Second Molars at 11 to 13: Spotting the New Back Molars and Getting Sealants

Between 11 and 13, second molars come in behind the six-year molars. How to spot these easy-to-miss teeth, brush them, and why to seal them once they're in.

By the later elementary years, it can feel like all the tooth changes are done. But around this time, new molars are quietly coming in at the very back of the mouth. No baby tooth falls out first, so both parents and kids often miss them. Here's what to know about the second molars.

New molars quietly come in at the back

The second molars come in between ages 11 and 13, right behind the first permanent molars that arrived around age 6 (the six-year molars). They're often called the "12-year molars." One comes in on each side, top and bottom, and they're permanent from the start.

With the front teeth and premolars, a baby tooth loosens and falls out first, so it's easy to notice the change. But second molars have no baby tooth that falls out first. They simply come up from the gums at the back, so many parents only find out at a regular checkup.

Because they sit at the very back, they come with a few challenges:

• The toothbrush has a hard time reaching them. It's the spot kids miss most when brushing on their own.
• While they're coming in, part of the tooth is covered by gum. Food and plaque get trapped in that gap, so the gum swells and hurts easily.
• The chewing surface has deep grooves. These deep grooves are where cavities start most often.

That's why, once the tooth is fully in, the grooves get sealed with a sealant. A sealant covers the deep grooves on the chewing surface with a thin layer so food and bacteria can't get in. Think of it as "round 2" of the sealants your child got on the six-year molars. It's also a good time to check whether the sealants on the six-year molars have worn down or come off.

Take a peek at the very back once a month

Here's what to do at home:

1. Once a month, in good light, have your child open wide and look for a new molar showing through the gums at the very back. A phone flashlight helps.
2. To brush the very back, have your child half close the mouth and slip in a small-headed brush. Opening wide stretches the cheek tight, which actually makes it harder to get the brush in.
3. If the gum is swollen and sore while the tooth comes in, don't avoid the spot. Brush it more gently and more often. Less plaque means the swelling settles down.
4. Once the tooth is fully in, get a sealant at the dentist.

Slide the brush in at an angle from the cheek side, and brush the chewing surface, cheek side, and tongue side of the back molar in turn. Finally, sweep the brush once more over the far back end of the last tooth to cut down on missed spots. Food gets stuck easily between the six-year molar and the new molar, so floss there too.

It's best to place the sealant after the tooth is fully through the gum. The chewing surface has to stay clean and dry for a sealant to stick, and that's hard while gum still covers part of it. So when it's only halfway in, the dentist watches its progress at checkups and times the sealant right. If your child has a high cavity risk, the dentist may use a different, temporary protection (such as a glass ionomer sealant) even before the molar is fully in, so talk with the dentist once you see a new molar.

A common mistake is thinking, "They're big now, they'll handle it," and never looking in the mouth at all. Even if your child brushes on their own, check the very back molars together now and then. Showing your child the spot in the mirror also helps them pay attention on their own.

Frequently asked questions

When to see the dentist

• The gum at the very back is very swollen, or your child has trouble opening the mouth (go right away)
• The new molars are fully in and it's time for sealants
• No second molars have shown up after age 13
• You see brown or black spots on the chewing surface of a new molar
• A sealant on a six-year molar seems to have come off

English ebook · Dentist Ingyoon An

A guide to the decisions behind dental care

Tooth Calendar follows dental care from pregnancy to eighteen in 78 chapters. Explore the reasons behind feeding, brushing, baby-tooth decay, sedation, and injury decisions—including what can be watched and when to seek help. Age-based contents and a topic index help you find the concern you have today.

Preview & buy on Google Play Books

The information in this article is for general educational purposes and does not replace professional dental care. Talk to a dentist about your child's condition.

← All articles