Hamadan University of Medical Sciences Avicenna Journal of Dental Research 2423-7582 1 1 2009 06 30 Knowledge of Dentists about Halitosis in Tehran(2004) 29 36 EN Z. Maleki K. Alavi S.Haji Mohammadi Journal Article Statement of the problem: Halitosis is a common condition. Many oral diseases, as well as several systemic diseases, may cause halitosis. According to some studies the prevalence of this symptom is more than 50%. Purpose: The aim of this study was to evaluate the knowledge of general practitioners (dentists), who work in Tehran, about "halitosis". Material & Methods: In this cross-sectional, descriptive study 379 dentists were evaluated. The questionnaire consisted of 15 multiple choice questions (5 choices with one of them being an "I don’t know"). There were 5 questions for evaluating knowledge about etiology of halitosis, 4 questions about pathogenesis, 4 questions on diagnosis and differential diagnosis, and 2 questions for treatment. Criterion scores (of 15) calculated as sum of correct answers and ¼ for an "I don’t know" answer. Spearman- Brown’s reliability index was 0.8. Chi-square and Lawshe’s ω test were used for statistical analysis. Results: Mean (±standard deviation) of criterion scores was 8.06±2.15 out of 15 (median of 8; range of 2.75 to 13). The mean of correct and wrong answers were 7.3±2.3 (median of 7) and 4.7±2.4 (median of 5), respectively. According to extreme groups’ scores all items were appropriately distinctive. Difficulty degree varied from 8.2% to 86.5%. Conclusion: The level of general practitioners’ knowledge was relatively low. Only about half of study population could achieve a criterion score more than 7.5 out of 15.