Biochemistry - Unit III - Caries

• 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

• 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

Following exposure to tea the pellicle proteins can get cross linked to form rubbery tenacious nodules that are stained.

• 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

• 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->glucose->glycolysis->acid->caries
• 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

• 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.

• 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

• NH3, urea
• increase pH
• helps prevent caries
• Arginine containing dental
• products

• enamel mostly mineral 97%
• dentin large amount of protein, collagen meshwork, more like bone

• 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

• 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

• polyserine or other structure bound by phosphate
• possibly the most acidic protein
• gets into the gaps between collagen and attract Ca++ and eventually mineralize

• dissolution of the mineral HA
• dissolution of the collagen matrix

• non-caries erosion
• cause sensitivity at the root area