Longitudinal changes in the molar relationship from primary to permanent dentition

Preschool children (n=721) aged between 4 and 5 years were examined and 60 were selected. Two pairs of dental casts were obtained for each child. The first pair was from primary dentition before eruption of permanent first molars; the second pair had the permanent first molars in occlusion. The sample was divided into 3 groups, according to the terminal plane. The findings indicate that 55% of the group with flush terminal plane developed into Class I, 40% into Class II, and 5% into Class III molar relationship in the permanent dentition. The group with mesial step, 70% progressed to Class I, 25% to Class II, and 5% to Class III molar relationship in the permanent dentition. Finally, the group with distal step developed into Class II in the permanent dentition. It can be concluded that the terminal relationship of deciduous second molars was associated with the permanent first molars occlusion.