Severe hypodontia: diversities in manifestations.

The material comprises 33 cases, 12 boys and 21 girls with 4 or more lacking teeth in the permanent dentition, randomly collected among patients referred to the Department of Pedodontics, University of Bergen. The total number of lacking teeth were 332, mean number in boys was 11.4, in girls 9.3, ranging from 4 to 24 (third molars excluded). The most prevalently lacking teeth were second premolars in both jaws, maxillary lateral incisors, mandibular central incisors and maxillary first premolars. The maxillary central incisors were the most stable teeth, lacking in only one patient. The female group was closest to this "classical" scheme by lacking teeth mostly in posterior segments. In males the anterior segments were most often afflicted. There was no significant difference between right and left sides in both sexes, but in girls the maxillary jaw was more afflicted than the mandibular jaw. The individual analyses of cases showed great diversities in the manifestation of hypodontia. Eighteen of them behaved fairly "balanced" with respect to lack of teeth in the different quadrants. Six cases were lacking most of the teeth in the maxillary jaw (total 34 maxillary teeth versus 11 mandibular). Five cases were lacking most of the teeth in the mandibular jaw (total 30 mandibular teeth versus 14 maxillary). One patient was lacking 10 of his 12 front teeth, but only 4 of his 20 posterior teeth, and one patient was lacking 12 of his 16 posterior teeth, but none of his front teeth. The author cannot offer any explanation for these strange and varying patterns of manifestations.