Background <p>The presence of supernumerary teeth (ST) may result in varying degrees of dentition problem.</p> Purpose <p>The aims of this study were to investigate the distribution and characteristics of ST in children in Shanghai, analyze the factors that have adverse effects on dentition, and provide some reference for clinicians.</p> Methods <p>A total of 309 patients (427 ST) who underwent cone-beam computed tomography (CBCT) were included in this study. The age and sex of the patients, and the characteristics of the ST, such as their number, distribution, direction and effect on adjacent teeth, were retrospectively collected.</p> Results <p>The average age of the patients was 6.3 years, and the male to female ratio was 4.15:1. ST mostly occurred in the maxillary anterior region, with the majority of cases involving one tooth. The ratio of the number of ST impacted in bone to the number of erupted ST was 14.8. The palatal side of the alveolar bone (68%) and inverted (59.5%) were associated with the greatest proportions of ST in terms of location and direction, respectively. When located on the palatal side of the dentition and in an inverted orientation, ST have minimal influence on the eruption and position of the central incisors, whereas the buccolingual ST have the most complications.</p> Conclusion <p>The impact of ST in different positions and directions on the eruption of adjacent permanent teeth varies. These findings may serve as reference information for clinical decision-making on the timing of tooth extraction.</p>