Facial Growth 2 Flashcards
Describe the neo-natal face
Face is small compared to cranium
Large eyes
Low set ears
Forehead is bulbous
Nasal region is shallow and close to infra-orbital rim
What are the different sites of facial growth?
Sutures
Synchondroses
Suture deposition
What are sutures?
Specialised fibrous joints found between intramembranous bone
Each suture is a band of connective tisssue which has osteogenic cells in the centre, at the periphery, new bone is laid down
When facial growth is complete, the sutures a fuse and become inactive
What are synchondroses?
Cartilage found in the midline and between the ethmoid, sphenoid and occipital bone
Growth centres
What is surface deposition?
New bone is deposited beneath the periosteum over the surfaces of the cranial and facial bones
Resorption is also occurring so bones maintain their shape
What is cortical drift?
The change in position of a bone due to remodelling
When and how does the cranial vault expand?
Expands in response to growing brain until age 7
Growth greatest in first 3 years
Growth occurs at the sutures, and external and internal surfaces are remodelled through surface deposition and resorption
When and how does the cranial base grow?
Growth through endochondral ossification and surface remodelling
Half the growth is completed by 3
When do the synchondroses fuse?
Sphenoid-ethmoidal synchondrosis fuses around 7
Spheno-occipital synchondrosis closes around 13-15 in females and 15-17 in males
Spheno-occipital synchondrosis fuses around 20
Why is the growth of the cranial base relevant to orthodontics?
Cranial base determines how the maxilla and mandible relate
A small angle of the cranial base is associated with a class III skeletal relationship
Large angle associated 9th a class II skeletal relationship
Describe growth of the mandible
Grows downwards and forwards
Growth occurs at the condylar cartilage by surface remodelling
Resorption mainly anteriorly and lingually and deposition posteriorly and laterally
Results in increased ramus height and increased length of dental arch
Describe growth of the maxilla/nasomaxillary complex
Growth downwards and forwards
Sutural growth at the zygomatic and frontal bones and mid palatine suture
Occurs by surface deposition and resorption
When does growth of the maxilla and mandible occur?
Maxilla - increases in length from 5.5-8mm between 4-20 years, slows down after 7 years
Mandible - increase in length from 20-26mm from 4-20 years, growth accelerates during puberty and slows from 17-19 years
In what dimension does facial growth occur?
Maxilla and mandible grow in width, then length, then height
What are the theories of craniofacial growth?
Remodelling theory - process of deposition and resorption, sutures and cartilage don’t exert an intrinsic force (historic)
The Sutural theory - growth at sutures is the prime factor for development (historical)
Cartilaginous theory - cartilage and synchondrosis provide the main force for facial growth
Functional matrix theory - growth occurs in response to individual units which are developing to provide a function - its the force exerted by the growing soft tissues that determine the direction and extent of the growth
