DENTAL CARIES
INTRODUCTIONDental caries is defined as a progressive irreversible microbial disease affecting the hard parts of tooth exposed to the oral environment, resulting in demineralization of the inorganic constituents and dissolution of the organic constituent, thereby leading to a cavity formation. Caries is one of the most common of all diseases and still a major cause of loss of teeth.
It is covered by plaque, which consists mainly of bacteria. Plaque is often found close to the gum, in between teeth, in fissures and at other "hidden" sites.
Demineralization: When sugar and other fermentable carbohydrates reach the bacteria, they form acids which start to dissolve the enamel - an early caries lesion occurs due to loss of Calcium and Phosphates
Remineralization: When sugar consumption has ceased, saliva can wash away sugars and buffer the acids. Calcium and Phosphates can again enter the tooth. The process is strongly facilitated by fluorides
A CAVITY occurs if the Demineralization "wins" over the Remineralization over time
The first indication of tooth decay are white spots on the enamel caused by the loss of calcium.
causing a consistent tooth pain, especially during the night.
The bacteria may also produce an abscess,and eventually the tooth may be extracted by the dentist.
A tooth surface without caries. The first signs of demineralization. The enamel surface has broken down. A filling has been made but the demineralization has not been stopped. The demineralization proceeds and undermines the tooth. The tooth has fractured.
Pathophysiology of dental caries is explained with the help of some theories 1. Acidogenic theory 2. Proteolytic theory
Acidogenic theory it proposed that acid formed due to fermentation of dietary carbohydrat by oral bacteria leads to progressive decalcefication of the tooth structure the final result is loss of integrity of tooth structure with formation of cavity.
According to this theory there are four important factor influence in the process of dental caries 1. dietary carbohydrates 2. micro organism 3. acid 4. dental plaque
Role of carbohydrates fermentable carbohydrates play important role in formed dental caries ,types include glucose,sucrose,and fructose among them sucrose the most potent one .sugar fermented by cariogenic bacteria to produce acid cause dissolution of hydroxyapatite crystalis of the enamel then dentin.
Role of micro organism: the most important type of micro organism is Streptococcus like S. Mutans S. salivarius , S. milleri and peptostreptococcus Actinomycotic Israelii produce root caries.
Role of acid: metabolism of carbohydrates by the cariogenic bacteria produces organic acid in ph below 5.5 causes demineralization of tooth surface.
Role of plaque: plaque helps initiation of dental caries by the following way. 1.it harbors the cariogrenic bacteria on the tooth surface. 2. it holds the acids on the tooth surface for long duration . 3. it protect acide produced by the bacteria .
Figure shows an illustration of dental plaque at the gingival margin.
Proteolytic theory : the proteolytic enzymes liberated by cariogenic bacteria cause destruction of organic matrix of enamel so the organic crystals of the enamel become detached from one another leading to cavity formation.
Contributing factor of dental caries A. intrinsic factor :tooth factor not all tooth surfaces are equally susceptible to caries there are many factors influence the rate of caries include composition of tooth if enamel surface is highly mineralized due to presence of ca, flouride, in higher concentration the chance of dental caries become less
Morphology: prescence of deep ,narrow,and retentive pit and fissures on the tooth surface may contribute to higher caries incidence Position malaligned, rotated or out of position teeth in the dental arch more susceptible to plaque accumulation and more susceptibility to caries formation
B. Extrinsic factors : saliva , diet, systemic and immunity saliva factor the saliva factor play a very important role to prevent of dental caries . flow rate if the flow rate is adequate it causes cleaning of the bacteria from the tooth surface so the chance of caries will decrease but if salivary flow rate is decreased the caries incidence becomes high. viscosity when viscosity of saliva becomes high more plaque deposition on the tooth surface.
Salivary antibodies salivary immunoglobulin inhibit the cariogenic bacteria by destruction process through phagocytosis reduced possibility of caries. remineralization of damaged tooth surface calcium and phosphate ions present in saliva help in partial repair of tooth caries. direct antibacterial action like lysozyme,lactoferin.
Diet factor: physical nature of diet if diet contains sufficient amount of fibrous foods help to keep tooth clean ,incidence of caries rate is less . While soft and sticky diet increases the possibility of caries composition of diet like vitamins associated with low caries systemic factor : like hereditary immunity: associated with formation of serum and salivary antibodies.
Clinical aspects of dental caries: clinical type:PIT AND FISSURE CARIES:Pits and fissures with high steep walls & narrow base retention of food debris, micro organisms fermentation acid productionCaries appear brown/ black, feel softEnamel bordering opaque bluish whiteLarge carious lesion with a tiny point of opening
INCIPIENT CARIESThe early caries lesion, best seen on the smooth surface of teeth, is visible as a ‘white spot’.Histologically the lesion has an apparently intact surface layer overlying subsurface demineralization.Significantly may such lesion can undergo remineralization and thus the lesion is not an indication for restorative treatment.Also on wetting the caries lesion disappear while the developemental defect persist.
Incipient caries SMOOTH SURFACE CARIESPreceded by formation of microbial/ dental plaqueBegins just below contact point and appear in early stages as white opacity of enamel (chalky spot) slightly roughened surrounding enamel bluish white as caries penetrate enamel
Smooth surface caries
Less favorable site for plaque attachment, usually attaches on the smooth surface that are near the gingiva or are under proximal contact..ACUTE DENTAL CARIESRapid clinical course & early pulp involvementProcess rapid little time for deposition of sec. dentin. Dentin stained a light yellowRampant caries.Nursing bottle caries (absence of caries in mandibular incisors distinguished from ordinary rampant caries).
ACUTE CARIES
These lesions are lighter colored than the other types, being light brown or greyPulp exposures and sensitive teeth are often observed in patients with acute caries.Process rapid …little for deposition of secondary dentin .dentin stained alight yellow.RAMPANT CARIES Acute fulminating type of carious process, characterized by simultaneous involvement of multiple number of teeth. Seen in all ages Affects primary and permanent dentition Mandibular incisors are also affected ETIOLOGY MULTIFACTORIA Decreased salivary flow ,Genetic background
NURSING BOTTLE CARIES Another type of acute caries which occurs among those children who take milk or fruit juices by the nursing bottle for longer duration during night .commonly occurs in the upper incisor but lower teeth are not affected . Both nursing bottle caries and rampant caries cause early pulp involvement .
Arrested caries Arrested caries is alesion whose progression is ceased after the initial development it can occurs in both enamel and dentin Enamel lesion : Arrested caries in enamel may occur when the carious process stops before cavity formation . It occurs when adjacent carious tooth is lost or extracted .remeneralization occurs from saliva or for topical flouride application
Dentin The arrested caries of dentin usually occurs when acarious cavity becomes wide open , so that it gets exposed to the cleaning measures like tooth brushing ,salivary secretion, mastication . Apear ahard ,black or brown colored dentinal surface at its base (eburnated dentin) its surface highly mineralized due to remineralized .
CHRONIC DENTAL CARIES Progress slowly and leads to involve pulp much later Sufficient time for both sclerosis and deposition of secondary dentin Carious dentin stained deep brown. Shallow cavity with softening of dentin Pain and undermining of enamel not a common feature.
Exclusively seen in caries of occlusal surface with large open cavity in which there is lack of food retention Also on the proximal surfaces of tooth in cases in which the adjacent approximating tooth has been extracted
SECONDARY CARIES (RECURRENT)
This type of caries is observed around the edges and under restorations. The common locations of recurrent caries are the rough or overhanging margin and fracture place in all locations of the mouth. It may be result of poor adaptation of a restoration, which allows for a marginal leakage, or it may be due to inadequate extension of the restoration. In addition caries may remain if there has not been complete excavation of the original lesion, which later may appear as recurrent caries.ROOT CARIES
Defined as soft progressive lesion that is found anywhere on root surface that has lost connective tissue attachment and exposed to oral environmentMicroorganisms involved in root caries are filamentousMicroorganisms invade cementum, along sharpey’s fibres-Plaque and micro-organisms are essential for the cause and progression of the lesion, mostly Actinomyces, -invasion of micro-organisms into the dentinal tunbules, finally leading to pulp involvement. -the rate is slower due to fewer dentinal tubules than crown area
Histological features of early enamel caries: The first change seen histologically is the loss of inter-rod substance of enamel with increased prominence of the rods. This is followed by the loss of mucopolysaccharides in the organic substance. Presence of transverse striations of the enamel rods Accentuated incremental lines of Retzius.
Carious lesion
Dentin reaction to cariesHistological feature of advanced enamel caries: Zone 1: Translucent zone, -lies at the advancing front of the lesion, -slightly more porous than sound enamel, -it is not always present Zone 2: Dark zone, this zone is usually present and referred to as positive zone -formed due to demineralization. Zone 3: Body of the lesion, -found between the surface and the dark zone, -it is the area of greatest demineralization, Zone 4: Surface zone, -relatively unaffected area, -greater resistance probably due to greater degree of mineralization and greater F concentration.
Histology of dentinal caries Zone I(normal dentin) This zone represents the innermost layer of the carious dentine Dntinal tubules appear normal . No crystals in the lumen of the tubules No bacteria in the tubules. Zone II(sub transparent dentin This is the zone of dentinal sclerosis and it is characterized by the deposition of very fine crystal structures within the dentinal tubules at the advancing front.
Dentinal sclerosis
zoneIII(transparent dentin) This zone appears transparent and this is because of the demineralization of dentin due to caries It is softer than normal dentin Further loss of mineral ions from inter tubular dentin . Zone IV (TURBID DENTIN) This zone is called the turbid dentin and is marked by the widening and distortion of the dentinal tubules ,which are packed with microorganism Little amount of mineral present and moreover denaturation of collagen fibers also takes place
Zone V(infected dentin) This is outermost zone characterized by complete destruction of the dentinal tubules The areas of decomposition of dentin that occur along the direction of the dentinal tubules called liquefaction foci of miller ,while the area perpendicular to the direction of the dentinal tubules are called the transverse clefts. Bacteria may no longer remain within dentinal tubules and they destroy the peri-and intertubular dentin
In the process ,the entire dentinal structure becomes destroyed and cavitations begin from dentino-enamel junction .
Radiological aspects of dental caries Radiographs are often helpful in the detection of dental caries Periapical x- ray Panoramic Bitewing …..for detection of proximal caries Smooth surface caries …triangular shaped radiolucent but its base is located towards the surface of the tooth.Pit and fissure caries…. Triangular shaped radiolucent with its base located towards the DEJ.