You do need to brush your 9 month olds teeth to keep the 9 month olds teeth and gums healthy and clean.
You should start brushing your baby's teeth as soon as their first tooth appears, which is often around 6 months of age.
Use a soft bristled children's toothbrush and water to brush their teeth.
You can also use a soft, wet cloth to wipe over the baby's teeth and gums.
Brush the baby's teeth gently in small circles and clean all surfaces of the teeth and gums.
The causes of babies getting teeth early include genetics, birth factors, oral habits and even maternal factors.
If either the mother or father has gotten their baby teeth early then the baby is likely to get their teeth early as well.
Being born early or at a low birth weight can also cause a baby to get teeth earlier than normal.
Babies who bite and chew on their fingers and toys may also start teething earlier than normal.
And maternal smoking during pregnancy can cause baby's to be more dentally advanced at the ages of 1 and 2.
Teething in babies can start as early as 3 months of age, although most babies get their 1st tooth between the ages of 4 months and 7 months of age.
It's not uncommon though for babies to have their teeth arrive out of sequence.
Although by the age of 3 the child should have 20 teeth.
Common signs that your baby is teething include pulling on their ears, flushed cheeks, trouble sleeping, swollen, sore or tender gums, refusing to eat, crying, fussiness, crankiness and irritability, face rash, drooling and chewing on objects.
Teething in babies before 6 months of age is usually not a cause for concern.
However, when a baby's teeth begin to come in significantly earlier than 6 months of age, the teeth and/or roots can sometimes be underdeveloped.
And in some cases, the teeth that do erupt very early have enamel defects, making them especially susceptible to cavities.