Comparison of three periapical techniques in distinguishing the roots of maxillary second molars and preventing superimposition

Introduction: A good radiograph with appropriate tube angulation can provide the dental practitioner with useful data, especially in multi-rooted teeth. The aim of this study was to compare three techniques of mesial tube shift, parallel and bisecting angle in preventing superimposition of zygomatic arch and the buccal and palatal roots of maxillary second molars on periapical radiographs. Materials and Methods: In this cross-sectional research, 240 periapical radiographs were taken with the mesial tube shift, parallel and bisecting techniques, from 80 maxillary second molars (80 radiographs from each technique). Each radiograph was scored from 0 to 4, based on superimposition of zygomatic arch and the roots. Chi-squared test was used for data analysis (α = 0.05). Results: The results of this research showed that in 73.8% of cases the parallel technique had separated the root canals from the zygomatic arch; the separation was 57.7% in the mesial tube shift technique but only 40% in the bisecting angle technique. There were statistically significant differences between the three techniques (p value < 0.05). Conclusion: Based on the results of this study, in the mesial tube shift technique separation of zygomatic arch from the roots of maxillary second molars was observed, but roots were superimposed on each other. However, in the parallel technique the roots and the zygomatic arch were separated without any superimposition. Mesial tube shift technique is the second choice in patients in which the parallel technique is not feasible; the bisecting angle technique is not recommended because of the superimposition of zygomatic arch on the roots. Key words: Localization, Radiography, Zygoma