Lower facial height = (80+50)/2=65mm which is greater than the
maxillary and mandibular base length
PLFH:ALFH::1:1.6

18. 4.Spatial rotation of the lower face
Determined by the cant of palatal plane to the upper
facial hieght

21. DISCUSSION
• CASE I:
• 16yr old white girl with Class III malocclusion having an
anterior crossbite and minimum vertical overbite of central
incisors with an openbite extending bilaterally from lateral
incisors to 2nd premolars
• Facial convexity 183o
• SNA angle 74o
• SNB angle 70o
• GoGn-SN anlge 41o

22. Maxillary base length =50mm
Mandibular bony base length =59mm
So,9mm discrepancy anteroposteriorly
ALFH=67mm
PLFH=37mm
LFH=(67+37)/2=50mm
So if mandibular bony base length is reduced by 9mm it becomes
proportional
Maxillary and mandibular posterior legs are both 71mm
Therefore the defect is in the bony base length and not the bony base
positioning

23. • If surgery were performed on the basis of normal diagnostic
information, the procedure would most likely be a combination of
maxillary advancement and impaction.
• But after the quadrilateral analysis the mandibular base length was
found to be faulty and the final treatment plan was :
• 18mnths presurgical orthodontic correction to align the maxillary
and mandibular teeth within each jaw
• Sagittal split procedure to reduce the mandible by 7mm
• Therefore improving the angle of facial convexity to 171o

24. • CASE 2:
• 17 yr old white girl with class III malocclusion, concave profile with
complete anterior crossbite and 3-4mm vertical overbite.
• Maxillary 1st premolars missing and mandibular 1st premolars were
malformed.
• Maxillary arch was constricted
• Moderate lower incisor crowding
• Facial convexity 179o

25. • Quadrilateral analysis:
• Maxillary base length =mandibular base length =51mm
• Maxillary posterior leg = 128mm
• Mandibular posterior leg = 136mm
• Therefore skeletal dysplasia was posterior to the mandibular bony
length

26. • The plan of treatment consisted of:
• Removal of mandibular 1st premolars
• Followed by 14mnths of presurgical orthodontic correction
• Vertical osteotomy was performed resulting in 8mm
reduction posterior to bony base
• Angle of facial convexity improved to 168o

27. CONCLUSION
• Surgical orthodontics requires reliable diagnostic methods that can
differentially assess the location and degree of the skeletal
dysplasias.
• The quadrilateral analysis not only attempts to satisfy these
objectives but also gives the clinician an individualized skeletal
assessment
• Proper incisal positioning prior to surgical intervention is essential if
we are to achieve optimum denture base relationships.
• An undesirable position of the upper and/or lower incisor teeth will
cause the surgeon to be misled during surgery, resulting in a less
than desirable facial harmony.

28. AIM: To show that this analysis has the capability of depicting any facial disharmony in
either the horizontal or the vertical dimension.
AJODO, 1970

29. MATERIAL AND METHOD
• A total of 180 untreated patients, between 9 and 15 years of age, were
selected for this study and grouped as follows:
1. Thirty-two patients with good occlusion.
2. Thirty patients with Class I malocclusion.
3. Twenty-nine patients with Class II malocclusion.
4. Twenty-nine patients with Class III malocclusion.
5. Twenty-nine patients with obvious hyperdivergent facial patterns.
6. Thirty-one patients with obvious hypodivergent facial patterns.
• The quadrilateral was constructed on tracing each patient’s lateral
cephalogram.

30. FACIAL TYPES
Type 1- facial growth pattern: Downward and forward growth.
• Quadrilateral structure with fairly equal bony arch lengths.
• Average vertical height equal to the maxillary arch length, indicating
harmony with the upper face.
• Malocclusions in this group are dentoalveolar in origin.
• Imbalance in tooth size to arch, forward position of upper teeth to
lower teeth, or forward position of lower teeth to upper teeth, etc.

31. Type 2 facial growth pattern: Horizontal growth dominance with little
vertical growth.
• Reduction of lower face height accompanies this pattern.
• Deep-bite associated with undesirable growth.
• Quadrilateral configuration exhibits deficient average vertical height
compared to maxillary arch length.(hypodivergent pattern)
• Subdivisions:
- A. Upper and lower bony arches are comparable in size.
- B. Upper bony arch is larger than lower bony arch.
- C. Lower bony arch is larger than upper bony arch.
Malocclusions of dentoalveolar origin may accompany all subdivisions

32. .
Type 3- facial growth pattern: Vertical growth dominance with little
horizontal growth.
• Increased lower face height accompanies this pattern.
• Open-bite associated with undesirable growth pattern.
• Quadrilateral configuration exhibits excessive average vertical height
compared to maxillary arch length. (hyperdivergent pattern)

33. RESULTS

34. An analysis of the geometry involved explains these findings.
Focusing solely on angle
measurements without
considering spatial
relationships and anatomical
context is significantly more
crucial.
Failure to consider lower face
height relative to these factors
can result in inaccurate
diagnoses.

35. CONCLUSION
 Accurate Diagnosis: Provides precise diagnosis for skeletal dysplasia
in both horizontal and vertical dimensions.
 Degree of Discrepancy: Indicates and quantifies the extent of the
discrepancy.
 Representation of Malocclusion: Shapes of the quadrilateral
accurately represent various malocclusions.
 Individualized Analysis: Tailored to each patient's maxillary and
mandibular functional units.
 Irrelevance of Patient Comparison: Treatment isn't based on
comparing patients to norms, focusing solely on individual needs.

36. AJODO, 1987
Aim:- To use the cephalometric lateral films to
determine the occlusal plane position for the
individual patient.

37. DETERMINING THE OCCLUSAL PLANE
POSITION
• Sagittal ratio is the ratio of the length of the PLFH to the
length of ALFH-namely, P : A.
• This ratio can then be expressed as 1:A/P.
• After the sagittal ratio is determined for the patient, it can
then be used to divide both the ALFH and the PLFH into
two parts. According to the ratio, this will divide the
quadrilateral into maxillary and mandibular parts.

38. • The sagittal ratio is 1 :A/P and P is
IN + A/P*N where N is the posterior
maxillary height and A/P*N will be
the posterior mandibular height.
• Similarly A= IM + A/P*M
• A line is drawn connecting the
points that divide the posterior
lower facial height and the anterior
lower facial height.
• This line becomes the occlusal
plane position for the patient .

39. • He took lateral ceph. of 18 girls and 17 boys between the
ages of 10 and 14 years.
• The occlusal plane position was located on each of the
cephalometric films by drawing a line between the
occlusal surfaces of the maxillary and mandibular 1st
molars and the maxillary and mandibular 1st and 2nd
premolars through the cusps of the teeth.
• Measurements were taken between the palatal plane and
the occlusal plane along the lengths of the PLFH and the
ALFH. This is anterior and posterior maxillary heights

40. • Similarly, measurements between the occlusal plane
position and the mandibular plane were taken and this is
anterior and posterior mandibular heights.
• Then, with the quadrilateral pattern and sagittal ratio of
each patient in the sample, the occlusal plane was
determined by the formula also.
• The results obtained from the direct measurements of the
drawn occlusal plane and the palatal plane position, and
the formula-determined measurements came out to be
similar

41. CONCLUSION
• A relationship exists between the occlusal plane position
and the lower-face skeletal pattern of the patient.
• The occlusal plane position can be determined after
identifying the individual skeletal pattern present.
• Identifying the occlusal plane position becomes an
important factor in dentistry, especially in procedures in
which changes occur in the occlusal relation, such as in
maxillofacial surgery, prosthetics, and orthodontics .

42. AIM:-The objective of this article is to pinpoint Point A, especially in
circumstances where its identification proves difficult.
AJODO,1980

43. POINT A
• Bjork defined it as the “deepest point on the contour of
the alveolar projection between the spinal point and
prosthion.”
• Located somewhere between
the root apex (and even
occasionally above this point)
and the coronal third of the
root of the tooth

44. MATERIALS AND METHODS
• 33 lateral cephalometric radiographs were selected.
• Acetate paper was placed over the radiographs 
nasion and point A were identified in each instance.
• These points were joined by a line NA drawn the outline
of the maxillary central incisor was traced along with
the long axis of the root of this tooth.

45. • On this long axis the following points were located
X = Root apex.
Y = Junction of upper third and lower two thirds of root length.
Z = Midpoint of root length.
• From these points, lines were dropped perpendicular to the NA
line, and points X1, Y1and Z1, were thus identified
• The lengths of the lines
• X-X1
• Y-Y1
• Z-Z1
• were measured and recorded.

46. RESULTS
• The means, variance, standard deviation and standard
error of the means of the measurements were
calculated
• The standard deviation of 1.075 for the Y-Y1 least
among the three.
• Consequently, the Y-Y1 was the parameter of choice.

47. • Therefore in the event of point A being difficult to locate,
an estimated NA line could be drawn from nasion through
point AE which, in turn,
• 3 mm ahead of a point between the upper third
and lower two thirds of the root axis of the
maxillary central incisor.

48. SUMMARY
• Point A cannot be accurately identified in all cephalometric
radiographs. In instances where this landmark is not clearly
discernible.
• An alternative means of estimating the anterior extremity of the
maxillary base is : A point plotted 3.0 mm labial to a point
between the upper third and lower two thirds of the long axis of
the root of the maxillary central incisor was found to be a
suitable point  through which draw the NAE line and one
which most closely approximates the true NA plane.

49. AIM : Main aim of this article is to see commonly used cephalometric landmarks follow
the accepted definition or not .
AJODO ,1971

50. MATERIAL AND METHOD:
• 64 skull of Asiatic Indians were studied .
• The pertinent bony structure were studied on the skull by
visual inspection and linear measurement was taken. Same
outline were then compared with the image of radiograph.
• The lateral cephalogram of 60 living person, representing
different developing stages were analysed to determine
whether the information obtained from the skull material
could be applied to living subjects.

51. FINDINGS:
• Point A didn’t follow the definition as the anterior outline
between anterior nasal spine and prosthion but was caused by
the para-sagittal structures in the inferior region and by midline
structures superiorly.
• The replacement of deciduous teeth by permanent ones is
associated with a renewal and reconstruction of the alveolar
bone so, there is constant change in position of point A from
deciduous to permanent dentition.

52. • The more anteriorly placed and labially inclined permanent
incisor crowns have more protruding accompanying alveolar
structures, as could be detected and recorded with the
contour gauge. The reverse is true for the relative height of
the distance from anterior nasal spine to prosthion. The
larger this distance, the more point A seemed to be located
superiorly and dorsally.

53. • Point L is independent of the midline structure and is, by
definition, located at the apical base region.
• When the permanent incisors before eruption are
positioned with their crowns at the apical base region, the
definition of point L has to be adapted to this situation.
• When the permanent incisors are erupted and their roots
are not fully formed, point L is located at the root end.
• Point L stays as such in more or less the same vertical
position when the root develops further and the tooth
continues to erupt.

54. SUMMARY:
• Individual local variations in skeletal structure played a role in the
location of sella, nasion, prosthion, infradentale, menton,
gnathion, and especially point A.
• Because of the considerable shortcomings of point A, a new
landmark, point L, has been suggested, tested, and found to be
superior.

55. AM.J.Orthodontics , 1978
AIM-The purpose of this study was to compare the accuracy of landmark identification
between xeroradiographic cephalograms and conventional cephalograms.

56. XERORADIOGRAPHY
• It is the process of recording a latent radiographic image on a selenium-
coated aluminum plate. The image is then transferred to a specially treated
paper for visualization.
• The selenium coating contains a uniform positive charge which, when
exposed to x-radiation, is selectively discharged according to the density of
the object being radiographed.
• In addition to the selenium-coated plates and plastic cassettes which hold
them, the Xerox System 125 consists of two free-standing units-a
conditioner which prepares the selenium-coated plates for exposure and a
processor which develops the image and transfers it to the special paper.

57. • In the processor a negatively charged blue powder is misted onto
the exposed plate, adhering differentially to the positively charged
selenium and resulting in a visible image.
• The image is transferred to the paper which is then heated,
making it permanent. The whole process is fully automatic, taking
90 seconds to complete.

58. MATERIAL AND METHOD
Spherical lead markers, 1 mm in diameter, were used to identify
fourteen landmarks on a dried skull. The skull was positioned in a
Wehmer wall-mounted cephalometer. A xeroradiographic
cephalogram and a conventional radiographic cephalogram were taken
with a Picker KMS300 medical x-ray unit at a film-focus distance of
60 inches (Fig. 1 and 2).

59. • Following the initial exposures, the lead markers were removed
without disturbing the skull position in the cephalostat. Another
xeroradiograph and conventional radiograph without lead markers
were made, using the previously described exposure values and
processing techniques.
• Ten examiners were asked to identify the fourteen landmarks on the
xeroradiograph without markers and on the conventional radiograph
without markers.
• The distances from their readings to the actual landmarks were then
measured by two examiners using vernier calipers.

60. RESULT
• The distances between the
actual landmarks and the
examiner-identified landmarks
for point A, upper incisor tip,
infradentale, and menton were
significantly less when
measured from the
xeroradiograph than when
measured from the
cephalogram.
• The distances for point B and
condylion were significantly less
when measured from the
conventional cephalogram.

61. CONCLUSION
• Four landmarks-point A, upper incisor tip, infradentale, and
menton-were more accurately determined on the
xeroradiograph, while two landmarks-point B and condylion-
were more accurately determined on the conventional
cephalogram.