1. Patient age and cyst location in pediatric cases of radicular cysts
Jaw cysts can occur in patients of all ages. The onset of maxillary cysts in children is more common in the mixed dentition stage (6–12 years old). The occurrence of internal cystic lesions in the jawbone and compression of the jawbone with an increase in volume leads to displacement of teeth, which affects oral health and may even cause facial appearance changes in patients9. This study included 19 female children and 7 male children with radicular cyst lesions (age, 8–15 years; mean age, 9.6 years). Sixteen lesions occurred in the left maxilla, five in the left mandible, two in the right maxilla, two in the right mandible, and one in the right maxilla and mandible simultaneously. All except two lesions occurred in the incisor or premolars. Most of the caries occurred in the first molar or premolar. The incidence in female children was higher than that in male children (2.7:1). The order of predilection for the sites was left maxilla > left mandible > right mandible At the same time, the lesions were likely to occur in the incisors or premolars, and permanent incisors were the most affected. These teeth were surrounded by a cyst and showed high displacement resistance. According to the experimental results, it was assumed that this was because caries may easily occur in the first molar. When the root tip is inflamed, it stimulates the lesion of the tooth capsule. The first premolar may then form a cyst10. These lesions may also affect the incisors. On the other hand, the first premolar tooth embryo develops earlier than the permanent cusp tooth embryo. When the first molar is decayed and develops periapical inflammation, the first premolars of children around 9 years of age are close to the alveolar crest, and the crown and root of the teeth had matured, so the tooth sac is not easily affected by inflammation and lesions. However, at this time, the permanent cusp tooth embryo is still located in the higher position of the jawbone, and the root of the tooth has not yet developed. The spread of inflammation up from the root tip stimulated the tooth sac to be susceptible to infection and turn into a cyst. Therefore, the carious first molars were damaged, and imaging examination suggested the formation of cysts around the permanent cusp tooth embryo.
2. Diagnosis of radicular cysts in children
Jaw cysts are common benign lesions in oral and maxillofacial surgery, among which odontogenic maxillary cysts are common. Odontogenic jaw cysts include odontogenic cysts, radicular cysts, odontogenic keratocysts, and ejective cysts. Most jaw cysts in children present with no clinical symptoms and are not easily detected. Usually, the reason for the first visit is delayed eruption of permanent teeth or disordered dentition. Panoramic radiography or CBCT can be used for diagnosis. On one hand, parents' awareness of oral health is gradually increasing, which has changed the old idea that replacement of deciduous teeth does not matter. Thus, early attention can be paid to children's oral diseases to avoid delayed treatment. On the other hand, the insufficient number of oral and maxillofacial surgeons and the uneven medical conditions and technical level in primary hospitals or dental clinics may prevent these cysts from being detected in time. Carious deciduous teeth in the lesion area are the clinical features of apical cysts in children. However, pulpitis and periapical periodontitis of the deciduous teeth generally present with no obvious pain, making them easy to ignore. The imaging findings showed that carious deciduous teeth damaged the medullary cavity, and the apical cystic lesions surrounded one or more permanent teeth embryos. Therefore, these cysts are often misdiagnosed as odontogenic cysts in the clinic. Previous studies have reported that dentigerous cysts are the most common jaw cysts in children11–14. In this group of cases, it was difficult to distinguish between radicular cysts and dentigerous cysts, which were initially diagnosed in most patients, since it is difficult to distinguish physiological apical absorption from pathological absorption in children's deciduous teeth. Periapical periodontitis can be easily neglected. The cyst surrounds the permanent tooth, which is easily diagnosed as an odontogenic cyst. In this case group, postoperative pathological examination showed inflammatory changes in the cyst wall, consisting of fibrous cyst and epithelial lining, presenting the histological characteristics of a radicular cyst.
The traditional treatment concepts for a root tip cyst and dental cyst are different. The radicular cyst should be thoroughly scraped and treated with the focus tooth. Insignificant teeth should be removed, while valuable teeth require endodontic treatment and root cutting. In contrast, dental cysts should be curetted and the tooth should be removed to prevent recurrence. Because of these differences, preliminary diagnosis is particularly important for the adoption of appropriate surgical methods. In this study, curettage and extraction of deciduous teeth and permanent teeth embryos were recommended for four cases diagnosed as dentigerous cysts at another hospital. The parents did not accept the operation plan, and the patients were then referred to our department.
3. Selection of treatment
Treatments range from single decompression, marsupialization, enucleation, and bone resection to a combination of these approaches. Curettage, as a traditional treatment, can eliminate the cyst once and reduce the time required for follow-up visits. However, the operation is so traumatic that it may permanently damage the tooth embryo and even damage the development ability of the jawbone. Therefore, it is not suitable for children with jaw cysts. In recent years, decompression has been widely used in children. This method causes less surgical trauma and fewer complications and affords maximum protection of important anatomical structures. Thus, decompression is an effective method for the treatment of jaw cysts. It is safer and less damaging than the traditional method of excision of jaw cysts and is more conducive to the normal development of children's maxillofacial region15 and the retention and eruption of permanent teeth16. For adult jaw cyst patients, decompression is the first step in early conservative treatment. The remaining cyst wall can be completely scraped by further curettage after the cyst scope is reduced. However, in children with mandibular cysts, decompression by fenestration follows a different course from that in adult patients. First, the permanent tooth embryo in the mandibular cyst emerges after decompression, and the cyst wall transforms into the oral epithelium and gingival tissue. Thus, the pain can be reduced and the best results can be obtained without a second operation. Second, tooth extraction is usually created from the focus tooth (carious deciduous tooth) in children by decompression and opening the cavity to drain the cyst fluid. Children are prone to maxillary dilatation deformities when the maxillary cortex is weak and the lumen pressure is high. At the same time, children's jaws have a strong growth capacity, and tooth extraction trauma can facilitate adequate drainage of cyst fluid. Once the pressure decreases, rapid bone formation begins. Simple extraction of deciduous teeth for cyst opening is safe with less injury for children. Therefore, outpatient local anesthesia is usually performed when the patient can cooperate, which reduces the risk of general anesthesia and treatment costs, making it easier for patients and parents to accept the treatment. In addition, none of the patients in this study were infected during treatment. Third, cyst fenestration in children usually does not require the preparation of the plug marker, which reduces discomfort. After fully draining the cyst fluid after fenestration, the cyst can be fully formed outside the cyst cavity, and the eruption ability of the permanent tooth embryo can be restored. After eruption of the permanent tooth, the cyst completely disappears.
Some studies have suggested that the total effective cure rate at 3 months is similar to the final cure rate at 1 year after surgery. Therefore, examinations performed at 3 months after the operation can be used to evaluate the efficacy of jaw cyst decompression17. In this study, the follow-up analysis showed an obvious osteoblastic cyst cavity around the cyst wall 1–3 months after fenestration. Follow-up assessments showed that the cystic space of jaw cyst lesions was progressively reduced and basically disappeared in 8–13 months. The bone around the permanent tooth embryo develops or sprouts out of the gingiva. In one case, because of the large lesion, it shrunk 3 months after the operation, but the low-density shadow still existed around the crown of the permanent tooth embryo. The patient received fenestration again under local anesthesia, and the permanent teeth rose to the upper gingiva 9 months after the operation. All patients were followed up for 6–12 months without recurrence.
This study reviewed the characteristics, diagnosis, and treatment of pediatric radicular cysts. Decompression could not only reduce the surgical trauma and risk, but can also protect and restore the power of permanent teeth eruption, restoring the maxillofacial shape and function of the patient. It can thus yield a good clinical treatment effect.