Introduction

Dental caries / cavities or tooth decay is breakdown in the continuity of enamel due to acid attack produced by the bacteria leading to tooth discoloration and formation of cavities. Decayed lesions should be immediately restored as their presence increase the bacterial count in mouth which in turn can lead to occurrence of new decayed lesions or progression of existing lesions to involve nerves of teeth and formation of abscess thus causing a painful condition requiring more extensive and expensive treatment planning and at times even leading to tooth loss.

Types of dental caries

Caries can be seen involving any tooth surface and thus can be named accordingly -

• Pit and fissure caries - Occurs on pits and fissures of teeth.
• Smooth surface caries - Occurs on smooth surfaces [labial or proximal surfaces] of teeth.
• Root caries - Caries involving cementum or cemento-enamel junction. This occurs predominantly in older age when there is a gingival recession.

According to severity and progress of lesion, caries can be -

• Incipient caries - Appears as white opaque region due to subsurface demineralization of enamel.
• Arrested caries - Carious lesion may stop progressing and becomes arrested if healthy oral environmental conditions are established following proper oral hygiene techniques.
• Recurrent caries - It occurs at the interface of tooth and restorative material due incomplete caries removal or poor adaption of restoration leading to micro leakage.
• Rampant caries - It is acute and widespread caries with rapid pulpal involvement of teeth which are usually immune to decay.
• Radiation caries - Decreased salivary secretion is frequently seen in patients undergoing radiation therapy. Rampant form of caries is seen in such cases due to decrease flushing of food debris by reduced saliva production.

Reasons why caries develop

Poor oral hygiene is the most common cause for caries. Plaque present on tooth surfaces acts as a habitat for bacteria which decomposes sugar mainly sucrose present in food and converts it to acid which then attacks the tooth surface causing surface demineralization thus leading to cavitations. Some important factors responsible are -

• Bacteria involved - There occurs a wide variety of bacteria in oral cavity but Streptococcus Mutans is mainly responsible for caries initiation and Lactobacilli for its progression.
• Acids - Acids are generally produced when sugars in food or drink reacts with the bacteria present on the surface of the tooth. Production of acid causes the loss of calcium and phosphate from the tooth surface resulting in demineralization.
• Saliva - Apart from having a cleansing action over food debris saliva results in dilution and neutralization of the acid produced thereby decreasing the time for which tooth is exposed to demineralization. Thus in cases where there is reduced saliva production widespread caries can be observed.
• Diet - Physical and chemical form of diet directly affects the caries development and progression. Too frequent intake or ingestion of lots of sticky and sweet food results in oral environment to stay acidic for longer duration thus increasing the risk of caries development.
• Bad oral hygiene - Poor oral hygiene results in more habitants of bacteria which act on food debris resulting greater caries incidence.
• Time - With food intake, the pH of the oral cavity drops and at pH of 5.5 [critical pH] tooth demineralization starts. More is the time period for which pH remains below 5.5, more will be the demineralization. It takes about 20 minutes for the pH to come back to neutral value, but if another meal is taken before this time period then it will increase the duration of acid exposure further. Therefore too frequent eating should be avoided.

Signs and symptoms

Caries lesions can go unnoticed until cavitation develops and in cases where there occurs proximal involvement the condition may even progress to pulpal tissue without noticing by the patient. Therefore regular oral hygiene check-up by the dentist is recommended to rule out the hidden lesion.

• Early tooth decay may have no symptoms except that the tooth surface may give frosty white appearance on drying.
• Area of demineralization may progress with change of tooth colour to yellow, brown to black.
• When the decay has progressed deeper in the enamel there occurs a break in continuity of surface leading to formation of cavity. Sometimes only a small hole is seen on the tooth surface but the caries progression can be very fast leading to wide destruction of underlying enamel and dentine as seen in case of pit and fissure caries.
• The teeth may now become sensitive to sweet foods or to hot and cold temperatures.
• Later, when the decay reaches the pulp it may manifests as acute pain and swelling.
• If left untreated then it may even lead to tooth fracture due to extensive loss of tooth structure and vitality.

Diagnosis of caries

If caries is diagnosed in earlier stages, it can be remineralised thus saving extensive treatment options as well as financial burden of the patient. Wide range of diagnostic aids are available these days with the evolving modern dentistry.

• Visual examination - Thorough visual examination under proper illuminated area is the first and foremost step for diagnoses of white spots, discoloration or frank cavitations. It can be further aided by magnification loupes and tactile examination.
• Tactile examination - Blunt probe should be used with tactile expertization to feel the catch caused by enamel surface breakdown. Sharp probe should be avoided as it can cause cavitations in initial caries lesions which are capable of self remineralisation.
• Radiographs - Hidden carious lesions which cannot be determined by clinical examination can be diagnosed with help of radiographs. Intraoral periapical radiographs are most commonly used. In case of children bitewing radiographs are usually preferred as they reveal the proximal lesions also.
• Dyes - Various kinds of dyes are available which can differentiate between active and arrested lesions.
• Newer methods - Recently many newer methods such as Laser auto fluorescence, Fiber optic transillumination, Digital imaging fiberoptic transillumination, Ultraviolet illumination etc. are available which can easily diagnose the hidden as well as initial caries.

Prevention of caries occurrence

To have caries free oral cavity is not difficult. By adopting sudden easy changes in our lifestyle we can save us from social, financial and painful troubles caused by caries. Here are some of the steps which can be easily followed.

1. Maintenance of good oral hygiene - Maintaining good oral hygiene to reduce the bacterial count is the most beneficial way to prevent caries. It can be gained by-
   1. Using proper brushing and flossing technique to remove the plaque and disrupt the bacterial colonization and use of mouthwashes which neutralizes the acid produced thus decreasing the chance of demineralization of enamel and initiation of decay. Brushing teeth at least twice a day especially at night before sleeping and flossing once a day is recommended on regular basis.
   2. Rinsing mouth with plain water after every meal as it helps in clearing the residual food debris from oral cavity and also dilutes the acid produced.
   3. Eating sugar free gums after meals especially when brushing cannot be worked upon, as during office hours or when out from home, as it helps in removal of sticky food and also increases the saliva production.
2. Good eating habits - Avoid eating between meal snacks as it increases the time for which oral environment is acidic thus endangering the enamel. Sticky snacks, candies and sugary drinks can be limited with meals to decrease the number and duration of acid attacks by frequent intake.
3. Food substitutes - Fibrous and non sticky food consumption should be encouraged as it keeps the tooth surfaces clean.
4. Fluorides - Using topical fluoride applications which can be helpful in self remineralisation of initial caries lesions and prevent development of new lesions by slowing down the process of demineralization. Use of fluoridated toothpaste could maintain a constant level of fluoride in mouth.
5. Pit and fissure sealants - They keeps the tooth surface clean by sealing the susceptible tooth surfaces such as fissures which harbours the plaque and bacteria especially in young children.
6. Scaling - Regular scaling helps to remove calculus and plaque which harbours the bacteria. It can thus prevent the occurrence of caries and also keeps the gums healthy.
7. Caries vaccine - As dental caries is caused by S.mutans so the best approach that could influence the pathogen in oral cavity can be by vaccination. Evidences showing topical application of antibody reduces bacterial colonization has also been recorded. Administration of S.mutans vaccine leads to accelerated clearance of bacteria from the human’s mouth.

Management of caries

Once the caries is initiated, its treatment becomes necessary. Earlier management can protect the tooth from further damage, which can even lead to tooth loss.

• Remineralization – White spot lesions [initial caries lesions] can be reversed with remineralization process by using topical fluorides and maintaining good oral hygiene.
• Restoration - Decayed tooth portion is removed and restored with various restorative materials such as amalgam, glass ionomer cements, ceramics and composite. With the advancement in esthetic dentistry a wide range of tooth colour materials such as composites is now available which can be used to build up the lost tooth structure to resemble the natural tooth.
• Crowns - Crowns are the caps used to cover the tooth when there is extensive loss of tooth structure. The tooth which becomes weak and is prone to fracture is then strengthen using crowns which can be made of different materials such as porcelain, gold or porcelain fused metal.
• Root canal treatment - If decayed tooth is not restored timely then decay progresses to involve the nerves leading to pain and swelling which then requires root canal treatment involving removal of the dental pulp and restoring it with biocompatible sealing material.
• Extraction - If a tooth cannot be saved even by root canal treatment then it should be extracted and replaced by artificial one.

Conclusion

Caries is most common diseases next to common cold affecting large number of people around the globe but by incorporating few changes in daily routine can act as a speed breaker controlling the progression of caries and help us to live a healthy life with a healthy oral hygiene.

References

1. A Sheiham, W.P.T. James. Diet and dental caries. The pivotal role of free sugars reemphasized. JDR 20015.
2. Declerck D,Leroy R et al. Exploring the contributions of components of caries risk assessment guidelines. Community Dent Oral Epidemiol. 36(4): 357-62:2007.
3. Ernest Newburn. Cariology. 3^rd edition. Quintessence publishing.
4. Featherstone JDB. Topical effects of fluoride in the reversal and prevention of dental decay. Journal of public health dentistry. 64(1):32-4:2004.
5. Featherstone JDB. The continuum of dental caries- evidence for a dynamic disease process. Journal of dental research. 83(1)39-42:2004.
6. H Kalsbeek and G. H. Verrips. Consumption of sweet snacks and caries experience of primary school children. Caries research.28:6:477-83,1994.
7. Weyant RJ, Manz M et al. Factors associated with parents and adolescents perceptions of oral health and need for dental treatment. Community Dent Oral Epidemiol. 35(5):321-30:2007.