Slides in Cariology Doctor Mokhtar

8/2/2019 Slides in Cariology Doctor Mokhtar

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1st slide in cariology doctor Mokhtar

Carious activity and role of related bio-environmental interaction

Review article

Dental caries is one of the most common oral diseases among adults and children, and one of the most

probable causes for the patents seeking dental restorative treatment, since it is progressive, irreversible

and always leaving a defect.

In recent years, dental caries has declined dramatically among children as a result of various preventive

regimens, including community water fluoridation and increased use of toothpastes and fluoride rinses

(1-3) Since the 1970s, there has been a 57.2% decreased in decayed, missing, and filled teeth (DMFT)

and a 58.8% decrease in decayed, missing, and filled surfaces (DMFS) in permanent teeth among 6-to-

18- yearolds (4-5).

Untreated dental decay can lead to extensive dental treatment, tooth pain, abscess of persons with

untreated dental decay varies by poverty status and race/ethnicity. At all ages, those living below the

poverty level were more likely to have untreated dental decay than those living at or above the povertylevel.

Filling cavities defects resulting from caries is now not considered to be the best treatment modality

since prevention in general is better than cure. So now the governments in the develop world direct a

great part of their health resources towards prevention rather than the actual treatment.

In order to better control and prevent dental caries a complete understanding of the etiology and

pathology of the disease is essential,

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the precipitating factors, and the hindering factors that have proven clinically successful should be will

addressed (6 -8)

Dental caries is a process that may take place on any tooth surface in the oral; cavity where dental

plaque is allowed to develop over a period of time. Plaque formation is a natural, physiological process

plaque is and example of biofilm, which, means it's not a haphazard collection of bacteria but acommunity of microorganisms attached to a surface. This community works together, having a

collective physiology. The bacteria in the biofilm are always metabolically active (7-8)

Some of the bacteria are capable of fermenting a suitable dietary carbohydrate substrate (such as the

sugars sucrose and glucose), to produce; cause the plaque PH in time below 5 within 1-3 minutes.

Repeated falls in PH may in time result in demineralization of the tooth surface. However, the acid

produced is neutralized by saliva, so the PH increases the cumulative results of the deanremineralization processes may be a net loss of mineral and a carious lesion that can seen. Alternatively,

the changes may be so slight that a carious lesion never becomes apparent (9-11) .So the etiologic

factors of dental caries are:

Host

Tooth morphology (12): Teeth with deep pits and fissures and angular grooves create areas for food

impaction and stagnation, which when unclean predispose for the initiation of carious activity (pit and

fissure caries) that doesnt rule out that caries do develop in areas where food is naturally cleansed(smooth surface caries) in presence of plaque

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Teeth alignment: Teeth crowding and misalignment do create areas of food stagnation.

Presence of appliances restoration tooth interface is predisposing to plaque retention, and thus dental

caries if not cleaned. Oral hygiene measures: Subjects applying oral hygiene measures and regular home

care have far less incidence of carious activity.

Salivary flow, consistency and rate is evident hinders the initiation and propagation of caries through

many mechanisms and that will be discussed in details later. Micro biota (0- 13) :

It is evident that cariogenic bacteria are Streptococcus mutants, Lactobacillus, acidophilus,

actinomysis viscousis and others. Acidogenic bacteria have the abilities to :


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Live and thrive at very low PH medium (acidouric). ferment suitable carbohydrates to produce acids

(acidogenic) produce extra cellular polysaccharides that are non soluble in the oral environment which

constitutes the plaque matrix. Carbohydrates (12)

Type of carbohydrate: The most cariogenic carbohydrate is thought to be sucrose, which is a

disaccharide because:

It has a very low molecular weight, which makes it easily diffusible into the plaque matrix.

Strepotococcus mutants synthesize lactic acid more rapidly from sucrose than any other carbohydrates

even glucose and fructose and the energy resulting from its split is used by bacteria in its metabolism.

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Consistency: Carbohydrates of fibrous consistency are less cariogenic than those of sticky consistency

because they are not easily washed away from tooth surface.

Frequency of intake: Frequent intake and snaking carbohydrates in-between meals is said to be one of

the major causes of caries activity as period of acid production will be multiplied. A study of caries

process reveals that. Bactria in plaque matrix ferment carbohydrates in plaque to produce acids, the

rapid and consistent drop of PH level in plaque cause the deminirelozation of tooth enamel, and thus

the pathology of caries could be staged into; fermentation of carbohydrates and production of acids by

cariogenic bacteria. Rapid and sufficient drop of PH enough to decalcify mineral or inorganic content of

tooth structure (which in two processes, first conversion of calcium hydroxyl apatite of tooth into

complex form then the final dissolution of mineral crystals). Invasion of decalcified enamel by bacteria.Continued fermentation and production of acids by bacteria which may or may not lead to cavitation.

Remineralization by incorporation of fluoride and phosphorus and calcium ions from saliva could take

place (12)

Thus, it is clear that the process of decalcification actually precede the actual bacterial invasion, and

thus the early layers of decalcified enamel and dentin are considered affected but not infected.

Also primary demineralization of inorganic tooth structure being a two step process, could be

interrupted and thus modified, which is a very important approach in modification and control ofcarious process.

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The point is that the process does not have to progress. When the destructive forces outweigh the

reparative powers of salvia, the process will progress. Conversely, if the reparative forces outweigh the

destructive forces, the process will arrest. Early diagnosis important because, once carious lesions have

cavitated; only operative intervention can replace the tissue. Fillings dont prevent caries, because new

lesions can develop adjacent to restoration (14-17) .If fillings are last, preventive non-operative

treatments must go hand-in-hand with operative treatment. The basis of preventive, non-operative

treatment is modification of one or more of the factors involved in the carious process. Since the

process usually takes months or years to destroy the tooth, time is on the patient's side. the dentist can

help the patient modify the carious process in a number of ways:

Oral hygiene instruction. Since the process is the metabolic activity in the biofilm (6,7), plaque

removal using fluoride tooth paste is very important. The different designs of tooth brushed, oral dental

flosses and the different inter dental cleaning devices are all set to enhance accessibility to different

teeth and restoration surfaces, and also enhance the manageability of plaque. In addition to the

importance of implication of the correct tooth brushing techniques mouth rinses containing antiseptics

like chlorhexidine gluconate and minerals such as fluorides are said to decrease bacterial population inthe mouth and enhance remineralization. Dietary advice. Relatively simple measures, such as confining

it to meal times, are usually sufficient replacing the more carigenic forms of sugar with less cariogenic

forms like xylitol has been postulated.

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Sugar free chewing gum is said to decrease caries incidence, by the interruption of plaque aggregation.Role of saliva in the prevention and control of caries: (12)

v From of acquired enamel pellicle which by neutralization of charges on the hydroxyapatite crystals

prevent bacterial aggregation and colonization.

v Washing out effect of saliva.

v Buffering effect of saliva.

v Direct antibacterial effect of saliva.

v sIgA content of saliva:

The role of sIgA

Killing or inhibition of bacterial growth. Opsonization of bacteria. Prevention of adherence of bacteria to

tooth surfaces. Inactivation of metabolism of bacteria. Inhibition of specific enzymes such as glucosyl

transferases which are responsible for the synthesis of extra cellular polysaccharides from sucrose.

Other bactericidal elements in saliva include peroxidases, lysozymes, and, and lactoferrins. Appropriate


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use of fluoride. Fluoride used in toothpaste, water, or mouthwashes and applied topically will delay

progression of the lesion. Role of fluorides in the prevention and control of dental caries:(18-20)

Fluoride is naturally occurring in food and drinking water. When fluoride is ingested it appears within

minutes in plasma.

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Hydroxyapatite to fluoroapatite crystals and this is a continuous process during tooth mineralization.

since ingested repeated daily ingestion is more beneficial than daily ingestion of single dose

It should be clear that ingestion of fluoridated water in concentration more than 1.2 PPM, at the time of

tooth mineralization is associated with a form of enamel hypolplasis known as floozies of mottling.

The appearance of hypo plastic form of enamel is due to the toxic effect of fluoride on ameloblasts.

Mottled enamel is more resistant to dental caries.

Fluoride has cariostatic effect due to three known mechanisms:

Fluoride decreases the solubility of apatite crystals by converting them to fluoroapatite. Explanation:

Fluoride ions substitute one of the hydroxyl groups in the center of the calcium triangles and

equidistant from the three calcium ions. The incorporated fluoride ions will form:

Strong ionic bonding with calcium ions, thus causing shrinkage of the calcium triangle with calcium ions

pulled in closer to the fluoride ions.

Hydrogen bond with the neighboring OH groups.

It is believed that both the strong ionic bonding and the formation of hydrogen bonds are responsible

for them most of the increases stability of fluoroapatite compared with hydroxyapatite.

Fluorides enhance remineralization of carious lesions by deposition of fluoride salts. Fluorides have an

antibacterial effect. Conclusion, it should be well understood that caries is a multifactorial process, in

which a combination of acting factors contribute. The sum of which induces mineral tooth structure

demineralization and subsequent loss of integrity steel cap. Recent researches show that caries in its

early stages in which no bacterial invasion occurs could be reversed, but this in turn needs early

diagnosis very much not presented clinically. The remineralization process is prompted by certain

materials such as Ca(OH)2 or fluorides, it is thought that their mineral content stimulates the

remineralization process. The value of implication of regular oral hygiene measures could not be underestimated, since the regular deposition of plaque harboring and concentrating the bacterial community;

their source of energy (intracellular polysaccharides) their products (acids; lactic acid) leads to the

eventually of dental caries.
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