2. Craniofacial growth and development. Flashcards by A F

What is craniofacial growth?

A complex of processes involving interactions between different bones of the skull and between hard and soft tissues.

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What hormone initiates facial growth postnatally?

Somatotropin hormone of the thyroid gland.

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Define hypertrophy in the context of skeletal growth.

Increase in the size of individual cells.

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Define hyperplasia in the context of skeletal growth.

Increase in the number of cells.

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What is interstitial growth?

Growth involving hyperplasia and hypertrophy of soft and hard tissues.

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What is apposition growth?

Secretion of extracellular material that mineralizes later.

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What happens to the hard tissue of the facial skeleton during the first year of birth?

Interstitial growth is observed in connective tissue and cartilage.

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At what age does surface apposition of bone typically finish?

> 25-30 years.

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What is the cranio-caudal gradient of growth?

The body grows more than the head, the facial skeleton more than the cranium, and the mandible more than the maxilla.

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Differentiate between growth and development.

Growth is quantitative changes; development is qualitative changes.

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What role do fontanelles play in craniofacial growth?

Sites of growth for the cranial vault, facilitating the passage of the baby through the birth canal.

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What is the primary mechanism of cranial base growth?

Endochondral ossification of several cartilages.

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What is a growth site?

Location at which bone enlarges and moves.

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What is a growth center?

Location at which independent growth occurs, genetically controlled.

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What is endochondral bone formation?

Bone forms a cartilaginous precursor which is then ossified.

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What is intramembranous bone formation?

Bone is formed by secretion of osteoid from osteoblasts directly into connective tissues.

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What is the cranial vault composed of?

Cranial vault and cranial base.

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What is the nasomaxillary complex?

Composed of the maxilla, nasal bones, and bones to which the maxilla is attached.

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What type of growth occurs in the nasomaxillary complex?

Intramembranous ossification of mesenchymal tissue.

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What happens to the maxilla’s transversal growth by the age of 15?

It ceases first.

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How does the mandible grow after birth?

Undergoes basic changes in form, size, and proportions during postnatal development.

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What triggers the growth of the maxilla in three planes?

Growth of the alveolar processes stimulated by teeth eruption.

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What are the two main parts of the mandible after birth?

Body (corpus) and ramus.

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What is the growth pattern of the mandibular ramus?

Sagittal growth through apposition of bone on the entire posterior surface.

What does the growth of the cranial base influence?

The relationship between maxilla and mandible.

True or False: The cranial base grows evenly in all directions.

False.

Fill in the blank: The growth of the maxilla in the sagittal direction increases the dental arch length, creating additional space for _______.

[primary and later permanent molar teeth to erupt].

What is compensatory growth?

Observed when there are pathological processes in the brain.

What is the role of synchondroses in cranial base growth?

Sites and centers of independent genetically controlled growth.

What is the significance of the spheno-occipital synchondrosis in growth?

It influences the length of the cranial base and the angle between cranial fossae.

What is sagittal growth in the context of the ramus?

Apposition of bone on the entire posterior surface of the ramus and reposition on the entire anterior surface.

In sagittal growth, which surface experiences greater apposition?

Inferior-posterior surface.

What is the outcome of reposition on the ramus during sagittal growth?

Reposition on inferior-anterior surface is greater than on superior-anterior surface.

What is vertical growth in the ramus primarily due to?

Endochondral bone formation at the condyle.

What role does cartilage play in vertical growth?

It is a site of growth but not an independent growing center.

What external factors can influence the growth of cartilage?

Orthodontic force and diseases.

How does the TMJ develop after birth?

The TMJ is initially flat and later deepens.

What is the growth rate of the ramus before puberty in height and body length?

1-2 mm/year in height and 2-3 mm/year in body length.

How does the growth rate of the ramus change during puberty?

The rates double.

Why do orthodontists treat the upper jaw before the mandible?

Mandibular growth is adapted to and closely related to the vertical and sagittal growth of the maxilla.

What does the rotation of the mandible refer to?

Modification of the forms, structure, and position of the mandible in relation to the cranial base.

What type of growth is characterized by forward rotation of the mandible?

Hypo-divergent type of growth.

What movement occurs during forward rotation of the mandible?

Forward condylar growth and upward movement until contact with the maxilla.

What type of growth is characterized by backward rotation of the mandible?

Hyper-divergent type of growth.

What movement occurs during backward rotation of the mandible?

Backward condylar growth and downward movement.

What is the first growth spurt of craniofacial development?

Growth of the cranium until the age of 3 years.

At what ages does cranial base growth occur?

Age 5-7 years.

When does active growth of the nasomaxillary complex occur for girls and boys?

10-12 years for girls and 11-13 years for boys.

What is the 'V' Principle?

An important facial skeleton growth mechanism involving 'V'-shaped regions of bones

How do areas grow according to the 'V' Principle?

By bone deposition on the inner side and resorption on the external surface

What does the movement of the 'V' involve?

The 'V' moves away from its tip and enlarges simultaneously

What is another name for the 'V' Principle?

The expanding 'V' principle

In which direction does the growth movement of the bone occur in the 'V' Principle?

Toward the broad end of the V

What is revealed by a longitudinal section through the coronoid processes of a mandible?

The processes are enlarged during growth

According to the 'V' Principle, where is bone deposited and resorbed in the mandible?

Deposited on the lingual surfaces and resorbed from the buccal surfaces

What happens to the height of the coronoid processes during growth?

They increase in height and tips diverge further

What happens to the bony bases of the coronoid processes during growth?

They converge

What ongoing conflict is mentioned regarding craniofacial complex development?

The conflict between geneticists and environmentalists

What does the text suggest about the roles of controlling factors in craniofacial development?

Significant roles attributed to both genetic and environmental factors at different times