The primary dentition begins to show teeth eruption by-
**Core Concept**
The primary dentition, also known as baby teeth, begins to erupt when the child is around 6 months old. This process is influenced by the development and growth of the jaw bones and the roots of the teeth.
**Why the Correct Answer is Right**
The primary dentition eruption is primarily driven by the growth of the jaw bones, particularly the mandible and maxilla. As the jaw bones expand, there is more space for the teeth to erupt. Additionally, the roots of the primary teeth begin to develop and resorb, allowing the teeth to move into the oral cavity. This process is mediated by hormones such as thyroxine and growth hormone, which regulate growth and development.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not provide a specific age range for the eruption of primary dentition.
**Option B:** This option may be tempting, but the exact age of 12 months is not universally accepted as the time of primary dentition eruption.
**Option C:** This option is incorrect because the eruption of primary dentition is not solely dependent on the growth of the tongue or the development of the oral cavity.
**Clinical Pearl / High-Yield Fact**
It is essential to note that the eruption of primary dentition is a normal part of childhood development, and most children have a full set of 20 primary teeth by the age of 3 years.
**Correct Answer:** **A. 6 months.**