How-to · Exam prep
Primary vs. permanent teeth: what new assistants need to know
Every mouth you'll ever assist on runs on one of two sets of teeth — or a mix of both. Knowing the two dentitions cold is foundational for charting, X-rays, and talking with parents in the chair. Here's the beginner's map.
The two dentitions (tap each)
Letters for little teeth, numbers for big ones
In the Universal Numbering System — the one most U.S. offices use — permanent teeth are numbered 1 through 32, starting at the upper right third molar (#1), sweeping across the upper arch to #16, dropping to the lower left (#17), and finishing at the lower right third molar (#32). Primary teeth get letters A through T following the same sweep. So when the doctor calls out "watch the distal on B," you know instantly it's a baby tooth near the upper right. This calling-out is the language of charting, and it has to be automatic — start with charting for beginners and practice free in the charting tool.
Kids have no premolars — the primary set is incisors, canines, and molars only (20 total). The premolars that eventually show up erupt into the spots where primary molars used to be. This trips up almost every beginner on quizzes, so lock it in now.
The mixed years: two sets at once
Roughly from age six into the early teens, a child's mouth holds both dentitions at once — permanent teeth erupting while primary teeth loosen and go. The first permanent molars come in around age six behind the last primary molars, without replacing anything, which is why parents often don't realize those are permanent teeth that need to last a lifetime. As an assistant you'll chart mixed dentitions constantly in family practice — letters and numbers in the same chart — and gently explain to parents which teeth are which.
Why baby teeth matter (a thing you'll explain weekly)
"They fall out anyway — why fix them?" You will hear this from parents, and the answer is one every assistant should own: primary teeth hold space for the permanent teeth coming behind them, guide those teeth into position, and matter for chewing and speech in the meantime. Losing them too early to decay can crowd and complicate the adult smile. You'll never diagnose — that's the dentist's call — but you'll be the one reinforcing the why, chairside, in plain kind language.
Tooth counts, letters, and numbering sweeps are pure recall material — perfect for the free flashcards in five-minute pockets. Reread notes and it slips; flash it daily for a week and it sticks.
How this shows up in training and beyond
Dental anatomy is early-weeks material in the ~12-week program, then it never leaves — every impression, X-ray, and chart entry sits on top of it. You'll drill numbering on our anatomical tooth chart in Practice Pro until calling teeth is as natural as reading. And on the free practice exam, anatomy questions are some of the easiest points once this foundation is in.
From tooth #1 to job-ready in ~12 weeks.
Anatomy, charting, radiology, chairside — built step by step, hands-on. Applying is free.
Apply now →Keep reading: How to chart teeth · Day-one terms cheat sheet · The flashcards tool walkthrough