ATDH Study Guide 2026
Everything you need to pass the ATDH exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 ATDH Exam Format at a Glance
📚 ATDH Topics to Study (21)
✍️ Sample ATDH Questions & Answers
1. The volume of a cylinder with radius 4 cm and height 10 cm is approximately: (Use π ≈ 3.14)
Volume of a cylinder = π × r² × h = 3.14 × 16 × 10 = 502.4 cm³.
2. A right angle measures exactly:
A right angle is exactly 90° and is indicated by a small square symbol in geometric diagrams.
3. In the geometric shape below, four interior angles are indicated. Which of the labeled angles is the smallest?
By inspecting the four labeled angles within the shape, Angle B is the most acute or 'sharpest' corner. Angle C is a right angle (90 degrees). Angles A and D are both obtuse, making them significantly larger than Angle B.
4. A dental hygienist mixes a 2% fluoride solution with a 10% fluoride solution to create 80 ml of a 5% fluoride solution. How many milliliters of the 10% solution are needed?
Let x be the amount of the 2% solution and y be the amount of the 10% solution. The two equations are x + y = 80 (total volume) and 0.02x + 0.10y = 0.05 * 80 (total fluoride amount). From the first equation, x = 80 - y. Substitute this into the second equation: 0.02(80 - y) + 0.10y = 4. This simplifies to 1.6 - 0.02y + 0.10y = 4. Then, 0.08y = 2.4. Solving for y gives y = 30 ml.
5. A dental hygienist is examining the angulation of different periodontal probes. Which of the following instruments shows the largest angle?
By visually comparing the four angles, Angle D is the most open, making it the largest (most obtuse) angle among the choices. Angle A is the smallest, followed by C, then B, with D being the largest.
6. Which hormone is secreted by the pancreatic beta cells to lower blood glucose levels?
Insulin, released by beta cells of the islets of Langerhans, promotes glucose uptake by cells, lowering blood glucose.