- Salivary globular proteins (w/ negative charges) attach to the positively-charged tooth surface (Ca++, HA) and form a continuous film, which is the pellicle
- stabilize the tooth surface, preventing dissolving or getting more mineral deposit
- lubricate the occlusal surface
- site for baterial attachment
- generating staining
- non-pathogenic organisms
- within 24hr
Extrinsic dental stains
- Adhesion of chromogenic compounds to the tooth surface.
- Chemical reactions resulting in the formation of colored compounds (browning reaction between sugars and amines).
- Reactions of iron, tin and other metals with sulfur resulting in dark compounds
Interaction of tea-tannins with pellicle-proteins
Following exposure to tea the pellicle proteins can get cross linked to form rubbery tenacious nodules that are stained.
Remineralization of teeth by pellicle - Statherin
- prevent precipitation or crystallization of supersaturated calcium phosphate in ductal saliva and oral fluid thus helps to maintain the integrity of enamel
- Produced by acinar cells in salivary glands
- an effective lubricant preventing tooth wear
Plaques - biofilm
- Cocci mostly nonpathogenic, early colonizers, binds to pellicle within 24hrs, thin
- Mixed population including pathogens anaerobes, thick plaque, mature pellicle, diverse species
- When the pathogenic species overgrows and take over the population, the diversity may go down again
- Maintains the plaque at the nonpathogenic cocci level will prevent caries
Sucrose is a particular bad sugar in terms of caries - more cariogenic than other sugar
- S. mutans use Glucosyl transferase (GTF) to break down sucrose and re-assembles individual monomeric forms into extracell homopolymers (glucans or fructans) which tightly binds to tooth surface and the bacteria
- fructose -> glycolysis -> energy + acid
- glucose -> glucan (amylose like polymer)
- highly specific to sucrose
- Broad pH range 5-7
- Enzyme is constitutetively expressed
- acts as a “glue” and glues bacteria to teeth.
- Two forms of glucans; soluble form (dextran) and insoluble form (mutan)
- Insoluble form causes an increase in number of S. mutans that can attach to teeth
Acid production of S. mutan
- glycolysis-> lactic acid
- can tolerate low pH environment
- breaks down lactic acid (low pKa) and produces acetic acid or Propionic acid, weaker acids.
- Veillonella colonization inhibits caries formation.
Xylitol anti-cariogenic sugar
- uptaken by the pathogenic bacteria
- can be transformed to xylitol phosphate, which can not be utilized -> starved to death
the bacteria take over the niche and produce alcohol instead of acid
Protein breakdown -> sulfur containing amino acids
amino acid break down to produce basic compounds by bacteria
- NH3, urea
- increase pH
- helps prevent caries
- Arginine containing dental
dentin vs enamel
- enamel mostly mineral 97%
- dentin large amount of protein, collagen meshwork, more like bone
Collagen break down enzyme
- matrix metaloproteiase (MMP)
- derived from bacteria as well as host (saliva and dentin matrix).
- activated by exposure to low pH followed by neutralization
- triple helical
- the gap between individual fibers are susceptible to caries
Phosphoproteins in Dentin Mineralization
- Collagen network forms first
- odontoblasts secrete proteins into the matrix to trigger the mineralization of the matrix
- • Dentin specific phosphoprotein:
- • identified at the mineralization front; very acidic protein.
- • Interacts with Ca to form mineral in-vitro.
- • This reaction is hindered by dephosphorylation
Role of phosphoproteins in dentin formation and repair
- polyserine or other structure bound by phosphate
- possibly the most acidic protein
- gets into the gaps between collagen and attract Ca++ and eventually mineralize
development of Caries of dentin involve two steps
- dissolution of the mineral HA
- dissolution of the collagen matrix
MMP may be activated in the acid erosion of dentin
- non-caries erosion
- cause sensitivity at the root area