5. Discussion
The radicular cyst in deciduous teeth is classified as an inflammatory odontogenic cyst, typically resulting from dental pulp necrosis caused by caries, trauma, abnormal tooth development, and other factors[1]. It can also arise from the use of materials containing cresol in dental pulp treatment [6].
Radicular cysts in deciduous teeth can cause local pain and swelling, as well as apical bone destruction. In severe cases, it may lead to extensive bone destruction and affect the inherited permanent tooth germ, resulting in impaction of the inherited permanent teeth. Small radicular cysts in deciduous teeth often resolve spontaneously after extraction of the affected deciduous teeth. For extensive radicular cysts in deciduous teeth, permanent tooth germs should be preserved as much as possible, because children have a strong bone regeneration ability and can repair bone defects quickly after operation[3]. Therefore, for a large range of radicular cysts in deciduous teeth, relatively conservative treatment schemes, such as bagging or decompression and drainage, should be considered to protect the permanent tooth germs under deciduous teeth as much as possible[4].
Root dilaceration refers to abnormal tooth development in which the crown or root deviates from the long axis of the tooth, often resulting in a certain bending angle between the crown and root (or part of the root), and this condition is considered an abnormality in tooth morphology. Root dilaceration usually fails to erupt smoothly, resulting in impaction. Impacted teeth with root dilaceration are usually caused by acute mechanical injury [7] or developmental interference factors, including apical periodontitis of deciduous teeth, cleft lip, and palate, ectopic tooth germ development, soft tissue scarring, insufficient space, or interference from surrounding structures, dental tumor, dental follicles, adhesion of the deciduous teeth root, genetic factors, and some syndromes[8]. This case demonstrates root dilaceration and impaction of the inherited permanent teeth caused by a radicular cyst in the deciduous teeth. It highlights the importance of maintaining the health of deciduous teeth for the proper development and eruption of permanent teeth. The prevention and treatment of children’s dental diseases still needs continued efforts. For impacted teeth without root dilaceration, early orthodontic traction can reduce the risk of developing root dilaceration. For the affected teeth with root dilaceration, early orthodontic traction can use the development potential of the epithelial root sheath to produce a secondary curvature, thereby promoting continued root development. It increases the root length and reduces the crown-root angle[9-11]. At the same time, orthodontic traction can prevent alveolar bone atrophy and adjacent tooth inclination after missing teeth. Even if the tooth becomes loose over time due to excessive chewing forces, it preserves sufficient alveolar bone mass for adult implant restoration.
Therefore, early detection, diagnosis, and traction are needed for impacted teeth with root dilaceration. Moreover, even for root dilaceration with short roots or bone fenestration after traction, as long as there is no significant abnormality in pulp vitality or abnormal looseness, the long-term postoperative effect of traction treatment is ideal. This may be attributed to the favorable physical chimerism between the curved roots and the alveolar bone, allowing the crown to withstand normal bite force [12, 13].