Radiological Evaluation of Retained Primary Molars in Adolescents with Mandibular Second Premolar Agenesis

Objectives: We aimed to evaluate the condition of retained primary molars in case
of mandibular second premolar agenesis. Materials and Methods: In total, 2692 panoramic
radiographs of adolescent patients were analyzed to determine the prevalence of tooth
agenesis. Patients (N = 156) with at least one mandibular second premolar agenesis
were further explored to determine the presence and condition of retained primary teeth.
Teeth were classified as good or poor based on root resorption, infraocclusion, caries, and
restorations. Results: The prevalence of mandibular second premolar agenesis was 5.8%
(N = 156). For the set period for this study, 138 (58.5%) primary molars were present. Out
of these retained teeth, N = 83 were in good condition. There was a statistically significant
positive weak correlation between age and the level of root resorption (rs = 0.348, n = 138,
p < 0.001). There was no association between infraocclusion and the level of root resorption
(p = 0.747). Signs of infraocclusion were noted in 32 out of 138 teeth. There was no
association between gender and the presence of infraocclusion (p = 0.067) and the presence
or lack of infraocclusion and the therapeutic status of a tooth (p = 0.450). Only 28 out of 138
(20.3%) were intact. There was a significant difference in the level of root resorption between
restored and/or carious (median = 3, IQR 2–4) and intact teeth (median = 2, IQR 1.75–3),
U = 1168, p = 0.044, r = 0.242. Conclusions: Overall, 35.2% of corresponding primary
molars were present in oral cavity, and were in good condition, and could potentially be
preserved in the long term.