Value of NewTom 3G Cone Beam CT for the detection of periapical lesions

Early diagnosis and treatment planning of periapical lesions in maxillary and
mandibular posterior teeth.

Primary objective: to assess the healing rate of apical periodontitis in cases
that received a root canal (re)treatment, with the use of the cone beam
computed tomography (NewTom3G) at the first or second year of recall.

Secondary objective: to compare the diagnostic efficacy of intraoral digital
periapical radiographs and cone beam computed tomography (NewTom 3G), regarding
the detection of periapical lesions in maxillary and mandibular posterior teeth
(molars and premolars) with a preliminary or suspected diagnosis of apical
periodontitis.

For the primary objective : a cohort study without a control group is conducted
For the secondary objective: a cross-sectional study is conducted.

The study protocol involves obtaining one intraoral periapical radiograph for
each tooth with a suspected periapical lesion plus a Cone Beam Computed
Tomography scan for the whole dentition. The benefits of 3D CT imaging over
periapical radiographs regarding the diagnosis of periapical lesions and the
subsequent treatment planning proved to be substantial in several previous
in-vitro and few in-vivo studies (Stavropoulos, Wenzel 2007, Velvart et al.
2001, Huumonen et al. 2002, Huumonen et al. 2006, Lofthag-Hansen et al. 2007).
CT scans can provide all the information required for diagnosis and treatment
planning in a single study which can reveal unsuspected pathosis frequently
missed by conventional 2D projection imaging due to image superimposition.
The radiation dose involved in Cone Beam CT is higher than that with a single
2D periapical radiographs alone (5-10 times higher) and varies with respect to
several scanning parameters including the selected field of view, tube current
and potential and exposure time * typical values are within 30-50 µSv * (Ludlow
et al. 2006). The field of view of a CBCT examination however is larger than
that of a single periapical radiograph. Certainly for multi-rooted teeth, often
more than one intraoral radiograph is required to collect all information
needed.
In addition, the total radiation dose delivered by CBCT is much less than that
of Medical Computed Tomography which was also previously prescribed for
endodontic treatment (Huumonen et al. 2006). In our study, the radiation dose
will be kept to a minimum by employing an optimized patient scanning protocol
and collimation of the scanning field to the region of interest (ROI). All
measures will be taken to minimize the net radiation dose to each patient in
concordance with the ALARA principle (as low as reasonably achievable)
Both radiographic equipments are available at the radiology department of ACTA
and all necessary scans can be performed in a single visit with no extra burden
to the patient. The duration of the scanning procedure for Cone Beam CT is 30
seconds with an effective exposure time of 5.4 seconds which is the lowest
effective exposure time in the industry in comparison with other Cone Beam CT
systems (Ludlow et al. 2006). The complete procedure lasts 5-10 minutes.