Indicators of mandibular dental crowding in the mixed dentition.

PURPOSE Dental crowding occurring in the anterior part of the mandible in the early mixed dentition has been a subject of increasing concern for child patients, their parents, and the pediatric dentist. The aim of this study was to evaluate indicators of crowding found at the primary dentition, which may lead to the future manifestation of crowding at the anterior part of the mandibular arch in the early mixed dentition. METHODS Skeletal and dental morphological characteristics at the stage of primary dentition were compared between two groups, using dental casts and cephalograms of 23 subjects. These two groups had been formed by evaluating the degree of crowding at 9 years of age (12 normal and 11 crowded cases). RESULTS The size of several teeth in the crowding group was significantly greater than that found in the normal group. For the cephalometric measurements, a statistically significant difference was found only in the cranial base dimension (S-SE). The stepwise discriminant analysis showed that the mesiodistal size of the maxillary primary canine, the maxillary and mandibular dental arch lengths, and the posterior cranial base length (S-Ba) were effective discriminators in separating the two groups. CONCLUSIONS It is concluded that larger primary tooth size is the chief indicator in the development of dental crowding. However, the maxillary and mandibular dental arch lengths and the cranial base dimensions, especially that of the posterior cranial base length in the primary dentition, should also be considered as indicators when attempting to predict dental crowding in the early mixed dentition.