IDRR APRIL -MAY -JUNE 2020 - Flipbook - Page 85
handled incorrectly, these patients may suffer
from the complicated treatment process, and
the final result will be compromised, with a
high risk of relapse.
Most often the clinicians relay on the clinical
judgement for evaluation of mandibular shift,
which may include the photometric diagnosis,
manipulation of jaw to get the mandible to a
centric occlusion and clinical experience of
the respective clinician.
Quantitative diagnosis of the shift is very
important without which the there could
be variations when examined by different
clinicians.
In this article we use a panoramic analysis by
which exact measurements of the mandibular
shift can be diagnosed. This technique also
allows to understand whether the shift is due
to structural or functional problem.
This technique was developed by Dr.Diego
Tatis and when used correctly will give
consistent results.
PREREQUISITES FOR THE PANORAMIC
RADIOGRAPHY FOR THIS ANALYSIS
1.The OPG is taken without the interdental
bite block and the image is taken in closed
mouth with maximum intercuspation1.
2. The radiographic positioning has to be
done perfectly without any positioning
errors. Rotation of head in the horizontal and
vertical plane should be avoided 2
3. The film must register the entire anatomic
and radiographic structures.
4.The image should be of the highest
diagnostic quality with the appropriate
density, contrast and clarity.
85
April-May-June 2020
ORTHODONTICS
ANATOMIC LANDMARKS USED FOR THIS
ANALYSIS:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Condylion (Cd) – The most superior point
on the head of the mandibular condyle.
Cdr- condylion right, Cdl – condylion left.
Porion (P) ; The most superior point of the
outline of the external auditory meatus.
Roof of the mental foramen (Tfm)- The
most superior point of the mental
foramen.
Middle bi-mental point (bi-Me/2) –
Midpoint between the two mental
foramen on the Bi-mental plane .ie Bimenton plane has to be measured and
the midpoint will give the Bi-Me/2
Bi -menton plane: plane formed by
joining right Tfm point and left Tfm point.
TN’ plane : plane perpendicular to the
bi-porion plane passing through the TN’
point and ANS.
Bi-Porion plane: plane from right P point
to Left P point.
Cd- bimenton plane: Plane from Cd point
to Bi-mentonian/2 point.
TN’ point : central point of the nasal
septum, located at the height level of the
bi-orbital plane.
For understanding mandibular deviations, we
would need to triangles to know the deviation
and with which we could know whether the
deviation is structural or functional.
A] Craniomandibular Triangle:
•
•
Triangle formed by the points Pr-bi-Me/2Pl
Isosceles triangle: Two sides are equal
and one different.
www.idrr.in
ISSN: 0973-7499