Dental Plaque Flashcards
definition of dental plaque
an organized mass, consisting mainly of MICROORGANISMS EMBEDDED IN A MATRIX OF GLYCOPROTEINS that ADHERES TO TEETH, PROSTHESES, AND ORAL SURFACES which is found in the GINGIVAL CREVICE AND PERIODONTAL POCKETS
definition of biofilm
a MULTI-SPECIES COMMUNITY of micro-organisms that ADHERE to EACH OTHER AND A SURFACE and are ENCASED IN AN EXTRA-CELLULAR MATRIX
environments that biofilm can grow in
minerals and metals underwater underground above ground plant tissues animal tissues implanted medical devices catheters and pacemakers
PERIODICALLY OR CONTINUOUSLY SUFFUSED WITH WATER
fossil evidence of biofilm?
dates back to 3.25 billion years ago in the deep-sea hydrothermal rocks of the pilbara -craton in australia
when does biofilm FORMATION begin
when free-floating micro-organisms come in contact with an appropriate surface
when does biofilm ATTACHMENT begin
when the microorganisms produce an EXTRACELLULAR POLYSACCHARIDE MATRIX (ESP) – which is a network of sugars, proteins, and nucleic acids
when does biofilm GROWTH occur?
when further layer os microorganisms and EPS build upon the first layers
EXTRACELLULAR POLYSACCHARIDE MATRIX definition?
network of sugars, proteins , and nucleic acids which facilitate the attachment of the biofilm
what determines the extent of growth of a biofilm?
the environmental conditions
advantages of microorganisms living in a biofilm?
communities of microbes are usually MORE RESILIENT TO STRESS
what is the composition of dental plaque?
- general percentage breakdown
80% water
20% solid material
- 35% cellular and 65% extracellular
what is the composition of dental plaque?
- microorganisms
- extracellular polysaccharide matrix (organic)
- 95% dextran , 5% levan - bacterial by-products - enzymes food debris, desquamated cells
- calcium and phosphate (inorganic)
breakdown of extracellular polysacharide matrix in dental plaque
95 % dextran
5% levan
structural traits of oral micro-organisms
- cocci
- bacilli
- spirilla
definition of aerobe
a microorganisms that can live and grow in the presence of oxygen
definition of anearobe
faculative?
obligate?
a microorganisms that can live in partial or complete absence of oxygen
faculative – capable of existing under different conditions, either aerobic or anaerobic
obligate – only anaerobic conditions, strictly
describe commensal micro-organisms
most of these exist in our oral cavity in SYMBIOTIC capacity 0 maintaining relationships with the host that are based on MUTUAL BENEFITS
commensal micro-organisms present in oral cavity
- streptococcus
- actinomyces
- veillonella
- fusobacterium
- porphymonas
- prevotella
- treponema
- nisseria
- haemophilis
- eubacteria
- lactobacterium
- capnocytophaga
- eikenella
- leptotrichia
- peptostreptococci
- staphylococcus
how do bacteria communicate?
describe this?
QUORUM SENSIN
- bacteria use this to coordinate gene expression
- SECRETE A SIGNALING MOLECULE - AUTOINDUCER – to regulate gene TRANSCRIPTION as a response
when a bacteria is adhering to a surface .. what does it depend on?
intricate, specific series of INTERACTIONS B/W THE SURFACE TO BE COLONIZED, THE MICROBE, AND AN AMBIENT FLUID MILIEU (environment)
4 main steps in formation
- acquired pellicle
- bacterial ADHESION
- growth of extracellular matrix
- formation of a moroe complex and mature biofilm
nutrition for bacteria in deeper pockets?
major source comes from the periodontal tissues and blood
these bacteria produce enzymes that cause periodontal destruction
primary colonization by who?
facultative anaerobic GRAM POSITIVE COCCI
after primary colonization? 24 hours later?
plaque consists of mainly streptococci : S Sanguis
after the 24 hour colonization period what accumlates?
more gram positive filaments - particularly Actinomyces species predominating in the LATER STAGES
what allow adherence of gram - negativve organisms? examples of these?
the surface receptors of gram-positive organisms
the gram negative that are adhering are Veilonella and Fusobacteria
formation of sub-gingival plaque consist mainly of?
ANAEROBIC SPECIES – GRAM-NEGATIVE SPIROCHETE AND BACILLI
what contributes to different types of plaque evolving at different locations?
the influence of the local environmental factors
what promotes the growth of gram negative bacterial species with an increased periodontopathic potential?
the availability of blood and gingival fluid components
what factors affect plaque formation?
- anatomical factors
- likek palatal/lingual incisors, crowding, malocclusion, furcations - iatrogenic factors
- like poor restorations, caries, dental calculus, pontic desing, margins , overcontoured restorations - diet and ph
if increase glucose what happens?
the ph will decrease because the bacteria s mutans will ferment sugars to produce acid
- these thrive in low ph environments and utalize the DIETARY SUCROSE – for the synthesis of ADHERENT GLUCANS VIA GTF - that faciliates the accumulation and adherence of dental plaque to tooth surfaces
T/F tea, raisins, and apples can decrease plaque formation?
TRUE
name the distinct ecological niches that bacteria live?
- tongue - especially the DORSUM
- buccal mucosa
- teeth
- saliva or gingival crevicular fluid
70% of oral bacteria are what gram…?
and what shape?
70% gram positive
and are streptococci
the gingival crevicular fluid is rich in what?
antibodies
presence of more fluid indicates inflammation because in health there is a very small amount of this coming from the sulcus
how do we assess plaque clinically?
- iodine
- gentian violet
- erythrosin
- basic fuchsin
- fast green
- food dyes
- fluorescein
- two-tone disclosing agent
*come in tablet or liquid form
what happens to plaque if it is not removed?
CALCULUS BUILDS UP ON IT
Composition of calculus in the early stages?
- octacalcium phosphate
- hydroxyapatite
- tricalcium phosphate or whitelockite
- brushite (early stages)
how long does it take for plaque to cause gingivitis?
10-21 DAYS!
Loe’s experimental gingivitis in man
12 subjects average age of 23 years old
phase 1 - extreme plaque control
phase 2 – take away the oral hygiene –> resulted in MARGINAL GINGIVITIS IN ALL SUBJECTS
phase 3 –> resume plawue control and you can get rid of the inflammation / gingivitis
what is the non-specific plaque hypothesis?
specific?
only the QUANTITY of bacteria mass is important and the abundant amount of plawue can cause the disease
QUANTITY > QUALITY / TYPE
specific
- QUALITY / TYPE > QUANTITY
ecological plaque hypothesis?
a change in key ENVIRONMENTAL FACTORS will cause a SHIFT IN THE BALANCE of residual bacteria species, which could then predispose a site to disease
Koch’s postulates
- pure cultures must be obtained
- must be able to isolated from diseased tissues
- must cause disease
modified koch’s postulate
PERIODONTAL DISEASES DO NOT READILY FOLLOW KOCH’S POSTULATES
- it explains diseases that are caused by a single infective pathogen- monoinfections
**Periodontal disease have several potential pathogens..they are POLYINFECTIONS OR MIXED INFECTIONS
what is the most significant environmental ris factor for both dental caries and periodontal inflammatory disease?
BACTERIA IN THE BIO-FILM KNOWN AS DENTAL PLAQUE
THE ASSOCIATION OF MICROBIAL SPECIES WITH THE ONSET OF PERIO DISEASE has greatlyy strengthened the belief that the periodontal diseases are OPPORTUNISTIC infections
BACTERIAL PLAQUE IS THE MAIN ETIOLOGY OF PERIO DISEASE
what is the general shift from gingivitis to periodontitis?
this shift DEPENDS ON HOST FACTORS and the nature of the bacteria
an IMMUNE - INFLAMMATORY response develops in the periodontal tissues in the chronic presence of plaque bacteria and results in the destruction of the periodontal structures
