Evaluation of dimensional accuracy of panoramic cross-sectional tomography, its ability to identify the inferior alveolar canal, and its impact on estimation of appropriate implant dimensions in the mandibular posterior region.
OBJECTIVE
To evaluate the dimensional accuracy of panoramic cross-sectional tomography, its impact on implant size estimation and its ability in identifying the inferior alveolar canal in the mandibular posterior region.


METHODS
Eight partially edentulous mandibles with 18 edentulous sites were obtained. Orthopantomograms and tomograms were made and the mandible's outline and the position of mandibular canals on tomograms were traced on a clear acetate paper. Horizontal and vertical magnification factors were calculated. The mandibular height, distance between mandibular canal and alveolar crest, maximum bucco-lingual width, distance between buccal cortex and mandibular canal, and cortical thickness at the inferior border of the mandible were measured. Potential implant sites were identified and implant sizes were estimated. Location and visibility of mandibular canals were also evaluated. The mandibles were sectioned at each site and all the above mentioned parameters were assessed which served as gold standard.


RESULTS
Mean horizontal and vertical magnification factors were 1.47 ± 0.048 and 1.53 ± 0.038. Total height and maximum bucco-lingual width were underestimated by 1.88% and 1.59%. Crest to canal distance, cortical thickness at the inferior border of the mandible and buccal cortex to mandibular canal were overestimated by 0.59%, 5.16%, and 3.64%. Implant sizes were estimated for 11 sites and changes were recorded at 2 sites between record 1 and record 2. However, there was no disagreement between record 2 and record 3. Of the canals, 61.11% were located lingually and the visibility of mandibular canals was poor in 44.44% of cases.


CONCLUSIONS
The tomograms were found to be accurate for the measurements in both horizontal and vertical planes and reliable for implant size estimation, taking into consideration proper magnification factors. They were also found to be useful in assessing the location of mandibular canal but were not very effective in discerning it.
Mehra
Anshul
A
Department of Oral Medicine and Radiology, U.P. Dental College and Research Centre, Faizabad Road, Lucknow, Uttar Pradesh, India. mehraanshul@yahoo.co.in
Pai
Keerthilatha M
KM
D000539:Alveolar Process / Q000000981:diagnostic imaging; D019412:Anatomy, Cross-Sectional; D002102:Cadaver; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D057918:Fiducial Markers; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000000981:diagnostic imaging; D008334:Mandible / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008340:Mandibular Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D015588:Observer Variation; D011858:Radiographic Magnification; D011862:Radiography, Panoramic / Q000379:methods*; D012015:Reference Standards; D015203:Reproducibility of Results; D014056:Tomography, X-Ray / Q000379:methods*
D015921:Dental Implants