The dental pellicle, or acquired pellicle, is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

film that forms on the surface enamel, dentin, artificial crowns, and bridges by selective binding of glycoproteins from saliva that prevents continuous deposition of salivary

calcium phosphate The term calcium phosphate refers to a family of materials and minerals containing calcium ions (Ca2+) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and hydroxide as well. Calcium phosphates are whi ...

. It forms in seconds after a tooth is cleaned, or after chewing. It protects the tooth from the acids produced by oral

microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

s after consuming

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...

Stages

Pellicle

The surface of enamel and dentin attracts salivary glycoproteins and bacterial products creating the pellicle layer. This thin layer forms on the surface of the enamel within minutes of its exposure. These glycoproteins include proline-rich proteins that allow bacterial adhesion.Newman, Michael G. Carranza's Clinical Periodontology, 10th Edition. Saunders Book Company, 072006. 9.4.2. Pellicle somewhat protects enamel, but not dentin, from acid and abrasion.

Plaque formation

Plaque Plaque may refer to: Commemorations or awards * Commemorative plaque, a plate or tablet fixed to a wall to mark an event, person, etc. * Memorial Plaque (medallion), issued to next-of-kin of dead British military personnel after World War I * Pl ...

is a

biofilm A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...

composed of several different kinds of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

and their products that develop over the enamel on the pellicle. Plaque formation takes several days to weeks and will cause the surrounding environment to become acidic, if not removed.

First bacteria

The first bacteria to attach to these pellicle glycoproteins are

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

, aerobic

cocci A coccus (plural cocci) is any bacterium or archaeon that has a spherical, ovoid, or generally round shape. Bacteria are categorized based on their shapes into three classes: cocci (spherical-shaped), bacillus (rod-shaped) and spiral ( of whi ...

such as ''

Streptococcus sanguinis ''Streptococcus sanguinis'', formerly known as ''Streptococcus sanguis'', is a Gram-positive facultative anaerobic coccus species of bacteria and a member of the Viridans Streptococcus group. ''S. sanguinis'' is a normal inhabitant of the healt ...

''. These bacteria are able to replicate in the oxygen-rich environment of the oral cavity and form micro-colonies minutes after attachment.

Later bacteria

Other bacteria, including '' Streptococcus mutans,'' are able to grow in these colonies. ''Streptococcus mutans'' is important, because it is associated with

dental caries Tooth decay, also known as cavities or caries, is the breakdown of teeth due to acids produced by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complicat ...

.Roberson, Theodore. Sturdevant's Art and Science of Operative Dentistry, 5th Edition. C.V. Mosby, 042006. 3.2.2. These bacteria produce the

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

glucosyltransferase Glucosyltransferases are a type of glycosyltransferase that enable the transfer of glucose. Examples include: * glycogen synthase * glycogen phosphorylase Glycogen phosphorylase is one of the phosphorylase enzymes (). Glycogen phosphorylase c ...

. Glucosyl transferase converts sucrose into

exopolysaccharide Extracellular polymeric substances (EPSs) are natural polymers of high molecular weight secreted by microorganisms into their environment. EPSs establish the functional and structural integrity of biofilms, and are considered the fundamental comp ...

s. These exopolysacharides create a sticky environment that allows other bacteria to attach to the initial colonies and protect them from acids. As the plaque develops and expands,

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

can no longer diffuse into the colonies. After a few days,

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

, gram-negative cocci, rods, and filaments begin to colonize the plaque. After several weeks, the cocci, rods, and filaments grow together forming colonies known as corncobs. This anaerobic environment causes

facultative anaerobes A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. Some examples of facultatively anaerobic bacteria are ''Staphylococcus' ...

such as ''S. mutans'' and

Lactobacilli The ''Lactobacillaceae'' are a family of lactic acid bacteria. It is the only family in the lactic acid bacteria which includes homofermentative and heterofermentative organisms; in the ''Lactobacillaceae,'' the pathway used for hexose fermentati ...

to break down sucrose through fermentation pathways. These bacteria produce

lactic acid Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...

as a metabolic byproduct.Miller, Chris H. Infection Control and Management of Hazardous Materials for the Dental Team, 3rd Edition. Mosby, 092004. 2.3.3.3). If the concentration of lactic acid becomes high enough, the pH around the plaque will drop below 5.5, and demineralization will occur.

References

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