RESUMEN
Evaluation of the prevalence and causes of bad breath [Halitosis] has engaged mans mind for centuries. In ancient medical literature, there have been some remarks about halitosis as well as suggestions for its treatment. Halitosis is not a disease by itself. This condition is a symptom of disease. Halitosis can be produced by three factors: Intra-and extra oral factor, and delusional halitosis. The aim of the investigation was to evaluate the prevalence and causes of halitosis. Four hundred patients referring to oral medicine clinics of the dental school of Yazd participated in this study. Prevalence of halitosis was 28%. 29% of these subjects were female and 28% were male. There was no significant difference between males and females [P> 0.05]. The most common intra oral causes of halitosis were dental carries [89%], food-impaction and other retentive factors [72%], periodontal pocket [71%] and coated tongue [60%]. Sinusitis [60%] was the most common extra oral cause of halitosis. The correlation between different age groups and halitosis was not significant [P>0.05]. The correlation between education and halitosis was also not significant [P>0.05]. This study also revealed that 68% of patients were aware of their bad breath. The most common causes of halitosis are intra oral, which can be prevented by appropriate treatment, education and increased public awareness