This document discusses the microbial flora of the oral cavity. It describes the various microbial habitats in the mouth and the acquisition of normal flora beginning at birth. The major types of flora are discussed as well as factors that modulate microbial growth. The document also examines the oral microbiome's role in oral diseases and conditions like dental caries, periodontal disease, and infections. Additionally, it summarizes how orthodontic appliances can impact the oral microbiome by facilitating plaque accumulation and altering the microbial environment. Maintaining proper oral hygiene is emphasized when wearing orthodontic appliances.

1. MICROBIAL FLORA OF
ORAL CAVITY
Dr. Simran Sharma

2. Contents
1. Oral ecosystem- Introduction, Microbial relationships and types of flora
2. Acquisition of normal oral flora
3. Window of infectivity
4. Microbial colonies in oral cavity
5. Factors modulating microbial growth
6. Nutrition of the oral microbiome
7. Défense mechanism in oral cavity
8. Oral Microflora and Orthodontics
9. Conclusion and Summary

3. MICROBIOME
Joshua Lederberg
“to signify the ecological community of commensal, symbiotic, and pathogenic
microorganisms that literally share our body space and have been all but ignored as
determinants of health and disease”

4. ORAL ECOSYSTEM

5. Microbial habitats in the oral cavity
teeth,
gingival sulcus,
attached gingiva,
tongue,
cheek,
 lip,
 hard palate,
 soft palate

6. • Contiguous with the oral cavity are
• the tonsils,
• pharynx,
• Esophagus,
• Eustachian tube,
• middle ear,
• trachea,
• lungs,
• nasal passages, and
• sinuses.

7. • Microorganisms from the oral cavity have been
shown to cause a number of oral infectious
diseases, including
caries (tooth decay),
periodontitis (gum disease),
endodontic (root canal) infections,
alveolar osteitis (dry socket),
tonsillitis
noma

8. Systemic diseases caused by oral microorganisms
• Theory of focal infection-foci of sepsis is
responsible for initiation and progression of variety
of inflammatory diseases.
• The oral cavity can act as the site of origin for
dissemination of pathogenic organisms to distant
body sites, especially in immunocompromised hosts
such as patients suffering from malignancies,
diabetes, or rheumatoid arthritis or having
corticosteroid or other immunosuppressive
treatment.
Li et al. Systemic Diseases Caused by oral infection
Clinical Microbiology reviews, Oct. 2000,

10. Symbiotic relationships

11. Types of flora
Resident flora
Intermediate flora
Transient flora

12. Acquisition of normal oral flora
• Infant mouth is usually sterile at birth, few organisms are acquired from mothers birth canal.
• The colonisation of the oral cavity starts about the time of birth.(facultative anaerobes)
• Beginning the second day, anaerobic bacteria can be detected in infantile’s edentulous mouth.
• The pioneer species are usually Streptococci (S. salivaris, S. oralis, S. mitis) which bind to the mucosal
epithelium.
• Metabolic activity of the pioneer community alters the oral enviorment to facilitate colonisation of other
species.

13. • Oral flora after 1 year consists of Streptococcus, Staphylococcus, Neisseria together with Gram negative
anaerobes such as Veillonella species. Less frequently isolated are Lactobacillus, Actinomyces, Prevotella
and Fusobacterium.
• The next evolutionary change in this community occurs during and after tooth eruption when two further
regions are provided for bacterial colonisation.
Gingival crevice
Enamel surface

14. Enamel surface
• S.mutans
• S.sanguinis
• Actinomyces
• Lactobacillus
• Rothia
Gingival crevice
• Prevotella
• Porphyromonas
• Neisseria
• Capnocytophaga

15. • During puberty, transition to an adult flora composition can be noticed due to hormonal changes.
Spirochaetes
Veilonella
Prevotella
Bacteroids
• The oral microbiome continues to grow in diversity over time until the composition of this complex
ecosystem reaches equilibrium between the resident microflora and the local enviormental conditions.

16. • This microbiota lives in harmony with the host but under special conditions , disease may occur.
• At advanced ages, the direct and indirect effects of senility affect the microbial homeostasis.
• Staphylococccus and lactobacillus increase at the age of 70.
• Introduction of prosthetic appliance at this stage changes the microbial composition that is increase in
candida species.

17. Window of Infectivity
• Explained by Caufield and his colleagues in 1993.
• It is the time of initial colonization of the infants oral
enviorment with the cariogenic bacteria mutans streptococci
(MS).
• Acquisition of some bacteria optimally occur at certain ages.
• Children at the age of 26 months are more susceptible for
colonisation by mutans streptococci.(initial acquisition of
MS)
• Another window of infectivity for MS is speculated at 6
years of age, when permanent teeth erupt.

18. Microbes found in oral
cavity

19. (Philip Marsh. Role of microflora in
health. Microbial Ecology in Health
and Disease 2000; 12: 130–137)

20. Samaranayake L (2011) Essential
microbiology for dentistry. 4th edn. Churchill
Livingstone Elsevier, Edinburgh.

21.  Candida
 Aspergillus
 Rhizopus
 FusariumOdds FC, Gow NA, Brown AJ. Fungal
virulence studies come of age. Genome
Biol. 2001:2. REVIEWS 1009.

22. Entamoeba gingivalis
Trichomonas tenax
Samaranayake L (2011) Essential
microbiology for dentistry. 4th edn.
Churchill Livingstone Elsevier,
Edinburgh.

23.  M.pneumonia,
 M.hominis
 M. salivarium,
 M. buccale,
 M.orale,
Samaranayake L (2011) Essential
microbiology for dentistry. 4th
edn. Churchill Livingstone
Elsevier, Edinburgh.

24. Microbial Colonies in Various Parts

26. Microflora of gingiva
• Streptococcus
• Actinomyces
• Eubacterium
• Fusobacterium
• Prevotella
• Treponema
Microorganisms found in gingival crevice:
• Streptococcus
• Actinomyces
• Prevotella
• Eubacterium
• Fusobacterium
• Treponema

27. Factors modulating microbial growth

28. ANATOMIC FACTORS
• Shape and topography of teeth
• Mal-aligned teeth
• Poor quality of restoration
SALIVA
• Plays an important role in modulation of bacterial growth by forming salivary pellicle that facilitates
bacterial adhesion
• Defense factors – lysozyme and lactoferrin – bacteriocidal and fungicidal action
• Buffering action
GINGIVAL CREVICULAR FLUID
• Crevicular fluid influence the ecology of crevice by flushing microbes out of crevice or can act as source
of nutrients like saliva.
• Defense mechanisms- IgG and presence of innate immune cells.

29. ENVIORMENTAL FACTORS
• Temperature, pH, Redox potential, ionic strength and osmotic pressure affect the growth and metabolism
of microorganisms.

30. MICROBIAL FACTORS
• Microbes in oral environment can interact with each other in promoting and suppressing the neighbouring
bacteria .
MISCELLANEOUS FACTORS
• Antimicrobial therapy, dental procedures like scaling , aging can influence microbial growth and can
affect the complexity of oral microbiome.

31. Nutrition of the oral microbiome

32. Defense mechanisms in oral cavity

33. Beneficial effects of Resident microflora
• The resident microflora contributes directly
and indirectly to the normal development of
the physiology, nutrition, and defense system
of the host.
• Colonization resistance
• The resident microflora is considered a part
of the innate host defenses.

34. The other defensive mechanisms in the oral
cavity include:
• Integrity of oral mucosa
• Lymphoid tissue
• Saliva
• Gingival crevicular fluid
• Immune system

35. ORAL MICROFLORA AND
ORTHODONTICS
Synergism or Parasitism

36. Orthodontic bands and Microflora
• Initially, the bacterial flora is composed exclusively of
cocci, filaments, fusiforms, and rods. Spirochetes or
motile rods were detected in extremely low numbers.
• After the placement of bands, there is significant
increase in the percentage of spirochetes, motile rods,
filaments, and fusiforms, conversely, a decrease in
cocci is observed.
• Placement of orthodontic bands is associated with the
establishment of microorganisms usually found in
periodontal diseases.

37. (Huser et al.Effects of orthodontic bands on clinical and microbiologic parameters. AJODO 1990)

38. Orthodontic appliances and Microflora
• Dental caries and periodontal diseases are recognized as consequences of inadequate oral hygiene during
orthodontic treatment.
• Fixed appliances and rough-surfaced adhesives in the oral cavity create new retentive sites favorable to
plaque accumulation and inflammatory response.
• Orthodontic appliances create an ecological environment favourable to qualitative alteration in
subgingival microbiota and the fixed appliances are associated with poor oral hygiene and produce
transitory gingival alteration.
(Freitas et al. The influence of orthodontic fixed appliances
on the oral microbiota: A systematic review. Dental Press
Journal of Orthodontics 2014)

39. • The grade of bacterial colonization related to orthodontic
appliances is affected by the energy and roughness of the
appliance surfaces, as well as their design and dimensions.
• Another significant variable for microbiota alterations is the
amount of time the appliance is worn in the oral cavity, with
removable appliances having significantly less impact on oral
bacteria than fixed appliances
• The quantitative alteration of the oral microbiota is related to
an increase in clinical parameters, PI and BOP, which are risk
indicators for oral pathologies
• Qualitative variation shows that there is an increase in gram-
positive and gram-negative more aggressive bacteria, such as:
S.mutans and Lactobacillus spp. (gram-positive) and P.
gingivalis, T.forsythia, and T. denticola (gram-negative).
(Changes in oral microbiota due to orthodontic
appliances: a systematic review by Alessandra et al.
Journal of oral microbiology 2018)

40. • Wang et al compared the microbiological aspect in pateints treated wih Invisalign and fixed appliances.
• He demonstrated that both invislaign and fixed orthodontic appliances cause microbial dysbiosos.
• In his study the oral microbiome was dominated by the phyla firmecutes, bacteroids, proteobacteria,
actinobacteria, fusobacteria, candida division TM7 and spirochaetes.
• This ecosystem dysbiosis could be reason for increased caries, white sopt lesions and periodontal
problems observed with orthodontic treatment.
• At the genus level, Nesseria was more abundant in Invisalign than fixed group.
(Wang et al. Alterations of the oral microbiome in patients treated with the Invisalign system or with fixed
appliances. AJODO 2019)

41. Oral hygiene for orthodontic patients
Patients with removable appliances
• Removable appliances provide more retention places for bacterial deposits.
• Different cleaning methods are recommended:
1. Cleaning with a toothbrush under running water.
2. Cleaning in a water bath containing cleanser tablet.
3. Ultrasonic bath
4. • Chlorhexidine: It may be used as
• a) SRD (slow release dosage): Releases continuously for 1 week (Friedman and Dyskind).
• b) As varnishes (cervitec): According to Huizinga et al., Petersson et al. and Lynch and Beighton use of
chlorhexidine as the varnish are better than oral rinse.

42. • Patients with fixed appliances

43. Summary
• Microbes are an important part of our oral cavity. The success
of an orthodontic therapy depends upon both orthodontists as
well as the patient. From fabrication to insertion of an appliance
and from oral hygiene maintenance to patient motivation all are
equally important. A balance and harmony have to be
maintained during initiation, progression and at the end of the
therapy.

44. THANK
YOU