Ankylosis of primary molar along with congenitally missing first permanent molar

Ankylosis of primary mandibular molars has been routinely found to be associated with various developmental disturbances in permanent dentition such as aplasia of the succedaneous tooth, ectopic eruption of the premolar, infraoclusion of the ankylosed tooth leading to tipping of the first permanent molar etc. This article describes a rare case where there was ankylosis of a mandibular second primary molar along with congenitally missing first permanent molar which resulted in the transposition of second premolar. Treatment options and prognosis of the case are discussed.