Growth of the maxilla and mandible

Growth of the Maxilla,Growth of the Maxilla,
Mandible, Soft Tissue andMandible, Soft Tissue and
BodyBody
www.indiandentalacademy.com

Changes in Overall BodyChanges in Overall Body
ProportionsProportions

Not all tissue systems of theNot all tissue systems of the
body grow at the same ratebody grow at the same rate
Scammon’s Curve

VariabilityVariability
Not everyone is alike in the way thatNot everyone is alike in the way that
they growthey grow
Percentile growth/ standard deviation toPercentile growth/ standard deviation to
the normthe norm
Racial and ethnic differencesRacial and ethnic differences
Boys vs GirlsBoys vs Girls

Growth CurvesGrowth Curves
Boys: 2 to 18 years Girls: 2 to 18 years
Boys reach most of their height at age of 17Boys reach most of their height at age of 17
whereas girls reach theirs at around 15.whereas girls reach theirs at around 15.www.indiandentalacademy.com

Deviations from the norm inDeviations from the norm in
growthgrowth
Sickness - nutritionSickness - nutrition
late/early maturerslate/early maturers
problems with growth (hormones orproblems with growth (hormones or
genetics)genetics)

Why do we assess growth?Why do we assess growth?
To determine optimum time forTo determine optimum time for
treatment (growth modification andtreatment (growth modification and
surgery)surgery)
to determine the amount of growth leftto determine the amount of growth left
to determine type of growthto determine type of growth

How to assess growthHow to assess growth
Hand wrist x-rayHand wrist x-ray
sexual maturity: onset of menarche insexual maturity: onset of menarche in
girls, voice changes and facial hair ingirls, voice changes and facial hair in
boysboys
lateral cephalogram tracings:lateral cephalogram tracings:
superimpositions

Other indicators of growthOther indicators of growth
Ask parents how muchAsk parents how much
the child grew last yearthe child grew last year
(height and shoe size)(height and shoe size)
look at parent’slook at parent’s
phenotype: tall or shortphenotype: tall or short

Principles of Tissue GrowthPrinciples of Tissue Growth
HypertrophyHypertrophy
hyperplasiahyperplasia
increased production ofincreased production of
extracellular matrix (cellextracellular matrix (cell
independent)independent)

Bone, muscle and soft tissueBone, muscle and soft tissue
growthgrowth
All are dependent on each other toAll are dependent on each other to
some degreesome degree

Growth of the soft and cartilaginousGrowth of the soft and cartilaginous
tissues = interstitial growthtissues = interstitial growth
Growth of mineralized tissues = can beGrowth of mineralized tissues = can be
done in the surface only (periosteum)=done in the surface only (periosteum)=
surface apposition of bonesurface apposition of bone

Growth of Cartilage/Growth of Cartilage/
Endochondral OssificationEndochondral Ossification
Long bonesLong bones
Epiphyseal plateEpiphyseal plate
contains dividingcontains dividing
cartilaginous cellscartilaginous cells
Rate of growth andRate of growth and
maturation of cellsmaturation of cells
need to be equal forneed to be equal for
growth to occurgrowth to occur
Proliferating cartilage
Epiphyseal plate

Intramembranous BoneIntramembranous Bone
FormationFormation
Cranial Vault and jawsCranial Vault and jaws
Meckel’s cartilage will be transformedMeckel’s cartilage will be transformed
into middle ear ossicles andinto middle ear ossicles and
sphenomandibular ligament and is notsphenomandibular ligament and is not
involved with the bone formation of theinvolved with the bone formation of the
jawsjaws

The growing faceThe growing face
8 months, 6 y, 8 y and 20 y old

The Human Head ShapeThe Human Head Shape
Brachycephalic Dolichocephalic
• short and wide • tall and narrow

Reasons for Describing HeadReasons for Describing Head
and Face Shapeand Face Shape
The growth direction of the face andThe growth direction of the face and
jaws is different in each type of headjaws is different in each type of head
and/or face.and/or face.

Reasons for Describing HeadReasons for Describing Head
and Face Shapeand Face Shape
““Brachy” tends to grow horizontally;Brachy” tends to grow horizontally;
“dolicho” tends to grow vertically.“dolicho” tends to grow vertically.
Knowing the general pattern of growthKnowing the general pattern of growth
and the expected direction can beand the expected direction can be
helpful in orthodontic diagnosis andhelpful in orthodontic diagnosis and
treatment planning.treatment planning.

Soft Tissue ProfileSoft Tissue Profile
Convex straight concave
retrognathic orthognathic prognathic

Soft Tissue Changes withSoft Tissue Changes with
GrowthGrowth
Boy growing normally
Black - 10 yo
red - 14 yo
Soft tissue profileSoft tissue profile
tends to flattentends to flatten
with growthwith growth
Nose and chinNose and chin
growth at teenagegrowth at teenage
years may changeyears may change
facial appearancefacial appearance

Theories of CraniofacialTheories of Craniofacial
GrowthGrowth
Classical: bone growth is primary, softClassical: bone growth is primary, soft
tissues adjust to the growth of thetissues adjust to the growth of the
bones.bones.
Functional matrix: soft tissue functionalFunctional matrix: soft tissue functional
demands are primary, bones grow indemands are primary, bones grow in
response to functional demands.response to functional demands.

Principles of GrowthPrinciples of Growth
ResorptionResorption
appositionapposition
surface remodeling of a bone in the oppositesurface remodeling of a bone in the opposite
direction to that in which it is being translateddirection to that in which it is being translated
by growth of adjacent structuresby growth of adjacent structureswww.indiandentalacademy.com

Growth of the CraniofacialGrowth of the Craniofacial
ComplexComplex
Cranial VaultCranial Vault
Cranial BaseCranial Base
MaxillaMaxilla
MandibleMandible

Cranial Vault GrowthCranial Vault Growth
Apposition of bone in the cranial suturesApposition of bone in the cranial sutures
accounts for growth after birth.accounts for growth after birth.
Pressure from the growing brain promotesPressure from the growing brain promotes
resorption of bone in the inner surfaces of theresorption of bone in the inner surfaces of the
cranial vault = remodeling allows for changescranial vault = remodeling allows for changeswww.indiandentalacademy.com

Growth of the Cranial BaseGrowth of the Cranial Base
The cranial base is composed mostly byThe cranial base is composed mostly by
bones formed by endochondral ossification.bones formed by endochondral ossification.
Bands of cartilage are formed betweenBands of cartilage are formed between
centers of ossification called synchondrosis:centers of ossification called synchondrosis:
Spheno-occiptal synchondrosisSpheno-occiptal synchondrosis
intersphenoid synchondrosisintersphenoid synchondrosis
spheno-ethmoidal synchondrosisspheno-ethmoidal synchondrosis

Growth of the Cranial BaseGrowth of the Cranial Base
Cranial base grows by endochondralCranial base grows by endochondral
ossification that occurs at both margins of theossification that occurs at both margins of the
synchondrosis.synchondrosis.

Growth of the MaxillaGrowth of the Maxilla
Remodeling of theRemodeling of the
palatal vault moves itpalatal vault moves it
in the same directionin the same direction
as it is beingas it is being
translatedtranslated
bone is removedbone is removed
from the floor of thefrom the floor of the
nose and added tonose and added to
the roof of the mouththe roof of the mouth

On the anteriorOn the anterior
surface, bone issurface, bone is
removed, partiallyremoved, partially
cancelling thecancelling the
forward translation.forward translation.
As the vault movesAs the vault moves
downward, thedownward, the
same process ofsame process of
bone remodelingbone remodeling
also widens it.also widens it.

Growth of theGrowth of the
surrounding softsurrounding soft
tissues translatestissues translates
the maxillathe maxilla
downward anddownward and
forward, openingforward, opening
spaces in thespaces in the
sutures wheresutures where
bone is added.bone is added.

Midpalatal suture is opened until teenage years.Midpalatal suture is opened until teenage years.
Apposition of bone in the molar area accounts forApposition of bone in the molar area accounts for
space for the third molars.space for the third molars.

Summary:Summary:
growth of the maxillagrowth of the maxilla
occurs in 2 ways:occurs in 2 ways:
by apposition of bone inby apposition of bone in
the sutures that connectthe sutures that connect
the maxilla to the cranialthe maxilla to the cranial
basebase
by surface remodeling.by surface remodeling.

Growth of the MandibleGrowth of the Mandible
Remodeling is done by resorption in the anteriorRemodeling is done by resorption in the anterior
part of the ramus and deposition in the posteriorpart of the ramus and deposition in the posterior
part of the ramuspart of the ramuswww.indiandentalacademy.com

Overall growthOverall growth
direction results in adirection results in a
downward anddownward and
forwardforward
displacement withdisplacement with
most of growthmost of growth
occurring in theoccurring in the
ramus.ramus.

Mandibular symphysis is closed by age of 1Mandibular symphysis is closed by age of 1
year.year.
Late mandibular growth:Late mandibular growth:
can occur in the late teenage years orcan occur in the late teenage years or
adulthoodadulthood
most often seen in asians and malesmost often seen in asians and males
can cause incisor crowding when there is acan cause incisor crowding when there is a
tight occlusion (overbite/overjet)tight occlusion (overbite/overjet)

When things go wrongWhen things go wrong
Congenital craniofacial malformations:Congenital craniofacial malformations:
cleft lip/palate, syndromes (Apert,cleft lip/palate, syndromes (Apert,
Crouzon, etc..), craniosynostosisCrouzon, etc..), craniosynostosis
Non-syndromic craniosynostosisNon-syndromic craniosynostosis
TraumaTrauma
AnkylosisAnkylosis
Juvenile rheumatoid arthritisJuvenile rheumatoid arthritis

When things go wrongWhen things go wrong
Trauma
Blow to one side of theBlow to one side of the
mandible may fracturemandible may fracture
the condylar process onthe condylar process on
the opposite sidethe opposite side
pull of the lateralpull of the lateral
pterygoid musclepterygoid muscle
distracts the condylardistracts the condylar
fragment including allfragment including all
the cartilage =the cartilage =
resorption occursresorption occurswww.indiandentalacademy.com

Growth of the maxilla and mandible

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Growth of the maxilla and mandible