Angles classification and cephalometric /certified fixed orthodontic courses by Indian dental academy

ANGLES CLASSIFICATION AND CEPHALOMETRIC
MEASUREMENTS OF FACIAL PROGNATHISM AND
SAGITTAL APICAL BASE DIFFERENCE

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


INTRODUCTION




Orthodontic diagnosis is an important criteria for the success of
any orthodontic treatment, it is pertinent that the orthodontist
have adequate knowledge of the dentoalveolar compensations
that with respect to the underlying skeletal relationships.
Even before Angle introduced his classification of
malocclusion

in

the

early

1900’s

the

anteroposterior

relationship was consider as an important clinical observation.
With the introduction of cephalometrics in 1930’s, the
importance has only increased.




Angles classification is the most widely used classification in
orthodontic diagnosis and treatment planning. This popular
system of classification has a number of drawbacks mainly
being that it represents only the dental relationship in the
sagittal plane and not the skeletal relationship.
In orthodontic

diagnosis and treatment

planning great

importance has been attached to evaluating the sagittal apical
base relationship. Both angular and linear measurements have
been incorporated into various cephalometric analyses to help

the clinician

diagnose anteroposterior discrepancies and

establish the most appropriate treatment plan.

A number of cephalometric parameters such as SNA, SNB, ANB
by Reidel and Steiners and Wits appraisal by Jacobson has been
introduced to evaluate the sagittal plane relationships of maxilla
and mandible.
In present study an attempt has been made
to

evaluate

the

skeletal

anteroposterior

relationships

between Angles malocclusion classes and cephalometric
measurements of facial prognathism such as SNA, SNB and

sagittal apical base difference such as ANB and Wits
appraisal.

Thus

the

validity

of

these

cephalometric

parameters may be assessed in the various malocclusion

classes.


Aims and Objectives


To evaluate and correlate the relationship between
Angle’s

malocclusion

classes

and

cephalometric

measurements of facial prognathism (angles SNA and
SNB) and sagittal apical base difference (angles ANB
and Wits appraisal).


Review of Literature:


Hurmerinta K et al (1997) : Study was done to evaluate
how 2 widely used cephalometric sagittal analyses, ANB angles
and WITS appraisal correlated. The results showed remarkable
differences

and

even

sparked

controversy

concerning

classification of sagittal jaw relationship.
Celar A G and Freudenthale (1999): study evaluated the
ability of some cephalometric measurements to differentiate
between horizontal and vertical malocclusions and normal

occlusion. Among the standard measurements, the wits
appraisal was the only one to show differences between all

horizontal groups with statistical significance. None of the
standard measurements could fully differentiate the vertical
groups.
Utomi I L (2004): Study was done to determine the antero
– posterior skeletal jaw relationship. Lateral cephalometric

radiograph were traced and analysed to produce values for
SNA, SNB, and ANB. The mean SNA was 82.4 degrees, mean
ANB 2.1 degrees. The normal range of ANB values was 0.5
degrees -4 degrees. The values obtained differ from those of
other population groups and should be used as guidelines in
the orthodontic treatment of the ethnic group studied.



.

Kasai K etal (1995): Study was done to investigate the

relationships between the cranial base and maxillofacial
morphology and to examine the differences between ClassI and

ClassIII samples. Results showed that the cranial base angle
was negatively correlated with SNA and SNB and positively
correlated with the palatal and occlusal plane angles. There

were

significant

differences

between

ClassI

and

ClassII

specimens in palatal width, SNA, ANB and the palatal plane
angle, but no significant difference in cranial base length or
angle.


Meterials and Methods:


This study was conducted in the department of Orthodontics
and Dentofacial Orthopaedics, A.B Shetty Memorial Institute of
Dental Sciences, Derlakatte, Mangalore.
CRITERIA OF SELECTION

• Sample consists of 100 untreated adult Orthodontic patients
above 18 years.
• Patients are classified into Angles classes on the basis of the
sagittal occlusal relationship between maxillary and mandibular first
molar.










Subjects are divided as follows:

Group I –

Consists of 35 untreated adult orthodontic
patients with Class I molar relation.

Group II – Consists of 35 untreated adult orthodontic
patients with Class II molar relation.

Group III – Consists of 30 untreated adult orthodontic
patients with Class III molar relation.
Subjects with a history of ectopic eruptions of the first permanent

molar, premature loss of primary molar such cases the occlusal
relationship between maxillary and mandibular canine is considered.



The patients are classified into a Class II category when a one
or both sided distal relationship is present.

•MATERIALS USED FOR THE STUDY:
• 100, well – oriented, good quality lateral cephalometric radiographs.
• Study models
• Acetate matte tracing paper ( 0.003 inch thick)

• Illuminated view box
• A sharp 3H, 0.5mm drawing pencil
• Geometry Box
• Paper clips




Patients are classified into Angle’s malocclusion classes such as
Angles Class I, Class II, ClassIII based on the sagittal occlusal
relationship of maxillary and mandibular first permanent molar.




Lateral cephalograms and study models of the patients are
prepared.
All lateral cephalograms were taken with the same cephalostat in
the Natural Head position.
The lateral cephalogram for each individual was traced accurately on

to the acetate tracing paper using 3H, 0.5mm pencil. The overall
tracings were carefully checked for any errors.



SNB

SNA -

The angle formed between S – N Plane and point A.

- The angle formed between S-N Plane and point B.

ANB - The angle formed by the intersection of lines extending from
Point A and point B of nasion.
Wits appraisal – The distance between points AO and BO which are
the points of contact of a perpendicular drawn from points A and B on

to the occlusal plane.


RESULT AND CONCLUSION


The results from this study showed that there was significant
correlation that existed between Angles malocclusion group
and skeletal base variables.




In Angle’s class I malocclusion group it showed a
prognathic maxilla, were SNA value is increased and
retruded mandible, were SNB value is decreased.
Skeletal base of this group showed a class II skeletal
base were ANB and Wits values is increased.
In Angle’s class II malocclusion group it also showed a
prognathic maxilla and retruded mandible. Skeletal
base of this group also showed a class II skeletal base
were ANB and Wits value is increased.




In Angle’s class III malocclusion group it showed a
retrognathic maxilla were SNA value is decreased and
prognathic mandible were SNB value is increased. The
skeletal base of this group showed a class III skeletal
base were ANB and Wits value is decreased.




Correlation of ANB and Wits appraisal:
The correlation
coefficient between the ANB angle and Wits appraisal was
very highly significant in each group. In present study, the
Wits appraisal showed a greater variation than the ANB
angle. It showed that when ANB value was 4 degrees or
more, it showed a positive Wits appraisal, there was a
significant correlation found when ANB and Wits were
positive. When ANB and Wits showed a negative value, there
was also a significant correlation between the two
parameters.






In individual diagnostic use, the angles SNA,
ANB and Wits appraisal should be handled with
caution.
In more recent years, alternative parameters
for establishing the anteroposterior relation
have been introduced. These include the Wits
appraisal using the maxilla – mandibular
bisector, anteroposterior dysplasia indicator
and beta angle. Since the validity and reliability
of these parameters in accurately forecasting
the anteroposterior relationship are not yet
established, further studies are required in
these field.



It does not suggest that clinicians should totally disregard any
previously established cephalometric measurements. Any
clinician should be aware of as many cephalometric analyses as
possible but should use them cautiously and appropriately. By
relying on a single cephalometric analysis that was developed
years ago, without periodically reevaluating it, diagnosis might
be misleading, and treatment planning based on such a
diagnosis can be insufficient or even harmful.


Thank you
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Angles classification and cephalometric /certified fixed orthodontic courses by Indian dental academy

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