Is it that time again when you have to remember your tooth eruption dates for your dental exams? Or are you a curious parent wondering whether your child’s tooth is delayed?

Fear not as there will be information for both of you.  Eruption dates for teeth can make your head spin if you do not have a proper system to remember them. Fortunately, there is an easy way for both deciduous teeth (Baby teeth) and permanent teeth (Adult teeth). For deciduous teeth, the system is called the “4 plus rule” and the “lower before upper rule”. But before we get into that a disclaimer:

Teeth eruption dates do vary from child to child so give each of these dates a leeway of 6 months before raising the alarm with your dentist. This first half of the guide has been written to simplify remembering tooth eruption dates, the numbers given here are averages. If you want detailed tooth eruption dates that are difficult to remember, click here to jump to the second half of the guide.  Always seek a clinician’s advice if you are worried.

The “4 plus rule” for Primary Dentition Eruption Dates

Upper Deciduous Teeth Eruption Dates
First Incisor (a)8 months
Second Incisor (b)12 months
First Molar (d)16 months
Canine (c)20 months
Second Molar (e)24 months

As you can see it is pretty simple. The primary upper tooth eruption dates start at 8 months for the first upper deciduous central incisor (a) and add 4 months to get the next eruption date and you just keep adding 4. There is a slight twist when the first deciduous molar (d) comes before the deciduous canine (c)  but no biggie.

The “lower before upper rule” for Primary teeth Eruption Dates

Lower Deciduous Teeth Eruption Dates
Lower First Incisor (a)6 months
Lower Second Incisor (b)10 months
Lower first molar (d)14 months
Lower canine (c)18 months
Lower second molar (e)22 months

As you can see from the table above, the “lower before upper rule” is exactly that. The lower teeth erupt  2 months before the upper teeth. This means the lower baby central incisor erupts at around 6 months compared to the upper deciduous central incisor which erupts at 8 months. Then just keep adding 4 months. As with the upper deciduous teeth the first molar (d) erupts before the deciduous canine (c)

The “3 plus rule” for Permanent Teeth Eruption Dates

For permanent teeth, it is slightly more complex. This time it is the “3 plus rule”  and again the “lower before upper rule”. The 3 plus rule is shown below:

Permanent Teeth Eruption Dates
First Molar (6), First Incisor (1) and Second Incisor (2)6-9 Years old
Canine (3), First Premolar (4), Second Premolar (5)9-12 Years old
Second Molar (7)12 Years old
Wisdom Tooth (8)18 Years old

So the order of eruption goes – First Molar (6), Central Incisor (1), Lateral Incisor (2) between 6-9 years old erupting in that order. Now here is the complex bit, the upper teeth do a different order to the lower teeth. The upper teeth go: First Premolar (4), Second Premolar (5), Canine (3)  and the lower teeth go: Canine (3), First Premolar (4) and Second Premolar (5) from the ages between 9-12 years old. Then the really simple second molar at 12 years old, a gap at 15 years old and the wisdom tooth at 18 years old. Then done! Phew!

The Mnemonic for permanent teeth eruption

If the 3 plus rule for permanent teeth eruption dates does not stick in your mind, why don’t you try this mnemonic? The Mnemonic is Mother Is In Bed, Baby Comes Monday Morning.

M – Molar – 6-7 years old

I – Incisor Central – 6- 8 years old

I – Incisor Lateral – 7-9 years old

B – Bicuspid 1 (First premolar) – 10-12 years old

B – Bicuspid 2 (Second premolar – 10-12 years old

C – Canines – 9 – 12 years old

M – Molar 2 (second molar) – 11-13 years old

M – Molar 3 (Wisdom tooth) – 17 – 21 years old

The Detailed  Guide

So you would like to know the accurate ranges for tooth eruption dates. We will start with the eruption dates of deciduous teeth:

Accurate deciduous teeth eruption datesUpperLower
Central incisor (a)8 to 12 months6 to 10 months
Lateral incisor (b)9 to 13 months10 to 16 months
Canine (c)16 to 22 months17 to 23 months
First molar (d)13 to 19 months14 to 18 months
Second molar (e)25 to 33 months23 to 31 months

As you can see this is a lot more tricky to remember. I will now move onto the adult teeth:

Accurate permanent teeth eruption datesUpperLower
Central incisor7 to 8 years6 to 7 years
Lateral incisor8 to 9 years7 to 8 years
Canine11 to 12 years9 to 10 years
First premolar10 to 11 years10 to 12 years
Second premolar10 to 12 years11 to 12 years
First Molar6 to 7 years6 to 7 years
Second Molar12 to 13 years11 to 13 years
Third Molar 17 to 21 years17 to 21 years

If you would like your FREE PDF printable copy of these accurate tooth eruption dates, fill in your email address below and a link will appear.

Some fun facts about teeth eruption

  • Girls teeth usually erupt faster than boys
  • Generally, teeth usually erupt in pairs so when the left-hand tooth erupts expect the right hand one to follow shortly afterwards
  • Humans only have two sets of teeth however rat’s teeth and shark’s teeth continually grow throughout their lives. Sharks on average replace a tooth a week!
  • Deciduous teeth do more than just allow kids to chew, they actually guide the permanent teeth into place.

If you found this guide useful please let me know in the comments section below, I love reading through them. Thank you for your support!

P.s. If you would like to find out which electric toothbrushes I recommend for children’s teeth click here.