Maxillary molar transposition.

To date, five types of maxillary tooth transposition are described in the international literature (canine/first premolar; canine/lateral incisor; lateral incisor/central incisor; canine/central incisor site; canine/first molar site), although the latter two are indeed extreme displacements and not true transpositions. In the present article a sixth type of transposition is recognized and described: the maxillary molar transposition (MxM3M2 and MxM4M3, respectively). Three cases of this anomaly were presented. The occurrence is extremely rare, about 0.04 percent in a sample of 7,000 orthodontic patients. Investigation of other family members (especially parents and siblings) could not substantiate an hypothesis of inheritance of this anomaly. Other possible causes (trauma, caries, tooth agenesis) were also absent in these cases.