Normal Microbial Flora Normal oral cavity contains a mixture of organisms which include bacteria, fungi, protozoa and occasionally virus. Some of the organisms are almost always in normal oral cavity and are called Resident Flora. Some organisms stay for a limited period in the oral cavity of a few individuals. These are named as Transient Flora.
Microbial flora of mouth Among all micro-organism present in the mouth bacteria are most predominant. These includes both aerobic and anaerobic bacteria
Of all bacteria present in mouth, streptococci are predominant group. Various species of Streptococci are encountered in mouth. Most of these are alpha-haemolytic streptococci, collectively named as viridians streptococci
Lactobacilli are frequently found in mouth.They are imp bacteria to promote the progress ofcarious lesion after the initiaton of dental cariesby Strep mutans
Veilonella is the most common among Gram- negative bacteria. Fusobacterium nucleatum is the most commonly occurring Gram-negative anaerobic bacillus Other anaerobes such as Bacteroids, Leptotrichia, Selenomonas etc have also been found to be an imp group
Oral treponema(T.vincenti,T.denticola,T.orale) are comman inhabitants of gingival crevice & sub gingival area Due to their presence in subgingival plagues, they have been imp role in causing gingivitis and most forms of periodontitis.
Besides bacteria normal flora of mouth may contain fungi and protozoa FUNGI Candida albicans C.tropicalis C.pseudotropicalis C.stellatoidea Cryptococcus sps PROTOZOA Entamoeba gingivalis Trichomanas tenax
Acquisition Of Normal Flora Of Mouth The mouth of newborn at birth is usually microbiologically sterile. Within few hours of birth Streptococci establish themselves in the mouth.
Acquisition Of Normal Flora Of Mouth – Cont’d Among Streptococci, Strep. salivarius is dominant at this stage. During the first year of life other species of Streptococci,Staphylococci,Neisseriae,Veilonella, Actinomyces,Lactobacilli and Fusobacteria also colonize.
Acquisition Of Normal Flora Of Mouth – Cont’d With the eruption of teeth, solid surfaces in the oral cavity are available for colonization. Strep mutans, Strep sanguis establish themselves on these hard surfaces. Simultaneously, there is also increase in number of obligate anaerobes