Interproximal contact hypoplasia in primary teeth: A new enamel defect with anthropological and clinical relevance

This study reports the prevalence, distribution, and expression of enamel d efects in a sample of primary teeth (n = 225) from a prehistoric site in we stern India (1400-700 BC). Five enamel surfaces of individual, isolated pri mary teeth were observed for surface defects using a binocular stereomicros cope with variable power of magnification (8-20x). Standards for evaluating dental enamel defects (DDE) recommended by the Federation Dentaire Interna tional (FDI) were employed. Details of defect expression were also recorded , including size, shape, and surface of tooth crown affected. Hypoplastic e namel defects were observed in 28% of teeth, but the distribution and expre ssion of defects was not random. More than 50% of canine teeth had hypoplas tic defects (HD); incisors and molar teeth exhibited far fewer KD. The bucc al surface of canines was the most commonly affected crown surface. Areas o f missing enamel were also common on the mesial and distal surfaces of cani nes and incisors and on the mesial surface of molar teeth. The high frequen cy of enamel defects found on interproximal crown surfaces warrants a label , and the name interproximal contact hypoplasia (IPCH) is proposed. Linear enamel hypoplasia (LEH) was absent from this primary dental sample. IPCH is more frequent in mandibular than in maxillary teeth, but no side preferenc e was detected. In canine teeth, buccal hypoplasias (localized hypoplasia o f primary canines; LHPC) were not positively correlated with interproximal hypoplastic defects. The etiology of IPCH may involve mesial compaction of developing teeth due to slow longitudinal growth of the jaws. Episodic bone remodeling results in ephemeral fenestrae in the mesial and distal walls o f the dental crypt permitting tooth-tooth contact and disruption of ameloge nesis. IPCH prevalence decreases across the subsistence transition from sed entary Early Jorwe agriculturalists to seminomadic Late Jorwe hunters and f oragers, but the difference is not statistically significant. This may be d ue to underrepresentation of mandibular teeth in the sample. (C) 1999 Wiley -Liss, Inc.