The document discusses several topics related to facial growth and development: - Facial growth is completed in width, length, and height, with growth in width finishing before puberty and growth in length and height continuing through puberty. - The mandible can undergo internal and external rotation, affecting the mandibular plane angle and position of the chin. - Factors like inclination of the condyle can predict whether future mandibular growth will involve forward or backward rotation. - Jaw rotation influences tooth eruption and positioning, with forward rotation tipping incisors forward and backward rotation uprighting them.

1. FINAL YEAR BDS
DR. TANIA ARSHAD SIDDIQUI

3.  Growth is completed in width (transverse plane),
length (sagittal plane) and height (vertical
plane)
 Growth in width completed before adolescent
growth spurt
 Growth in length and height continues through
puberty
 Late vertical growth occurs primarily in mandible
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4. CONDITION BJORK SOLOW, HOUSTON PROFFIT
Posterior growth
greater than
anterior
Forward Rotation
Anterior growth
greater than
posterior
Backward rotation
Rotation of
Mandibular Core
relative to cranial
base
Total rotation True rotation Internal rotation
Rotation of
mandibular plane
relative to cranial
base
Matrix rotation Apparent rotation Total rotation
Rotation of
mandibular plane
relative to core of
mandible
Intramatrix
rotation
Angular
remodelling of the
mandible
External rotation

5. • Internal Rotation- occurs in core of jaw bone. In mandible,
it is the bone that surrounds IAN
• External Rotation- occurs on jaw bone surface.
• In mandible, the functional processes are:
• Alveolar process
• Muscular process
• Condylar process

6.  Has two components:
 Rotation around condyle (25%)
 Rotation centered within body of mandible (75%)
 Decreases mandibular plane angle
 Rotates mandible up anteriorly and down
posteriorly

7.  Increases mandibular plane angle
 Rotates mandible down anteriorly
 Direction is backward, Clockwise
 Given a positive sign
 Chin comes downward and backward

8.  Implant Radiography- Inert metal pins are placed .
Developed by Dr. Arne Bjork
 7 areas on cephalogram which predict future
mandibular growth direction:
 Inclination of condyle
 Curvature of mandibular canal
 Shape of lower border of the mandible
 Symphysis inclination (anterior aspect below point B)
 Interpremolar / intermolar angle
 Interincisal angle
 Lower anterior face height

9. Structure Forward Rotator Backward Rotator
Inclination of
condyle
Curves forward
Straight OR slopes up
and back
Curvature of
mandibular canal
Curved forward Straight
Shape of lower
border of the
mandible
Curved downward
Notched, antegonial
notch
Symphysis
inclination
(anterior aspect
below point B)
Slopes backward Slopes forward
Interpremolar /
intermolar angle
Vertical OR obtuse Acute
Interincisal angle Vertical OR obtuse Acute
Lower anterior face
height
Short Long

10.  Less easy to divide maxilla
 Core is above the alveolar process and this is the site
of internal rotation
 External rotation is modeling of the palate and
dento-alveolar growth
 External rotation is opposite in direction and equal in
magnitude to internal, hence the net effect is zero

11. SHORT FACE LONG FACE
Forward rotation Backward rotation
Decreased LAFH Excessive LAFH
Horizontal palatal
plane
Palatal plane rotates
down posteriorly
Low mandibular plane
angle
Increased mandibular
plane angle
Square shape and
prominent gonial
angle
Internal rotation at
condyle
Deep bite and
crowded incisors
Anterior open bite
and mandibular
deficiency occurs

12. SHORT FACE

13. LONG FACE

14. RATIO OF POSTERIOR FACE HEIGHT TO
ANTERIOR FACE HEIGHT
RATIO OF LOWER ANTERIOR FACE HEIGHT
TO TOTAL ANTERIOR FACE HEIGHTY-AXIS
SUM OF POSTERIOR ANGLES SN- MANDIBULAR PLANEMAXILLOMANDIBULAR PLANE ANGLE

15. QUESTIONS?

16.  Jaw rotation influences:
 Magnitude of tooth eruption
 Direction of incisor eruption
 Ultimate antero-posterior position of incisor teeth
 Translocation : Tooth moves along with jaw bone
 True Eruption : Movement of tooth within its jaw

17. Translocation : Tooth moves along
with jaw bone
True Eruption : Movement of tooth
within its jaw
Pre
Mid
Post
Pre
Mid
Post

18.  Normal eruption pattern is downward and forward
 Forward rotation increases prominence of teeth as incisors
are tipped forward- direction of jaw rotation and tooth
eruption is same
 Backward rotation decreases incisor prominence and
uprights them- direction of jaw rotation and tooth eruption
is opposite

19. Pre
Mid
Post
Mid
Pre
Post
Forward Rotation
Backward Rotation

20.  Normal eruption path is upward and forward
 Internal rotation alters eruption path of
incisors, tending to upright them
 Arch length decreases

22.  Facial growth continues in adult life
 Vertical growth is most prominent
 Jaw rotation continues into adult life
 Males have net forward rotation while females have
backward rotation
 Facial soft tissue changes are greater
 Elongation of nose, flattening of lips and augmentation
of soft tissue occurs

23.  Lips and other soft tissue sag downward with
aging
 Exposure of upper incisors decreases and
lower incisors increases at rest and on smile
 Lips become progressively thinner with less
vermilion display

24. • Lips become thinner
• Lips appear less full and elongatedas vertical
height of the vermilion decreases
• Lower part of the face lengthens
• Interlabial line descends
• Number of vertical muscle fibers in the upper lip
decreases
• Philtrum columns become less prominent
• In profile, upper lip flattens
• Jowling develops due to flattening of nasolabial
fold
• Commisures drop giving the face appearance of
a frown
• M and W shapes of the lips becomes a flat line

25.  Alveolar bone bends due to heavy
mastication allowing teeth to move relative
to one another
 Coarse diet causes occlusal wear which
reduces height and width of teeth
 Spacing develops in anterior teeth but not
posterior due to mesial migration of molars

26.  Crowding of mandibular teeth in late teens and early 20s
 Theories are:
 Lack of normal attrition in the modern diet
 Pressure from third molars
 Late mandibular growth
 Contact relation between upper and lower incisors changes and one of
the following may happen:
 Mandible is displaced distally – myofascial pain and dysfunction
occurs; rare phenomenon
 Upper incisors flare forward, space opens- rare phenomenon
 Lower incisors displace distally and become crowded

27.  Pulp chamber decreases in size
 Apical movement of attachment from vertical growth
of the jaws and accompanying eruption of teeth
 Gingival attachment shifts from its high position in
crown to CEJ level
 Passive eruption- actual gingival migration of the
attachment without any eruption of the tooth