Introduction: One of the fractal analysis methods to examine the structure of a texture is fractal dimension (F.D.) measurement. F.D is a quantitative method to show the complexity of a structure using a number. The aim of this study was to determine the effect of different exposure conditions, voltages and angle of x-ray tube on F.D. values of mandibular bone.
Methods: This lab-trial analytical research was conducted on ten healthy, non-fracturing human mandibles. Periapical digital images were obtained by the Peri-Apical Focus (Planmeca, Finland) with a constant time of 0.2 seconds and changes in exposure conditions and angle of the tube. Periapical radiographs were obtained with 2 kV voltages of 60, 70, with2 mA of 400, 500, and 3 tube angles of -5, 0, +5 degrees. Data was analyzed by SPSS version 16 software  and Kolmogorov–Smirnov test, mann whitney test‌and ANOVA test.
Results: No significant difference was observed in fractal mean values between 60 and 70 kVp and among 5-, 0, 5+ degrees in all 10 mandibles.There was a significant difference between the 400 and 500 mA just in one case (p≤0.05).
Conclusion: Considering the incompatibility of the amount of calculated fractal dimension from kVp, mA and tube angle, this method can be used as a useful tool in dentistry to examine the structure of spongy bone and its changes in various pathological conditions. Then, standardize the periapical imaging technique to compare it is not necessary.