DENTAL CARIES - A Study

DENTAL CARIES

INTRODUCTION:

          Dental  caries and periodontal diseases are probably the most common chronic  diseases in the world. Although caries has affected humans since prehistorical times, the prevalence of this disease has greatly increased in modern times. There  is now evidence this trend  peaked and began to decline in the last decade. This is attributed to the wide range of caries preventive measures like increased use of florides, increased oral hygiene awareness, increased parental care and improvement in preventive dentistry.

          The cost of caries to society is enormous. The total indirect costs like loss of time from work and training dentists outweigh the direct costs. In addition caries results in other significant although intangible costs in the form of pain, suffering and cosmetic defects.

          Considering the magnitude and almost universal impact of caries, it is remarkable that a public  supported program for the eradication of the disease never developed as did programs against polio and cancer. Inspite of the tremendous benefits of fluoridation of public water supplies, the time is appropriate for such a comprehensive program, since it now appears that eradication of caries of caries is an achievable goal.

          Caries research is by no means complete but the etiology and pathogenesis are sufficiently well understood that caries can be totally prevented in motivated persons.

DEFINITIONS OF DENTAL CARIES

          The word caries is derived from Latin, meaning ‘rot’ or ‘decay’. It is similar to Greek word ‘ker’ meaning death.

1. Dental caries is an infectious microbiological disease that results in localized dissolution and destruction of the calcified tissues of the teeth. (Purkit).
2. Dental caries can be defined as a localized post eruptive pathologic process of external origin involving the destruction of hard tooth tissue, which if continued results in the formation of a cavity.  (Norman H. Harris)
3. Dental caries is a multifactorial disease requiring the presence of  a susceptible host, cariogenic microflora and a diet conducive to enamel demineralization. (Soben Peter)
4. Dental caries is defined as a progressive, irreversible, microbial disease affecting the hard parts of the tooth exposed to the oral environment, resulting in dimeneralization of the inorganic constituents, dissolution of the organic constituents, thereby leading to a cavity formation. (Soben Peter)

CLASSIFICATION OF DENTAL CARIES

A. Black’s Claffication

Class 1 :

• Cavities on the occlusal surfaces of premolars and molars
• Cavities on the occlusal 2/3rds of the facial and lingual surfaces of molars
• Cavities on the lingual surfaces of maxillary incisors

Class 11:

• Cavities on the proximal surfaces of posterior teeth

Class 111:

• Cavities on the proximal surfaces of anterior teeth that do not involve the incisal angle.

Class IV:

• Cavities on the proximal surfaces of anterior teeth that do involve the incisal edge.

Class V:

• Cavities on the gingival third of the facial or lingual surface of all teeth.

Class VI:

• Cavities on the incisal edge of the anterior teeth or occlusal cusp heights of posterior teeth.

B[1]: According to location on individual teeth

1. Pit and fissure caries
2. Smooth surface caries

B[2]: According to the rapidity of the process

1. Acute dental caries
2. Chronic dental caries

B[3]: Depending on the origin

1. Primary caries
2. Secondary Caries
3. Residual caries

B[4]: Depending on extent of lesion

1. Incipient (reversible) caries
2. Cavitated caries

B[5]: Depending on the tissue involved

1. Enamel caries
2. Dentine caries
3. Cemental caries (root caries)

B[6]: Depending on the patient’s age

1. Nursing bottle caries
2. Senile caries

HISTORICAL ASPECT

          Dental caries may be considered a disease of modern civilization, since prehistoric man rarely suffered from this form of tooth destruction. Anthropologic studies of VON LENHOSSEK revealed that the dolicocephalic skulls of men from preneolithic periods (12,000 BC) did not exhibit dental caries, but skulls from Brachycephlic man of the Neolithic periods (12,000 – 3000 BC) contained carious teeth. The cervical areas of  teeth in older persons were frequently affected.

EARLY THEORIES OF CARIES FORMATION

1.     The legend of the worm

2.     Endogenous theories

a.      Humoral theory

b.     Vital theory

3.     Exogenous theories

a.      Chemical (Acid) theory

b.     Parasitic (Septic) theory

4.     Miller’s chemicoparasitic theory (acidogenic theory)

5.     Proteolysis theory

6.     Proteolysis chelation theory

PRESENT SCENARIO

Etiologic factors in Dental Caries

1. Host Factors

A. Tooth

          Not all teeth or tooth surfaces are equally susceptible to caries, nor is the rate of progression of all carious lesions are constant. Factors influencing the site of attack and the rate of caries in relation to a tooth depend upon the following factors:

Composition of Tooth:

• If the solubility of the surface enamel is higher the chance of caries formation is more.
• Increased permeability of the enamel surface increases the possibility of caries development and it can be seen in case of a tooth having hypoplastic enamel.

Morphology:

          Presence of deep, narrow and retentive pits and fissures on the tooth surface may contribute to a higher caries incidence, as they tend to trap food, bacteria and debris.

Position:

          The malaligned, rotated or out of position teeth in the dental arch are attacked by caries more frequently as there is more possibility of plaque accumulation in these regions and more over these teeth are difficult to keep clean.

B. Saliva:

          The saliva factor play a very important role in the prevention of dental caries.

          Flow Rate à when the salivary flow rate is decreased, the caries incidence becomes higher as saliva causes cleaning of the bacteria from the tooth surface by its flushing action.

Viscocity:

          When viscocity of saliva is increased, there will be more and more deposition of plaque on the tooth surface since the thick saliva fails to produce adequate cleaning action.

Buffering Capacity:

          High concentrations of salivary bicarbonate  ions cause neutralization of acids produced by the cariogenic bacteria by their buffering action and this results in a decrease in rate of tooth decay.

C. Sex :

          Most of the studies have shown that dental caries is more common in females.

D. Race:

          Dental caries is more in whites compared to blacks.

E. Age:

          It is more commonly seen in childhood. Over 60 years of age root caries is seen which is mainly due to gingival recession.

F. Familiar Heredity:

          Inheritance of a characteristics tooth structure has lesser influence than environmental factors.

G. Developmental Disturbances:

          The presence of deep pits and fissures, enamel hypoplasia and enamel defects make the tooth more prone to dental caries.

H. Economic Status:

          In young primary school children dental cares decreases with increase in income. Among adults as income decreases there is a decrease in dental caries.

I. Oral Hygiene Habits:

          Dental caries is found to be less among those who maintain good oral hygiene.

II. Agent Factors (Microflora)

          Consists of dental plaque forming streptococci role of micro organism in caries:

• Microorganisms are  prerequisite for caries initiation
• The ability to produce acid is a pre requisite for caries induction, but not all acidogenic organisms are cariogenic
• Streptococcus strains that are capable of inducing caries are also able to synthesize extra cellular dextrans or levans.

Properties of Cariogenic Plaque:

• The rate of sucrose consumption was higher
• Synthesize more intra cellular polysaccharides
• Higher levels of streptococcus mutans
• More lactic acid is produced

III. Environmental Factor

Diet Factor

Physical nature of diet: If the diet contains sufficient amounts  of fibrous foods  that help to keep the teeth clean as well as simulates the salivary flow, then the chances of caries formation will be less, whereas more and more intake of soft and sticky foods increase the possibility of caries development.

Composition of Diet:

• Presence of phosphates and fats can reduce the incidence of caries
• Traces of molybdenum and vanadium in the diet may reduce caries

Role of Acids:

• Following the ingestion of fermentable carbohydrates a variety of acids are produced namely the lactic acid, butyric acid, acetic acid, aspartic acid
• Metabolism of carbohydrates by streptococcus mutans produce organic acids, which results in a highly localized drop in PH at ‘plaque tooth interface’
• A drop in local PH below 5.5 causes demineralization of tooth surfaces

Geographic Variations:

          DMFT is found to be decreasing in developed countries, and increasing in developing countries.  The use of fluorides, oral hygiene practice and diet play a major role as a cause for this difference.

Soil:

          Selenium is found to increase dental caries whereas molybdenum and vanadium are said to decrease dental caries.

Urbanization:

          Dental caries is said to increase with urbanization.

Climate:

          Sunlight is said to decrease caries whereas rainfall is said to increase dental caries.

The Carious Process

Enamel Caries: It consist of 4 zones

Zone 1: Translucent zone

Zone 2: Dark zone

Zone 3: Body of the lesion.

Zone 4: Surface zone

Dental Caries: It consists of 5 zones

Zone 1: Normal Dentin

Zone 2: Subtransparent Dentin

Zone 3: Transparent Dentin

Zone 4: Turbid Dentin

Zone 5: Infected Dentin

Root Caries:

          These are the carious lesions, which involve the cemental wall of the exposed root surfaces of teeth.

Clinical types of Caries:

1.           Pit and fissure caries : This type of caries occurs in the developmental pits and fissures of the teeth which include occlusal surfaces of molars and premolars, buccd and lingual surfaces of molars and lingual surfaces of maxillary incisors.

2.           Smooth surface caries: This type of carious lesion occurs in relation to the smooth surfaces of teeth. They occur mostly in the proximal surfaces of the teeth just below the contact point.

3.           Rampant Caries: This is an acute fulminating type of carious process, which is characterized by simultaneous involvement of multiple number of teeth in multiple surfaces.

4.           Nursing Bottle Caries: This is another type of acute carious lesion which occurs among those children who take milk or fruit juices by the nursing bottle, for a considering longer duration of time, preferably during sleep.

5.           Arrested Caries

6.           Recurrent Caries

7.           Forward Caries

8.           Radiation Carries

Caries Activity Tests:

          A number of caries activity tests have been evolved to help detect the presence of oral conditions  associated with increased risk of caries.

Synder Test:

          Synder test measure the ability of salivary microorganisms to produce organic acids from a carbohydrate medium. Glucose – agar media containing an indicator dye is used for this test. The indicator dye changes from green to yellow in the range of PH between 5.4 to  3.8 paraffin stimulated saliva (0.2ml) is added into the medium, change of the medium from green to yellow is indicative of the degrees of caries activity.

Salivary Reductase Test:

          It measures the activity of the reductase enzymes present in salivary bacteria.

Salivary Buffering Capacity Test:

          It is a chair side test to measure the buffering capacity of the saliva.

Microbiological Test:

          It helps to measure the number of streptococcus mutans and lactobacillus acidophilus per microliter of saliva.

Levels of Prevention

Primary Prevention:

1.     Diet planning

2.     Periodic visits to dentists

3.     Appropriate use of fluoride, ingestion of fluoridated water, use of fluoride dentrifices

4.     Oral hygiene practices

Community Level:

1. Dental teeth education programs
2. Community or school water fluoridation
3. Flouride mouth rinse, tablet and sedant programs

Professional Level:

1. Patient education
2. Diet counseling
3. Topical application of flourides
4. Flouride supplements and rinses
5. Pit and fissure sealants

Secondary Prevention

Individual Level:

1. Self examination & referral
2. Use of dental services

Community Level:

1. Periodic screening and referral
2. Provision of dental services

Professional Level:

1. Complete examination
2. Prompt treatment of incipient lesions
3. Preventive resin restoration
4. Simple restorative dentistry
5. Pulp capping

Tertiery Prevention

Disability Limitation:

1. Complex restorative dentistry
2. Pulpotomy
3. Root canal therapy
4. Extractions

Rehabilitation:

1. Removable and fixed prosthodontics
2. Minor  tooth movements
3. Implants

Future Trends in Dental Caries

          New knowledge is molecular and cellular biology, genetics,  pharmacology, radiation biology, radiation physics and technology, including  tomography, dental materials based on polymer  chemistry and ion exchange,  microbiology, immunology and behavioural  science are all relevant to the understanding and clinical management of dental problems.

          De paola further states, “In terms of future scientific achievement, it is not difficult to predict starting new advances due to the application  of recombinant DNA technology, the applicant of space age technology, and the general advancement of scientific methodology.  Advances in these area scan have direct impact  on dental practice through the development of new treatments and preventive modes, new biomaterials applicable to dental practice, and more sophisticated techniques to measure the health status of individuals.

          The use of lasers may become a mechanisms for welding dental alloys and may even be used in the future in cavity preparation.

          In the near future a method to adhesively bond composite materials to dentin is expected. Such a development could have dramatic effects resulting in minimal tooth preparation.

         

          The remineralization of a tooth surface affected by a beginning carious lesion  may not only decrease the need for restorative care but also result in a tooth surface that will be more resistant to subsequent  attacks. The development of appropriate fluoride applications and techniques to produce this remineralization appears to be a reality in the near future.

          Efforts are also being made to develop an anti caries vaccine which is still in the experimental stages.

Caries Vaccine:

          There exists the possibility of preventing dental caries by stimulating the defense mechanisms of the mouth. Once it was established that caries was an infectious disease, it was realized that caries might be controlled by use of a vaccine.

          The currently favoured targets for such a vaccine are :

1. Glucosyl Transferase enzyme (GTF) from S. Mutans or
2. A yet to be selected wall fraction of S. Mutans

          Protection against dental caries by immunization  could be achieved by immune components from serum by IgA antibodies in salivary secretions or by a combined effect of serum and salivary components.

          Parenteral immunization  directed to S. Mutans could favour the early establishment of a non-cariogenic microflora on the teeth which in turn could prevent or delay the colonization of pathogenic S. mutans and thereby reduction in dental caries.

CONCLUSION

          Prevention and control of dental caries must be the foremost objectives of dentistry. Preventive measures for caries should not be applied to all patients. Only caries active patients and those at high risk who will most likely benefit from preventive measures should be treated.

          Caries activity should be viewed as a problem of oral ecology in which there is an abnormal abundance of cariogenic organisms. Preventive treatment is based on reducing the pathogen population size and increasing the resistance of the tooth to cariogenic attack.

          Research efforts in understanding of the carious process, maximizing the benefits of fluoride use, and developing anticaries, vaccines must be continued. Patient education  and motivation in the prevention of dental caries must be stressed.  Finally, the clinical expeditiously and judiciously.

SUMMARY

          Caries in an infectious disease of microbial origin. Numerous cross sectional and longitudinal surveys have found a strong association between dental caries and the levels of mutans streptococci in dental plaque. This association is stronger for pit and fissure caries.

          The properties of cariogenic bacteria that appear to correlate with their pathogenicity are their ability to rapidly metabolize dietary carbohydrates to acid over a range of environmental conditions, but especially at low PH, and to be able to survive and grow under acidic conditions so generated.

          Strategies to control or prevent dental caries are based on

1. Reducing levels of plaque
2. Using fluoride to strengthen the resistance of enamel to acid attack and
3. Inhibiting acid production by avoiding the frequent intake of fermentable carbohydrates.

          In practice, the early identification and expeditious treatment of caries greatly minimizes the loss of teeth. When such routine diagnostic and treatment services are linked with a dynamic preventive dentistry program, there is a realistic expectation that the loss of teeth can be reduced to zero or near zero.

REFERENCES

1. Soben Peter  - Essential of Preventive and Community Dentistry
2. Shaffers and Purkit – Textbook of Oral Pathology
3. Philip Marsh – Textbook of Oral Microbiology
4. Norman Harris – Primary Preventive Dentistry
5. Sturdevant – Textbook of Operative Dentistry