From the ADEA website
The Dental Admission Test consists of 280 multiple-choice items distributed across a battery of four tests. The DAT is a computer-based examination, which takes approximately 4.5 hours to complete with an optional 15 minute break. The four components of the DAT are:
1. Survey of the Natural Sciences 100 items
General Biology 40
General Chemistry 30
Organic Chemistry 30
2. Perceptual Ability Test 90 items
(six 15-item sections: paper folds,cubes,3-D apertures, angles, views, shape folds)
3. Quantitative Reasoning 40 items
4. Reading Comprehension 50 items (3 reading passages)