Dental Caries

It is one of the most common infectious diseases affecting the human race

Dental caries ia a microbial disease of the calcified tissues of the teeth, characterised by dimineralisation of the inorganic portion & destruction of the organic substance of the tooth. Two groups of bacteria are responsible for initiating caries Streptococcus mutans and Lactobacillus.If left untreated, the disease can lead to pain, tooth loss and infection.Cariology is the study of dental caries.
The presentation of caries is highly variable; however, the risk factors and stages of development are similar. Initially, it may appear as a small chalky area that may eventually develop into a large cavitation. Sometimes caries may be directly visible, however other methods of detection such as radiographs are used for less visible areas of teeth and to judge the extent of destruction. Lasers for detecting caries allow detection without radiation and now are being used for detection of interproximal decay (between the teeth). Disclosing solutions are also available that are used during tooth restoration to minimize the chance of the recurrence.
Tooth decay is caused by specific types of acid-producing bacteria that cause damage in the presence of fermentable carbohydrates such as sucrose, fructose, and glucose.
he mineral content of teeth is sensitive to increases in acidity from the production of lactic acid. To be specific, a tooth (which is primarily mineral in content) is in a constant state of back-and-forth demineralization and remineralization between the tooth and surrounding saliva. For people with little saliva, there also exists remineralization gel, especially due to radiation therapies that may destroy the salivary glands. These patients are particularly susceptible to dental caries. When the pH at the surface of the tooth drops below 5.5, demineralization proceeds faster than remineralization (meaning that there is a net loss of mineral structure on the tooth's surface). Most foods are in this acidic range and without remineralization, this results in the ensuing decay. Depending on the extent of tooth destruction, various treatments can be used to restore teeth to proper form, function, and aesthetics, but there is no known method to regenerate large amounts of tooth structure, though stem cell related research suggests one possibility. Instead, dental health organizations advocate preventive and prophylactic measures, such as regular oral hygiene and dietary modifications, to avoid dental caries.

Etiology

1. Dietary factor- Carbohydrates with types like monosaccharides, disaccharides or poly saccharides &amount consumed.
2. Microorganisms- acidogenic strptococcus mutans & Actinomycosis
3. Systemic factors- Herediatary, pregnency & lactation factors
4. Host factor- Poor oral hygiene, improper brushing technique
5. Immunological factor- The functional role of circulating antibiotics as protective agents against tooth decay has been demonstrated in non-human primates

Pathogenesis

 

1. Whenever carbohydrate is consumed, oral micro-organisms rapidly begin fermentation producing organic acids like lactic acids , acetic acid & formic acid. this leads to fall in pH of the oral fluids
2. these organic acids attack the tooth structure, resulting in loss of tooth minerals specially calcium & phosphate ions, which leach out from hydroxyapatite. this process is known as demineralization
3. After a period of 30 mins, due to salivary buffering by bicarbonate ions & ammonia production from salivary proteins, there is am increase in pH of the oral fluids. the acid is neutralised & the condition now favours precipitation of calcium & phosphate ions in to tooth surface. this process is called as re mineralisation & is hastened if fluoride is present in a small amount in either plaque fluid or saliva
4. the miocroorganism which is of primary concern in the pathology of dental caries is Streptococcus mutants. it forms soluble, sticky extracellular polysaccharides which help in further colonization & increases the contacy of the acids which ultimately leads to cavitation.
5. The balance between the caries causing & caries protective factors is very delicate. it is only when repeated attacks of demineralisation occur that there is a net loss of minerals from the tooth & caries result. the surface layer of enamel overlying the lesion remains intact & the demineralisation occurs primarily sub surface location. once this happens the process gradually extends deeper, involving enamel & subsequently the dentin & pulp

First classification

based on location of the lesion

 

pit & fissuer caries

• occlusal
• buccal or lingual pit

smooth surface caries-

• proximal
• buccal or lingual surface

root caries

based on tissue involved:

 

1. enamel caries
2. dental caries
3. cemental caries

based on virginity of the lesion

 

• primary caries
• secondary caries

based on progression of lesion:

 

progressive caries-

• rapidly progressive like nursing caries & radiation caries
• slowly progressive

arrested caries

2nd classification

Mount GJ in 1997 classified dental caries based on site and size

 

site & size

Site:

Site 1- include lesion on the pit & fissure of the posterior teeth on other surfaces, these include the buccal grooves on the mandibular molars, palatal grooves of the maxilarry molars & erosion lesion on the incisal edges.
Site 2- includes lesions in the contact areas of posterior and anterior teeth.

Site 3- includes lesions originating in the gingival third of all teeth.

Size:

Size 1( mild)- includes lesions which have progressed just beyond remineralization

Size 2 ( moderate)- includes larger lesions with adequate tooth surface to support the restoration.

Size 3(enlarged)-includes lesions in which the tooth structure and the restoration are susceptible to fracture.

Size 4 (severe)- includes lesions which have destroyed a major portion of the tooth structure.

Diagnosis of dental caries

Clinical method

 

• Use of sharp explorer- if slight pull is required to remove the explorer from the tooth surface. i.e if there isa catch then the surface is counted as being decayed
• Use of mirror & probe- this is the most common method
• A mirror & blunt probe visual examination

Radiographic method

Bite wing radiography is used. Dental radiographs, produced when X-rays are passed through the jaw and picked up on film or digital sensor, may show dental caries before it is otherwise visible, particularly in the case of caries on interproximal (between the teeth) surfaces. Large dental caries are often apparent to the naked eye, but smaller lesions can be difficult to identify

Fiberoptic transillumination

a shadow visible in dentin has been suggested as the criteria. It does not detect small lesions.
it does not detect small lesions

Digital Fiberoptic transillumination

this is relatively new methodology.Illumination is delivered on the tooth surface by means of fiberoptic which acts as a light source. the resultant change in light distribution is captured by the camera & is sent to the computer for analysis

Electrical conductance measurement

 

Theory behing this is that sound surface should possess limited or no conductivity, where as carious or deminralized enamel should have a measurable conductivity that will increase with increasing demineralization.
Indicator:
Green- no caries
Yellow-enamel caries
Orange-dentin caries
Red-pulpal involvement

Visible luminescent spectroscopy

The visible emission spectra for decayed & non decayed regions of teeth differ. Quasi monochromic light from a tungsten source dispersed with a grating monochromatic is focused on the teeth & emission spectra are recorded & analyzed

disclosing dye

disclosing dyes have been recommended for uVarious dyes such as silver nitrate, methyl red & alizarin stains have been used to detect carious sites by change of colour.se as an adjunct when diagnosing smaller carious lesions in pits and fissures of teeth

Control of dental caries

Control of all active lesions

• Initial treatment of all active lesions.
• Gross excavation of all carious lesions followed by systemic manner of restoring a tooth to normal contour

Nutritional measures for caries control

• Diet high in fat, low in carbohydrate & practically free from sugar have low caries activity.
• In a study, when refined sugar was added to the diet in the form of a mealtime supplement there was little or no caries activity
• Phosphates diet causes significant reduction in incidence of caries.

Mechanical measures for caries control

Tooth Brushing

 

tooth brush removes gross amount of food debris & plaque material.

Mouth Rinsing

it helps in loosening food debris from the teeth.

Dental floss

it helps to remove plaque from an area gingival to the contact areas on proximal surfaces of teeth, an area impossible to reach with toothbrush

Detergent

Fibrous food prevents lodging of food and act as detergent

pit & fissure sealants

 

Chemical measures of caries control

Substances which alter the tooth structure or tooth surface

 

Fluorine

• The cariostatic activity of fluoride involves several different mechanisms.The ingestion of fluoride results in its incorporation into the dentin & enamel of unerupted teeth.This makes the teeth more resistant to acid attack after eruption into oral cavity.
• Ingested fluoride is secreted in to saliva, although present in low concentration in saliva, the fluoride is accumulated in plaque where it decreases microbial acid production & enhances the remineralisation of the underlying enamel. Fluride from saliva is also incorporated in to the enamel of newly erupted teeth, thereby enhancing the enamel calcification

Bis-biguanides

chlorhexidine & alexidine are potential anti caries agent as they are anti plaque agent

Zinc chloride & potassium ferrocynide

it effectively impregnate the enamel & seal off caries invasion pathway

Silver nitrate

Silver plugs the enamel by either the organic invasion pathways such as enamel lamellae or the inorganic portion to form a less soluble combination

Substances which interfere with carbohydrate degradation through enzymatic alteration

1. vitamin k
2. sarcoside

Subsatnces which interfere with bacterial growth & metabolism

1. Urea & ammonium compounds
2. chlorophyll
3. Nitrofurans
4. penicillin