Formation of Formation of Dental PlaqueDental Plaque

Dr. Marcel Hallare Dr. Marcel Hallare

Dental plaque may be readily visualized Dental plaque may be readily visualized on teeth after 1 to 2 days with no oral on teeth after 1 to 2 days with no oral hygiene measures hygiene measures

Plaque is white, grayish, or yellowish and Plaque is white, grayish, or yellowish and has globular appearance has globular appearance

Comprised of bacteria in a matrix of Comprised of bacteria in a matrix of salivary glycoproteins and extracellular salivary glycoproteins and extracellular polysaccharides like glucans and fructans polysaccharides like glucans and fructans

This matrix makes it impossible to rinse This matrix makes it impossible to rinse plaque away with water plaque away with water

Mechanically removed by means of hand Mechanically removed by means of hand instruments, the toothbrush or other oral instruments, the toothbrush or other oral hygiene aids hygiene aids

Plaque is typically observed on the Plaque is typically observed on the gingival third of the tooth surface where it gingival third of the tooth surface where it accumulates without disruption by the accumulates without disruption by the movement of food and tissue over the movement of food and tissue over the tooth surface during masticationtooth surface during mastication

Plaque deposits also form preferentially in Plaque deposits also form preferentially in supragingival and subgingival calculus, supragingival and subgingival calculus, cracks, pits, fissures in the tooth structure cracks, pits, fissures in the tooth structure under overhanging restorations and under overhanging restorations and around malaligned teetharound malaligned teeth

Mouth breathing leads to dehydration of Mouth breathing leads to dehydration of the oral cavity, rendering the plaque the oral cavity, rendering the plaque tougher and stickier and protective tougher and stickier and protective function of saliva is reduced function of saliva is reduced

Rough areas at the cementoenamel junction Rough areas at the cementoenamel junction enhance plaque retention enhance plaque retention

Location and rate of plaque formation vary Location and rate of plaque formation vary among individuals, and determining factors among individuals, and determining factors include oral hygiene, as well as host factors include oral hygiene, as well as host factors such as diet or salivary flow ratesuch as diet or salivary flow rate

In the absence of oral hygiene measures, In the absence of oral hygiene measures, plaque will continue to accumulate until a plaque will continue to accumulate until a balance is reached between the forces of balance is reached between the forces of plaque removal and those of plaque plaque removal and those of plaque formationformation

Process of Plaque FormationProcess of Plaque Formation

1.1. Formation of the pellicle coating on the Formation of the pellicle coating on the tooth surfacetooth surface

2.2. Initial colonization by bacteriaInitial colonization by bacteria

3.3. Secondary colonization and plaque Secondary colonization and plaque maturationmaturation

Formation of the Dental PellicleFormation of the Dental Pellicle

All surfaces of the oral cavity including all tissue All surfaces of the oral cavity including all tissue surfaces as well as surfaces of teeth and fixed surfaces as well as surfaces of teeth and fixed and removable restorations are all coated with a and removable restorations are all coated with a glycoprotein pellicleglycoprotein pellicle

The pellicle is derived from components of saliva The pellicle is derived from components of saliva and crevicular fluid, as well as from bacterial and and crevicular fluid, as well as from bacterial and host tissue cell products and debrishost tissue cell products and debris

The mechanism involved in enamel pellicle The mechanism involved in enamel pellicle formation include electrostatic, van der Waals, formation include electrostatic, van der Waals, and hydrophobic forcesand hydrophobic forces

The hydroxyapatite surface has a The hydroxyapatite surface has a predominance of negatively charged predominance of negatively charged phosphate groups that interact directly or phosphate groups that interact directly or indirectly with positively charged indirectly with positively charged components of salivary and crevicular fluid components of salivary and crevicular fluid macromoleculesmacromoleculesPellicles function as a protective barrier, Pellicles function as a protective barrier, providing lubrication for the surfaces and providing lubrication for the surfaces and preventing tissue dessicationpreventing tissue dessicationAlso provides a substrate to which Also provides a substrate to which bacteria in the environment attachbacteria in the environment attach

Initial Colonization of the Tooth Initial Colonization of the Tooth SurfaceSurface

Within a few hours bacteria are found on Within a few hours bacteria are found on the dental pelliclethe dental pellicle

Initial bacteria colonizing the pellicle-Initial bacteria colonizing the pellicle-coated tooth surface are predominantly coated tooth surface are predominantly gram-positive facultative microorganisms gram-positive facultative microorganisms such as such as Actinomyces viscosus Actinomyces viscosus and and Streptococcus sanguisStreptococcus sanguis

Initial colonizers adhere to the pellicle through Initial colonizers adhere to the pellicle through specific molecules, termed specific molecules, termed adhesinsadhesins on the on the bacterial surface that interact with receptors in bacterial surface that interact with receptors in the dental pelliclethe dental pellicleThe plaque mass matures through the growth of The plaque mass matures through the growth of attached species as well as the colonization and attached species as well as the colonization and growth of additional species growth of additional species In the ecologic succession of the biofilm, there is In the ecologic succession of the biofilm, there is a transition from the early aerobic environment a transition from the early aerobic environment characterized by gram-positive facultative characterized by gram-positive facultative species to a highly oxygen-deprived species to a highly oxygen-deprived environment in which gram-negative anaerobic environment in which gram-negative anaerobic microorganisms predominatemicroorganisms predominate

Secondary Colonization and Secondary Colonization and Plaque MaturationPlaque Maturation

Secondary colonizers are the Secondary colonizers are the microorganisms that do not initially microorganisms that do not initially colonize clean tooth surfaces, including colonize clean tooth surfaces, including Prevotella intermedia, Prevotella loescheii, Prevotella intermedia, Prevotella loescheii, Capnocytophaga Capnocytophaga species, species, Fusobacterium Fusobacterium nucleatum, nucleatum, andand Porphyromonas gingivalisPorphyromonas gingivalis

These microorganisms adhere to cells of These microorganisms adhere to cells of bacteria in the plaque massbacteria in the plaque mass

CoaggregationCoaggregation is the ability of different species is the ability of different species and genera of plaque microorganisms to adhere and genera of plaque microorganisms to adhere to one anotherto one another

This process occurs primarily through the highly This process occurs primarily through the highly specific stereochemical interaction of protein specific stereochemical interaction of protein and carbohydrate molecules located on the and carbohydrate molecules located on the bacterial cell surfaces in addition to the less bacterial cell surfaces in addition to the less specific interactions resulting from hydrophobic, specific interactions resulting from hydrophobic, electrostatic, and van der Waals forceselectrostatic, and van der Waals forces