A technique to locate Ricketts' Xi point in 3D CBCT images: A cross-sectional study

To develop a protocol for locating the Xi point using three-dimensional (3D) cone-beam computed tomography (CBCT) and to evaluate the linear distance between the Xi point and the mandibular foramen on the CBCT image.

A retrospective cross-sectional study.

The study was conducted on standardised CBCT records of 35 patients aged >18 years (13 men, 22 women). The CBCT scans were analysed using Dolphin 3D 11.9 software.

The Xi point was constructed on the right and left lateral views of the ramus using the four points R1, R2, R3 and R4 based on Ricketts' analysis. The mandibular foramina were located on CBCT and the linear distance from the mandibular foramen to the Xi points were recorded.

The 3D Xi point was located on the lateral surface of the mandibular ramus superior and distal to mandibular foramen. The mean distance of the Xi point from the mandibular foramen was 2.3 ± 1.46 mm on right side and 2.3 ± 1.53 mm on left side.

The study identified the accuracy of Xi point construction and its linear relation to the mandibular foramen. Xi point validation in relation to the mandibular foramen serves as a guide for inferior alveolar nerve course identification. The results of the study also find applications in bone screw placement and growth prediction.