Dental Plaque: Structure, Formation, Classification

Dental Plaque: Structure And Formation

Dental plaque is Defined as an adherent intercellular matrix consisting primarily of proliferating microorganisms along with the scattering of epithelial cells, leucocytes and macrophages.

Classification of Dental Plaque

Based on the relationship to gingival margin

• Supragingival
  • Coronal plaque: Plaque in contact with only tooth surface
  • Marginal plaque: Associated with the tooth surface at gingival margin
• Subgingival
  • Attached plaque: It can be tooth, epithelium and/or connective tissue
  • Associated.
  • Unattached subgingival plaque

Dental Plaque Composition

Walter Loesche proposed the nonspecific and specific plaque hypothesis in 1976.

Nonspecific Plaque Hypothesis

• It states that it is the total bulk of plaque, which determines the pathogenicity rather than the individual species within it
• It means all plaque is equally pathogenic
• According to this, when only small amount of plaque are present, the products released by this get ‘neutralized by the host. Large amount of plaque would produce large amount of noxious products, which would overwhelm the host’s defense.
• Inherent concept of non specific plaque hypothesis is that control of periodontal disease depends on control of amount of plaque accumulation.

Specific Plaque Hypothesis

• It states that not all plaque is pathogenic and its pathogenicity depends upon the presence of the certain specific microbial pathogens in plaque. This is based on the fact that the specific microorganisms responsible for periodontal disease release certain damaging factors that mediate the destruction of the host tissue. For example, Actinobacillus actinomycetemcomitans as a possible pathogen responsible for localized juvenile periodontitis.
• This hypothesis was revisited to state that the disease associated with specific strains of given species. Revision was done because there is fiding of multiple strains of any given bacterial species which show diffrence in their virulency.

Dental Plaque Formation

Supragingival Plaque

• It is adherent to tooth structure and consists of gram positive cocci and gram-negative rods and filaments.
• Morphologic arrangement of flora in supragingival plaque is described as corncob formation.
• Corncob formation has a central core which consists of rod shaped bacterial cells which attaches along the surface of the rod-shaped cell.

Subgingival Plaque

• It has many large fiaments with flgella and is rich in spirochetes.
• Tooth-associated plaque is same as supraginigival plaque while tissue associated plaque is covered with flgellated bacteria and numerous bristle brush formations. Extracellular matrix is not well Defined. This arrangement is called as test tube brush formation.
• Test-tube brush formation is characterized by large filaments that form long axis and short filaments or gram-negative rods embedded in an amorphous matrix.