Hypertrophy of the lingual cingulum in modern human maxillary deciduous molars

Abstract

KALLAY (1956 and 1966) has described an unusual morphological variant of the second maxillary deciduous molar to which he has given the name “Kragenmilchmolar” or “collar molar”. The fully developed “collar molar” differs from a normal deciduous molar in two respects: firstly, marked development of the cusp of Carabelli which is fused to a small hypocone, thus forming a continuous ridge or “collar” on the lingual aspect of the tooth; and secondly, confluence of the paracone, metacone and protocone to form an annular structure. KALLAY (1966) also described two teeth which, he believed, represent intermediate stages between the normal second deciduous molar and the “collar” molar. In both of these intermediate forms, the hypocone and cusp of Carabelli were stout, rounded structures, separated from each other by a deep, distinct groove, and from the rest of the crown by another deep fissure. A morphological variant of the second deciduous molar, which in some respects resembles Kallay’s “collar molar”, has been observed in Glasgow Dental School. During routine examination of a Caucasoid male child, G.R., aged 4, an unusual configuration of the lingual surfaces of E/E was noted. Figure 1 shows the appearance of these maxillary second deciduous molars. A flattened ridge encircles the lingual surface of each tooth, running from the mesiolingual comer in a distal direction to reach the mesial slope of the hypocone with which it becomes continuous. Each ridge is divided by two grooves, one opposite the tip of the protocone and the other slightly more distally placed. Both grooves are clearly marked in the tooth from the right side (Fig. la), while in the left tooth (Fig. lb) the mesial groove is much deeper than the distal one. It is interesting to note that the two elder brothers of G.R. both show well-marked but normal cusps of Carabelli on the upper second deciduous molars and the upper first permanent molars (Figs. 2 and 3). The father of the three boys is edentulous. In the maxilla of the mother, 8/78 are still present, but none of these teeth shows any trace of the Carabelli cusp, norof any other structure (pit or furrow) believed to form part of the Carabelli complex. There are basic similarities between the deciduous molars in the present case and Kallay’s “collar molar” in so far as both result from the fusion of the hypocone with