The purpose of this study was to test the predictive ability of specific questions in diagnosis of pulpal and periradicular disease in a dental school population. 210 patients were recruited to fill out a questionnaire, and undergo a clinical examination for pulpal and/or periradicular disease.The Questionnaire asked if the patient had in the last 6 months: 1. a toothache that kept them up at night 2. a toothache that required pain killers 3. facial swelling caused by a tooth 4. injury to any teeth 5. a broken tooth 6. a tooth darker in color than the surrounding teeth 7. a bump, pimple, or boil on the gums. 8. a toothache after eating or drinking something hot or cold 9. repeated sharp pain in the same area while chewing 10. A toothache or facial swelling that caused them to visit an emergency room.Examiners were blinded to the responses on the questionnaire and then, based on the clinical examination and testing, determined the presence or absence of endodontic disease. The data was analyzed using univariate logistic regression models.Results: The most predictive questions were #1 and #2 (p-value Conclusion: Patients with pain that wakes them at night or that requires analgesics were greater than 3 times more likely to have endodontic disease at the time of examination.