Facial Growth Flashcards
what determines position of teeth and malocclusion
size shape and position of underlying jaws
why is it important to study facial growth
insight into growth of face
understand development of facial anomalies
measure changes in growth and treatment
when do the limbs, organs and face form in utero
within first two months
what can cause cranio-facial abnormalities early on in the pregnancy
external environmental influence
what is neural crest migration important in
development of face
when do the neural folds fuse and what do they form
neural tube
end of week 3
what will failure of neural folds to fuse cause
spina bifida
what does the neural tube develop into
brain and spinal cord
if the neural tube fails to develop what does it cause
anencephaly
what is absent with anencephaly
cerebral hemisphere and cranial vault
what cells are developed from ectoderm during folding of the neural plate
neural crest cells
what do neural crest cells undergo
migration and differentiate into other cell types
what contributes to the branchial arch cartilage, bone and connective tissue and dental tissues
ectomesenchyme
what does the ectomesenchyme come from
neural crest
when does formation of the face occur
during first eight weeks after fertilisation
what are defects of the face, particularly in the midline related to
defects of anterior parts of brain
what is the face formed from
migrating neural crest cells
what can failure of fusion between facial processes lead to
cleft formation
why can cleft lip occur independently of cleft palate
upper lip and anterior palate have different embryological origins from posterior palate and fuse at different times
what forms the branchial arches and when are they formed
migrating neural crest cells in week 4
when does the extension and fusion of facial processes occur
weeks 5-7
what is the skull divided into
neurocranium and viscerocranium
what does the neurocranium form
protective case around the brain
what does the viscerocranium form
skeleton of face
what bones of the head are intramembranous
vault of skull, maxilla and mandible
what is intramembranous ossification
bone deposited directly into primitive mesenchymal tissue
describe intramembranous ossification process
needle like bony spicules form which radiate from ossification centres to the periphery
progressive bone formation results in fusion of adjacent bony centres
what is endochondral ossification
bones are preceded by a hyaline cartilage model
what does endochondral ossification form
base of skull
when does the basi-occiput form
at 10-12 weeks
at birth where do cartilaginous growth centres remain
between sphenoid and occipital bones and in nasal septum
when does intramembranous ossification of the vault occur
in third month
when does the anterior fontanelle close
2 years of age
when does the posterior fontanelle close
1 year of age
why does growth occur at fibrous sutures
in response to intracranial pressure
how long does growth of the skull continue for
7 years
what do the maxilla and mandible develop adjacent to
Meckel’s cartilage
what do the maxilla and mandible develop adjacent to
nasal capsule and Meckel’s cartilage
what does the angular unit of the mandible form in response to
lateral pterygoid and masseter muscles
what does the coronoid unit of the mandible form in response to
temporalis muscle development
when would the alveolar unit of the mandible form in response to
only if teeth are developing
what does the body of the mandible form in response to
inferior dental nerve
what are the 3 main sites of secondary cartilage formation in the mandible
condylar cartilage
coronoid cartilage
symphyseal end of each half of mandible
how long does growth continue at the condylar cartilage
until about 20 years of age
what is a primary abnormality
defect in structure of an organ or part of an organ that can be traced back to an anomaly in its development
what is a secondary abnormality
interruption of the normal development of an organ that can be traced back to other influences
what is a deformation
anomalies that occur due to outer mechanical effects on existing structures
what is agenesia
absence of an organ due to failed development during embryonic period
what is sequence
single factor results in numerous secondary effects
what is a syndrome
group of anomalies that can be traced to a common origin
what 5 types of maxillary hypoplasia are associated with clefts
aperts syndrome
crouzons syndrome
oral facial digital syndrome
cleidocranial dysostosis
cleft lip and palate
what 5 mandibular problems can be associated with clefts
treacher collins syndrome
pierre robin
sticklers syndrome
van der woude syndrome
hemifacial microsomia
what is an environmental factor that can cause a facial syndrome in the first 1-8 weeks of development
foetal alcohol syndrome
what are the multifactorial factors that can cause problems with facial development
hemifacial microsomia
treacher collins syndrome
clefts of lip and palate
what is foetal alcohol syndrome caused by
high maternal intake of alcohol
what features do people with foetal alcohol syndrome present with
microcephaly
short nose
small midface
small mandible
long upper lip with deficient philtrum
mild mental retardation
what does hemifacial microsomia present like
unilateral mandibular hypoplasia
zygomatic arch hypoplasia
high arched palate
malformed pinna
deafness
cardiac and renal problems
why does treacher collins syndrome occur
deformity of 1st and 2nd branchial arches
what does treacher collins syndrome look like
anti-mongoloid slant palpebral fissures
hypoplastic or missing zygomatic arches
hypoplastic mandible with antigonal notch
conductive deafness
what group of people have higher incidence of cleft lip and palate and also of cleft lip alone
males
what group of people have higher incidence of cleft palate
females
what are the genetic factors of cleft lip and palate
monozygotic twins
syndromes
familial pattern
what are the environmental factors of cleft lip and palate
social deprivation
smoking
alcohol
anti-epileptics
multivitamins (decrease chances by 25%)
what are the dental features of cleft lip and palate
impacted teeth
crowding
hypodontia
supernumeraries
hypoplastic teeth
caries
why does achondroplasia occur
problem with endochondrial ossification
what does achondroplasia present like
defective long bones = short limbs
retrusive middle third of face
frontal bossing
depressed nasal bridge
what is crouzons
premature closure of cranial sutures
what does crouzons look like
proptosis
orbital dystopia
retusion and vertical shortening of midface
prominent nose
class 3 malocclusion
what is early closure of sutures called
cranial synostosis
what is aperts
premature closure of almost all cranial sutures
what does aperts present like
maxillary hypoplasia
class 3 occlusion
AOB
parrots beak nose
syndactyly of fingers and toes
