Mandible Growth and Tooth Eruption

Mandible Growth

• The body of the mandible grows longer by periosteal apposition of bone only on its posterior surface.
• The ramus grows higher by endochondral replacement at the condyle accompanied by surface modeling.

Facial Soft Tissue Growth

• Lip height is relatively short during the mixed dentition years.
• Lip incompetence is maximal during childhood and decreases during adolescence.
• Lip thickness reaches its maximum during adolescence, then decreases.

Growth of the Nose

• Growth of the nasal bone is complete at about age 10.
• Growth thereafter is only of the nasal cartilage and soft tissues, both of which undergo a considerable adolescent spurt.
• The nose and chin both become more prominent with adolescent and post-adolescent growth, while the lips do not.

Theories of Growth Control

• Three major theories:
  • Bone is the primary determinant of its own growth.
  • Cartilage is the primary determinant of skeletal growth, while bone responds secondarily and passively.
  • The soft tissue matrix is the primary determinant of growth, and both bone and cartilage are secondary followers.

Level of Growth Control

• Site of growth: a location at which growth occurs.
• Center of growth: a location at which independent (genetically controlled) growth occurs.
• All centers of growth are also sites, but the reverse is not true.

Functional Matrix Theory of Growth

• Introduced by Melvin Moss.
• The theory holds that growth of the face occurs as a response to functional needs and neurotrophic influences and is mediated by the soft tissue in which the jaws are embedded.
• Growth of the cranium illustrates this view of skeletal growth very well.

Growth of the Cranium

• Growth of the cranial vault is a direct response to the growth of the brain.
• Pressure exerted by the growing brain separates the cranial bones at the sutures, and new bone passively fills in at these sites.

Mandibular Growth

• Growth of the mandible occurs by both endochondral proliferation at the condyle and apposition and resorption of bone at surfaces.
• The mandible is translated in space by the growth of muscles and other adjacent soft tissues, and addition of new bone at the condyle is in response to the soft tissue changes.

Social and Behavioral Development

• Learning and the development of behavior:
  • Classical conditioning: operates by the simple process of association of one stimulus with another.
  • Operant conditioning: can be viewed conceptually as a significant extension of classical conditioning.
  • Observational learning: acquisition of behavior through imitation of the behavior of others.

Emotional and Cognitive Development

• Emotional Development: 8 stages.
• Cognitive Development: 4 stages.

Learn about the growth of the mandible through periosteal apposition and endochondral replacement, as well as the sequential eruption of primary and permanent molar teeth. This quiz covers the development of the jaw and teeth in relation to facial soft tissue growth.