Orthodontics I/5
Dr Jamal Naim
PhD in Orthodontics
The Cranial Vault
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2nd semester 2015-2016
Growth of the Cranial Base
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2nd semester 2015-2016
The Cranial Base
The cranial base: The bony floor under the brain, which is
also a dividing line between the cranium and the face.
It is made up of the midline base and the three (anterior,
middle and posterior) cranial fossae.
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2nd semester 2015-2016
The Cranial Base
The cranial base grows primarily enchondral in the
sphenoethmoidal, intersphenoidal, spheno-occipital and
intraoccipital synchondroses.
Activity at the intersphenoidal synchondrosis disappears
at birth.
The intraoccipital synchondrosis closes
in 5th year of life.
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2nd semester 2015-2016
The Cranial Base
The spheno-ethmoidal synchondrosis remains active until
about 6 years of age.
The spheno-occipital synchondrosis is a major
contributor as the ossification here could extend till the
20th year of life. Average closure at 13-15.
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2nd semester 2015-2016
The Cranial Base
The direction of growth in these sutures is forwards and
upwards carrying the cranial base and the upper face
forwards and upwards.
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2nd semester 2015-2016
Growth of the Nasomaxillary
Complex
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2nd semester 2015-2016
The Nasomaxillary Complex
The nasomaxillary complex made up of the nose, maxilla,
and the associated structures.
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2nd semester 2015-2016
The Nasomaxillary Complex
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It is connected to the cranial base by six pairs of sutures,
which are most important sites of growth:
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Fronto-maxillary suture
Fronto-nasal s.
Zygomatico-frontal s.
Zygomatico-temporal s.
Zygomatico-maxillary s.
Pterygo-palatine s.
2nd semester 2015-2016
The Nasomaxillary Complex
Regarding its growth some aspects should be marked:
1. The formation is intramembranous (exception Vomer)
2. The shift in the position of the maxillary complex due
to:
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2.
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Sutural growth (primary or secondary translation).
The enlargement and remodeling of the complex itself.
2nd semester 2015-2016
The Nasomaxillary Complex
The general growth of the Maxilla is according to the
functional matrix theory
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Teeth >>>>>>> Alveolar process
Maxillary sinuses
Orbitae
After the age of 7 years remodeling and surface
deposition dominates.
In the sum the nasomaxillary complex moves
downwards and forwards on an ‘expanding V”.
2nd semester 2015-2016
The Growth of the maxilla
Growth direction:
 Growth in vertical direction (height)
 Growth in transverse direction (width)
 Growth in antero-posterior direction (length)
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2nd semester 2015-2016
The Growth of the maxilla
Growth in vertical direction:
 Sutural growth
 Appositional growth in adjacent matrices
 Growth of the alveolar processes
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2nd semester 2015-2016
Growth in vertical direction (height)
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Sutural growth
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Primary translocation
Secondary translocation
2nd semester 2015-2016
Growth in vertical direction (height)
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Apposition and resorption in adjacent structures
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Orbits
Nasal floor and palate
2nd semester 2015-2016
Growth in vertical direction (height)
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Apposition on the alveolar bone accompanied with the
eruption of primary and later permanent teeth.
This growth leads to deepening of the palatal vault.
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2nd semester 2015-2016
Growth in horizontal direction (width)
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Occurs early in the postnatal life
(first 5 years of life).
Occurs by two processes:
Remodeling of the alveolar process
 Growth of the midpalatal suture
(intermaxillary and interpalatal sutures)
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The growth occurs on an
expanding V:
Apposition buccally
Resorption palattally
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2nd semester 2015-2016
V-Shape Growth Principle of Bang and Enlow
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2nd semester 2015-2016
Growth in A-P direction (length)
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primary and secondary Displacement
Lengthening (apposition) of the maxillary tuberosity
during eruption of non-succedaneous teeth accompanied
with lengthening of the palatal processes of both the
maxillary and the palatine bones.
Apposition and resorption
at the anterior portion of the
alveolar process
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2nd semester 2015-2016
The Growth of the maxilla
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2nd semester 2015-2016
The Growth of the Mandible
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2nd semester 2015-2016
The Growth of the Mandible
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The mandible is formed by intramembranous ossification.
Secondary growth centers, coronoid, condyloid and
symphysial cartilages are cartilaginous.
The two halves of the mandible are early in postnatal life
fused at the symphysis (about 6th month).
The general growth of the mandible is according to the
functional matrix theory
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Teeth
Alveolar process
Muscles of mastication
coronoid, condyloid
processes and angle of the mandible
2nd semester 2015-2016
The Growth of the Mandible
Growth sites:
 Condyles: enchondral and interstitial (major)
 Remodeling in all planes
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2nd semester 2015-2016
The Growth of the Mandible
Growth direction:
 Growth in vertical direction
 Growth in transverse direction
 Growth in antero-posterior direction
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2nd semester 2015-2016
Growth in vertical direction (height)
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The growth at the head of the condyle occurs in an
upward and backward direction >>>> mandibular
downward and forward displacement (primary
translation).
It ends after adolescent growth spurt
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17 in girls, 18 in boys
2nd semester 2015-2016
Growth in vertical direction (height)
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The growth of the alveolar process occurs
upwards and laterally (Tooth eruption)
Appositional growth at the superior border of the rami
and inferior border of the body.
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2nd semester 2015-2016
Growth in transverse direction (width)
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Occurs by two processes:
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Remodeling of the alveolar process (tooth eruption) and
mandible
Condylar growth (lateral)
2nd semester 2015-2016
Growth in transverse direction (width)
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Completed before the adolescent growth spurt.
Intercanine distance does not increase after 12 y. of age.
Molar and intercondylar distance increases little after
adolescent growth spurt till end of growth about 18.
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2nd semester 2015-2016
Growth in A-P direction (length)
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Condylar grwoth
Appositional growth at the anterior and posterior border
of the rami
Mental remodeling (less)
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2nd semester 2015-2016