The document discusses the normal microbial flora found in the oral cavity. It notes that the oral cavity contains a mixture of bacteria, fungi, protozoa, and occasionally viruses. The bacteria found include both aerobic and anaerobic species. Among the bacteria, streptococci are the most predominant group, including Strep. mutans and Strep. sanguis. Lactobacilli, veillonella, and fusobacteria are also commonly found. The normal flora is acquired shortly after birth and diversifies as the teeth erupt providing surfaces for colonization.
2. 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.
3. Microbial flora of mouth
Among all micro-organism present in the mouth
bacteria are most predominant.
These includes both aerobic and anaerobic
bacteria
8. 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
9. Lactobacilli are frequently found in mouth.
They are imp bacteria to promote the progress of
carious lesion after the initiaton of dental caries
by Strep mutans
10. 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
11. 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.
12. 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
13. 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.
14. 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.
15. 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