Help Children Remain Cavity-free. Oral hygiene for kids is vitally important so that they can have healthy primary (baby) and secondary (permanent) teeth. In addition, taking care of the mouth and gums can prevent problems such as halitosis or gingivitis. However, most parents are concerned about helping their children remain cavity-free. This is because the decay in a tooth will require drilling-and-filling for a small cavity or a dental crown for a larger cavity. Not only do children want to avoid needing a filling or crown, but also, extensive decay can lead to an infection, requiring a root canal procedure.