Dental Caries

Definition: “Progressive irreversible damage to hard part of the teeth exposed to oral environment characterized by demineralization of inorganic constituents and dissolution of organic contents resulting in cavitation.”

• One of the commonest diseases in the world
• Begins asymptomatically as a destructive process of hard surface of tooth
• Plaque: bacterial acids demineralise enamel: fissures and pits: decay site
• Surfaces adjacent to tooth restorations and exposed roots are also vulnerable

Effects of dental caries:

1. Tooth loss
2. Destruction of enamel and dentine: invasion of pulp: infection of pulp (pulpitis): progression of infection to periodontal tissue (periodontitis) ultimately osteomyelitis

• As dentine and enamel don’t have blood supply, natural healing doesn’t occur
• Aim of treatment is to stop progression

Etiology

• Bacterial acid production causes demineralization of enamel and dentine followed by destruction via infection
• Many theories regarding mechanism of evolution of caries.
• Acidogenic theory:
• Widely accepted
• According to this theory, dental decay is a chemico-parasitic process consisting of 2 stages
• Decalcification of enamel and its destruction
• Decalcification of dentine with dissolution of softened residue: acid affecting dissolution is obtained from starch and sugar fermentation by microorganisms which are mostly acidogenic
• Dental plaque helps acid to stay in contact
• Proteolytic theory
• In addition to acid production, plaque bacteria produce Proteolytic enzymes that destroys organic portion of tooth making it easier for microorganisms to invade enamel and dentine
• Proteolysis-chelation theory (latest)
• Latest theory, widely accepted
• Bacterial attack on enamel is initiated by keratolytic microorganisms: breakdown of proteins and other organic portion of enamel especially keratin
• This results in formation of substance which may form soluble chelates with mineralized portion of teeth: organic and inorganic portion of tooth undergo demineralization simultaneously
• Chelation is complexing or freeing metallic ion
• Factors responsible for caries
• Role of microorganism
• Role of carbohydrates
• Role of acids to demineralize
• Role of dental plaque
• Acid that is formed is kept in contact with teeth surface for longer time

Prerequisites for Development of Dental Caries

• Dental plaque containing cariogenic bacteria
• Bacterial substrates esp –CHO)
• Susceptible tooth surface (decreased fluoroapatite, decreased salivary outflow)

Cariogenic bacteria:

• Streptococcus mutans ( most potent) because of:
• Its ability to produce aid by sugar fermentation
• Its ability to polymerize sugar into polysaccharides like polyglyans or dextrans which helps:
• Dental plaque to adhere to tooth
• Bacteria to adhere to tooth
• Streptococcus viridians, streptococcus salivarics, Streptococcus mites, strep sanguislactobacilli
• Main acids produced are:
• Lactic acid
• Acetic acid
• Propionic acid
• Disaccharides are more cariogenic than monosaccharides
• Sucrose is the most imp bacterial substrate because Streptococcus mutans polymerize it into polygalactans and is consumed in greater quantities by it
• Glucose and fructose through unrefined foods can be severely cariogenic (less than sucrose)

Susceptibility to Caries

• Depends on:
• Intake of fluorides in calcification stage
• Sugar content of diet
• Shape of tooth
• Constant use of antibiotics
• Salivation: Hyper salivation decreases caries incidence due to:
• Assists in clearance of –CHO
• Fluorides in saliva are good for teeth
• Buffering action of saliva helps in neutralizing acid in formation in dental plaque

Clinical Detection of Caries

• Appears first as chalky white soft on tooth
• This spot is slowly demineralized forming a cavity which is detected by
• A probe (catch on probing)
• Dental floss
• Dental x-rays
• History of sensation in teeth

Management

• Principles of Management Of Caries:
• Removal of decayed enamel and dentine
• Removal of adjacent stagnation surfaces e.g. pits and fissures
• Protection of pulp( by putting an insulation lining to prevent sensitivity with a metallic filling like ZnSO4 or by indirect pulp capping
• Maintenance of water tight restoration
• Restoration of original shape and form of tooth

Prevention of Caries

1. Removing plaque

• Proper brushing
• Regulars scaling

2. Dietary control

• Avoid soft, sugary and sticky diet, and brushing once any food gets stuck (4’S’)

3. Decreasing resistance

• Antibacterial measures
• Antibiotics prevent caries but use is not advisable only for this purpose
• e.g. penicillin in long term with RHD
• Antiseptics: e.g. Chlorhexidine gluconate 0.2% mouthwash
• Mechanism: destroys cell membrane of bacteria
• Disadvantages: not very effective as on stopping its use, causes growth of bacteria again
• If long term use: extrinsic discoloration (staining) but no other harmful affect
• Very unpleasant taste
• Immunization against caries: still in experimental stage, vaccine not yet developed as it is not practical since many organisms are responsible

4. Denial of substrate to plaque bacteria

• Avoid 3S (artificial sweeteners are not Cariogenic because they cannot be fermented by bacteria)

5. Complete removal of plaque

• Brushing
• Scaling

6. Modifying plaque

• Addition of Na, Ca phosphate to Cariogenic diet decreases caries in animals

7. Increasing resistance of tooth to bacterial action

• By addition of fluoride to water 1PPM most effective
• If addition of >2PPM fluoride: fluorosis: enamel mottling of teeth, opaque tint, and pitted stained, more brittle.
• Ways of taking fluoride: Systemic and Topical.
• Systemic application of fluoride
• Water fluorination (1PPM in water supply)
• Salt fluorination(1/2 to 1/3 water concentration_
• Milk fluorination
• Fluoride tablets
• Dual effect: systemic as well as local
• One tab: 2.2 mg of NaF (O.D) : equivalent to taking 1L of water containing 1PPM of fluoride
• Started immediately after birth
• Up to 2yrs: 1.1 mg (1/2 tab daily)
• 2–12 yrs: 2.2 mg daily one tab
• >12 yrs (1/2 tab daily)
• Topical application of fluoride
• Get incorporated into superficial enamel which is available in the following forms
• Fluoride mouth rinse
• Fluoride containing dentifrice: gel, powder, paste
• Shouldn’t rinse vigorously after brushing
• Fluoride tablets
• Fluoride in toothpaste
• Directly in contact with teeth
• Used everyday
• Disadvantage: casual process, only in accessible areas

Note: Mechanism of Action of Fluoride

• Hydroxy apatite + fluoride -> fluorohydroxyapatite crystals which are larger and have few imperfections: make enamel more stable stronger and resistant to dissolution by acids
• Fluoride interferes with bacterial metabolism in plaque and depresses acid production by inhibiting bacterial enzymatic action