Thursday, December 31, 2009

Dental Caries

Dental Caries

It is seen very often that many children and other age groups suffer from toothache which calls for immediate pain relief. We also notice that many children do not have regular balanced teeth, due to lack of right amount of chewing, hence the growth of the jaw is not up to the mark, resulting in crowded teeth. Dental caries is an infectious disease frequently called as tooth decay, characterised by localised destruction of the enamel and dentin of teeth. If caries process is not arrested, bacteria may invade the dental pulp and form an abscess (A pocket of infection). Dental caries constitute a major public health problem, particularly in children and young adults.
The process of tooth decay involves demineralisation of the outer surface (Enamel) of the tooth by organic acids. These acids are produced by fermentative action of bacteria in dental plaque. Dental plaque is generally considered to be sticky, colourless, gelatinous material that is very densely populated by bacteria. Plaque adheres to the surface of teeth and can only be removed by mechanical cleansing.

Current stats: About 26% of school children below the age of 10 have mild to moderate caries. We have noticed kinder garden children having dental stains and they got converted into caries within two years

In order to comprehend the modern theory of caries development, it is necessary to understand clearly the interaction of saliva, enamel, fluoride, bacteria and carbohydrate.
Saliva is supersaturated with calcium and phosphate that comprise the bulk of tooth enamel. Saliva protects enamel. The enamel surface is bathed in saliva, allowing for a continuous inter change of calcium and phosphate ions between saliva and enamel, which typically is in equilibrium. The high levels of calcium and phosphate in saliva inhibits mineral loss and enhances mineral gain. Bicarbonate buffers in saliva help to neutralise the plaque acid. Dental caries begin to form if, over the time equilibrium is disturbed by organic acids that are by-products of bacterial metabolism of fermentable carbohydrates. Net demineralisation over the time, below the enamel surface, eventually causes loss of support and caving-in, inducing a cavity. If the enamel surface is not broken, the surface can be re-mineralised with mineral derived from the saliva. When present at the tooth surface the fluoride ions inhibit demineralisation and favour remineralisation. This is believed to be the major action of fluoride in preventing caries.
The initiation of caries depends on the interaction of several factors, including,
a. A susceptible host
b. Cariogenic bacteria
c. A favourable environment
d. A sufficient period of time.
Reducing any one of these factors can markedly decrease risk of tooth decay.

Susceptibility of Host:

The tooth’s susceptibility to decay is done by many factors. Nutrition plays a significant role.

Nutrients with special role in Oral Health.

Fluoride apparently promote oral health in different ways, Fluoride ingested during tooth development seems to strengthen enamel. Topical application of fluoride has a local effect on teeth after they have erupted. Fluoridation of Drinking water is an effective safe economical way to administer fluoride is through fluoridation of community drinking water. The incidence of dental caries is reduced by about 60% in communities where drinking water is fluoridated.
Fluorosis: If too much fluoride (more than 2 PPM) is ingested when the teeth are forming, fluorosis of the enamel may occur. The enamel becomes roughened, mottled, and discoloured. If fluorosis is of a minor degree, the teeth remain strong and caries resistant but appear less attractive. Some dentists recommend use of non-fluoridated water for infants under six months of age to reduce the chance of fluorosis.
Other Nutrients:
The result of various studies has suggested that phosphate have cario-static (decay-retarding) properties. Dietary proteins and fats may actually cario-static. A diet high in protein increases the level of urea in the saliva. The urea, in turn, acts as buffer, neutralising acids formed by bacterial fermentation. It has been suggested that fats may form a protective coating on the tooth surface or that they may exert some anti microbial action.

Cariogenic Bacteria
Cariogenic bacteria (mainly streptococcus mutans and Lactobacilli) play a key role in the development of dental caries. They produce large amounts of Lactic acid and other acids when they are supplied with suitable foods such as sugar. These acids lower the pH of the plaque. When the pH drops to 5.5 or less demineralisation of susceptible tooth enamel begins. The longer the pH remains low, the greater the demineralisation. Demineralisation allows proteolytic (protein-decomposing) bacteria to invade the dentin and destroy it. The nutrients a person ingests influence the types of bacteria present in the oral cavity, their proliferation in dental plaque, and the resistance of teeth to decay.

Favourable Environment
Important environmental factors include presence of suitable food substrate for bacterial growth and the amount of saliva.
Suitable substrate:
Fermentable carbohydrates are necessary substrates for the development of dental caries. Sucrose has been identified as the most cariogenic carbohydrate. Other sugars such as fructose, lactose and glucose also support the growth of cariogenic bacteria. Complex carbohydrates such as starch are less cariogenic. Some foods such as dried fruits and bananas are potentially cariogenic.
Saliva has protective effects. It helps to wash away food debris and also helps to neutralise the acids that are produced by bacteria.

Saliva, Food and Acid production.
Recent findings have increased our knowledge about the complex relationship between foods, saliva and fluoride. Savoury foods and those foods perceived as tasty stimulate greater saliva production. Stimulation of salivary flow increases the rate of oral carbohydrate clearance leaving less time for acid production. In conditions that results in reduced salivation, caries development accelerates dramatically. Whenever fermentative carbohydrate is eaten, it is metabolised by plaque bacteria. When fluoride is present in saliva it inhibits bacterial metabolism and its by-products, acid production.

Oral Clearance Time
The frequency and form of carbohydrate ingestion affect the time required for oral clearance that is for food to be completely removed from the mouth. It takes approximately 20 min after food is cleared from the mouth for the acidic pH of dental plaque to return to neutral. This means each time a sugar containing food is ingested teeth may be exposed to decaying acids for 20 min or longer. Foods having a long oral clearance time are potentially more cariogenic than those rapidly cleared from the mouth. Sticky solids such as dates, raisins or caramels adhere to the surface of teeth and remain in cracks and crevices of teeth for long period of time on the other hand, fibrous foods such as raw fruits, and vegetables have a short oral clearance time and exert a natural cleansing activity by promoting the flow of saliva as they are chewed. Apart from major meals, sugar snacks consumed in between the meals remaining longer time in the mouth. These snacks are devoid of mechanical action of chewing which serve to clean the teeth, liquids taken may help to wash sticky carbohydrate, away from teeth or brushing is the best way after the snacks. However the caries potential depends upon the type and amount of carbohydrate, frequency, pattern of use of foods rate of clearance of mouth and acid buffering action of the food.

Preventive Measures:

a. Fluoride to strengthen the tooth enamel. Frequent delivery of fluoride to the tooth surface with dentifrice, drinking water and mouth rinses is highly effective in controlling caries.

b. Oral hygiene measures such as brushing or flossing of teeth immediately after every meal or with snack helps to prevent dental caries.

c. Dietary measures to decrease the frequency of ingestion of cariogenic foods.

d. All sugars, not only Sucrose, are potentially cariogenic; cooked starch is also potentially cariogenic.

Dr S Bakhtiar Choudhary; Hyderabad Spine Clinics