"9-year-molars" aberrantly developing and erupting: report of cases.

This paper describes delayed development and eruption of the first permanent molars, in most cases only in the upper jaw. The development and eruption of the teeth are chronologically between that of the first and second molars. The anatomy of the aberrant teeth is closest to that of the second molars. The aberrant teeth are often laying at a distance during development from the second primary molars. The clinical implications of the aberrancy are few, because the teeth will normally migrate into close contact with the tooth mesial to them, however, often into a crossbite. Most often the teeth are mistaken to be a first molar with some eruption disturbance and therefore referred for surgical or orthodontic treatment. However, such interception should be avoided because at least in the present cases all teeth are observed to erupt by themselves.