Bilateral Symmetry and Variability in Permanent Tooth Development in Mixed Dentition: A Radiographic Study Using Nolla’s Staging System
Udit Chaudhary, Tasneem Naeem Ahmed, Neeti Mittal, Achint Juneja, Monis Raza, Aakansha SharmaPurpose:
To evaluate bilateral symmetry in permanent tooth development using Nolla’s staging method and to examine the impact of primary tooth status, age, and gender.
Materials and Methods:
A retrospective analysis was conducted on panoramic radiographs of 210 children aged 6–12 years. Each permanent tooth (excluding third molars) was assessed bilaterally using Nolla’s 10-stage classification. Symmetry was measured as the absolute difference in stage between contralateral teeth. Subgroups were formed based on primary tooth status (present, absent, and retained), radiographic signs suggestive of infection, age group (6–8 years vs. 9–12 years), and gender using appropriate nonparametric tests (Wilcoxon signed-rank test for paired comparisons and Mann–Whitney
Results:
Overall, high bilateral symmetry was observed, with mean stage differences typically <0.3. Premolars and canines showed the highest rates of ≥1-stage difference in >20% of cases. However, no statistically significant differences were observed between contralateral tooth pairs after adjustment for multiple comparisons. Increased asymmetry was observed in association with retained, absent, or infected primary teeth, as well as among males and younger children (
Conclusion:
Symmetry in permanent tooth development is generally maintained, but can be altered by primary tooth conditions, age, and gender. Recognition of such variability is important for timely pediatric, orthodontic, and forensic applications.