Bilateral Asymmetry and Concordance in Cusp Number and Crown Morphology of the Mandibular First Molar

Abstract

Bilateral asymmetry and concordance as related to genetic analyses was investigated on mandibular molar cusp number and groove pattern in 256 Ohio white subjects. On an intra-individual basis (with sexes combined), comparison of cusp number (3-4-5-6) on the left mandibular 1st molar with cusp number on the right mandibular 1st molar showed concordance in excess of 95%; it was 97% for the 2nd molars. Groove pattern (+, Y, X) considered separately demonstrated a 97% concordance for both 1st and 2nd mandibular molars. Morphological asymmetry for the polymorphism considered does not appear to be a deterrent to genetic analyses or population studies.