Modified bisecting angle technique in eliminating zygomatic superimposition over apices of maxillary molars.

Background: Image superimposition is a part and parcel of two‑dimensional radiography. However, some overlappings are a result of radiographic technique itself. The technique induced superimposition of zygomatic buttress on apices of maxillary molars is common in bisecting angle technique (BAT), which affects the endodontic performance. Certain alterations were carried out in BAT to remove these undiagnostic shadows. The aim of this study was to compare two techniques of periapical radiography namely, BAT and modified BAT (MBAT) in preventing zygomatic superimposition over apices of maxillary molars. Materials and Methods: A total of 62 patients requiring endodontic treatment for at least one maxillary molar were recruited in this cross‑sectional study. One tooth from every patient was subjected for two periapical radiographs, one with each BAT and MBAT respectively giving a total of 124 radiographs. Each radiograph was recorded as acceptable or unacceptable, based on zygomatic superimposition and different technical aspects. Chi‑square test was used for data analysis. The kappa statistic was used to test intra‑observer reliability. Results: With MBAT, the acceptability was 82.3% (n = 51) compared with 43.5% (n = 27) when BAT was employed. The statistically significant difference was found between these two techniques (P = 0.000). The level of agreement between two oral radiologists in their interpretation was high (kappa index = 0.897). Conclusion: Modified BAT was more accurate for periapical radiography of maxillary molars in preventing zygomatic superimposition and related technical errors than BAT.

Validity Of The Parallax Method With A Combination Of Imaging Receptors ' A Revisit

To determine the amount of displacement of a structurenoticed on an image when the tube of a dental X-raymachine was shifted vertically and horizontally. Inaddition, various intraoral images were combined withdental panoramic images to determine the location ofstructures. Our research is based on the parallaxtechnique which requires manipulation of horizontaland vertical angulations of the X-ray tube. A metalobject is positioned on the buccal and palatal side ofthe maxilla on the canine area of a skull. The X-raytube is shifted incrementally to obtain images onphosphor plates. Subsequently, panaromic and occlusalimages were taken to assist in localization of the metalobject. To obtain a clear image shift of 2-3mm usingthe parallax method, there must be an adequatehorizontal tube shift of approximately 30-35 degrees.When images were used in combination of dentalpanoramic images, it was found that the buccallyplaced structures can be accurately located with theperiapical or occlusal images. However, thedisplacement of images in the palatally placedstructures in panoramic imaging is not fullyappreciated with the principle of parallax method. Tubemovement of 30-35 degrees horizontally is needed fora 2-3 mm image shift. To successfully localize a buccalstructure, a combination of either periapical or occlusalimages with a dental panoramic imaging can beemployed. However, this combination with panoramicimaging is limited when looking at palatally placedstructures.