Permanent Teeth Pushing Baby Tooth Out. In the natural scheme of things a childs permanent teeth grow in behind the baby teeth. Ordinarily as the permanent teeth push up the roots of the baby teeth dissolve and the baby tooth eventually falls out allowing the permanent teeth to come in.
However in some cases the adult tooth doesnt develop. This pressure and a biological cue tell the root to dissolve causing a loose tooth. Dentists can intervene to remove the primary teeth and make space for the permanent ones.
All 20 baby teeth tend to be fully grown in by age 3.
The upper primary incisors front teeth do not fall out in which case even the tongue cannot help by pushing on the baby teeth to make them mobile or on the permanent teeth to move them forward. Simply put when a permanent tooth starts pushing against the roots of a baby tooth the roots begin to dissolve. As noted above baby teeth get loose and fall out when the permanent tooth is ready to grow in. If the adult tooth is visible when the baby tooth falls out it still may take 6-12 months for the permanent tooth to fully grow in.