The spacing of the incisors in the temporary and permanent dentitions
Human Teeth and Incisors
The purpose of this investigation has been to study the association between the space conditions of the deciduous and permanent incisors of the same individuals.
The space conditions are determined as the difference between the length of the dental arch from canine to canine and the sum of the widths of the incisors. The association between the space conditions is expressed by the correlation coefficient, r.
The material consists of 50 series of models from the upper jaw, and 47 series of models from the lower jaw, each series of models covering the development from the deciduous to the adult dentition.
It was found that a statistically significant correlation between the space conditions could be shown in the upper, but not in the lower jaw. An examination of the determination coefficients, however, showed that in the individual case the development could not be accurately predicted, either in the upper or in the lower jaw.
The difference between the conditions in the maxilla and the mandible was further stressed by the finding, that the standard deviations of the space values are very small among the lower permanent incisors.