Molar polymorphisms and body growth.

Body growth at adolescence was later in children of the serial experimental sample of the Burlington Growth Centre who had agenesis of third molars of 4-cusped mandibular permanent first molars. These groups of children tended to have later maximum increment of growth, later completion of the growth spurt, less adolescent prepeak gain and greater postpeak gain in height and weight than the children with four third molars and 5-cusped first molars. Growth of the boys differed significantly (P less than 0.05) according to absence or presence of third molars, whereas in girls it differed significantly (P less than 0.05) by the number of cusps of the mandibular first molars. In skeletal age, the children with the molar reductions were slightly advanced before adolescence, fell behind during prepeak adolescent growth, and caught up to the other children by the end of their growth spurt. Later maturation in association with dental reduction may be an evolutionary trend in man.