When Do Children Get Their Molars?

Children get their first set of molars (the baby molars) between roughly 13 and 33 months of age, and their first permanent molars around age six, well before losing any baby teeth in that area. The full molar story unfolds over nearly two decades, though, with second permanent molars arriving around age twelve and wisdom teeth potentially emerging into the early twenties. Because molars are the workhorses of chewing, their arrival at each stage marks a real shift in what a child can eat, how their jaw develops, and what kind of dental care they need.

Baby Molars Come in Two Waves

A child’s primary (baby) teeth include two sets of molars on each side of both jaws, for a total of eight baby molars. The first primary molars typically break through around 13 to 16 months of age, and the second primary molars follow roughly between 20 and 30 months. A large systematic review pooling data from over 42,000 children across multiple continents found that the mandibular second molar, the last baby tooth to arrive, erupted as early as about 20 months in European populations and as late as 29 months in South American ones.¹ That spread is a useful reminder that “normal” covers a wide window. A toddler who gets their last baby molar at two years old and one who gets it closer to two and a half are both on track.

These baby molars serve an important purpose beyond chewing. They hold space in the jaw for the larger permanent premolars that will eventually replace them, and their presence helps guide how the permanent teeth line up. Losing a baby molar too early, whether from decay or injury, can create space problems that affect the permanent teeth for years afterward.

The Six-Year Molars

The first permanent molars are sometimes called “six-year molars” because that is roughly when they appear. Unlike other permanent teeth, they do not replace any baby tooth. Instead, they emerge behind the last baby molar, in an area of the gum that was previously empty. This means parents sometimes miss them entirely, assuming a child has not started getting permanent teeth yet because no baby teeth have fallen out.

A longitudinal study tracking individual children found that girls averaged eruption of their first permanent molars at about 6.1 years and boys at about 6.3 years. But the range was striking: some children had them as early as five years and two months, and others did not see them until nearly eight years old. The time it took for a single molar to work its way fully through the gum ranged from five months to over two and a half years.² Another study found that by about five and a half to six and a half years of age, the majority of children had at least one permanent molar visible, with girls consistently ahead of boys at every age point checked.³

That girls-before-boys pattern holds across nearly every tooth in the mouth. The gap is modest, usually a few months, but it is consistent enough that dental professionals consider sex when evaluating whether eruption timing is unusual.

Second Permanent Molars Around Age Twelve

The second permanent molars, sometimes nicknamed the “twelve-year molars,” emerge behind the first permanent molars. One study placed the mean eruption age at about 12.2 years.⁴ These teeth arrive during a time when many children are managing their own brushing with minimal supervision, and the teeth themselves are harder to reach. Both factors help explain why second molars tend to pick up cavities quickly after they come in. That same study found that within just one year of the average eruption date, nearly half of second permanent molars already had cavities.

The second molars also arrive during a phase of active jaw growth. Their eruption can coincide with the period when orthodontists first evaluate whether a child will need braces, since the positioning of these molars affects the overall bite. In children who already have crowding issues, the arrival of second molars can make things feel tighter and sometimes tips the decision toward treatment.

Wisdom Teeth and the Long Wait

Third molars, better known as wisdom teeth, are the final set. They develop deep in the jaw during the teenage years and, if they erupt at all, generally break through somewhere between the late teens and mid-twenties. Research on a population in northeastern India found that the average age of complete eruption for wisdom teeth was about 20.3 years, with the earliest complete eruptions recorded at age 15. Lower wisdom teeth tended to appear before upper ones.⁵

Many people never get functional wisdom teeth. Some develop wisdom teeth that remain fully buried in the bone (impacted), others have them come in only partially, and a meaningful percentage of the population is missing one or more wisdom teeth altogether because the tooth buds never formed. Impacted or partially erupted wisdom teeth can trap food and bacteria, which is why extraction is so commonly recommended. But in people who have room in their jaw and whose wisdom teeth come in straight, keeping them is perfectly fine.

Why Molar Timing Varies

When parents compare notes, they often find that one child’s molars arrived months or even over a year earlier or later than another’s. Several factors contribute.

Genetics plays a role in the underlying pace of dental development, but some of the differences people attribute to ethnicity may actually reflect nutrition and overall health. A study that compared tooth development in ethnic Finns and Somalis who were all born and raised in Finland, controlling for the shared environment, found that the observed differences in timing between the two groups were minimal.⁶ When living conditions are similar, children from different backgrounds tend to develop teeth on a similar schedule. This suggests that much of the worldwide variation seen in large surveys reflects environmental conditions rather than deep genetic programming.

Preterm birth and low birth weight can shift the entire dental timeline later. One study found a statistically significant delay in the eruption of the first tooth among infants with very low birth weight compared to those with higher birth weight.⁷ Premature birth can also affect the symmetry and development of the jaws themselves, with cascading effects on how teeth eventually line up.⁸ For premature children, pediatric dentists usually evaluate eruption timing using corrected age rather than chronological age, at least during the first couple of years.

How Teeth Actually Push Through Bone and Gum

A tooth does not simply grow upward like a plant. Getting from its initial position deep in the jawbone to its final spot in the mouth requires the body to actively dissolve bone above the developing tooth while building new bone below it. These two processes, bone breakdown and bone building, work in tandem to create a pathway and push the tooth along it.⁹

The soft tissue surrounding a developing tooth, called the dental follicle, appears to play a key role in directing this process. Research using computational modeling has proposed that the follicle senses strain in the surrounding bone caused by bite forces, and then signals bone-remodeling cells to reshape the bony crypt around the tooth, effectively opening a path for eruption.¹⁰ This means that chewing activity may actually help drive the eruption of teeth that are still forming beneath the gum. It is an elegant feedback loop: using the teeth you already have helps the next set come in.

What Teething Symptoms Look Like with Molars

Baby molar eruption tends to produce more discomfort than the front teeth because molars have a broader surface that has to break through the gum. A clinical trial that tracked symptoms day by day around eruption events found that drooling occurred in about 92% of cases, sleep disturbances in about 82%, and irritability in about 76%. A slight increase in body temperature was measurable on the day a tooth actually broke through the gum, but it was low-grade, around 36.7°C (98.1°F), and gone by the next day.¹¹

That last point is worth underscoring: teething can cause a mild temperature increase, but it does not cause real fevers. A study examining objective signs associated with primary tooth eruption confirmed that fever, drooling, and diarrhea were all associated with eruption, with fever the most frequently observed sign.¹² However, a temperature above about 38°C (100.4°F) should not be blamed on teething without ruling out infection, especially because the molar eruption window overlaps with ages when children frequently catch bugs from daycare and other group settings.

With permanent molars, particularly the six-year molars, some children notice soreness or mild swelling in the gum behind their last baby teeth. The discomfort is usually less dramatic than infant teething, partly because the gum tissue in that area is thinner and partly because older children can communicate what they feel and use simple remedies like cold water or gentle pressure.

Why New Molars Are Cavity Magnets

Freshly erupted molars are more vulnerable to decay than mature ones for a couple of reasons. The enamel has not yet fully hardened through a process called post-eruptive maturation, where minerals from saliva gradually strengthen the tooth surface over months and years. And the chewing surface of a molar is full of deep pits and grooves (fissures) that trap food and bacteria in places a toothbrush bristle cannot easily reach.

Research on the caries vulnerability of permanent molars found that over 10% of first permanent molars had cavities within one year of their average eruption date, and for second molars, that figure was roughly 45%.⁴ The second molars’ higher rate likely reflects both the difficulty of reaching them and the reality that twelve-year-olds tend to be less diligent brushers than their parents were on their behalf at age six.

Dental sealants, thin coatings painted into those fissures, are a standard preventive measure. A study evaluating sealant performance on young permanent molars noted less sealant detachment when the material was applied around age seven, suggesting that timing the application soon after eruption but not too soon, when the tooth may still be partially covered by gum tissue, matters for how well the sealant sticks.¹³ Fluoride varnish applications during routine dental visits also help shore up the enamel while it is still maturing.

Molar Incisor Hypomineralization

Some children’s first permanent molars come in with patches of white, yellow, or brown discoloration and enamel that chips or crumbles easily. This condition, called molar incisor hypomineralization (MIH), affects the first permanent molars and sometimes the permanent incisors. It happens because something disrupted the enamel-forming cells during the period when those teeth were developing beneath the gum, roughly from late pregnancy through the first few years of life.¹⁴

Because the enamel defect is built into the tooth’s structure, it cannot be reversed after the tooth erupts. Research into MIH’s causes has identified several early-life health events that correlate with it, including kidney disorders, digestive system problems, and episodes of severe diarrhea in infancy.¹⁵ Affected teeth are more sensitive to temperature and more prone to rapid decay, so children with MIH often need extra protection such as fluoride treatments, sealants, or in severe cases, crowns.

When Molars Simply Do Not Come In

Occasionally a child’s molar fails to erupt at all, even though it is visible on an X-ray and no physical obstruction is in the way. This condition, primary failure of tooth eruption (PFE), is a rare genetic disorder. The most commonly implicated gene involves the parathyroid hormone receptor (PTH1R), and the condition follows an autosomal dominant inheritance pattern, meaning a single copy of the variant from one parent can cause it. The result is often a progressive open bite, where the affected teeth sit lower than their neighbors, and conventional orthodontic force cannot pull them into position because the biological eruption mechanism itself is not working.¹⁶

PFE is distinct from teeth that are simply late. A tooth that is developing normally on X-ray but running behind schedule will almost always eventually erupt on its own. In PFE, the tooth development itself may look normal, but the eruption process is fundamentally impaired. Genetic testing can help confirm the diagnosis, which matters because attempting to orthodontically move a PFE-affected tooth can cause root damage without actually getting the tooth into place. Treatment usually involves prosthetic solutions rather than braces.

What Happens When a Baby Molar Is Lost Too Early

Baby molars normally stick around until the permanent premolars are ready to replace them, usually between ages 10 and 12. If a baby molar is lost early due to decay or trauma, the teeth on either side can drift into the empty space, narrowing the room available for the permanent tooth underneath. A systematic review and meta-analysis found significant space loss on the extraction side within six months of premature removal of a primary first molar, though the overall arch dimensions were not dramatically altered in the short term.¹⁷

This is why pediatric dentists often recommend a space maintainer, a small metal appliance that holds the gap open until the permanent tooth is ready. The decision depends on which tooth was lost, the child’s age, and how far along the permanent successor is in its development. If the permanent tooth is already close to erupting, a space maintainer may not be necessary. If the child is only five or six and the replacement tooth is years away, keeping that space open becomes more important.

Teeth as a Biological Clock

Molar eruption patterns are so predictable across human populations that they are used as a tool for estimating age in forensic and archaeological contexts. Tooth formation, which can be assessed from X-rays, tends to be a more reliable indicator of biological age than bone development or body size because it is less influenced by nutritional fluctuations.¹⁸ The maturity of the second and third molars, in particular, is used in legal settings to help estimate whether an individual has crossed specific age thresholds.¹⁹

Anthropologists have also leaned heavily on molar eruption timing to reconstruct life-history patterns in human ancestors. The age at which first molars erupt correlates with key developmental milestones like weaning across primates, making molar emergence a window into how fast or slow a species grows up. Dental tissues contain faithful records of birth and incremental growth, and researchers use molar eruption age, tooth wear, and chemical signatures in enamel to piece together how ancient humans and their relatives developed.²⁰ The slow pace of human molar eruption, spread out over roughly 18 years from first baby molar to last wisdom tooth, reflects the unusually long childhoods that distinguish us from other primates.

How Diet Shapes the Jaw That Receives Molars

One reason wisdom teeth cause so many problems in modern humans is that our jaws have gotten smaller over the course of recent evolution and cultural history, partly because our food has gotten softer. An experimental study in pigs compared jaw development between animals fed hard food and those fed soft food. The hard-food group developed shorter dental arches from normal wear and migration of teeth, but the wear itself reduced crowding and rotation.²¹ The soft-food group, by contrast, had less wear but more crowding, a pattern that mirrors what we see in modern human populations eating heavily processed diets.

This does not mean you should hand your toddler a raw carrot to chew on as soon as their baby molars appear (choking hazards are real). But the broader point is relevant: the jaw is a “use it or grow it” structure, and the mechanical demands placed on it during childhood influence whether there will be room for all the teeth that are genetically programmed to arrive. Children whose diets include firmer foods that require more chewing may develop slightly broader dental arches, potentially easing the crowding that makes third molars problematic. The evidence here is mostly from animal models and cross-cultural comparisons rather than randomized trials in children, so it is more suggestive than definitive, but it aligns with what orthodontists observe clinically.