The effect of untimely loss of deciduous molars on the development and eruption of the premolars

Abstract

The effect of untimely loss of deciduous molars on the eruption and development of succedaneous premolars was serially studied in eight children in the mixed dentition stage from 45 degree cephalometric films made at three and six month intervals. Each child had one mandibular deciduous molar removed for reasons other than periapical infection and a lingual arch space maintainer provided. The premolar beneath the extracted molar served as the study tooth; its antimere, as the control tooth. Eruptive movement was measured as the distance between the cusp-tip of a premolar on a superpositioned initial tracing and the corresponding cusp-tip on successive films. Antero-posterior movement of premolars was evaluated on a composite tracing along grid lines oriented to a common base line. Tooth formation was assessed by the increase in root length on successive films. Variation was found in the amounts of eruptive movement and root growth during a three month interval, for all premolars within the sample, within an individual and for a single tooth. In no case did a control tooth erupt more than a study tooth in a given interval. The initial effect of deciduous molar loss on eruptive movement in this study appeared to be accelerative. Tooth development was not found to be effected. While moderate correlation was found between eruptive movement and root growth for all premolars, one process did not appear to be solely dependent on the other. A posterior component of eruptive movement was occasionally demonstrated but was not related to the extraction. The clinical value of this study is limited due to its small sample and short duration. Longer and more comprehensive studies of this problem are recommended.