**1. Introduction**

Parallax is the effect whereby the position of a tooth or similar structure appears to differ when viewed from different positions of the X-ray tube.[1] This method (Image/Tube Shift Method, Buccal Object Rule or Clark's Rule) has been the technique of choice to localize impacted teeth anterior to the molars in both jaws using Vertical or Horizontal Tube Shift (VTS /HTS).[2] With the continued technologic advances, the role of Cone Beam Computed Tomography (CBCT) is changing in orthodontic workup and should be viewed as complementary to plain X-rays or 2D X-rays in effective diagnosis, especially in impaction cases as a 3D evaluation. Effective dose of radiation measured in micro-Sievert (µSv)) is decreased from full field of view (FOV) to both jaws (13 cm) and single jaws (6 cm), from large-volume to small-volume and from high resolution (HR) to conventional.[3] Therefore, as the effective dose is of foremost concern, it can be decreased by appropriate selection of exposure parameters, FOV and resolution (only for impacted tooth/teeth) to be comparable from a "dose" perspective with several periapical and occlusal radiographs (parallax). However, the results of dosimetry on a specific CBCT scanner may not be transferable to another CBCT scanner and every image involving ionizing radiation, including CBCT, must be justified and optimized.

The treatment (including decision makings) of impacted teeth can be categorized into five steps:


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	- **a.** Anchorage preparation (Direct vs. Indirect)
	- **b.** Force application
