The bottle is used as a pacifier rather than a feeder.
The milk remains in the mouth for long periods of time and as it ferments in the mouth, the teeth also get infected.
Unfortunately, most of children are not treated timely. They usually need to be given a General Anesthetic in a hospital setting and then treated.
Treating this kind of infection is extremely vital. The milk teeth act as space maintainers for the permanent teeth that have yet to erupt. Delay in treatment causes infections requiring repeated administration of Antibiotics.
This is a situation that can be avoided by timely treratment of the child.