Fusion of mandibular third and supernumerary fourth molars.

Fusion of the permanent molars is a relatively uncommon dental anomaly. In this article, a case of fusion of a symptomatic mandibular third molar with a supernumerary fourth molar is reported. The differentiation with other forms of 'double teeth' is explained and the possibility of the initial panoramic radiograph view being misinterpreted as an artefact is discussed.