Plaque Flashcards
What is dental plaque?
Structured resilient yellowish grayish substance that adheres tenaciously to the intraoral hard surfaces including removable and fixed restorations.
Microbial deposit representing a biofilm which consists of bacteria in a matrix composed mainly of extracellular bacterial polymers and salivary/ gingival exudate products.
Why do we call plaque as biofilm?
- Biofilm has an organized structure.
- Composed of bacterial microcolonies within a matrix.
- In deeper layers microbes are bound together in matrix.
- On top, microbes are loose and irregular.
- Have a primitive microcirculatory system.
- Resistant to host defense.
Can you remove dental plaque/biofilm just by rinsing?
No, plaque adheres strongly to teeth and requires mechanical removal through brushing or flossing.
What is materia alba, and how does it differ from plaque?
Materia alba is a soft, white material consisting of bacterial aggregations, leukocytes, and desquamated oral epithelial cells accumulating on uncleaned teeth surfaces.
It can be easily removed by a strong water spray mechanically unlike plaque, which strongly adheres to teeth.
What is Calculus and how is it different from plaque?
- Calculus is a hard deposit formed by mineralization of dental plaque.
- It is covered by a layer of unmineralized plaque.
- Cannot be removed by brushing—requires professional scaling.
What is the acquired salivary pellicle?
A thin, transparent and adhesive layer that forms on teeth immediately after cleaning.
It contains salivary glycoproteins to resist tooth wear and protects enamel from acid.
Which is more harmful: plaque or calculus? Why?
Plaque is more harmful because it contains active bacteria that cause caries and gum disease. Calculus is hardened but allows new plaque to form.
What are the two main types of dental plaque?
- Supragingival plaque: Above the gum line, on clinical crowns, restorations, implants & prostheses.
- Subgingival plaque: Below the gum line, in sulcus or pockets, and more harmful to gums.
How does dental plaque appear clinically?
Invisible in thin layers. Thick plaque appears whitish-yellow, mainly along the gum line. In small amounts, it can be scraped off with a probe. Can be detected using: Probing, Disclosing dyes, Illuminating light.
How does disclosing dye help in detecting plaque?
- Stains plaque, making it more visible.
- Helps patients see and remove plaque effectively.
- Useful for dentists to educate and assess oral hygiene.
Why is subgingival plaque difficult to detect?
- Located beneath the gums, making it invisible.
- Often found in areas that are not mechanically cleaned (e.g., deep pockets, misaligned teeth, restorations, and orthodontic appliances).
-Can contribute to gum disease if not removed.
What is the composition of dental plaque?
- 70% microbes
- Host cells
- Bacterial products
- Other microorganisms like Mycoplasma, yeast, and protozoa.
How fast does plaque grow, and how does it accumulate?
- 1mm³ of plaque weighs ~1mg and contains more than 200 million bacteria.
- Plaque accumulation occurs by:Internal bacterial multiplication & surface deposition from saliva/food.
- Bacterial growth doubles in just 3 hours!
What are the stages of dental plaque biofilm formation?
4 stages:
- Acquired pellicle forms.
- Bacteria attach to the pellicle via long-range physico-chemical interactions.
- Co-adhesion (additional bacteria bind to initial layer). Secondary colonizers join, leading to maturation.
- Multiplication and biofilm formation.
What are the primary colonizers of plaque?
Mostly Gram-positive cocci like Streptococcus species, which attach directly to the acquired pellicle.
Either independent of defined complexes or members of the yellow complex (streptococcus species) or purple complex (A.odontolyticus).
What are secondary colonizers?
Bacteria that attach to primary colonizers, including Gram-negative species from Green, Orange, and Red complexes.
How does plaque change over time?
Initially Gram-positive, but shifts to Gram-negative anaerobes as plaque matures, leading to periodontal disease.
What are the three main bacterial complexes in plaque?
Green, Orange, and Red complexes.
What is the role of Green Complex bacteria?
Capnocytophaga, Eikenella corrodens, Aggregatibacter Actinomycetumcomitans.
Green and orange complexes include species which are pathogens in periodontal and non periodontal infections.
What is the significance of the Orange Complex?
Fusobacterium nucleatum, Prevotella intermedia, Campylobacter species.
Green and orange complexes include species which are pathogens in periodontal and non periodontal infections.
Why is the Red Complex important in periodontitis?
Because this complex is associated with bleeding on probing.
e.g Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola.
What is the bacterial composition of supragingival plaque?
Healthy gingiva - 90% Gram-positive cocci and rods (e.g., Streptococcus, Actinomyces), rest G -ve.
What is the bacterial composition of subgingival plaque?
Mostly Gram-negative rods and anaerobes (e.g., Fusobacterium, Wolinella, Spirochetes).
What is the composition of plaque in 2 to 3 month old gingivitis?
25% Streptococci
25% Actinomyces species
50% G -ve rods (e.g., Fusobacterium, Wolinella, Campylobacter, Spirochetes)
