Lecture 3 - Microbiology of Dental Caries Flashcards
This is the most common site for caries; patients have otherwise low caries rates
pits & fissures
Caries are found here less often and are usually diet-related; found in patients with moderate to high caries rates
smooth surface and proximal caries
Caries found here in patients with exposed root surfaces (sequelae of periodontitis)
root surface caries
Caries found at restoration margins or under restorations
secondary caries
Lactic acid produced by bacteria dissolves mineral from enamel
demineralization
Salivary minerals are deposited in enamel
remineralization
Bacteria in biofilms on surface of tooth produce ______ _____ from glycolysis of sugars.
lactic acid
Lactic acid ________ pH and mineral matrix of tooth dissolves
decreases (becomes more acidic)
Tooth surface is stabilized by _________ proteins so initial demineralization is subsurface (thin shell of enamel left overlying body of lesion)
pellicle
________ occurs when subsurface demineralization becomes too severe or extraordinary force is applied to surface.
Cavitation
As long as surface is retained, ____________ and “healing” of lesion are possible.
remineralization
Remineralized tooth structure is (stronger or weaker) than virgin enamel.
stronger
due to the incorporation of fluoride into HA crystal structure
What are the 5 properties of caries-causing bacteria?
- attach and form biofilm
- produce acid (acidogenic)
- survive acid (aciduric)
* **4. continue to produce acid at low pH - survive “famine” between meals
What are the most common supragingival organisms (difficult to distinguish)?
Streptococci
Which bacteria is involved in both caries initiation and progression?
S. mutans
This bacteria is the primary caries pathogen, is a gram + cocci, facultative, and ferments carbohydrates as only nutrient source.
S. mutans
Which bacteria does S. mutans attach to in forming a biofilm?
S. sanguinis
S. mutans is well-adapted for ______ or _______ (it can thrive during good times and bad)
feast (active transport)
famine (good scavenger)
T/F
S. mutans has an advantage to host due to low levels of lactate which is protective.
True
What interferes with transport and intracellular processes of S. mutans?
Fluoride
This bacteria is closely related to S. mutans and is strongly associated with caries, but is usually found in lower numbers than S. mutans.
S. sobrinus
This bacteria is ubiquitous, is the earliest acquired oral bacteria, is bound by salivary amylase, and is not typically cariogenic.
S. mitis
This bacteria is found in healthy (non-cariogenic) plaque, adheres well via adhesins, can survive without sugar, and is often causative agent of infective endocarditis.
S. sanguinis
This bacteria is detected in saliva, but grows on tongue and teeth; some strains make bacteriocins that prevent S. progenies colonization (probiotic).
S. salivarius
This bacteria may contribute to root caries and early stages of enamel caries.
Actinomyces
This bacteria ferments lactate and protects against acid; anaerobic gram negative cocci
Veillonella
This group of bacteria includes casei, rhamnosus, gasseri, fermentum and is important in established or deep lesions; anaerobic gram + rod
Lactobacilli
These bacteria may be important in deep caries and are anaerobic gram + pleomorphic rods.
Bifidobacterium and scardovia
S. sanguinis binds to ________ via specific adhesins.
pellicle
S. mutans binds to _ ________ via specific adhesins.
S. sanguinis
S. mutans uses _____________ to make extracellular matrix from sucrose.
glucosyltransferase (Gtf)
Extracellular matrix is composed of ______, a cross-linked insoluble polysaccharide.
glucan
S. mutans attaches to glucan via _______-________ proteins.
glucan-binding
Can survive low pH
aciduric (acid tolerant)
Can drive pH down
acidogenic (acid producing)
S. mutans can ferment sugars at ___ pH.
low
______ bacteria grow and make acid at high pH and stop at low pH.
Healthy
_____ bacteria grow and make acid best at low pH.
Caries
A short term effect of sugar consumption is…?
decreased pH
T/F
Long term effects of sugar consumption may be more important and results in a vicious cycle.
True
Studies have shown that the pH of plaques significantly decrease after a 2-minute 10% _______ rinse.
glucose
It is hypothesized that the “window of infectivity” for S. mutans is around __ months based on cultivation, but can be acquired earlier.
26
Caries vaccines would target what two things?
glucosyltransferase (Gtf)
glucan-binding proteins
Mucosal vaccination would provide _____ immunity (nasal & ingested).
active
Antibodies raised in tobacco plants and in immunized cow’s milk would provide ________ immunity and show effects when repeated doses are combines with removal of biofilm.
passive
Pheromone or antibody guided antimicrobials kill only target species.
Specifically targeted antimicrobial peptides (STAMPs)
