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Growth and Development

Development of the Nasomaxillary Complex

• Grows downwards and forwards relative to the cranial base and greatest during pubertal growth spurt.
• Areas near sutures found at maxilla and cranial base have bone deposition as brain grows and soft tissue of face forms.
• During pubertal growth spurt, facial skeleton growth starts and is almost completed at age 15.5 years in girls and later in boys.

Mandibular Growth

• Greatest during pubertal growth spurt.
• Growth of mandible coordinates with growth of maxilla and cranial base in forward and downward direction (translation of the mandible).
• Bony deposition at ramus and in condyles allows mandible to grow downwards and forward.
• Mandibular condylar cartilage (reactive growth site) is involved in bone formation with cartilage proliferation and its replacement by bone.

Tooth Development

Teeth start to form very early on, around the 5th week of the embryo. The dental lamina gives rise to epithelial buds that then differentiate into the tooth germ, within which reside the cells for the development of the various tooth structures. The odontoblasts form dentine and ameloblasts form the enamel. The epithelial structure known as the root sheath of Hertwig arises from an apical migration of the epithelial cells at the cervical loop of the enamel organ and is responsible for the development of the roots of the teeth.

Tooth Eruption

Eruption Times for the Primary Teeth (In Months)

Eruption Times Permanent Dentition (In Years)

Methods of Assessing Growth

The growth periods as described by Lowrey (1973) are shown in Table 2.1.

• Chronological age.
• Neurological age.
  
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