Biofilm, Calculus, & Tooth Accumulations

dental plaque

a structured, resilient, yellow-grayish substance that adheres tenaciously to intraoral hard surfaces, including both natural teeth and removable or fixed restorations

intercellular

dental plaque is composed primarily of microorganisms embedded within an ? matrix

materia alba

a soft accumulation containing:

• Salivary proteins

• Some bacteria

• Many desquamated epithelial cells

• Occasional disintegrating food debris

materia alba

• a yellow or grayish-white, soft, sticky deposit that is less adherent than dental plaque

• Unlike plaque, it lacks an organized structure and is therefore less complex

calculus

a hard deposit produced through the mineralization of dental plaque

10¹¹

Approximately ? bacteria may be present in one gram of wet plaque

10⁹

The bacterial population on a single supragingival tooth surface can exceed ? cells

10³ ; 10⁸

bacterial counts in periodontal pockets range from approximately ? cells in a healthy crevice to more than ? cells in a deep pocket

archaea

• single-celled, prokaryotic microorganisms that form a distinct domain of life separate from bacteria and eukaryotes

• They are particularly associated with anaerobic portions of the subgingival biofilm

sessile

means fixed in one place without moving around, or attached directly by its base without a stalk or stem

planktonic

state in which microorganisms exist freely suspended in fluids such as:

• Saliva

• Gingival crevicular fluid

marginal plaque

Particularly important in:

• Initiation
• Development of gingivitis

Supragingival and tooth-associated subgingival plaque

Important in:

• Calculus formation

• Root caries

Tissue-associated subgingival plaque

Important in:
• Tissue destruction associated with different forms of periodontitis

• Streptococcus spp.

• Actinomyces spp.

Early colonizers include organisms such as:

Gram-positive, facultative organisms

The early community is generally characterized by greater proportions of:

• Prevotella intermedia

• Prevotella loescheii

• Capnocytophaga spp.

• Fusobacterium nucleatum

• Porphyromonas gingivalis

Examples of secondary colonizers

microbial succession

plaque formation is a process of ? rather than random accumulation

Streptococcus spp.

Yellow Complex

Primarily associated with:

Actinomyces odontolyticus

Purple Complex

Includes:

• Eikenella corrodens

• Aggregatibacter actinomycetemcomitans

• Capnocytophaga spp.

Green Complex

Includes:

• Fusobacterium spp.

• Prevotella spp.

• Campylobacter spp.

Orange Complex

Includes:

• Porphyromonas gingivalis

• Tannerella forsythia

• Treponema denticola

Red Complex

Includes:

red complex

particularly associated with bleeding on probing

coaggregation

refers to direct interaction between different bacterial cells

adhesin-receptor interactions

Stronger, specific attachment occurs through complementary:

corn-cob formation

In this arrangement:

• A central filamentous bacterial structure forms the core

• Coccal bacteria attach around the filament

intercellular matrix

the material surrounding and embedding the bacterial cells within the biofilm

1. saliva

2. GCF

3. bacterial products

The intercellular matrix is derived from 3 principal sources:

polysaccharides

• They have an important role in maintaining the integrity of the biofilm.

• They help create the structural framework that holds the microbial community together.

Proteins

• incorporated into the matrix from host and microbial sources

• they contribute to the biochemical environment surrounding the microorganisms

glycoproteins

1. Participate in formation of the acquired pellicle.

2. Become incorporated into the developing plaque biofilm.

lipids

This component may originate from:

• Membranes of disrupted bacterial cells

• Membranes of disrupted host cells

• Bacterial vesicles

• Possibly food debris

DNA

Its presence reflects the contribution of bacterial and host cellular material to the extracellular environment

albumin

has been identified in plaque matrix and probably originates primarily from gingival crevicular fluid

saliva

The inorganic components in supragingival plaque are derived primarily from

GCF

The inorganic components in subgingival plaque are derived primarily from

serum transudate

GCF is described as a?

a. Formation of the acquired pellicle
b. Initial adhesion/attachment of bacteria
c. Secondary colonization/biofilm maturation

3 major phases of plaque formation

acquired pellicle

All oral surfaces are coated by an organic layer called the

thin basal layer

Layer of the acquired pellicle

• very difficult to remove

• resistant to harsh chemical and mechanical treatment

thicker globular layer

Layer of the acquired pellicle

• up to approx. 1 μm or more

• easier to detach

• Peroxidases

• Lysozyme

• α-Amylase

Examples of proteins retain enzymatic activity after incorporation into the pellicle

bacterial adhesins & complementary receptors

More stable attachment is then established through specific interactions between

2nd and 3rd phase of plaque formation

Coaggregation occurs between?

early plaque

primarily gram-positive facultative organisms

maturing plaque

increasing gram-negative organisms

mature plaque

increased anaerobic and proteolytic organisms

capnophilic bacteria

requires elevated CO2 for growth

dysbiosis

an imbalance in the different microorganisms living together in a microbiome

1. Buccal surfaces of maxillary molars

2. Lingual surfaces of mandibular anterior teeth

Common locations of supragingival calculus

supragingival calculus

Characteristics

It is generally:

• White or whitish-yellow

• Hard

• Claylike in consistency

• Relatively easy to detach from the tooth

• Capable of rapidly recurring after removal

subgingival calculus

It is generally:

• Hard

• Dense

• Dark brown, dark green, or greenish-black

• Firmly attached to the tooth surface

• hydroxyapatite

• octacalcium phosphate

crystal forms common in supragingival calculus

brushite

crystal form common in mandibular anterior region

magnesium whitlockite

crystal form common posteriorly

1-14

Mineral precipitation generally begins within approximately ? days after plaque formation

4-8 hours

calcification has been reported to begin as early as ? after plaque formation

reversal phenomenon

• Calculus accumulation may continue until a maximum level is reached, after which the amount may decline.

• The decline is termed the ? and may be related to mechanical wear of bulky deposits from food and movement of the cheeks, lips, and tongue