As noted in the current candidate manual
, the Diagnostic Skills Exam (DSE) has been reduced from 280 questions to 150 scored questions. This went into effect on Feb. 1, 2013. The new DSE is about half the length of the previous exam and runs 4.25 hours rather than 7 hours. It has two parts with one break in the middle while the old exam had three parts and two breaks. The exam covers the exact same material, has the same overall difficulty and is psychometrically identical. The only difference is that the new exam takes significantly less time. For more information, please refer to the section in the candidate manual on this part of the American Dental Licensing Examination (ADLEX).