About 600 different species of bacteria live in the mouth of a normal person. We are ammutual cooperation between these bacteria must. Plenty of nutrients for microorganisms we call the oral flora, such as intra-oral secretions and constant temperature conditions,are well adapted to live. However, establishing colonies from abroad, foreign and potentially harmful microorganisms proliferate and secrete chemicals that kill germs in the colony to establish a foreign place and they help the immune system.