Craniofacial Growth and Development
Domain 2: Craniofacial Growth and Development
The exam tests growth timing, pattern, and mechanism enough to decide when interception is possible and when it is not. Questions often use cephalometric superimposition, cervical vertebral maturation, and growth rotations.
Core rules
- Growth is cephalocaudal and follows Scammon's curve: neural tissue grows early, lymphoid tissue later, and general somatic and genital growth at puberty.
- The face grows by displacement and remodeling. The maxilla moves downward and forward; the mandible grows mainly at the condyle, with apposition at the posterior border and resorption at the anterior border.
- Sutures are secondary growth sites. The nasal septum and functional matrix influence midface position; do not treat sutures as the primary driver.
- Björk's implant studies show rotational growth: forward rotation increases chin projection and deepens the bite; backward rotation reduces chin projection.
- Cervical vertebral maturation: CS3 marks the onset and CS4 the peak of the pubertal spurt. Peak mandibular growth usually occurs around CS3-CS4, earlier in girls than boys.
- Mandibular growth continues into the late teens, later than maxillary growth, which matters for Class III prognosis.
Worked example
A 10-year-old girl has Class II division 1 with overjet 8 mm. CVM shows concavity beginning on the lower border of C2 but not C3, consistent with early maturation. The question asks whether to start a functional appliance now or wait. Early CVM staging indicates the pubertal spurt is approaching but not yet at peak; starting now and reviewing every 6-9 months allows the appliance to be active during the spurt. Waiting until CS4 risks missing the peak. The plan is to start a functional appliance, repeat the cephalogram in 9-12 months, and switch to fixed appliances when the spurt is underway.
Traps
- Using chronological age alone; children vary by 2-3 years at the same age.
- Over-reading CVM on a rotated or poorly traced cephalogram.
- Assuming maxillary and mandibular growth finish together.
- Confusing remodeling with displacement when interpreting superimpositions.