 Indications of CBCT, according to the SEDENTEXCT (Safety and Efficacy of a New and Emerging Dental X-ray Modality) guidelines include

Developing dentition


Restoration of dentition (if conventional imaging is inadequate)


Surgical


The concept of parallax was first introduced by Clark in 1909.It is defined as “the apparent displacement or difference in apparent direction of an object as seen from two different points not on a straight line with the object”.It is used to overcome the limitations of the 2D image in the assessment of relationships of structures in a 3D object.