Maxillary canine anomalies and tooth agenesis.

The aims of the study were to analyse the records of 26 subjects (18 females, eight males) with maxillary canine-first premolar transposition (Mx.C.P1) together with 160 subjects with a palatally displaced canine (PDC) to determine the pattern of tooth agenesis in these cases and to compare them with similar samples reported in the literature. A strong association between Mx.C.P1, lateral incisor and lower second premolar agenesis was found, with a 20 per cent prevalence of lateral incisor agenesis and a 24 per cent prevalence of lower second premolar agenesis. There was a lesser association with third molar (M.3) agenesis, with a prevalence of 52.2 per cent. Weaker associations were found for a PDC, with a prevalence of 5 per cent for lateral incisor agenesis. The prevalence of lower second premolar (5 per cent) and M.3 (27.5 per cent) agenesis approached reference values. Evidence for the implication of the MSX1 or PAX9 genes in the aetiology of PDC was weak.