Skeletal, Dental, Somatic and Sexual Maturation in Children

Postnatal Maturation and Age Assessment

1 Bone Age (Skeletal Maturity)

Ossification begins in the womb and continues throughout the first two decades after birth. For radiological assessment, small areas (commonly the hand) are imaged to minimize exposure and potential risks. Through the study of ossification it was determined that:

• Girls' bones ossify earlier than boys'.
• The two sides of the body mature symmetrically.
• The genetic component is of great importance in bone maturation.

2 Dental Age

Dental age is the study of emergence of teeth (primary and permanent) and its comparison with established standards. This index assesses the degree of calcification and eruption of teeth as indicators of jaw and dental development. Important distinctions include:

• Calcification level at the alveolar ridge.
• Clinical eruption at the gumline.

The primary dentition appears between approximately 6 months and 2 years. The permanent dentition develops roughly between 6 and 13 years. Bone age is more closely related to dental development and can be used together with dental age for comprehensive assessment.

3 Morphological (Somatic) Age

The morphological or somatic age refers to comparison of a child's height and weight with standardized growth charts. Estimating age from the correlation between height and weight is less satisfactory than other methods, but these charts remain useful for assessing overall physical growth patterns.

4 Age of Sexual Characteristics

Sexual age corresponds to the time when primary and secondary sexual characteristics become evident. These characteristics are used to categorize individuals into different maturational stages. The age at which menarche occurs is a commonly used index for female maturation. During adolescence, major development occurs in the bones, muscles and reproductive systems.

5 Pubertal Signs and Timing

The first visible signs of puberty vary by sex. Typical patterns include:

• In boys, the first onset of puberty is usually testicular enlargement followed by the appearance of pubic hair.
• Growth acceleration (height spurt) commonly follows the earliest sexual signs and is accompanied by enlargement of the penis.
• Axillary (armpit) hair typically appears about two years after pubic hair, and facial hair develops later in boys.
• With increased stature comes enlargement of the larynx (the voice becomes deeper) and progressive completion of penile development.
• In girls, the onset of breast development and the appearance of pubic hair are early signs. The first menstruation (menarche) usually occurs toward the end of the growth spurt, often after the adolescent has reached near-maximum height.

Regulatory Factors of Postnatal Growth

1 Inheritance

The role of inheritance in human growth and development is complex and can be difficult to quantify precisely. There is a high correlation between heredity and adult height, and genetic factors influence both normal variation and susceptibility to pathological conditions. Evidence shows that certain syndromes and diseases are heritable and can be transmitted from parents to children.