Most parents know that baby teeth fall out. Fewer understand what they’re actually for while they’re there, or why losing them too early can cause problems that outlast childhood. The distinction between primary and permanent dentition matters more than it’s often given credit for.
At our children’s dentistry practice in West Byfleet, we discuss the development of a child’s teeth at every check-up — because understanding what’s normal makes it much easier to notice when something isn’t.
The Primary (Baby) Teeth: A Full Set of Twenty
Humans develop two sets of teeth. The first — primary teeth, also called deciduous teeth or milk teeth — consists of twenty teeth in total: eight incisors, four canines, and eight molars (four in each jaw). There are no premolars in the primary dentition.
The first primary tooth typically erupts around six months of age, though anywhere from four to twelve months is considered normal. The lower central incisors usually arrive first, followed by the upper central incisors. By around two and a half to three years old, most children have all twenty primary teeth in place. Some children reach this milestone a little earlier, others a little later — both are usually fine.
The primary molars, which arrive between roughly twelve and thirty months, are particularly important. They maintain the space in the back of the arch that the adult premolars will eventually need. When baby molars are lost prematurely through decay or extraction, adjacent teeth drift into that space, and the permanent premolars that follow can become impacted or misaligned.
The Permanent (Adult) Teeth: Up to Thirty-Two
The permanent dentition comprises up to thirty-two teeth: eight incisors, four canines, eight premolars, eight molars, and (in most people) four wisdom teeth. The wisdom teeth are the last to arrive — typically in the late teens or early twenties — and not everyone develops all four. Some people are congenitally missing one or more wisdom teeth, and in many cases this causes no problems at all.
The first permanent teeth to arrive are typically the first permanent molars at around age six, along with the lower central incisors. Parents sometimes don’t realise the six-year molars are adult teeth because they don’t replace any baby tooth — they erupt further back in the arch where no primary molar sat. These first permanent molars are among the most decay-prone teeth in the mouth, partly because of their anatomy and partly because they arrive early, when dietary and brushing habits may still be developing.
The Eruption and Loss Timeline
| Feature | Baby Teeth (Primary) | Adult Teeth (Permanent) |
|---|---|---|
| Total number | 20 | Up to 32 (28 without wisdom teeth) |
| Types present | Incisors, canines, molars | Incisors, canines, premolars, molars |
| First eruption | Around 6 months | Around 6 years (first molars and lower incisors) |
| Full set complete | Around 2.5–3 years | Around 12–13 years (excluding wisdom teeth) |
| Shedding period | 6–12 years | Not shed (unless lost through disease or injury) |
| Enamel thickness | Thinner — more vulnerable to decay | Thicker — still vulnerable but less so |
| Root length | Shorter; absorbs as adult tooth develops beneath | Full length — stable once fully developed |
The shedding of primary teeth and arrival of permanent teeth spans roughly six years, from around age six to twelve. Front teeth tend to go first: lower central incisors typically loosen around six to seven years old, upper central incisors at seven to eight. The back baby molars are usually the last to go, shed around ten to twelve years old when the adult premolars push through beneath them.
Why Baby Teeth Matter
The “they’ll fall out anyway” reasoning doesn’t hold up once you understand what primary teeth actually do. They serve four functions that directly affect long-term dental health.
- Space reservation: baby teeth hold the jaw’s architecture in place until the adult teeth are ready to erupt. Premature loss allows neighbouring teeth to drift and the opposing teeth to over-erupt, creating space problems for the permanent teeth that follow.
- Jaw development: chewing on both sides of the mouth stimulates the bone and promotes symmetrical jaw growth. A child avoiding a painful side because of an untreated cavity can affect this.
- Speech development: the front teeth are central to the production of several consonant sounds. Children who lose front teeth prematurely, before the adult teeth are ready to erupt, sometimes develop a lisp or modified articulation patterns.
- Nutrition and confidence: toothache interferes with eating. Visibly decayed or missing front teeth can also affect a child’s willingness to smile and interact socially — something that’s difficult to quantify but shouldn’t be dismissed.
Common Myths About Baby Teeth
Several ideas about primary teeth persist despite being incorrect.
The first is that baby teeth don’t need to be brushed because they’ll fall out. In our experience, the habits established during the primary dentition years carry over — children who learn proper brushing routines early are far more likely to maintain them when the adult teeth arrive. And an infected baby tooth sits millimetres above the developing permanent tooth bud, with real potential to damage it.
The second myth is that all loose teeth indicate the baby tooth is ready to go and should be pulled. A tooth that’s wiggly because the root is absorbing naturally — the normal process — is fine to leave until it falls on its own. But a tooth that’s loose due to trauma or gum disease is a different matter and warrants a check-up before anything is done to it.
The third is that adult teeth come in crooked because the parents had crooked teeth, and there’s nothing to be done. Genetics plays a role, but so does jaw development, which is influenced by factors we can affect: early orthodontic assessment, fissure sealants to preserve baby molars, and timely treatment of decay that might cause premature tooth loss.
When to Seek Advice
You might be wondering when a child’s dental development warrants a call to the dentist rather than a wait-and-see approach. A primary tooth that shows no sign of loosening but whose permanent replacement is already visible in the gum alongside it warrants a check. A permanent tooth that’s erupted significantly behind or in front of the baby tooth it was supposed to replace — rather than pushing it out — should be looked at. Any tooth that causes consistent pain, however mild, deserves an appointment rather than ongoing paracetamol.
But most of those situations arise less often than parents fear. The human dentition is robustly designed, and the vast majority of children move through eruption and shedding without any complications beyond the mild discomfort that’s perfectly normal during these transitions.
If you have questions about your child’s dental development, or if it’s simply time for their check-up, Coniston Dental Practice in West Byfleet is accepting new young patients from across the Woking area. Call us on 01932 343675 and we’ll find an appropriate appointment time.
