Additional teeth to the normal dentition are called supernumerary teeth; they can be found in higher rates in permanent than in deciduous dentition, in both sexes, associated or not with other diseases or syndromes. The aim of this article is to report three rare cases of unilateral supplemental lateral incisors, in Romanian child and adult patients, and to evaluate the treatment options in each case, considering particularities such as age, physiognomy, associated issues and occlusion. The differential diagnosis between a supernumerary lateral incisor in formation and a rudimentary is sometimes difficult to make using only panoramic X-ray, so a cone-beam computed tomography analysis can be indicated. Usually, due to the pathological issues that they can cause, the supplemental maxillary lateral incisors are removed; although, in some cases, it may be necessary to remove the normal tooth, for example in cases of major crowding, in which the normal tooth is more displaced from the line of the arch than the supplemental one, or when there is a lack of periodontal support surrounding the normal tooth. This article highlights that even if, in younger patients, the majority of these teeth is extracted because later in life they can cause difficulties in orthodontic and prosthetic treatment, there are still rare cases which do not necessitate treatment, because they are asymptomatic, rather well aligned and go unnoticed. Also, the article includes a detailed literature review of reported cases of supplemental maxillary lateral incisor.