Does the resident flora of the mouth cause dental caries?

Yes: Some of the bacteria normally present in the mouth form plaque and produce acid that dissolves the mineral in teeth causing caries.

Yes!: Dental caries is the result of bacteria settling onto teeth- particularly the pits and fissures on the top of teeth, under the contacts in between teeth, and at the gumline. The bacteria metabolize the foods you eat, and produce acid. At a ph below 5.5, the acid demineralizes your tooth structure. Demineralization is the earliest stage of dental caries.

Part: Takes bacteria (flora) converting sugars/starches into acid which etch holes in the teeth.

Yes: Many bacteria are found in caries, the most common named is streptococcus mutans. But in answer to your question, the bacteria are from your mouth, but your mouth received the original bacteria from somewhere or someone..probably your mom sharing food with you. Bacteria also are transmitted from kissing, etc.