Final answer:
In the Universal/National System, primary teeth are identified with letters and permanent teeth with numbers. Deciduous teeth appear from 6 months of age and are replaced by permanent teeth between ages 6 to 12, which include incisors, canines, premolars, and molars.
The correct option is 1.
Step-by-step explanation:
In the Universal/National System used in dentistry, the primary teeth are identified using letters, and the permanent teeth are identified using numbers. Therefore, the answer to the question is: 1) Numbers, Letters. Primary teeth, also known as deciduous or baby teeth, make their appearance from around 6 months of age.
These are replaced by permanent teeth from the age of approximately 6 until 12 years old. Permanent teeth include 8 incisors, 4 canines, 8 premolars, and 12 molars, summing up to a set of 32 in total.
Deciduous teeth generally emerge in infancy and are later replaced by permanent teeth during middle childhood. The second set of permanent teeth emerge mainly during middle childhood and most of which replace deciduous teeth after they are lost. Wisdom teeth, which are part of the permanent teeth, typically emerge in adolescence or early adulthood.
The correct option is 1.