When the alveolar crest appears to be parallel to a line drawn between the cementoenamel junctions of adjacent teeth, reduction in height of the interdental septum is known as which of the following:

Which of the following statements about subgingival plaque are true?

Periodontal disease can be assumed to be active disease sites and progressing if:

All of the following are Gram-negative rods except:

Tobacco use is related to an increased risk for severe periodontal disease. Smokers have a diminished neutrophil function.

The principal antibody in tears and saliva is    

A bacterial product that attracts leukocytes to an area of irritation is  

Long, fine, wavy filamentous structures that are used for motility

A bacterial plaque sample taken from a healthy mouth would show which of the following:

Stage IV or the advanced stage of gingivitis is still a reversible stage of the disease.