Caries: Impact of Diet and Nutrition

• Diet and nutrition affect caries etiology and pathogenesis through systemic and local effects.
• Diet refers to food and drink consumption, while nutrition is the process of absorbing and metabolizing food for growth, energy, tissue repair, and reproduction.

Carbohydrates in Caries Development

• Dietary carbohydrates are conducive to caries and exert a cariogenic effect locally on the tooth surface.
• This effect is influenced by the quality and quantity of dental plaque.
• Fermentable carbohydrates can be hydrolyzed by salivary amylase and then fermented by bacteria.

Carbohydrate Classification

• Free-form monosaccharides (simple sugars) such as glucose and fructose are found in fruits, vegetables, and honey.
• Galactose occurs from the breakdown of lactose.
• Disaccharides consist of two linked simple sugar molecules.
• Sucrose, refined from sugar cane or sugar beets, is a major part of dietary sugar and is formed from one glucose and one fructose molecule.
• Lactose is formed when a glucose molecule combines with galactose (milk sugar).
• Maltose is formed when two glucose molecules combine and is mainly derived from starch hydrolysis.
• Polysaccharides are unlike monosaccharides and disaccharides because they are not sugar.
• Polysaccharides are made of multiple individual sugar molecules, particularly glucose, joined together.
• Digestible forms include starch, which is found in rice, potatoes, and peas.

Evidence for Diet and Caries Relationship

• Observational studies show that caries prevalence is low in populations that adhere to a primitive lifestyle and consume local foods with little sugar.
• Interventional studies involve altering people's diets and monitoring the impact.
• Such studies are now constrained by ethical concerns.

The Hopewood House

• The Hopewood House was an orphanage in Australia.
• Sugar and other refined carbohydrates were excluded from the children's diet from the beginning.
• Dental surveys of these children aged 5-11 years showed a significantly lower incidence of caries compared to the state school population.
• After the children began earning wages and deviated from the original diet, the increase of decayed, missing, and filled teeth (DMFT) after 11 years shows the teeth did not acquire any permanent resistance to caries.

The Vipeholm Study

• The study, conducted in Sweden between 1945 and 1953, investigated the relationship between sugary foods and caries.
• It examined the effect of consuming sugary foods with varying stickiness and oral retention times at different times during the day on the development of caries.

Main Conclusions of the Vipeholm Study

• Sugar consumption, even in large amounts, had limited impact on caries.
• Consumption of sugar between meals was associated with a marked increase in dental caries.
• Increased dental caries activity disappeared after sugar-rich foods were withdrawn.
• Dental caries experience varied widely among individuals.

Other Study Types

• Animal studies were conducted to determine the effect of sugar intake.
• Enamel slab experiments show the effects of diet on demineralization in slabs of enamel.
• Plaque pH studies are relatively simple experiments that measure the effect of food on the pH of dental plaque, but assess diet acidogenicity rather than cariogenicity.
• Incubation studies test for acid production with plaque or saliva.
• Whole enamel, powdered enamel, or calcium phosphate are added to the saliva/substrate mixture, and the rate of mineral dissolution is measured as a measure of cariogenic potential.

The Basic Stephan Curve

• The resting pH of dental plaque is generally between 6.5 and 7; resting plaque refers to plaque 2-2.5 hours after consuming carbohydrates.
• The pH of plaque rapidly drops below the critical value within 2-5 minutes when the plaque is exposed to sucrose or glucose.
• A pH value of 5.5 is considered critical, with dental enamel beginning to dissolve.
• The rapid pH decline is followed by recovery over the next 30-60 minutes, which is known as the Stephan curve.
• The rapidity of pH fall depends upon the speed at which sucrose diffuses into plaque and the bacteria in the plaque.

Caries Production

• The slow rate of recovery to the resting pH depends mainly on:
  • Rapid production of high concentrations of acids within the plaque.
  • The diffusion-limiting properties of plaque, which delays acids escaping to saliva.
  • Diffusion of salivary buffers into plaque is hampered by the diffusion-limiting properties of plaque.
  • Continued sugar production from bacterial intracellular polysaccharides.

Factors Affecting Food Cariogenicity

• One factor is the types of carbohydrates, including extrinsic and intrinsic sugars:
  • Extrinsic sugars are located outside the cellular structure of foods.
  • Intrinsic sugars are located within the cellular structure of foods.
  • Non-milk extrinsic sugars include all added sugars and sugars found in fruit juices, honey, and syrups.
  • Milk sugars are naturally present in milk and milk products.
• Sucrose has been called the arch-criminal in dental caries due to the following evidence:
  • Low caries prevalence in populations with low sucrose consumption.
  • Caries prevalence decline during wartime sucrose shortages.
  • The rise of caries prevalence with increasing availability of sucrose.
  • Archaeological evidence of low caries prevalence in eras before sucrose became freely available.
  • Low caries prevalence in heredity fructose intolerance, or disorders of sucrose.
• Starch is a heterogeneous food group comprised of polysaccharide molecules which are too large to diffuse into the plaque.
• Starches are broken down by salivary amylase, releasing maltose, maltotriose, and glucose which may be metabolized by oral bacteria to produce acids that cause dental caries.
• Uncooked starch has very low cariogenicity, but heating at cooking temperatures causes partial degradation.
• The partial degradation results in soluble products such as maltose, maltotriose, and glucose.
• A mixture of starch and sucrose will cause more dental caries than starch alone.
• Physical and organoleptic properties such as particle size, solubility, adhesiveness, texture, and taste are important for cariogenicity.
• These influence eating patterns and oral retention of foods.
• Carbohydrates in drinks are cleared within 5 minutes, while sweets like sugar-containing chewing gum, toffees, and lozenges generally give high oral sucrose concentration and clearance time.
• Chewing gum has a clearance time of 40 minutes and other sweets have a clearance time of 15-20 minutes.
• Tooth brushing after meals, chewing sugar-free gum, or peanuts increases salivary flow to speed up carbohydrate clearance.
• Mouth rinsing with water offers only a limited effect.
• Consumption of sugar-rich foods at meal times is preferred to alone or in between meal, because when the pH is minimized due to the dilution effect.
• Increased salivary flow rate results from the mastication of other foods.
• Frequency of eating as a more significant factor than the overall sugar consumption.
• Frequent intake of sugars induces prolonged and intense acid attacks on tooth surfaces and decreases the time available for remineralization.
• The pH of dental plaque falls rapidly when sugar is consumed leading to demineralization.
• A more frequent intake of refined carbohydrate increases damage time and proportionally decreases tooth repair time (remineralization).