How Long Does It Take for Baby Molars to Come In?

First baby molars typically break through the gums between 13 and 19 months of age, and second baby molars follow between about 23 and 30 months. But “coming in” is a bit misleading, because each molar doesn’t just pop through overnight. The tooth has been forming and migrating inside the jawbone for months before it becomes visible, and the process of cutting through the gum can stretch over days or weeks. The full molar timeline, the symptoms that come with it, and the wide range of normal variation are worth understanding, because molars tend to be the teeth that give families the most trouble.

When First and Second Baby Molars Usually Appear

A baby’s twenty primary teeth arrive in a roughly predictable order, and molars come in two waves. The first primary molars, which sit just behind the canines, tend to erupt between about 15 and 19 months in the upper jaw and 15 to 20 months in the lower jaw, based on data from a cross-sectional study of children’s eruption patterns.¹ The second primary molars, the farthest-back teeth in a toddler’s mouth, arrive later, generally between 23 and 30 months. By roughly the age of two and a half, most children have their full set of twenty baby teeth, though stragglers are common and not cause for alarm.

That said, a Romanian study tracking eruption timing found the average child had about 17 teeth by 24 months, meaning a few teeth, often those second molars, were still making their way through at that point.² The data from both studies suggest that finishing off the second molars by 30 months is well within normal range, and some children take a few months beyond that.

Something worth noting: first molars often arrive before the canines (the pointy teeth), even though the canines sit in front of the molars. This surprises many parents who expect teeth to fill in strictly front-to-back. In several study populations, the first molars appeared around 15 to 19 months while canines didn’t show up until about 18 to 24 months.¹ So if your toddler has flat molars visible in the back but a gap where the canines should be, that’s entirely typical.

What Happens Under the Gums Before a Molar Appears

By the time you notice a white bump on your child’s gum, the tooth has already been on a long journey. Tooth eruption is a tightly regulated process that starts deep inside the jawbone. Before a tooth can move toward the surface, specialized cells called osteoclasts have to be recruited to the tissue surrounding the developing tooth. These cells dissolve bone to carve out a pathway, essentially tunneling through the jaw so the tooth has an exit route.³ Without this bone remodeling, the tooth would remain trapped.

At the same time, the tooth’s roots are growing and lengthening, which helps push the crown toward the surface. Research has shown that root growth actually accelerates as a baby tooth approaches gum-line emergence, suggesting the final push through the gum is the culmination of weeks or months of increasing underground activity.⁴ This explains why teething discomfort can seem to come and go: the tooth may be actively remodeling bone and stretching soft tissue for a while, pause, then surge forward again.

For molars specifically, the eruption process underground can feel more dramatic than it was for the incisors. Molars have larger, broader crowns and multiple roots, which means more bone has to be cleared and more gum tissue has to stretch before the tooth breaks through. This is one reason molar teething is often reported as more uncomfortable than incisor teething.

How Molar Teething Symptoms Differ From Other Teeth

The classic teething symptoms, increased drooling, gum irritation, fussiness, disrupted sleep, tend to cluster in a fairly narrow window. A prospective study that tracked babies closely found that symptoms were only significantly more frequent during the four days before a tooth emerged, the day it appeared, and the three days after, making it roughly an eight-day window per tooth.⁵ Outside that window, the symptoms weren’t meaningfully different from baseline fussiness.

But not all teeth create identical symptoms. A clinical trial comparing eruption-related signs across tooth types found that canines actually caused more appetite loss than either incisors or molars.⁶ This might seem counterintuitive given that molars are larger, but canines have a sharp, pointed crown that seems to irritate gum tissue in a particularly uncomfortable way. Molars, with their flatter tops, may cause more of a dull aching pressure than a sharp piercing sensation. Still, many parents report that molar teething disrupts sleep more than earlier teeth, likely because the broader surface area means a larger patch of gum is swollen and tender.

The same study also measured body temperature and found that on the actual day of eruption, there was a small but real rise in temperature, though only to about 36.7°C (98.1°F), which is well within the normal range.⁶ That finding is consistent with the broader research consensus on teething and fever, which is worth its own discussion.

Teething Does Not Cause Real Fevers

This is one of the most persistent myths in parenting, and it matters because believing teething causes fever can lead parents to dismiss an actual illness. A meta-analysis pooling results from multiple studies found no overall association between fever and primary tooth eruption.⁷ A separate prospective longitudinal study found that while body temperature might nudge upward very slightly around teething, it did not reach anything that qualified as a fever, and concluded that severe symptoms like high fever could not be attributed to teething.⁸

A third meta-analysis confirmed the same pattern: eruption can lead to a slight rise in body temperature, but it was not characterized as fever.⁹ The takeaway is straightforward: if your baby has a temperature above 38°C (100.4°F), something else is going on, even if a molar happens to be coming through at the same time. The coincidence is common because babies are teething on and off for roughly two years, the same period when they’re picking up frequent infections. It’s easy to conflate the two.

What Actually Helps With Molar Discomfort

When molars are causing visible distress, parents understandably want to know what works. A systematic review of treatments for teething symptoms found that the most effective non-drug approach was chilled teething rings, which helped with drooling, disrupted sleep, gum irritation, and crying.¹⁰ A clinical trial comparing non-drug options specifically found that teething rings produced the fastest recovery and highest parent satisfaction, followed by comforting the baby and gently rubbing the gums.⁶

Something parents should avoid: benzocaine-containing gels marketed for teething. The FDA issued a warning in 2011 advising against using any benzocaine product on infants because of the risk of methemoglobinemia, a rare but serious condition where the blood’s ability to carry oxygen is impaired.¹¹ Numbing gels also wash away quickly with saliva, providing only brief relief at best. For more persistent discomfort, age-appropriate doses of acetaminophen or ibuprofen (the latter only after six months of age) are the standard recommendation from most pediatric organizations, though you should check with your pediatrician for dosing.

Why Some Babies Get Molars Months Earlier or Later

The ranges given above are averages, and individual variation is substantial. Several factors influence when molars show up:

Sex: Boys tend to get their first tooth about a week earlier than girls, and at one year of age, boys had slightly more erupted teeth on average in a large study tracking eruption patterns.¹² The gap narrows with age, and by two it was no longer statistically significant.
Genetics: Family history is a strong predictor. If one or both parents teethed early, their child is more likely to as well. Some genetic conditions dramatically accelerate the process: children with certain ADNP gene mutations, for instance, were found to have nearly a full set of teeth including molars by one year of age, far ahead of the typical schedule.¹³
Nutrition and birth weight: Preterm birth and low birth weight have been associated with delayed eruption in some studies. Adequate nutrition, particularly calcium and vitamin D, supports the mineralization process that allows teeth to develop on schedule.
Ethnicity: Eruption timing studies conducted in different countries consistently find population-level differences of a few months, though the sequence of eruption tends to be more stable across populations than the exact timing.

If your child hasn’t shown any teeth by 12 to 13 months, or if first molars haven’t appeared by around 20 months, it’s worth mentioning at your next pediatric visit. Genuinely delayed eruption is uncommon but can occasionally signal nutritional deficiencies, hormonal conditions, or issues with jaw development. In the vast majority of cases, though, the teeth are just taking their time.

Starting Oral Care When Molars Arrive

Molars change the oral hygiene equation. Incisors are smooth and relatively easy to wipe clean, but molars have grooves and pits on their chewing surfaces where food and bacteria can collect. This makes them far more vulnerable to cavities than the front teeth, which is why the eruption of first molars is a practical turning point for dental care.

The American Academy of Pediatrics recommends that fluoride toothpaste be introduced with the eruption of the first tooth, using a smear or rice-grain-sized amount for children under three. After age three, when the child can reliably spit, a pea-sized amount is appropriate. The guidance specifically advises spitting without rinsing, so that some fluoride remains on the teeth.¹⁴ European guidelines from the EAPD similarly endorse daily fluoride use and recommend that parents assist with or supervise brushing until at least age seven.¹⁵

Many parents are surprised by how early cavities can develop on baby molars. Because primary teeth have thinner enamel than permanent ones, decay can progress quickly once it starts. And since those first molars need to last until the child is about ten or eleven years old (when the permanent premolars replace them), keeping them healthy matters more than people often assume.

What Happens When Baby Molars Are Lost Too Early

Baby molars aren’t just placeholders; they actively hold space in the jaw for the permanent teeth developing beneath them. When a primary molar is lost well ahead of schedule, whether from decay, trauma, or extraction, the neighboring teeth can drift into the gap. A study investigating space loss after premature extraction of first primary molars found that the average space loss was about half a millimeter, with the maximum occurring in the 8 to 18 months following extraction.¹⁶ That might sound tiny, but in a small child’s jaw, even a fraction of a millimeter can crowd the incoming permanent tooth.

Premature loss of first primary molars has also been linked to midline shift, where the center line of the upper and lower teeth no longer aligns, potentially creating bite problems that later require orthodontic treatment.¹⁷ Second primary molar loss tends to cause somewhat different downstream effects, showing higher concordance with changes in molar classification rather than midline issues. In some cases, a dentist will place a small device called a space maintainer to hold the gap open until the permanent tooth is ready to erupt.

When a Molar Seems Stuck

Occasionally, a baby molar partially emerges and then seems to stop moving. In some cases this is simply a normal pause in eruption, but in others it can signal dental ankylosis, a condition where the tooth root fuses directly to the surrounding bone. When this happens, the tooth stops erupting and gradually appears to sink below the level of its neighbors as the jaw continues to grow around it.

Diagnosing ankylosis isn’t straightforward. A study of primary molars found that diagnosis typically involves looking for infraocclusion (the tooth sitting lower than the teeth next to it), loss of the normal space between root and bone on X-ray, and displacement of neighboring teeth.¹⁸ Standard panoramic X-rays aren’t very reliable for confirming ankylosis on their own. Cone-beam CT scans perform better, catching all confirmed cases in one study, though they can produce false positives.¹⁹ Mild ankylosis in a primary molar sometimes resolves on its own as the permanent tooth beneath pushes up and resorbs the baby tooth’s root. Severe cases may require extraction to prevent the permanent tooth from being blocked or deflected.

The Broader Evolutionary Picture

Human babies get their teeth remarkably slowly compared to our closest primate relatives. In chimpanzees, the first permanent molars come in at around three and a half years of age, while in humans they don’t appear until about six. Research comparing tooth development across species has found that in chimpanzees, the timing of root growth spurts closely matches the timing of tooth eruption: the root accelerates, and the tooth appears. In modern humans, those two events have become dissociated. The root growth spurt occurs earlier, while the tooth itself erupts later, often staying buried in the jawbone well after the root has done its pushing.²⁰

This dissociation is thought to reflect humanity’s unusually extended childhood. A longer period of dependence on caregivers, delayed weaning, and a diet that increasingly relied on processed or cooked foods meant there was less evolutionary pressure for teeth to arrive quickly. Fossil evidence from earlier human ancestors like Homo erectus suggests their molar eruption timing was intermediate between great apes and modern humans, pointing to a gradual stretching of the dental development timeline over hundreds of thousands of years.²⁰ So when your toddler seems to be taking forever to cut those back molars, they’re right on track for a species that has been slowing down its dental clock for millennia.

1
PubMed Central. Eruption Chronology in Children: A Cross-sectional Study
2
PubMed Central. Eruption Timing and Sequence of Primary Teeth in a Sample of Romanian Children
3
PubMed. Cellular, molecular, and genetic determinants of tooth eruption
4
PubMed. Root growth and dental eruption in modern human deciduous teeth with preliminary observations on great apes
5
Pediatrics. Symptoms Associated With Infant Teething: A Prospective Study
6
PubMed Central. Signs and symptoms associated with primary tooth eruption: a clinical trial of nonpharmacological remedies
7
PubMed Central. Association between Fever and Primary Tooth Eruption: A Systematic Review and Meta-analysis
8
Pediatrics. Prospective Longitudinal Study of Signs and Symptoms Associated With Primary Tooth Eruption
9
Pediatrics. Signs and Symptoms of Primary Tooth Eruption: A Meta-analysis
10
Brazilian Oral Research. Efficacy of treatments used to relieve signs and symptoms associated with teething: a systematic review
11
PubMed. What are pharmacists recommending for infant teething treatment?
12
PubMed Central. Maternal and early life factors of tooth emergence patterns and number of teeth at one and two years of age
13
Translational Psychiatry. Premature primary tooth eruption in cognitive/motor-delayed ADNP-mutated children
14
Pediatrics. Fluoride Use in Caries Prevention in the Primary Care Setting
15
PubMed. Guidelines on the use of fluoride for caries prevention in children: an updated EAPD policy document
16
PubMed Central. Investigating the Factors Affecting the Need for Unilateral Space Maintainer for First Primary Molars in Late Mixed Dentition
17
PubMed Central. Effects of Premature Primary Tooth Loss on Midline Deviation and Asymmetric Molar Relationship in the Context of Orthodontic Treatment
18
PubMed Central. Prevalence and Manifestations of Dental Ankylosis in Primary Molars Using Panoramic X-rays: A Cross-Sectional Study
19
European Journal of Orthodontics. Diagnosis of tooth ankylosis using panoramic views, cone beam computed tomography, and histological data: a retrospective observational case series study
20
PLOS ONE. Human Life History Evolution Explains Dissociation between the Timing of Tooth Eruption and Peak Rates of Root Growth