Type 1 (oral halitosis) also termed oral malodor:  Originates from the oral cavity due to bacterial metabolism. 

Type 2 halitosis (airway): Originates in the airway (nose, throat, tissues of the windpipe)

Type 3 halitosis (gastroesophageal) : Originates from the stomach.

Type 4 halitosis (blood-borne) : Originates from dissolved substances in the bloodstream that come out through the lungs when breathing out. 

Type 5 halitosis (Subjective):  A perception or concern about having bad breath due to disorders in the sense of smell or due to psychological reason 

Source: Aydin M, Harvey-Woodworth CN. Halitosis: a new definition and classification. Br Dent J. 2014 Jul 11;217(1)

From the desk of Bassel Paul Gebrael DDS, Dip. Perio, FRCD(C), FICD

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