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Orthodontics > Facial Growth > Flashcards

Facial Growth Flashcards

1
Q

Why is the study of facial growth important to orthodontics?

A

Predict changes
Utilise growth to correct malocclusion
Time our orthodontics and surgery
Understand development of facial anomalies
To measure changes in growth and treatment using cephalometry

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2
Q

What happens when the neural folds fail to fuse to form the neural tube?
What week does this occur in embryology?

A

Leads to spina bifida
Occurs at the end of week 3 in vitro

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3
Q

What does the neural tube develop into?
What occurs when there is a development failure?

A

Into the brain and spinal cord
Failure to develop will lead to anencephaly (in which the cerebral hemispheres and the cranial vault are absent)

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4
Q

What is the difference between a cleft lip and a cleft palate?

A

If the cleft is before the incisive foramen it is a cleft lip
If the cleft is behind the incisive foramen it is a cleft palate

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5
Q

What is the neurocranium?

A

Forms a protective case around the brain

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6
Q

What is a viscerocranium?

A

Forms the skeleton of the face

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7
Q

What is intramembranous bone formation?

A

Bone is deposited directly into mesenchymal tissue
Needle like bone spicules form, which progressively radiate from the primary ossification centres to the periphery

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8
Q

What is endochondral bone formation?

A

Bones are preceded by a hyaline cartilage
Forms the base of the skull
Several centres of ossification which eventually fuse

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9
Q

Why does growth occur at fibrous sutures at ossification centres?

A

Due to intracranial pressure

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10
Q

What are the 3 main sites of secondary cartilage formation in the mandible?

A

Condylar cartilage, coronoid cartilage and the symphyseal cartilage at the end of each half of the bony mandible
Appear 12-14 weeks in utero

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11
Q

When does ossification of the face and skull commence?

A

7-8 weeks

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12
Q

How is the vault of the skull formed?

A

Intramembranously

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13
Q

How is the base of the skull formed?

A

Endochondral ossification

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14
Q

How are the maxilla and mandible developed? What precedes this?

A

They both develop intramembranously
They are preceded by a cartilaginous facial skeleton
Meckel’s cartilage precedes the mandible and the nasal capsule is the primary skeleton of the face

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15
Q

What is a primary abnormality?

A

Defect in the structure of an organ or part of an organ that can be traced back to an anomaly in its development (spina bifida, cleft lip)

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16
Q

What is a secondary abnormality?

A

Interruption of the normal development of an organ that can be traced back to other influences
–Tetratogenic agents: infection (rubella virus), chemical (thamidomide)
–Trauma: amniotic bands

17
Q

What is the definition of deformation?

A

Anomalies that occur due to outer mechanical effects on existing structures

18
Q

What is agenesia?

A

Absence of an organ due to failed development during embryonic period

19
Q

What is a syndrome?

A

Group of anomalies that can be traced to a common origin

20
Q

On what day does foetal alcohol syndrome occur?

A

Day 17

21
Q

What day does hemifacial microsomia occur? What is this due to?

A

Day 19-28
Neural cell crest migration

22
Q

What does hemifacial microsomia appear as?

A

Unilateral mandibular hypoplasia, zygomatic arch hypoplasia, high arches palate, malformed pinna
As one side grows the other doesn’t usually
Deafness on one side

23
Q

What day does treacher collins (mandibulofacial dystosis) occur?
What is this due to?

A

Day 19-28
Deformity of the 1st and 2nd branchial arches

24
Q

What are some clinical signs of Treacher Collins?

A

Hypoplastic or missing zygomatic arches
Hypoplastic mandible with antigonial notch
Deformed pinna

25
Q

What are some dental features of a cleft lip and/or palate?

A

Impacted teeth
Crowding
Hypodontia
Supernumeraries
Hypoplastic teeth
Caries

26
Q

What is the aetiology of clefts?
Genetic and environment?

A

Genetic
-monozygotic twins
-syndromes
-familial pattern
-epidemiology
Environment
-social deprivation
-smoking
-alcohol
-anti-epileptics

27
Q

Who is involved in a cleft team?

A

Specialist cleft nurse
Speech therapist
Orthodontist
Paediatric dentist
Cleft surgeon
ENT
Geneticist
Psychologist

28
Q

What is achondroplasia?

A

Problem with endochondrial ossification
Defects in base of skull, depressed nasal bridge, retrusive middle third of the face
Dwarfism in 70%

29
Q

What is Crouzon’s syndrome (craniofacial dysostosis)?

A

Premature closure of cranial sutures
Proptosis (shallow orbits) and orbital dystopia, mild hypertelorism
Prominent nose
Class III malocclusion

30
Q

What is apert’s syndrome?

A

Premature closure of almost all cranial sutures

31
Q

What are the clinical features of Apert’s syndrome?

A

Exopthalmos (bulging or protruding of the eyeballs)
Hypertelorism (abnormally large distance between the eyes)
Maxillary hypoplasia
Class III occlusion, AOB, narrow spaced teeth
Parrot’s beak nose
Syndactyl of fingers and toes

32
Q

What are sutures?

A

Specialised fibrous joints situated between intramembranous bone
Each suture is a band of connective tissue which has osteogenic cells in the centre and the most peripheral of these cells provide new bone growth

33
Q

What are synchondroses?

A

A cartilage-based growth centre with growth occurring in both directions
The bones on either side of the synchondrosis are moved apart as growth takes place
New cartilage is formed in the centre as cartilage at the periphery is transformed to bone
Found in the midline

34
Q

What is surface deposition?

A

New bone is deposited beneath the periosteum over the surfaces of both the cranial and facial bone
In order for bones to maintain their shape as they grow resorption is also taking place
This process of deposition and resorption is known as remodelling

35
Q

What is a growth rotation?
What do forwards & backwards rotations lead to?

A

Is due to an imbalance in the growth of the anterior and posterior face heights
Forward rotations lead to a short face
Backwards rotations lead to a long face

36
Q

What kind of bites do forwards & backwards rotations lead to?

A

Forwards growth rotation can lead to the development of a deep bite
Backwards growth rotation can lead to the development of an anterior open bite

37
Q

What are the indications for taking a lateral cephalogram?

A

To aid diagnosis
Treatment planning
Progress monitoring

38
Q

What position should the teeth be in when taking a lateral cephalogram?

A

RCP

39
Q

What is the Eastman Analysis?

A

Measures the antero-posterior position of the maxilla and mandible relative to the base of the skull

Orthodontics (7 decks)

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