Cariogram Model
A new model, the Cariogram, was presented in 1996 by Bratthall for illustration of the interactions of caries-related factors. The model makes it possible to single out individual risk or resistance factors. A special interactive version for the estimation of caries risk has been developed.
The original Cariogram was a circle divided into three sectors, each representing factors strongly influencing carious activity: diet, bacteria, and susceptibility. The development of the model was based on a need to explain why, in certain individuals, carious activity could be low in spite of, for example, high sucrose intake, poor oral hygiene, high mutans streptococci load, or nonuse of fluorides.
Examples of Cariograms are presented in Fig 139. They can represent a situation at a single tooth surface, in a particular individual, or for a whole population. A closed circle, as in Fig 139 (a), describes a situation where demineralization occurs, meaning that caries will develop over a given time. The point is that there are enough bacteria, there is a caries-inducing diet, and there is a susceptible host.
An open circle, as in Fig 139 (b to h), illustrates a situation where no carious lesions will occur, the reason being that something necessary to the development of demineralization is missing. For each component, a large sector thus indicates an unfavorable situation, while a small sector means favorable conditions. Each sector can be very large or small, but none of them can disappear totally. Bratthall (1996) explained the various Cariogram examples in the following way:
In Fig 139 (a), there are three components responsible for closing the circle, bacteria, diet, and susceptibility to disease. The term bacteria is here understood to include type and amount of bacteria, bacterial adhesion, plaque formation rate, acid producing capacity, and all other factors which make the dental plaque more or less cariogenic.
Similarly, diet describes all factors making diet more or less suitable for bacterial growth and acid formation. That means that contents of fermentable carbohydrates and frequency of food consumption are included, as well as possible antibacterial components in the food. In susceptibility, all factors are included that reflect the resistance to disease, such as mineralization of teeth, fluorides, saliva secretion and buffer capacity, salivary antibodies, and all other salivary or "host" components affecting demineralization and remineralization.
The bacteria sector becomes larger if there is abundant plaque, if there is a high portion of mutans streptococci and lactobacilli, if the plaque is very sticky and fastgrowing, etc. The diet sector becomes larger if there is a high and frequent intake of fermentable carbohydrates, in particular sucrose, if sugar substitutes are seldom being consumed, if diet is deficient from other crucial aspects. The susceptibility sector becomes larger if there is a lack of fluoride, if fluoride toothpastes are seldom being used, if saliva secretion is low, if saliva buffer capacity is low, if there are other important saliva factors missing, etc.
The three sectors represent factors with an immediate action on a tooth surface, at a
site where a cavity may or may not occur. However, behind each sector there are
several factors that determine why the sector in a particular case is large or small. For
example, a disease may explain why saliva secretion is low, a troublesome social
situation can result in a minimal interest to clean the teeth and thus explain why
plaque is abundant and fluoride from toothpaste absent, etc.
In Fig 139 (b), the circle is open, thus describing a situation where caries will not
develop¾"something is missing" for cavity formation. In this particular case, the
reason is that all sectors have "improved." The bacterial sector has been reduced, for
example, due to reduced amount of plaque or a change to less cariogenic
microorganisms. The diet sector is reduced, perhaps because of reduced sugar intake.
Also, the susceptibility to disease has been reduced; in other words, the resistance has
increased, perhaps because of implementation of a fluoride program.
Based on the Cariogram concept, an interactive version for caries risk estimation was
developed (Bratthall et al, 1997). There are a few fundamental differences between
this program and the original version. First, the risk for future carious activity varies
on a scale from 0% to 100%, but it cannot be more than 100% (Fig 140). Thus, the
sectors cannot overlap each other. Second, a further sector, circumstances, was
included. This sector includes factors such as caries experience and systemic diseasesfactors
to consider when the risk is calculated, in spite of the fact that these factors
themselves do not participate directly in the development of the lesion.
The purpose of the program is educational, and it illustrates a possible risk evaluation:
It does not replace the responsibility of the dentist, but it may help in making proper
decisions. The program operates in such a way that individual data for a patient
regarding bacteria, diet, saliva, and fluoride are entered into the program, together
with information regarding circumstances. The values entered are based on specific
criteria. The score 0 is the most favorable value, and the maximum score, 3, indicates
a high, unfavorable risk value.
According to a formula, the program calculates the caries risk and indicates the
"chance to avoid new cavities." A large chance to avoid caries thus means a low
caries risk. The formula is based on weighted figures, meaning that factors believed to
have a high impact on the caries risk will influence the risk to a higher extent. Figures
141, 142, 143, and 144 illustrate some examples of Cariograms for selected patients.
Thus, the Cariogram model is a simple way to illustrate how various caries-related
factors can interact. It is useful in various situations when there is a need to discuss
the importance of etiologic factors. In its interactive version, it is possible to
demonstrate how the risk may change as a result of various actions. Also, the program
will accept the influence of the "clinical feeling" of the operator.
