A short summary of Research project work on PREVALENCE AND PATTERN OF THIRD MOLAR IMPACTION IN PATIENTS THAT VISITED UNIVERSITY OF GHANA DENTAL SCHOOL’S CLINIC IN 2008

1. PREVALENCE AND PATTERN OF THIRD MOLAR
IMPACTION IN PATIENTS THAT VISITED UNIVERSITY OF
GHANA DENTAL SCHOOL’S CLINIC IN 2008.
By Dr. Gabriel Doe Ketemepi
Supervised by: Prof G Parkins, Dr J Sackeyfio, Dr E Abdulai, Rev T Ndanu

2. • This study is a retrospective radiographic
study of the prevalence of impacted third
molars, the jaw and sex predilections and the
types of impaction in patients between the
ages of 15 and 60 years that reported at the
University of Ghana Dental School’s clinic from
January 2008 to December 2008.

3. Third molars
• Third molar teeth are the last teeth in the
dental arch and usually appear between the
ages of 16 and 25.
• They are called wisdom teeth because they
come in when a person is old enough to have
supposedly gained some wisdom.
• They vary very widely morphologically.

4. IMPACTION
• In 1926, George B Winter defined impaction
to be failure of a tooth to fully erupt after root
formation is completed.
• The third molar teeth are last to erupt and
have a relatively high chance of becoming
impacted.

5. • Several classifications of third molar
impaction exist but in this study, a modified
Winter’s classification was adopted. (shown below)

6. Orthopantomogram (OPG):
Since its introduction in the 1960s, it has remained a
valuable adjunct to conventional diagnostic procedures
in dentistry.

7. • Third molar teeth are impacted more than
other teeth of the human dentition. Their
impaction is of concern due to several
reasons.
– Partially impacted teeth, particularly mandibular
third molars, may communicate with the oral
cavity via inconspicuous periodontal pockets on
the distal aspect of adjacent second molar, thus
predisposing the impacted tooth to pericoronal
infection and dental caries.
– Common complications of impacted third molars
include root resorption of adjacent normal teeth,
infection and its associated pain, and dentigerous
cyst formation.

8. Aim and objecives
• The aim of this study was to determine the
prevalence and pattern of third molar
impaction in a Ghanaian population.

9. Method
• Five hundred orthopantomogram records of Ghanaian
patients between the ages of 15 and 60years that
reported in 2008 at UGDS were sampled through a
number of sampling stages. All folders of patients
treated in 2008 within the specified age group were
collected. Then a systematic random sampling was done
in which every 5th folder containing an OPG was
selected.
• Personal details including age, sex, type of impaction
and the jaw with the impaction of these patients were
recorded. These parameters were gathered and fed into
a Microsoft access program and analysed using SPSS16

10. Results
21.20
78.20
Prevalence of third molar impaction
Impaction Present
Impaction Absent

11. 0
50
100
150
200
250
Male Female
NumberofPatients
Sex
Third molar Impaction in the different sexes
Impaction Absent
Impaction Present

12. Pattern Of Impaction
MAXILLA MANDIBLE
Left maxilla Right maxilla Left
mandible
Right
mandible
Total
Mesioangular 1 0 52 46 99 (53.80%)
Distoangular 12 15 1 2 30 (16.30%)
Vertical 13 14 6 5 38 (20.65%)
Horizontal 0 1 9 7 17 (9.24%)
Total 26 31 68 60
184 (100%)
56(30.43%) 128(69.57%)

13. 0
10
20
30
40
50
60
70
80
90
100
Mesioangular Distoangular Vertical Horizontal
PercentageofImpacted
Type of impaction
Patterns of Impaction
Right mandible
Left mandible
Right maxilla
Left maxilla

14. DISCUSSION
• The prevalence of third molar impaction was 21.2%
among the patients studied in UGDS clinic (106 out of
500). This compares favourably with a prevalence of
22.8% in an urban Nigerian population as reported by
Olasaji and Odusanya.
• This prevalence is less than that of American males
aged 17 - 26 years, in which 65% have 1 to 4 impacted
third molars but higher than 9.2% among rural
Nigerians (Morris and Jerman, 1971; Odusanya, 1986).
• The prevalence of impacted third molar therefore
seems to increase with increasing modernisation.

15. • The study revealed that the mean age of those
with impaction was significantly lower than
(30.29years) that of those without impaction
(35.74years).
• Third molar impaction can therefore be said to
be a problem of the youth.

16. • Odusanyi alluded to this fact. He studied the
incidence and pattern of presentation of
impacted third molar of Nigerian youths (aged
16 - 25) and older Nigerians (age 35 years and
above) and discovered that impacted third
molar were four and half times more common
among Nigerian youths.
• This can be attributed to the fact that the
younger generation tends to have smaller jaws
due to changes in their diets which has
become softer.

17. • Darwin, had previously noted that, the posterior
dental portion of the jaw was always shortened in
the more civilized races of man. He attributed this
to “Civilized man’s habitually feeding on soft
cooked food.”( Darwin, 1881)
• There are diverse opinions concerning the effect of
masticatory function on the growth of the jaw
bones. Brash and Brodie suggested that the size of
the jawbone was determined by inherent genetic
factors and that environmental condition were of
little influence. (Brash, 1929 and Brodie, 1948)

18. • Roger and Stillman however maintained that
functional stimulus is an important consideration
and that without this stimulus jawbones were not
likely to develop to their fullest extent providing
space for the third molar to erupt.
• The dental arch length of Ghanaians may be
undergoing an unnoticed transition process of
disuse atrophy. With the continuous
modernization of Ghana and copying of western
life styles by the youth coupled with the
attendant development of the urban areas, a
number of significant alterations in the diet of
Ghanaians occurred.

19. • As a result of these changes, the diet became
much softer in its consistency.
• Bergman emphasized this view when he stated
that, “our ancestors had larger jaws, so there was
room in the human mouth for 32 permanent
teeth, including third molars. But now our jaws
are smaller.
• The result is that there is no longer room in most
of our mouths to house 32 teeth. So the last
teeth we develop often become impacted”.
(Bergman J, 1998)

20. • The feminine dominance of this study may be
due to the perception that women generally
care more about their teeth and esthetic than
male and report more often to treatment
centres.
• The study however showed that there was no
significant difference between the number of
men (55) and women (51) that had third
molar impaction.

21. • The most frequent angulation of impacted
third molar teeth in the mandible was the
mesioangular position. This pattern has been
observed in most studies done by Odusanya in
Nigeria, Kramer and Williams in Harlem and
Guthua et al in Kenya. (Odusanya, 1984; Kramer et al, 1970;
Guthua et al, 1992)
• The higher frequency of the mesioangular
impaction in the mandible could be due the
fact that when lower third molar teeth are
developing, they have a mesial tilt. And until
they are in full occlusion they do not get erect.

22. • Inability of the teeth to erupt into normal
occlusion leaves it mesioangularly impacted
against the second molar.
• Vertical impaction was the second overall
highest pattern. The vertical pattern together
with the distoangular pattern of impaction is
the most frequent pattern of third molar
impaction in the maxilla.

23. • The higher frequency of vertical and
distoangular impactions in the maxilla may be
due to the fact that the maxillary third molar
develops in the maxillary tuberosity and
generally erupt vertically as the maxillary bone
enlarges, impaction against the second upper
molar may therefore occur where maxillary
growth is inadequate.
• The third molar therefore remains vertically
below the second molar or gets displaced
distally.

24. • The high prevalence of third molar impaction
in the mandible is probably due to the short
mandibular arch length and the fact that the
mandible curves upward (forming the angle)
around the region of the third molars making
impaction more likely.

25. Conclusion
• The prevalence of third molar impaction in the
population studied was 21.2% and the affected
population was significantly younger than the
unaffected.
• Compared with other studies, prevalence of
impaction increases with increasing
modernisation with the mandible having more
impaction than the maxilla.

26. THANK YOU