[Occurence of dens invaginatus among a group Norwegian children].

The aim of the present investigation was: 1) to determine radiographically the prevalence of maxillary incisors with invaginations, and of individuals with such teeth in a Norweigian population. 2) to classify the invaginations according to Hallett (1953), 3) to test the findings for sex differences, 4) to determine the concordance between a radiographical and a clinical method for identifying invaginations. Based upon a material of 415 school-children it was found radiographically that approximately 1/8 of the maxillary central incisors and nearly one half of the lateral incisors had invaginations. More than half of the children had one or more invaginated teeth (Table 2). The majority of the invaginations were of class I/III. Only a few were classified as class III (Table 2). The findings are comparable to those of Hallett (1953). Boys had a higher incidence than girls of class III invaginations in lateral incisors. The difference was statistically significant (5%). The girls had more class I/II invaginations in the central incisors than the boys, but the difference was not statistically significant. In the clinical examination three of four lateral incisors, one of four central incisors and four of five individuals were found to have invaginations. All invaginations found in the radiographic investigation were also registered in the clinical examination.