Introduction: Worldwide research has shown that mandibular third molars are the
most often impacted teeth in the jaw, followed by maxillary canines then mandibular
premolars. Impacted third molars may be associated with several pathologies related
to impacted tooth itself or adjacent second molar such as periodontal problems, root
resorption and distal caries of adjacent teeth. Aim: The purpose of the present study
was to determine the prevalence of distal surface caries in mandibular second molars
adjacent to impacted third molars in a sample of Ismailia population using CBCT.
Methods and Methods: The present study was conducted on 196 unidentified CBCT
scans selected from the archives of the Oral and Maxillofacial Radiology Department,
Suez Canal University. Demographic data regarding (gender), side of impaction
distribution and impaction angulation was assessed. Angulation of impacted third molar
was evaluated using Winter's classification, then radiographic assessment for each scan
was carried out using On-Demand software to determine the presence and prevalence
of coronal and radicular caries on the distal surface of the second molar adjacent to
impacted mandibular third molars. Additionally, correlation of the associated risk
factors for caries occurrence was carried out. Results: The results of the current study
revealed that mesio-angular impaction was the most frequent type of impacted third
molar (63.8%) followed by horizontal impaction (17.3%). The prevalence of DSC
for both coronal and radicular distal caries, was 8.7% with relatively higher female
predilection and higher occurrence in association with mesio-angular and horizontal
types of impactions. Conclusion: Cone Beam Computed Tomography being a threedimensional
imaging modality, is considered an accurate and precise radiographic
modality that can be reliably used for early detection of distal surface caries. Moreover,
the presence of DSC in mandibular second molar adjacent to impacted third molars
among Ismailia population is relatively low and is more related to mesio-angular and
horizontal type of impaction.