Objective: This study aims to measure the trueness of post space scans using 3 intraoral scanners with 2 post cervical diameters.

Materials and Methods: A sample of 18 single-rooted mandibular second premolars, was collected for this study. These teeth exhibited root dimensions just below the CEJ, with mesiodistal and bucco-lingual ranges of 5-6 mm and 5-7 mm, respectively. Root-canal treatment was done for the 18 premolars. Subsequently, the crowns were reduced in height to remain 2 mm above the CEJ then preparation of the post space was done. After the preparation of each root, the corresponding teeth were allocated randomly to two groups (n=9/ group) according to the cervical diameter of the preparation. Group A: 2.5 mm and Group B: 3 mm. All teeth were scanned using (inEos X5 Sirona- Germany) to produce a reference scan, then scanning of post space directly using 3 intraoral scanners for all teeth.

Results: In Group A, the highest value was found in Trios (86.08±2.50), followed by Medit (85.35±5.46), while the lowest value was found at Prime Scan (36.21±4.36).

In Group B, the highest value was found in Trios (39.55±4.49), followed by Prime Scan (38.27±4.93), while the lowest value was found at Medit (37.48±10.37).

Conclusion: On the basis of the results and conditions of this study, the following conclusions can be drawn, Prime scanner is recommended for higher trueness value for direct post space scanning then followed by Medit. While trios have the lowest trueness value. Scanners that employ the confocal microscopy technology have the highest levels of trueness.