Periodontitis is the inflammation of the tissue surrounding the teeth, resulting in shrinkage of the gums and loss of bony support.  

A bio film of bacteria called dental plaque starts to accumulate on teeth particularly at the gum line. The bacteria in the bio film releases toxins. The body reacts to the toxins by causing an inflammation of the gums. The gums bleed easily when touched and can omit a foul odour.