Twelve-year molars are the second permanent molars, and they usually come through between the ages of 11 and 13. They erupt right at the back of the mouth, behind the six-year molars, and they do not replace any baby tooth. Because they sit so far back and have deep grooves, they are among the most decay-prone teeth in a young mouth. Knowing when to expect them, and how to protect them, gives your child's back teeth the best start. Here is what parents should know.
Key takeaways
- Second permanent molars usually erupt between ages 11 and 13, slightly earlier in girls on average.
- They come through behind the six-year molars and do not replace a baby tooth.
- Deep grooves and a hard-to-reach position make them prone to decay.
- Sealants applied soon after they erupt can prevent a large share of cavities on these teeth.
- Mild soreness or a tender gum flap during eruption is common and usually settles.
What are twelve-year molars?
Adults have three sets of molars. The first, the six-year molars, arrive around age six. The second, the twelve-year molars, arrive around age twelve. The third are the wisdom teeth, which come much later if at all. The twelve-year molars are the second permanent molars, and like the first molars they erupt into space at the back of the jaw rather than pushing out a baby tooth. That is why parents sometimes miss them arriving. Our guide on the six-year molars covers the first set.
When do they come through?
Most children get their twelve-year molars between 11 and 13 years of age. Girls tend to be a little ahead of boys on average. As with all teeth, there is a normal range, so a few months either side of these ages is nothing to worry about. If you are unsure whether a back tooth is a late baby molar or a new permanent one, the eruption order chart and your dentist can help you tell.
Why they are prone to decay
Two things put twelve-year molars at risk. First, their biting surfaces have deep grooves and pits that trap food and are hard to clean with a brush alone. Second, they sit at the very back, where a child's brushing often runs out of patience and reach. Newly erupted enamel is also slightly softer for the first year or two while it fully hardens. Together, this makes the grooves of these molars one of the most common places for a first cavity.
Protecting the new molars
The single most effective step is a dental sealant, a thin protective coating painted into the grooves soon after the tooth is fully through. Sealants keep food and bacteria out of the deep pits and can prevent a large share of cavities on treated teeth. Alongside sealants, help your child brush the back teeth thoroughly with a fluoride toothpaste, and keep sugary snacks and drinks to mealtimes. Our guide on dental sealants for children explains how they are applied and how long they last.
| Molar | Typical age | Replaces a baby tooth? |
|---|---|---|
| First permanent molar (six-year) | Around 6 | No |
| Second permanent molar (twelve-year) | 11 to 13 | No |
| Third molar (wisdom tooth) | 17 to 25, if present | No |
What eruption feels like
As a molar breaks through, the gum over it can be tender, and a small flap of gum may sit over part of the tooth for a while. Mild soreness, and sometimes a wish to chew on that side less, are normal. Warm salt-water rinses and keeping the area clean help. See a dentist if the gum becomes very swollen, painful or has a bad taste, as a flap of gum over a partly erupted molar can occasionally trap food and become inflamed.
Frequently asked questions
Do twelve-year molars replace baby teeth?
No. Like the six-year molars, they erupt into new space at the back of the jaw and add to the number of teeth rather than replacing any baby tooth.
Should my child get sealants on them?
Sealants are often recommended for these molars because of their deep grooves. Your dentist will advise based on your child's decay risk and the shape of the tooth.
Is soreness during eruption normal?
Yes. A tender gum and mild ache as the tooth comes through are common. See a dentist if the area becomes very swollen or painful.
How do I clean the very back teeth?
Angle the brush to reach the back surfaces and spend extra time there. A smaller brush head helps, and supervising brushing until the early teens keeps technique on track.
What if a molar seems slow to appear?
A few months either side of the usual age is normal. If a molar is well overdue, a dentist can check with an examination and, if needed, an X-ray.
The bottom line
Twelve-year molars are the second permanent molars, arriving between 11 and 13 behind the six-year molars. Their deep grooves make them decay-prone, so sealants and careful brushing are worth the effort. To book a check-up and ask about sealants for your child, see our current offers.
This article is general information and not a substitute for personal dental advice. Please see a dentist for care tailored to your child's situation.
