Which statement indicates a parent understands dental care for a 9-month-old?

The statement that indicates a parent understands dental care for a 9-month-old is that the parent should clean their baby's teeth with a cool, wet washcloth. This action reflects the appropriate approach to maintaining oral hygiene for infants who have just begun to develop their teeth. At this age, it is essential to establish good dental care practices, even before the full set of teeth erupts. Using a wet washcloth is safe and gentle, promoting healthy gums and helping to remove any plaque buildup that might occur.

As for the other statements, while they may touch on relevant topics—such as teething relief or bottle use—none promote optimal dental care practices for infants. For instance, using a teething ring can be soothing but does not address the actual cleaning of teeth. Giving Advil for teething is also appropriate under guidance, but it does not pertain directly to dental hygiene. Lastly, placing diluted juice in a bottle, especially at sleep time, could encourage tooth decay and is not recommended in caring for an infant's dental health. Thus, cleaning a baby's teeth with a washcloth is a fundamental step in fostering good dental hygiene habits from the very beginning.