Dental caries Flashcards
Name 5 etiological factors involved in dental caries
Plaque micro-organisms
Dietary factors
Host physiology - eg salivary buffering
Teeth - oral hygiene/preventative measures
Time
Name 4 methods to prevent teeth caries and example
Reduce carbohydrates in saliva-change diet /artificial sweeteners
Increase tooth resistance to acid- eg fluoride In water
Reduce tooth susceptibility eg seal fissures
Reduce /eliminate cariogenic microorganisms eg antibiotics
Definition of a tooth carie
localised destruction of tooth tissues by bacterial fermentation of dietary carbohydrates
what are the 2 stages of tooth decay
- decalcification
- dissolution of softened residue
what is the critical pH and what does this mean
pH <5.5 - below this decalcification of tooth enamel starts to occur
Name steps in plaque development
Adherence most importnat
Pellicle developed–>pioneering bacteria_adhere to pellicle_> bacteria proliferate and form microcolonies with extracellular matrix ___> secondary aerobic bacteria and extracellular polysaccharides aggregate and BIOFILM forms __> mature plaque
How does a mature plaque cause tooth decay
Biofilm bacteria produce lactic acid from Fermentable carbohydrates which causesa pH drop which if it reaches critical pH 5.5 causes decalcification of the tooth enamelled increased softening and pourosity of the enamel so acid can penetrate deeper onto tooth and demineralize the subsurface.
Name 3 places Where caries occur and percentage
Fissure caries ( >99%)
Approximal caries (5-60% )
Smooth surface caries ) 5%)
What is the incipient phase of tooth caries also known as
White spot phase- demineralisation causing decalcification on enamel due to plaque
What bacteria is noted to be prevalent pre care formation and in the incipient phase of tooth cary formation
Streptococci mutans ( increases 10-100fold )
Who do we see root caries ( cementum caries ) in usually
Older patients who have exposed roots from - gingival recession ( age ) or decreased saliva production ( medications )
Also if too vigorous brushing damaging gums and exposing roots
What is different in root surface caries vs other dental caries except for site
Critical pH is 6.7 not 5.5 !
What are rampant caries and name a population these are seen in
Severe decay on multiple surfaces of multiple teeth seen in high risk groups such as “nursing bottle “ caries or decreased salivary flow (- irradiation /Sjogrens syndrome /medications )
what are the 4 stages of caries
Depends on enamel damage :
- Initial caries, also called “white spot -. matte light spot on the enamel surface at the place of enamel demineralization. Over time, the process can go from an acute form to a chronic one and pause for a while, the stain becomes dark.
2
Superficial caries. - in the area where the stain has formed, roughness appears, , the destruction of the enamel begins.
3
Medium caries. - the infection attacks and begins to destroy the dentin tissue.
4
Deep caries.( DENTINE caries ) A large carious cavity forms inside the tooth, the infection affects most of the dentin, gets very close to the pulp, or even inflame the pulp
What are dentine caries
Advanced caries into dentine of tooth- see lots of lactobacilli bacteria but still some mutans streptococci
what is white spot on teeth
demineralization creates white areas of decalcification of the enamel on teeth, resulting from the accumulation of bacterial plaque.-reversable if treated quickly
What are the 2 main mutan streptococci in humans
Streptococcus mutans ( 70-80%)
Streptococci sobrinus (20-25%)
Name the 4 virulence features of streptococcus mutans that makes it cariogenic
1.Produces extracellular polysaccharides -glucans and fructans from sucrose
2. Carbohydrate fermenter -lactic acid production
3.Aciduric
4. Can store polysaccharides intracellularly
How does the production of extracellular polysaccharides glucan from St. Mutans ,cause caries
Glucans (by glucosyltransferase) driven by sucrose , causes polymerazation and branching of glucan ( so more insoluble ) and adheres to tooth allowing no diffusion in or out of plaque.
This blocks movement of Calcium ions ( so tooth not remineralised ) AND the tooth gets no nutrients - only St. Mutans gets nutrients
How does the production of extracellular polysaccharides fructan from St. Mutans ,cause caries
Fructan promotes carbohydrate storage so prolonged acid production that means prolong lowered pH environement
How doe St. Mutans ability to ferment carbohydrates cause caries
High fermentation rate of all simple sugars except mannitol and sorbitol - meaning high lactic acid rates (pH 3.13 )-tooth demineralisation occurs
How is being acidic help st .mutans
Survives in low pH zones so at fermentation rates pH 5.5 survives
How does storage of intracellular polysaccharides enable St.mutans to be cariogenic
When there is no exogenous carbohydrates it uses it stored polysaccharide s and glycogen to continue fermentation of sugars and continue the acid production and acidic environment
What type /class bacteria are Streptococci mutans
Gram+ve facultative anaerobic cocci
What is the lactobacillus bacteria and where is it found
Gram +ve micro-aerophilic rod bacterium found in severe caries. very acidogenic, makes lactic acid from carbohydrates
What pH does lactobacilli metabolise in
Very acidic pH<4
Do lactobacilli initiate cary formation
No - only in severe caries once formed
