There’s actually a name for this. Dentists and doctors call it baby bottle tooth decay — and it’s common enough to have its own name for a reason. Some medical organizations now use the broader term “early childhood caries,” but the cause is the same.
Here’s what happens: when a baby falls asleep with a bottle of milk, formula, or juice, that liquid just sits on their teeth. For hours. The sugars in those drinks feed bacteria in the mouth, and those bacteria produce acid. That acid attacks the teeth the entire time the baby sleeps. It’s basically a long, slow cavity machine.
Water is the only exception. Putting a baby to sleep with anything other than water — milk, formula, fruit juice, sweetened drinks — sets the stage for decay. Even breast milk contains natural sugars that can cause decay when they sit on teeth for extended periods during sleep.
Some people assume baby teeth don’t matter much since they fall out anyway. They do matter. Damaged baby teeth can cause pain, eating problems, and affect how adult teeth come in later.
The fix is simple: don’t make the bottle a sleep habit. If a baby needs something to soothe them at bedtime, water is fine. And if they’ve already got teeth coming in, gently wiping or brushing them before sleep makes a real difference.
Pediatric dentist told us this with our first kid and we immediately stopped. The “it’s just baby teeth” thing is such a common misconception.