The primary goal of this research is to calculate the effective doses of dental X-ray devices using standard scanning techniques. The equivalent dose in the eye lens, thyroid, left parotid, and right mandible, was measured in pediatric patients undergoing a dental orthopantomography (OPG), Cone-beam Computed Tomography (CBCT) and intraoral left bite-wing. Measurements were carried out on a pediatric phantom with thermolmuminiscent dosimeters at the University of Sharjah Dental hospital. Mean effective doses with their standard deviations were calculated using tissue weighting factors recommended by ICRP. The exposure factors (mAs and kVp) were altered and the effect on the effective dose of the five organs in the three imaging modalities was studied. This study showed that the 20% increase in kVp doubles the effective dose. Also, the effective dose increased linearly when the mAs were raised. The effective doses varied considerably among and within the radiosensitive tissues of interest. The highest effective doses were obtained in the right mandible in all imaging modalities under all exposure factors. The total effective dose of dental CT received by all organs of interest was 0.3517 mSv, and that of dental panoramic machine (OPG) and intraoral radiography were 0.0693 and 0.0268 mSv, respectively. Among the three dental X-ray devices studied, dental CBCT scan causes much higher effective dose than the other two: effective dose received in a CBCT is 5 and 16 times greater than that received in OPG and intraoral, respectively. Doses were compared with published data and the findings were consistent with the literature. Some of the limitations of the current study were discussed.