Knowledge of root and canal morphology is essential for the effective practice of root canal treatment. Paediatric endodontics aims to preserve fully functional primary teeth in the dental arch; however, pulpectomy procedures in bizarre and tortuous canals encased in roots programmed for physiologic resorption are unique challenges. A new coding system for classifying the roots and main canals (https://doi.org/10.1111/iej.12685), accessory canals (https://doi.org/10.1111/iej.12800) and developmental anomalies (https://doi.org/10.1111/iej.12867) has been introduced recently. This paper discusses challenges for describing root and canal morphology in primary teeth and describes the potential application of the new classification system for root canals in the primary dentition.