If a baby has white growths inside the mouth, there are two causes that can cause them: the first is horse teeth; the second is thrush. It is mainly formed by the keratinization of the tissue part of the dental plate during embryonic development, which usually falls off automatically and does not need to be treated. Thrush is a mucosal disease that occurs inside the baby’s mouth and is caused by Candida infection. It is mainly manifested as a white patch-like structure on the surface of the buccal mucosa, lips or tongue, which can be wiped off and has red bleeding spots on the surface after wiping off. Thrush requires early treatment measures, otherwise it is likely to cause prolonged and recurring.