👉 Memorizing the eruption age of milk teeth often feels overwhelming for students (and even parents!). But with the Rule of 7 + 4, remembering the timeline becomes unbelievably simple.
👉 This rule is widely used in pediatric dentistry and is extremely high yield for NEET MDS, NBDE/INBDE, BDS exams, and OPD counseling.
▶️What is the Rule of 7 + 4?
It’s a progressive 4-month interval rule starting at 7 months.
Every 4 months, the child gets 4 new primary teeth.
Let’s break it down.
▶️Tooth Eruption According to the Rule of 7 + 4
🦷 At 7 months → 1st teeth appear
Usually the lower central incisors.
🦷 At 11 months (7 + 4) → 4 teeth
Now the child has central incisors in both arches.
🦷 At 15 months (11 + 4) → 8 teeth
All incisors + first molars start appearing.
🦷 At 19 months (15 + 4) → 12 teeth
First molars fully erupt, canines start erupting.
🦷 At 23 months (19 + 4) → 16 teeth
Canines emerge completely.
🦷 At 27 months (23 + 4) → 20 teeth
Full primary dentition is now complete
→ total: 20 milk teeth.
▶️Why This Mnemonic Works?
✔ Perfect for quick revision
✔ Makes eruption ages predictable
✔ Reduces confusion during exam MCQs
✔ Easy for parents to understand during counseling
✔ Helps track delayed eruption cases
📝 Short Summary
Here is the breakdown shown in the image you shared:
📌 7 months → 1st teeth
📌 11 months → 4 teeth
📌 15 months → 8 teeth
📌 19 months → 12 teeth
📌 23 months → 16 teeth
📌 27 months → 20 teeth
Simple. Predictable. Easy to remember.
💡Quick Exam Tip
“Total primary teeth = 20
Complete by ≈ 2–2.5 years (≈ 27 months).”
This shows up in every pediatrics, pedodontics, and oral histology exam.
📍 Final Takeaway
The Rule of 7 + 4 is the cleanest, fastest way to recall tooth eruption ages.
Master it for NEET MDS, use it in clinics, and teach it to parents for reassurance.
🔖 Save this post for revision and share it with your classmates — trust me, they’ll thank you later! 😃😎
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