Objective
To assess the image quality of the mandibular third molar region using different milliamperage (mA) settings of cone-beam computed tomography.
Methods
Twelve dry mandibles with impacted third molars were scanned with a Kodak 9000 unit (Kodak Dental Systems, Carestream Health, Rochester, NY, USA) using different mA settings (2, 4, 6.3, 8, 10, 12, and 15 mA). Two oral radiologists evaluated the images. They classified the tooth root, periodontal space, lamina dura, trabecular bone, mandibular canal, and overall image quality as excellent, good, poor, or inadequate for diagnosis. Statistical analyses were performed by one-way ANOVA with a post hoc Tukey test to investigate the influence of the mA settings in the image quality of the structures analyzed. The significance level was set at 5 %.
Results
The 15 and 12 mA settings provided the highest mean values for all the evaluated criteria, with significant differences from the values for the other mA settings. The 10, 8, and 6.3 mA settings showed no significant differences in relation to tooth root and periodontal space. For the other evaluated criteria, no significant differences were observed for the 10 and 8 mA settings. The 4 and 2 mA settings gave the lowest mean values.
Conclusions
The best low-dose protocol with good image quality was the 10 mA setting. Lower dose protocols with 8 and 6.3 mA settings can also be used for these purposes, but caution is necessary because of increased image noise.