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Inherited primary failure of eruption in the primary dentition: report of five cases.

Unerupted primary teeth are a rare event and in most cases involve the second primary molars. The impaction may be primary, meaning that the teeth never have been erupted (also called primary failure of eruption), or it may be secondary, meaning that the teeth after eruption are reimpacted. The present report describes five cases (three boys and two girls) with primary failure of eruption of totally fourteen second primary molars. None of these teeth ever erupted and were removed surgically at an age of 10-11 yrs. Additionally, in all five cases the eruption of the entire permanent dentition was severely retarded. Consequences of the nonerupting primary molars put a more functional strain, with severe attrition, on the remaining teeth. The unerupted primary molars also seemed to prevent the development of the corresponding premolars. In addition the impacted primary molars were in some cases a threat to the eruption of first permanent molars. The etiology of the present primary failure of eruption seems to be inheritance, and the mode of transmission is judged to be autosomal dominant.