Modified Bisecting Angle Technique: A Novel Method to Eliminate Zygomatic Superimposition over the Apices of Maxillary Molars

Objectives Intra oral radiographic imaging is the most widely used method for obtaining information about root canal anatomy and working length determination. Measuring exact working length is the most essential step for the success of root canal treatment. Bisecting angle technique (BAT) is the most widely used technique for this purpose. However, zygomatic superimposition over the apices of maxillary molars makes it difficult for the dentist to estimate exact working length. The present study made certain modifications in BAT to overcome these undiagnostic shadows. The aim of the study is to compare three techniques, namely paralleling cone technique (PCT), BAT and modified bisecting angle technique (MBAT) to prevent such superimposition over molar apices. Materials and Methods A total of 53 patients requiring endodontic treatment for maxillary molars were included in the study. Three radiographs one with each PCT, BAT, MBAT were made. Each radiographic image was recorded acceptable or unacceptable based on the zygomatic superimposition. The data thus collected was subjected to statistical analysis using chi-square test. Results The percentage of acceptability in MBAT was 56.6% (n = 30) when compared with BAT which was only 28.3% (n = 15) and PCT was 58.3% (n = 31) indicating statistically significant difference between BAT and MBAT. But no statistically significant difference was found between MBAT and PCT. Conclusion In the present study, MBAT was found to be more accurate than BAT, and it was relatively as accurate as PCT in eliminating zygomatic superimposition over the apices of maxillary molars.

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.

The accuracy of the radiographic method in root canal length measurement / 대한구강악안면방사선학회지

For the successful endodontic treatment, root canal should be cleaned thoroughly by accurate mechanical and chemical canal preparation and sealed completely with canal filling material without damaging the periapical tissues. The accuracy of the root canal length measurement is a prerequisite for the success of the endodontic treatment, and the root canal length is often determined by the standard periapical radiographs and digital tactile sense. In this study, the accuracy and the clinical usefulness of Digora(R), an intraoral digital imaging processor and the conventional standard radiographs were compared by measuring the length from the top of the file to the root apex. 30 single rooted premolars were invested in a uniformly sized blocks and No.25 K-file was inserted into and fixed in each canal. Each block was placed in equal distance and position to satisfy the principle of the bisecting angle and paralleling techniques and Digora(R) system's image and standard periapical radiographs were taken. Each radiograph was examined by 3 different observers by measuring the length from top of the file to the root apex and each data was compared and analyzed. The results were as follows; 1. In the bisecting angle technique, the average difference between the Digora(R) system and standard periapical radiograph was 0.002 mmand the standard deviation was 0.341 mmwhich showed no statistically significant difference between the two systems(p>0.05). Also, in the paralleling technique, the average difference between these two system was 0.007 mmand the standard deviation was 0.323 mmwhich showed no statistically significant difference between the two systems(p>0.05). 2. In Digora(R) system, the average difference between the bisecting angle and paralleling technique was -0.336 mmand the standard deviation was 0.472 mmwhich showed a statistically significant difference between the two techniques(p 3. In Digora(R) system and the standard periapical radiographs, there was a statistically significant difference between the measurement using the bisecting angle technique and the actual length(p0.05). In conclusion, the determination of the root canal length by using the Digora(R) system can give us as good an image as the standard periapical radiograph and using the paralleling technique instead of the bisecting angle technique can give a measurement closer to the actual canal length, thereby contributing to a successful result. Also, considering the advantages of the digital imaging processor such as decreasing the amount of exposure to the patient, immediate use of the image, magnification of image size, control of the contrast and brightness and the ability of storing the image can give us good reason to replace the standard periapical radiographs.