Panoramic radiograph is a routine investigation tool in orthodontic diagnosis and treatment planning however the limitation of two-dimensional image in assessing the position of impacted canine and surrounding tissues had cause unnecessary treatment options and complications during treatment. This report highlights the differences in investigation outcome and orthodontic treatment planning of two similar cases of patients with impacted upper canine, in which one only had panoramic radiograph and another case supplemented with Cone Beam Computed Tomography (CBCT). The case supported only by panoramic radiograph had changes in treatment planning during canine removal surgery as prevention from oro-antral fistula. This event could have been prevented if CBCT was taken where the canine can be assessed for proximity towards maxillary sinus. It is recommended for CBCT in orthodontic assessment for canine impaction especially for cases where canine is positioned higher than root apex of adjacent teeth and when root resorption is suspected.