Plaque & Caries Flashcards
Dental Plaque
Complex microbial community that forms on tooth surfaces
Contains living, dead, and dying bacteria and their products, as well as salivary compounds
What is calcified plaque
calculus
What are microorganisms in dental plaque surrounded by
organic matrix
What is the purpose of biofilm formed of communities of microorganisms that are attached to a surface
may protect them from host defenses and antimicrobial agents and can render them more pathogenic
What is the benefits of biofilm
contains hundreds of microorganisms
have a communication system to adapt and respond to their environment
share resources and activites
have resistance
What bacteria is a large proportion of resident oral flora
viridans streptococci
What is a major bacteria species found in saliva
streptococcus salivarius
How does colonization occur on a freshly cleaned tooth surface
acidic glycoproteins from saliva form a film on tooth called a pellice
What streptococcus species colonize biofilm
S. oralis
S. mitis
S. gordonii
S. sanguis
What is dental plaque
Plaque= a firmly attached growth of bacteria + matrix (biofilm)
2 types: supragingival and subgingival
How do early colonizer bacteria adhere through specific molecules
They have adhesins on their surface
What type of bacteria are typically early colonizers
Gram (+) facultative anaerobic bacteria
What type of bacteria are early colonizers
Actinomyces spp
Oral streptococci
Which bacteria species make up over 80% of the initial biofilm
oral streptococci
Aerobic environment
Gram (+) facultative anaerobic species
Highly oxygen deprived
gram (-) anaerobic microorganisms
What type of bacteria is found in Supragingival plaque
gram (+) facultative anaerobic bacteria
What type of bacteria is found in Subgingival plaque
more complex
gram (-) anaerobic bacteria
What is dysbiosis
the transition of the polymicrobial community from largely gram (+) commensal microbes to a gram (-) enriched inflammogenic community
True/false: If plaque continues to form, it attracts other bacteria to adhere to the bacterial matrix
true
What are gram (-) anaerobes
prevotella intermedia
capnocytophaga spp
fusobacterium nucleatum
What bacteria is a late colonizer
porphyromonas gingivalis:
adheres to earlier colonizers and identified as a keystone pathogen in the pathogenesis and progression of periodontitis
Composition of dental plaque
Proliferating bacteria
Host cells
Adherent intercellular matrix
Other microorganisms
What are the inorganic components of plaque
Calcium and phosphorus w/ small amounts of magnesium, potassium and sodium
How much inorganic content is present in early plaque
low inorganic content
How much inorganic content is present in calculus
high inorganic content
What is plaque
complex microbial community composed of polysaccharides, proteins, and other compounds
What is the purpose of plaque
acts to protect the biofilm from the host’s immune system, and from antimicrobial and antibiotic agents
Dental biofilm stages of formation
Stage 1: pellicle formation
Stage 2: bacterial attachment
Stage 3: colonization and multiplication –> pathogenic potential
Stage 4: growth –> increase in mass and thickness
Stage 5: maturation –> intermicrobial matrix connects colonies
what do early colonizers do
gram (+) bacteria bind to pellicle
What do secondary colonizers do
gram (-) bacteria attach after 1-2 days of plaque accumulation and have the ability to adhere to gram (+) already present
What do late colonizers
Gram (-) bacteria adhere to previous colonizers –> attach after 1 week of plaque accumulation –> have ability to adhere to gram (+) already present
Pellicle
glycoprotein deposit rapidly covering newly cleaned tooth
Plaque development starts with
Microbial adherence –> binding of a microbe to an oral surface is a prerequisite for colonization and it’s initial step in the path leading to infection and invasion of tissues
Challenges with microbial adhere
host cleansing factors
Plaque development
Early plaque: gram (+) facultative bacteria –> shift in plaque composition –> mature plaque: gram (-) anaerobic bacteria (disease)
What is tooth-associated plaque
Structure similar to supra gingival plaque
mainly gram + filamentous bacteria with some gram (-) cocci and rods
associated with calculus formation, root caries, root resorption
Epithelium- Associated plaque
Loosely adherent structure
Contains one layer in contact with epithelial cells and other loose in the sulcular or pocket lumen
Mainly gram (-) rods and cocci
Leads to development of periodontal disease
Connective tissue-associated plaque
observed in periodontal disease conditions –> bacteria penetrate through the pocket epithelium wall and basal lamina into the CT
Demonstrated in acute ulcerative gingivitis, advanced periodontitis, and aggressive periodontitis
What is supragingival calculus
white or whiteish yellow
results from poor hygiene, lack of adequate masticatory function and tooth malposition
What is subgingival calculus
calculus below gingival margin usually in periodontal pockets
dark-brown or greenish-black
dense and hard
firmly attached to the tooth surface
significance of dental calculus
provides surface for attachment of bacteria
maintains and accentuates periodontal disease by keeping plaque in close contact with the gingival tissue and creating areas where plaque removal is impossible
True/false: supragingival and subgingival calculus consists of mineralized plaque always covered by unmineralized bacterial layer
true
What does microflora usually consists of
non-mutans streptococci (salivarious group) on root surface
mitis group in pit and fissures
small number from mutans group (not enough to induce caries)
Loss of hydroxyapatite crystals causes what
slow decomposition of teeth
Key factors in development of caries
susceptible tooth surface
nature of saliva flow
plaque bacteria
consumption of fermentable carbohydrates
Development of caries
- primary lesion
- development of cavity
- spread into dentine and destruction of dental pulp
- development of periapical infection
Root caries key factors
multifactorial infection:
host
bacteria
diet
time
Is lactobacillus involved in the initiation of dental caries
may not be involved in the initiation of dental caries but are involved in the progression of caries deep into enamel and dentin
What is the source of nutrients for microorganisms
saliva
What happens when the pH drops below 5.5 for enamel
dissolution of tooth mineral
hydroxyapatite= demineralization
When fluoride is present in saliva what happens?
fluorapatite (instead of hydroxyapatite) forms during remineralization
What hypothesis is a good model for why caries develops
ecological plaque hypothesis
what hypothesis is a good model for why periodontitis occurs
keystone pathogen hypothesis
How can you manage caries
- early detection
- the importance of accurate diagnosis
- minimal cavity preparation techniques
- active prevention
Low incidence of caries consist of
case history
clinical and radiographic examination
high incidence of caries consist of
assessment of dietary habits
determination of salivary flow and buffering capacity
microbiological analysis
prevention of caries
reduction of sugar intake
fluoridation
pit and fissure sealants
control of cariogenic plaque flora: mechanical cleansing techniques & antimicrobial agents
replacement of cariogenic bacteria
True/false: Artificial sweeteners can be absorbed and metabolized to produce acids by bacteria
FALSE: Artificial sweeteners cannot be absorbed and metabolized to produce acids by bacteria
