Dental aesthetics are a key factor in overall physical attractiveness, which also contributes to self-esteem. This is one of the main reasons for patients to consider or undergo orthodontic treatment. Like any other medical intervention, orthodontic treatment has, in addition to its benefits, also associated risks and complications. In orthodontics, the risk of "doing harm" is considerably lower compared to other medical interventions, e.g., the surgical ones. However, during the medical act, through usage of various procedures, devices and materials, there might appear unwanted side effects, both local (tooth discolorations, decalcification, root resorption, periodontal complications) and systemic (allergic reactions). An increased risk of complications may contraindicate the orthodontic therapy or influence its objectives, phases and conduct, aspects directly linked with the quality of the final outcome and prognosis. Generally speaking, the consecutive benefits of the medical intervention must overcome any potential damage. The book highlights the risks associated with orthodontic treatment.