SUSNA SARAH PAUL
SEVEN SIGNS OF GROWTH ROTATION
BJORK'S FACIAL DIAGRAM
ANGULAR AND LINEAR PARAMETERS
Dr ARNE BJORK (1911-1996)
Arne Björk was born on 1911 in Dalarne, Sweden.
After his dental training in Stockholm, he practised
dentistry from 1937 to 1951.
During these years he also studied anthropology
and genetics at the Swedish Institute
for Human Genetics.
In 1947 he published the famous
dissertation “The Face in Profile”.
1949-1950 chairman of orthodontics in Malmo,
1951-1981 professor of orthodontics in Royal
Dental college, Denmark
1973 received the Ketcham award of Am. Board of
1980 nominated as member of World Federation of
Bjork conducted a study in 1951 using metal implants
to find the sites of growth and resorption in individual
jaws, and individual variation in direction and
Bjork gave seven structural signs to find the
direction of mandibular growth rotation.
FORWARD ROTATION OF
About the centre in the
About the centre located at
the incisal edges of the lower
Centre of rotation to the
BACKWARD ROTATION OF
Centre lies at the TMJ
Centre is at the most distal occluding
This occurs in connection with
growth in the sagittal direction at the
The soft tissue of the chin may not
follow this movement and a
characteristic double chin may form.
Difficulty in closing lips without
The seven signs were:
1.Inclination of the Condylar head.
2.Curvature of the Mandibular canal.
3.Shape of the lower border of mandible.
4.Inclination of the Symphysis.
6.Intermolar or Interpremolar angles.
7.Lower Anterior face height.
INCLINATION OF THE
Three groups of Scandinavian(Swedish) male school
Group I – 20 twelve year old
Group II – 322 twelve year old
Group III -281 high school graduates.
Roentgenograms taken at a distance of 155 cms were used.
The facial diagram was constructed and analysed.
He put forward a facial diagram in which the linear and
angular configurations determine the amount and
distribution of facial prognathism.
This facial diagram that implicates these changes
constitutes the Bjork’s Analysis.
LANDMARKS USED WERE:
A – Articulare.
Gn – Gnathion.
Pg – Pogonion.
Id – Infradentale.
Sp – spina nasalis anterior (ANS)
Dd – Chin angle, pt of intersection
of mandibular plane and line
tangent to ID and pogonion.
Pr – Prosthion
Kk – gonial angle
The plane of reference he took was
the SN plane.
Construction of facial diagram
A line drawn from the
prosthion to ANS to the
nasion, to the center of
sella turcica (S), to
articulare to the Gonial
angle (KK), to Chin angle
(DD), and from these to
Angles formed by lines at N
Angles formed by lines at S
Angle formed by lines at Ar
Angle formed by lines at KK
Angle formed by lines at DD
ANGLES AT NASION
These measures the facial
profile in relation to
the cranial base.
Max. Alv. Prog. 84±3
Mand. Alv. Prog.79±6
ANGLE AT SELLA
It provides a means of
measuring the shape
of the cranial base.
ANGLE AT ARTICULARE
It shows the forward or
backward diversion of
Facial prognathism may be due to
Shortening of the cranial base.
Angular deflection of the cranial base.
A small ramus – cranial base angle.
Increased jaw length.
Go ANGLE (KK)
INCREAED THAN NORMAL
INCREASED THAN NORMAL
INCREASED THAN NORMAL