In superior image quality of P.S.P image

In present study, we have
observed that number of voids can be easily identifiable on R.V.G (2-D) evaluation
compared to C.B.C.T (3-D) evaluation. This great difference in the number of
voids was the limitation of C.B.C.T image. C.B.C.T image
quality is altered by streaking artifacts (due to beam hardening effects) which
appear as dark bands of fracture lines with cuppings, streaks or hypodense
halos at edges around radiopaque materials (root fillings materials, sealers, implants,
root canal pins, guttapercha cones, metal post and crowns) or even by high density neighbouring structures like enamel12,13,24.

These artifacts and dimensional alterations related
to C.B.C.T images can be reduced only by using a less dense materials and new
software of artifact reduction algorithams24.  So C.B.C.T decreases the
diagnostic value, as it causes misdiagnosis which indicates that periapical
radiograph is better25.
Voids might be sheltered by artifacts caused by root canal filling materials or
artifacts may mimic the voids, which shows poor performance of CBCT in void
detection26. So due to
this uncertainity about the dark areas, C.B.C.T is not recommended for assessment
of root filling quality27.

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Greater volumetric distortion(9-100%)  were seen in root canal fillings (both in
sealer and obturating material) and it is more for sealers when C.B.C.T images
were compared with Micro–computed tomographic images(gold standard for
endodontic evaluations)24. According
to Song et al C.B.C.T is superior to
periapical radiograph for evaluating the apical extension of root canal
obturation, but it is inferior in evaluating the void detection26.

Spatial resolution of C.B.C.T (0.6 to 2.8 line pair
millimetre) is lower than intra oral radiographs (which gives high-resolution image)11. In a study by Brito et al R.V.G and C.B.C.T showed similar
radiographic accuracy for separated instruments in unfilled canals, while in
filled canals a better accuracy was shown by R.V.G28. Sogur et al in his study on evaluating the homogenicity and length of
root fillings in single rooted teeth, found superior image quality of P.S.P
image and conventional film images compared to those of C.B.C.T images15. According to present study, R.V.G was
superior to C.B.C.T in detecting voids. This is in accordance with the study
conducted by Huyberchats et al, in
which he concluded that digital intra oral type perfomed better than C.B.C.T
for detecting voids sizes smaller than 300µm29. CBCT was found to be
inferior to intra oral techniques when assessing the teeth with insufficient
condensation and teeth with overfilled canal treatment11.

In the present study we observed that lentulospiral
technique is better compared to insulin syringe or endodontic plugger for
obturation quality. High resolution 2-D radiographic techniques will supplement
the 3-D C.B.C.T scans and thus the benefits of each system may be harnessed11,12. The vast contrariety of discrepancies
seen in the present study and previous studies is due to the differences in the
type of material and teeth used, sample size, needle thickness, technique used
and often influenced by operators skill and experience.

In-vitro
nature of the study limited to incisors and lesser sample size are the
drawbacks of this study. Further in-vivo
studies are required to evaluate obturation quality by different techniques.