Evaluation of dietary factors
The human longitudinal studies described earlier showed that, in individuals with little or no plaque control and no use of fluoride, frequent intake of sugar-containing products is a significant risk factor or prognostic risk factor for dental caries.
In addition, in vivo plaque pH measurements have shown that the drop in pH and sugar clearance time in undisturbed plaque (more than 2 days old) is related to the sugar concentration and consistency of the food item being evaluated (see Figs 63, 64, 65, 66, 67, 68, and 69). Frequent intake of sticky sugar-containing products results in prolonged sugar clearance time, which further prolongs the drop in pH on all tooth surfaces covered with undisturbed cariogenic plaque.
Because a prolonged drop in plaque pH eventually results in demineralization of the enamel and development of a carious lesion, the sugar clearance time, based on an evaluation of dietary habits and eating patterns, would seem to be essential information to obtain for all caries-active individuals. Data obtained from evaluation of dietary habits not only provides background material for caries risk assessment but also aids dietary counseling in needs-related caries control and the encouragement of good dietary habits in general health promotion.
Dietary assessment in dental practice is aimed at estimating the cariogenic challenge caused by carbohydrates and assessing the general nutritive value of a diet. This means that information on eating patterns and intake of fermentable carbohydrates, as well as energy and other nutrients, should be collected and evaluated. The goal is to establish the absolute magnitude of these variables with the least degree of measurement error. These objectives form the basis for selecting a method. Of several available methods, the following are suitable for dental practice: dietary history, 24- hour recall, dietary record, and food frequency questionnaires.
Dietary history
All methods can be used in dental practice, but, in its original version, the dietary history method takes 1 to 2 hours. This method is considered accurate when validated with nitrogen excretion in urine, but is generally too time consuming for dental practice. However, modified forms may be combined with one of the other interview methods.
24-hour recall
This method is widely used. A trained member of the dental team interviews the patient about the intake of food and beverages during the latest 24-hour period.
Consistency in the technique and the skill of the interviewer are important factors
influencing communication and patient cooperation and thereby the result. Food
models or life-sized illustrations are recommended by most researchers as an aid in
estimating quantities. The portion size can also be given in household measures, such
as glasses, cups, tablespoons, ounces, and pounds.
To reduce bias, the 24-hour recall is done without prior notice to the patient. It should
then be repeated for at least 4 days to establish the eating pattern and intake of energyproviding
nutrients. For nutrients with large day-to-day variations, the number of days
is increased. For example, the time required to estimate the true intake of vitamin A is
reported to be approximately 40 days. The days should be selected to represent
ordinary days and include weekdays as well as a weekend. Boxes 3 and 4 present
examples of 24-hour recalls of a highly cariogenic diet and a noncariogenic diet,
respectively.
Dietary record
In dietary records, also called food diaries, the patient records the type and quantity of
all food and drink consumed over a prescribed period, usually 3 to 7 days. Estimates
of portion sizes and selection of days are the same as for the 24-hour recall. The
patient is given the following detailed instructions:
1. To make the evaluation as accurate as possible, ordinary dietary habits should be
kept. Record carefully and precisely. For example:
a. How many slices and what kind of bread is used for sandwiches¾what kind of
spread is used and what filling?
b. What is drunk with or between meals?
c. Is jam or sugar used with milk, buttermilk, or yogurt?
d. How many lumps of sugar in tea or coffee?
e. Are vegetables raw or boiled?
2. Include all snacks: soft drinks, sweet rolls, fruit puree, milk with a sandwich, fruit
or sweets, chewing gum, and throat lozenges.
This prospective strategy may increase measurement error because of incomplete
registration or deliberate or inadvertent changes in diet. Both the dietary record and
the 24-hour recall method are reported to underestimate intake slightly compared to
the dietary history method and excretion of urinary nitrogen.
Food-frequency questionnaires
A food-frequency questionnaire contains a list of food items, usually 50 to 150 items,
selected to illustrate the whole diet or a specific nutrient, eg, sucrose. The patient
marks his or her consumption on a scale, ranging from never to several times per day.
An example of this is a questionnaire aiming to measure intake of food items (Fig 71).
The patients mark with a cross the most appropriate square. Figure 72 shows another
questionnaire with special reference to the frequency of sugar-containing products.
The frequency questionnaire also can be used to estimate nutrient intake. There is a
strong correlation between consumption frequency and intake of energy and nutrients.
The frequency questionnaire method is uncomplicated and inexpensive and may be
useful as a screening instrument or for obtaining dietary data at a group level.
Analysis of dietary data
When the advantages and disadvantages of these methods are assessed, use of the
repeated 24-hour recall and the food record method for 4 to 7 days seems to be the
most appropriate for dental practice. The 24-hour recall method is preferable for
adolescents, for the elderly, and when communication is poor. The length of the study
period is decided according to demands for precision of micronutrients, such as
vitamins and minerals. For caries, a 4-day record usually meets the requirements.
After completion of data collection and a check on the plausibility of the reported
consumption, the intake is evaluated. Evaluation of the cariogenic potential includes
an estimation of factors such as the number of intakes containing fermentable
carbohydrates, the consumption of snacks and sugar-containing drinks at night, and
the retentiveness of the cariogenic products. In children and adolescents with an
uncomplicated pattern of caries, simply scoring sucrose intake is often adequate.
Several inexpensive computer software programs for evaluation of energy and
nutrients in the diet are available in Scandinavia, and computer-based analysis of
dietary registrations is common. This is a convenient way to evaluate the nutritive
value of the intake. The results of changes to the diet are readily demonstrated, which
is of great educational value for patients.
Another way to estimate nutritive value of the diet is to score the number of intakes
representing six specific food groups (Fig 73). Samples of charts that can be used in
such a food group-based evaluation are shown in Tables 9 and 10.
When the cariogenic potential and nutritive value are assessed, other properties of the
food, known to modify the carious process, for example, food that requires chewing,
should also be considered. The ensuing stimulation of salivary secretion and
distribution reduces the duration of a drop in plaque pH.
