Your baby's first tooth probably will appear after 6 months, though some babies are born with one or more teeth. In other cases, teeth don't appear until the child is almost a year old.
Many nursing parents decide that it's time to stop breastfeeding when they first notice a tooth. Usually, this is because the baby has nipped the breast at the end of a feeding session. Or, the nursing parent fears they will be bitten soon. Yet many babies with teeth (or those who are teething) never bite when breastfeeding.
How to prevent a breastfeeding baby from biting
If your baby has sprouted a tooth and you are concerned that they may nip you as a feeding ends: Keep your finger ready to break the suction and remove your breast as soon as her rhythmic suckling stops (and before she starts to drift off or feel playful).
If your baby has already bitten you while nursing: Say no firmly and then remove your baby from your breast. Try to keep this action as bland and matter-of-fact as possible. Too much anger or even amusement may interest them enough to make them want to repeat the experiment again. Once they realize that biting means no more breast, they will learn to stifle the impulse. (Meanwhile, don't forget to offer your baby a one-piece teething ring when they are not nursing.)
How to prevent baby-bottle tooth decay
Once your baby's teeth have begun to come in, keep in mind that even breastfeeding babies are sometimes susceptible to baby-bottle tooth decay (BBTD). BBTD is a major cause of dental cavities in infants that can also cause serious damage to permanent teeth later on.
Baby-bottle tooth decay results from teeth being coated in almost any liquid other than water for long periods. It occurs most commonly among babies who are put to bed with a bottle of formula or juice. Breastfeeding infants who fall asleep while nursing with unswallowed milk remaining in their mouths are also vulnerable to tooth decay.
Beyond the first year, dental caries—tooth decay—can occur in toddlers who receive sugary liquids in a bottle or who are nursing and eating foods with sugar and carbohydrates. Make a point of removing your breast from your baby's mouth once they have fallen asleep.