Introduction: Radiographs are often used in many branches of dentistry to assess linear measurements and mandibular indices to allow quantification of mandibular bone. The purpose of this study was to evaluate the efficacy of the most frequently used digital radiographic techniques in dental measurements; digital intra-oral periapical radiography using PSP system, CBCT multiplanar reformation “cross sectional images”, and digital panoramic radiographic images derived from conventional and CBCT generated methods, regarding their indices and linear measurements’ accuracy in different anatomical sites in dry human mandibles compared to the gold standard direct measurements by a digital vernier caliper.Materials and Methods: Five dry human adult mandibles of unknown age or gender were used in our study. Gutta-percha was used as radio-opaque markers to verify the correct sites of the mental, mandibular and lingual foramina in radiographs. The mandibles’ outer surfaces were covered by pink set up modeling wax in order to simulate soft tissues. Radiographic indices and linear measurements obtained from the different digital imaging modalities were compared with the direct real measurements performed by using 0.01 mm precision vernier digital caliper. Direct measurements of the mandibles were considered the gold standard. Measurements were obtained separately from the right and left mandibular sides ending up with ten evaluated samples. All direct real and digital radiographic measurements were obtained in millimeters.Results: "Excluding M/M index and M/M index half MF". There was no statistically significant difference between all indices measurements’ means and the real ones. Regarding linear measurements; Most of linear measurements’ means showed no statistically significant underestimation; except superior R.O. point to the lower border of the mandible which was significantly underestimated in the digital, auto and manual reformatted panoramic. Meanwhile, superior R.O. point to the upper border of the mandible was significantly overestimated in manual reformatted panoramic.Conclusion: There was no statistically significant difference between most of linear & indices measurements’ means and the real ones. Radiation dose to patients must be concerned. Conventional digital panoramic radiographs must not be replaced by CBCT images, but CBCT should be taken only if there is a clear indication. M/M index is mostly used to assess the level of bone resorption. In our study M/M index and M/M index half MF were statistically significant overestimated when measured in all modalities in our study. Thus shown to be unreliable.