Abstract:

Objective

To evaluate the usage of angulated radiography technology in periapical film of MB2 root canals maxillary first molars and seek better shooting method using digital imaging system.

Methods

Two hundred maxillary first molars with MB2 root canal were selected from clinical case. Radiographs of 100 teeth were taken with every 10 degrees from distal to mesial direction by bisecting angle technique. Meanwhile， radiographs of 50 teeth were taken with different exposure time，while the other half were taken with different position of sensor. The radiographs were identified and recorded by 2 independent doctors. Data of discriminant rate， clarity and integrity of radiographs were analyzed by Chi-square test using SPSS 16.0.

Results

Discriminant rate of MB and MB2 of radiographs taken by 30 degrees from distal direction was the highest （94%）， which was significantly higher than that of orthotopic radiographs （10%）（χ²=84，P=0.000）. With the same angular， discriminant rates of radiographs taken from distal direction were better than mesial direction （30°：χ²=18.382，P=0.000；20°：χ²=16.282，P=0.000；10°：χ²=14.019，P=0.000）. Clarity of radiographs taken from distal direction were aslo better than mesial direction （30°：χ²=7.848，P=0.005；20°：χ²=12.033，P=0.001；10°：χ²=14.700，P=0.000） and the clarity were 78%， when radiographs were taken by more than 20 degrees from mesial direction increasing exposure time by 1/4. The change of position of sensor may improve integrity of radiographs 94%.

Conclusions

Taking radiographs from distal direction is the best way to show MB2. If taking radiographs from mesial direction， the angular and exposure time should increase. The position of sensor should be considered as an important factor which influences the quality of image directly.

Key words: Periapical angulated projection, Maxillary first molars, Second mesiobuccal canal, Periapical films