You should consider sitting the exam at least 1 year or a couple months before applying to dental school. That way, you can apply to those schools that best matches your scores (and overall performance).
The Dental Admissions Test has four sections:1. Natural Sciences - Biology (40 items), General Chemistry (30 items) and Organic Chemistry (30 items)
2. Perceptual Ability - Two and three dimensional problem solving.
3. Reading Comprehension - Dental and basic sciences reading passages.
4. Quantitative Reasoning - 40 items including algebra, trigonometry, numerical calculations, etc.
Click here for DAT study and test preparation materials.
To read more about the DAT or to apply to sit the exam, visit the (ADA) American Dental Association website.