Root resorption is the destructive process of the cementum and/or dentine layers of a tooth root due to clastic cell activity which leads to a subsequent loss root structure of a tooth. This process may be physiological or pathological. Physiological root resorption of deciduous teeth naturally occurs when the permanent teeth begin to erupt. It may also occur to a small degree in the permanent dentition associated with physiological tooth movement.1 Pathological root resorption has been related to orthodontic tooth movement, trauma, and ectopic eruption of adjacent teeth and in association with other pathology. Root resorption is an unpredictable, unavoidable pathologic consequence that occurs during orthodontic tooth movement. Fortunately in the majority of cases, root resorption is minimal. There are many possible causes to root resorption as a sequel of orthodontic treatment with fixed appliance. It is therefore essential for a clinician to be aware of these factors, to be able to estimate the risk of root resorption individually for each patient.