Practical class № 1

The concept of dental disease prevalence and intensity. Indices

of caries intensity. Levels of prevalence and intensity caries and periodontal
disease according to WHO criteria.

According to the WHO, three main indicators are used to assess the incidence of
caries in the population: prevalence, intensity and intensity increase.

The prevalence of caries is an indicator determined by the ratio of the number of

children with caries to the total number of surveyed (calculated as a percentage):

To assess the prevalence and intensity of caries of permanent teeth at the population
level, the key age group is 12-year-old children.

The prevalence of dental caries in 12-year-olds (WHO criteria):

• low 0-30%;
• average 31-80%;
• high 81-100%.

The intensity of caries is characterized by the degree of tooth decay and caries is
determined by the average value of the indices of DMFT, DMFS, dmf, dmfs
DMFT and DMFS describe the amount - the intensity - of dental caries in an
individual. DMFT and DMFS are means to numerically express the caries
prevalence. The Decayed, Missing, Filled (DMF) index has been used for almost
80 years and is well established as the key measure of caries experience in dental
epidemiology. The DMF Index is applied to the permanent dentition and is
expressed as the total number of teeth or surfaces that are decayed (D), missing (M),
or filled (F) in an individual. When the index is applied to teeth specifically, it is
called the DMFT index, and scores per individual can range from 0 to 28 or 32,
depending on whether the third molars are included in the scoring. When the index
is applied only to tooth surfaces (five per posterior tooth and four per anterior tooth),
it is called the DMFS index, and scores per individual can range from 0 to 128 or
148, depending on whether the third molars are included in the scoring.

When written in lowercase letters, the dmf index is a variation that is applied to the
primary dentition. The caries experience for a child is expressed as the total number
of teeth or surfaces that are decayed (d), missing (m), or filled (f). The dmft index
expresses the number of affected teeth in the primary dentition, with scores ranging
from 0 to 20 for children. The dmfs index expresses the number of affected surfaces
in primary dentition (five per posterior tooth and four per anterior tooth), with a
score range of 0 to 88 surfaces. Because of the difficulty in distinguishing between
teeth extracted due to caries and those that have naturally exfoliated, missing teeth
may be ignored according to some protocols. In this case, it is called the df index.

Calculating DMFT: The teeth not counted are unerupted teeth, congenitally
missing teeth or supernumerary teeth, teeth removed for reasons other than dental
caries, and primary teeth retained in the permanent dentition. Counting the third
molars is optional. When a carious lesion(s) or both carious lesion(s) and a
restoration are present, the tooth is recorded as a D. When a tooth has been extracted
due to caries, it is recorded as an M. When a permanent or temporary filling is
present, or when a filling is defective but not decayed, this is counted as an F. Teeth
restored for reasons other than caries are not counted as an F.
Calculating DMFS: There are five surfaces on the posterior teeth: facial, lingual,
mesial, distal, and occlusal. There are four surfaces on anterior teeth: facial, lingual,
mesial, and distal. The list of teeth not counted is the same as for DMFT calculations,
and listing D, M, and F is also done in a similar way: When a carious lesion or both
a carious lesion and a restoration are present, the surface is listed as a D. When a
tooth has been extracted due to caries, it is listed as an M. When a permanent filling
is present, or when a filling is defective but not decayed, this surface is counted as
an F. Surfaces restored for reasons other than caries are not counted as an F. The
total count is 128 or 148 surfaces.
Calculating dmft and dmfs: For dmft, the teeth not counted are unerupted and
congenitally missing teeth, and supernumerary teeth. The rules for recording d, m,
and f are the same as for DMFT. The total count is 20 teeth. For dmfs, the teeth not
counted are the same as for dmft. As with DMFS, there are five surfaces on the
posterior teeth and four surfaces on the anterior teeth. The total count is 88 surfaces.
Limitations of DMF Index: While DMF indices can provide powerful data and
perspectives on dental caries, they also have some limitations. For one, researchers
have noted a significant amount of inter-observer bias and variability.7 Other
criticisms include that the values do not provide any indication as to the number of
teeth at risk or data that is useful in estimating treatment needs; that the indices give
equal weight to missing, untreated decay, or well-restored teeth; that the indices do
not account for teeth lost for reasons other than decay (such as periodontal disease);
and that they do not account for sealed teeth since sealants and other cosmetic
restorations did not exist in the 1930s when this method was devised.
To assess the prevalence and intensity of caries of permanent teeth at the population
level, the key age group is 12-year-old children.
The intensity of dental caries in 12-year-olds (WHO criteria):

• 0-1, 1 -Very low

• 1,2-2,6 - Low
• 2.7-4.4 - Average
• 4.5-6.5 - High
• 6.6 and above - Very high

The intensity of dental caries in 35-44-year-olds:

• 0,2 -1, 5 -Very low
• 1,6 - 6,2 - Low
• 3.3 - 12.7 - Average
• 12.8 - 16.2 - High
• 16.3 and above - Very high

The intensity increase is defined as the average number of teeth in which new caries
cavities have appeared for a certain period of time, for example, per year.
The intensity increase is determined by the difference in the indices of DMF after a
certain period of observation, for example, one year, several years. As a rule, the
increase in caries is calculated in a year, and in persons with an increased risk of
caries (patients with pathology of internal organs, active course of the carious
process, etc.) — in 6 months.

Δ DMF = DMF 2 – DMF 1,

Tasks:

1. What is prevalence? Prevalence calculation formula.

2. What is DMF? What is the difference between DMF and dmf?
3. DMF calculation formula.
4. A survey of 6-year-old children found that 48 out of 50 people have
temporary teeth affected by caries. Determine the prevalence of caries of
temporary teeth.
5. On examination of 52 children aged 3 years, it was established that 22
children teeth are affected by caries. The total number of affected teeth 120.
Determine the intensity of dental caries in 3-year-old children.
6. A survey of 50 children 12 years of age, found that the total number of teeth
affected by caries is 156. A survey of these children a year ago allowed us to
set an index DMF intensity = 2.8. Determine the increase in the intensity of
caries.
7. A survey of 15-year-olds made it possible to establish that DMF index = 4.5.
A year ago, the DMF index was 3.9. Determine the increase in the intensity
of caries.
8. Writing a dental formula for a 5-year-old child:
c c
55 54 53 52 51 61 62 63 64 65
85 84 83 82 81 71 72 73 74 75
c f f
Determine the intensity of caries in a 5-year-old child.
9. Record of the dental formula of a 15-year-old teenager:

c f f m
17 16 15 14 13 12 11 21 22 23 24 25 26 27
47 46 45 44 43 42 41 31 32 33 34 35 36 37
f
21 – removed due to injury. Determine the intensity of caries.
10.When carrying on an epidemiological investigation of 15-year-olds teenagers
using the CPITN index found that 40 out of 50 surveyed there is bleeding
gums. Determine the prevalence of periodontal disease. Determine
prevalence rate according to WHO criteria.
11. When conducting an epidemiological survey using CPITN found that 20 out
of 50 surveyed 15-year-olds teenagers revealed the presence of tartar.
Determine the prevalence of pathology and rate level prevalence according
to WHO criteria.
12.During examination of a 4-year-old child, 62 and 72 teeth with carious lesions
on the vestibular surfaces, 55 and 65 teeth with fillings located on the
chewing and contact surfaces, tooth 45 is removed due to complicated caries.
Determine the index DMF teeth and DMF of surfaces.
13. When examining a group of 15-year-olds teenagers, individual DMF index
values were: 3; 2; 4; 5; 2; 7; 1; 2; 3; 4; 2; 8; 0; 2; 0; 10; 8; 1; 2; 0 Determine
the prevalence and intensity of decay caries teeth.
14. When examining 50 adolescents aged 15 years with CPITN index found that
15 students have signs no lesions, 24 revealed bleeding gums, 10 -
supragingival dental calculus, in 1 teenager - periodontal pocket 4-5mm deep.
Determine the prevalence of periodontal disease in the group surveyed
adolescents.
15.In the city of U., an epidemiological survey of 12-year-olds was carried on.
Of the 100 children examined in 25 - not identified dentomaxillary
abnormalities, abnormalities detected in 32 schoolchildren bite, 18 -
anomalies of individual teeth, 25 - dental anomalies rows. Determine the
prevalence of dental anomalies in this group of students.