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Cons sheet #7 done by : Mohammed Basel4/11/2013

Dental caries

Caries: are infectious microbiological diseases that result in a localized dissolution and destruction of the calcified tissue .. So basically we have bacteria this bacteria will produce acids causing dissolution and destruction of the tooth structure . ** the term infectious indicates that "caries" are infections .** microbiological means that "caries" are caused by micro-organisms that come from outside the body.Q / if there is an infant that isn’t exposed to these micro-organisms yet, do you expect him to have caries ? NO ..

There are 4 main elements required for caries :1/ tooth surface (usually enamel, Dentine, or cementum).2/ cariogenic or potentially-carious-causing Bacteria. 3/ fermentable carbohydrates (such as sucrose .. Needed because this is the food for the bacteria)4/ Time .. You need to have enough time in order for the caries to progress.

Different individuals will be susceptible to different degrees of caries depending on :1/ The shape of the teeth.2/ The oral hygiene.3/ The buffering capacity of their saliva.

So if you have the exact same 4 main elements in two different individuals, you don’t expect them to have the same end resulting caries because of the differences in the points mentioned above.

Caries can occur on any surface of the tooth that is exposed to the oral cavity, this means that caries do not start in the root that is buried in the bone.

It's essential to understand that any destruction of the tooth surface creating cavity or defect is a sign of bacterial infection.

Here we remove the defected enamel and dentine & replace them with a filling material .. Did we eliminate the etiology* of the infection? NO, we just treated the symptoms.

1 | P a g eetiology : is the study of causation, or origination.


The proper treatment of caries must indicate the removal of the etiology* .. How to do that? We will discuss that later on.

Caries activity, as evidenced by demineralization and loss of tooth structure, is highly variable, and therefore the course of individual lesions is not always predictable, we can't really predict the course of the caries in the tooth, so sometimes you can find very extended caries on one tooth and very tiny ones on the other.

Carious lesions occur under a mass of bacteria called as Dental plaque, this dental plaque is capable of producing a sufficiently acidic environment to demeneralize the tooth structure .

As you see in this picture .. The teeth do have some surface deposits (Dental Plaques) .. Dental plaque: basically a gelatinous mass of bacteria adhering to the tooth surface, so it has to be a group of bacteria in addition to other things sticking to the tooth surface.

If you prevent (plaques) from adhering to the tooth structure then you will prevent the caries formation .. How to do that? There are two types of prevention : 1/ temporary by tooth brushing. 2/ Permanent scientists are searching till now

The bacteria that present in the plaque metabolize refined carbohydrates for energy producing by-product (organic acid which is the lactic acid), the main carbohydrate to be metabolized is the Sucrose (white table sugar), why sucrose? Because it’s a Disacharide that is easy metabolized by the bacteria.

These organic acids produced by the bacteria may cause carious lesions by the dissolution of the tooth structure, then these lesions will progress as a series of exacerbations & remissions, The pH of the tooth surface varies due to the change in plaque metabolism.

The saliva contains some Ions acting as a buffer, the more your salivary flow the better for your teeth because saliva will decrease the effect of these acids.



The good salivary flow means a good buffering capacity so the decrement in the pH (increment in the acidity) will be diminished by the effect of the buffering capacity of the saliva in addition to the oral hygiene and fluoride consumption.

You should keep in mind that you do not have a constant phase of deminireliztion and reminirelization, it’s a dynamic process .. If the net total of this process is toward the deminirelization then caries will start.

The teeth are not shiny at all, they're covered with dental plaque, here you can judge that the patient doesn’t know the meaning of tooth brushing. Dental plaques can vary in their degrees from things that we can’t see with the naked eyes to the level shown in the picture.

Plaque formation steps :

1/ the formation of a layer that is called (acquired pellicle), which is formed by some salivary proteins deposited on the tooth surface after 30 seconds to 1 minute of the brushing process and takes (12-24) hours , this layer is not a bad thing, it’s a natural physiologic layer, its function to prevent the friction between teeth lubricating their movement against each other, it also prevents deminirelization because it coats the tooth surface (protective role).



This layer also forms a scaffold for future remenerelization, WHY ? Because it eases the attachment of minerals to the tooth surface.

2/ after the formation of this layer, if you didn’t brush your teeth after eating then some bacteria will adhere to it (to the pellicle), the first bacteria to attach to the surface is from the cocci type (MS mutans streptococci).

3/ Then there will be a horizontal spread of this bacterial accumulation, so the plaque will start growing horizontally, then its no longer called acquired pellicle.

4/ Then some vertical growth starts to take place, another type of bacteria will adhere to the plaque layer (filamentous Bacteria lacto bacilli ), some bacteria will go away due to the friction, mastication and other factors, so the plaque matures.

If you brushed the tooth after 24 hours then you will go back to the level of the acquired pellicle.(steps from 2-4 take from 1-3 days)

5/ if the plaque calcified then it will be called as calculus (تكلسات), this is harder than the plaque .

Usually the formation of plaque on the buccal surface indicates that the patient does not brush his teeth at all, But lingually even if the patient brush his teeth very well the plaque formation will occur, and its easier to calcify lingually because there is more salivary pouring in the floor of the mouth.

The availability of simple carbohydrates (such as the sucrose) greatly stimulates plaque metabolism, so that tells you if you don’t want to have caries, do not have sugars.Exacerbations of caries activity are characterized by periods of high bacterial metabolic activity and low pH in the plaque near the tooth surface. During intervening episodes when fewer carbohydrates are available, there is less bacterial metabolic activity, and the pH rises near the surface of the tooth.

So the determinant of the " demineralization-reminerilization rate " is the pH, so you can eat a piece of cheese after eating sugar in order to raise the pH in the oral cavity, this will help in the prevention of the formation of the caries.

Remenerilization of the damaged tooth structure occurs as the local pH rises above "5.5", so you have to know that the critical pH in the oral cavity is "5.5".



The saliva contains high ratios of ( Ca & Phosphate ) that functions as the main supplier of the raw material of the remenerilization process.

Acid attacks the tooth surface continuously so you can't prevent it, but you can increase the pH of the oral cavity.

Understanding the balance between demineralization and remineralization is the key to enlightened caries management, because if the demineralization increased at the expense of the remineraliztion the risk of the caries occurrence will increase.

Bacteria in the dental plaque:

We said that the plaque is basically a gelatinous mass of bacteria ..But what kind of bacteria do we have ?

It has become clear that a relatively small group of bacteria is primarily responsible for the two major oral diseases; caries and periodontal disease.

1/ MS (mutants streptococci) and its serotypes (A-H), it’s a part of the normal flora, so if you took a swab from a patient’s mouth that is full with caries you will find high amount of MS and vice versa, this type of bacteria is associated with the onset of the caries.

2/ lactobacilli (filamentous Bacteria) they can produce good amounts of acids so we call them (acidogenic), and they are tolerant to the acidic environment so we call them (aciduric), this type is associated with the active progression of the cavitated lesions.

These types of bacteria are stimulated by the sucrose. So what makes them cariogenic is their capability to produce caries. NOTE: Both types of the bacteria are acidogenic, aciduric and cariogenic.

Virulence factors of these bacterias :1/ They are acidogenic, aciduric and cariogenic, and vigorously stimulated by sucrose.2/ the ability of the MS to adhere to the tooth structure.

Glucosyltransferase (enzyme presents in the bacteria) metabolizes the sucrose forming the ECM of the bacteria, and this helps in the adhesion of the MS to the tooth structure, the scientist are trying to target this enzyme in order to deactivate it, cause this may help in the prevention of the caries.



Theories that explain the pathogenecity of the plaque :

The first theory : #1(non specific plaque hypothesis)

Indicates that the whole plaque accumulations are harmful and they should be totally eliminated, either by killing them or brushing your immediately after each meal.

Wrong theory.

The second theory :#2(specific plaque hypothesis)

Says that certain organisms (MS) & (lactobacilli) cause caries and if you want to do the proper treatment you just need to deal with these types of the bacteria .

The model of treating caries depending on the #2 theory :

Etiology MS & lactobacilli infections

Symptoms Demineralization lesions in teeth

Treatment (symptomatic) Restoration of cavitated lesions

Treatment (therapeutic)(radical) Eliminate the infections

Post-treatment assessment (symptomatic) Examine teeth for new lesions

Post-treatment assessment (therapeutic) Bacteriologic testing for MS

Q / how to eliminate the infection? We usually do not prescribe anti-biotics for caries, WHY? Because the surrounding media of the caries is saliva(not blood), so it’s very hard for the anti-biotic to reach to the caries, so we use anti-microbial mouthwashes instead, and then follow the bacterial levels using the bacteriologic testing.

One of our colleagues mentioned the ultrasonication as a method to eliminate the infection .. But that is not true cause this method eliminates the whole plaque not just the infectious agent.



Now lets go back to the pH: We mentioned that the critical pH = 5.5 *When pH = 5 demineralization will occur, you know that the hardest layer of the enamel is the outer surface of it, so when you have lactic acid at the surface, would you expect the minerals to get out easier from the superficial or from the deeper layers? Surely from the deeper ones, and this is called subsurface demineralization (occurs initially), leading to an incipient caries.Incipient caries slight demineralization in the surface (intact surface), but the subsurface is demineralized, this will lead to a weak tooth structure that will break either chemically or mechanically.

*When pH = (3-4) the surface will be itched or roughened more serious caries.

The Minerals of the enamel, dentine and cementum are highly substituted calcium phosphate salt apetite.The apetite of the newly formed teeth is carbonated hydroxy-apetite, with time maturation and conversion of the apetite into fluor-hyroxy-apetite will occur.

The fluor hydroxy apetite is more resistant to the acidic environment, so the teeth are more susceptible to have caries when they first erupted, then they will gain some sort of resistance against acids.

If the tooth erupted and stayed (3-4) years without having caries then you can tell that this tooth won't have caries unless there is a significant change in the patient’s oral hygiene, diet or he stopped cleaning his teeth.

Fluoride-rich, low carbonate apatite can be up to ten times less soluble than apatite low in fluoride and high in carbonate. Topical fluoride also inhibits acid production by plaque bacteria, so the fluoride interferes with the bacterial plaque metabolism .

When the scientists found that the Fluoride is very good in the prevention of the caries they start to put it in food, drinks, dentifrices, oral rinses and gels, and in filling materials therefore all reduce the solubility of the teeth, helping to reduce caries risk.

Fluoride in the saliva is a very effective buffer, so people who have a reduced salivary flow tend to have much higher caries’ risk, so anything affects the salivary gland will lead to a higher risk of having caries.

Salivary flow may alter the demineralization-remineralization-balance.



Pits and fissures caries :

Pits and fissures are very susceptible to caries, they have the highest % of caries .. WHY?

Because of:1/ food stagnation.2/ inability to clean these areas.3/ they have a reduced enamel thickness, sometimes around 0.

As you see the shape is base to base cones at the DEJ (one in enamel and the other in the dentine), why do they take this shape? That is due to the direction of the enamel rods, once the caries reach the dentine it spreads laterally with a cone apex toward the pulp.

A good fissure. B Bad fissure .C also bad, because its very sharp.D if you have such a fissure then be sure that you are gonna have caries.



How do I prevent pit and fissure caries ?

Seal it with fissure sealant.

Hidden caries: from the name, you see like a small pit at the surface then when you start working & cleaning it you will end up with a huge cavity.. WHY? Because in this type of caries there is undermined tooth structure, this is because when the caries started the patient started to clean his teeth so at the surface a remineralization process occurred but deeply there is no Remineralization .

Best of luck

Done by : Mohammed Basel


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