Third Molar Clinical Studies
Summary of Data
Third molar clinical studies were
initiated because of the scarcity
of published scientific data on
the incidence of pathology
associated with retained third
molars, and on outcomes after
third molar surgery. Thesetargeted studies focused in threeareas:

adjacent to the periodontal site
contains immune system cells
that, in response to the threat
posed by the pathogens, produce
what are called “inflammatory
mediators.” Unfortunately these
mediators destroy local tissue
and produce a systemic
inflammatory response.

cardiovascular disease suggested
that few subjects, less than 2%,
had disease-free third molars.
Why are third molars,particularly lower third molars,
prone to accumulate periodontal
pathogens?
When all other teeth erupt, thejaw is still growing and sufficient
jaw space to accommodate theteeth is not a problem. The
situation differs for third molars.

Periodontal probing depth refers
to the space between gum andtooth, and reaching under the
gum line that is readily
2. analyses of the impact of third
On average, jaw growth isaccessible with a dental probe.
molar surgery on the subjects’
The more shallow the depth, the complete by age 18; yet, the peakquality of life; and,
eruption of third molars at 19.5
better. Once deep periodontal
3. analyses of third molar data
probing depths exist around third years. Thus, third molarfrom population and clinicalemergence is often incomplete,molars, third molar removal isstudies conducted for otherleaving deep probing depths that
effective treatment. In study
purposes.
are conducive to the collection
subjects with third molar
and reproduction of anaerobic
periodontal
pathology,
removalTwo-thirds of the young adultpathogens. Once established,has
improved
periodontal
statussubjects with symptom-free third
not only on teeth adjacent to third these bacteria can spread tomolars, were found to haveadjacent molars and other teeth.
periodontal pathology in the third molars but also on teeth more
forwardinthemouth.
molar region. This indicates that
A recent review of population
1. analyses of outcomes withsubjects who retained third
molars;an absence of symptoms does not The prevalence of periodontal
and clinical studies totaling overequate to an absence of disease. pathology encountered in the
8,000 subjects suggests that thepresence of third molars is
studiessuggeststhat
few
In a subsequent study,
associated with a worsened
individuals
arewithout
third
periodontal pathology affectedperiodontal status on other teethmolar
pathology.
Eightypercent
four-fifths of the subjects who
as compared to when third
of
young
adult
subjects
had third molar symptoms when
(averaging 25 years of age) with molars are absent. In addition,
they enrolled. Over time, those
average third molar probing
subjects had increased odds of a no previous symptoms had
depths were always deeper thandeveloped
periodontal
pathology
deteriorating periodontal
average probing depths on teethorcariesexperience
withinseven
condition not just around thetoward the front of the mouth.
years.
Cross-sectional
data
were
third molars but also other teeth.
obtained from 800 seniors who
Data from those subjects having
These findings are compatible
averaged 72 years of age andthird molar surgery confirmedwith known models of
were studied for oral healththat more difficult surgery leads
periodontal inflammatory
status; a fifth had retained at least to delayed clinical healing, anddisease, which results when thesome third molars pathology
older age at surgery is associatedanaerobic pathogens that havefree. In contrast, cross-sectional with more post-surgery pain andcollected in deep periodontal
oral health data of retained third delayed return to usual lifestyleprobing sites react to themolars from a study of 6,700
and oral function.
patient’s immune system. Tissue subjects enrolled to study

Why are data on third molar
pathology so limited?
No clear answer exists. In a
recent review of periodontal
studies by Savage et al, third
molar periodontal data were
either not collected, or they were
excluded from analyses.
Subsequently, Eke et al studied
methods for estimating theprevalence of periodontal

pathology in population andclinical studies, and suggested
that the current reported
prevalence may be higher if third
molar data were collected.
Do options exist to third molar
surgery since so many
individuals are affected?
Currently, no. However, studies
currently underway suggest that,in the future, the anaerobic
bacteria colonized in deep
periodontal probing sites might
be altered in such a way thatvirulence factors are notexpressed, which, in turn, would
lead to an immune system
response that does not destroy
tissue.