[Histological examinations of persisting milk teeth (author's transl)].

In twelve patients aged 13 to 24, histological examinations of twenty persistent milk teeth (with persistency having been due to aplasia of permanent teeth) showed that root resorptions are possible in such cases too. Cellular resorption results in the root being decomposed lacunally or linerly, respectively. The formation of osteodentin, which is a result of the phase of apposition and which is taking place in the pulp and along the surface of resorption, respectively, is considered a characteristic concomitant phenomenon. However, this tissue does not cause "true ankylosis". Accordingly, use of the term "ankylosis" to describe such cases is questionable. The author, on the strength of the results obtained in these studies, believes that root resorption of persistent milk teeth is a pathological process in the case of congenital absence of permanent teeth.