Window decompression surgery for the treatment of large mandibular dentigerous cysts in the mixed dentition stage: a case report

Abstract

Dentigerous cyst is a common type of odontogenic jawbone cyst in clinical practice, often involving immature permanent tooth germ in children. Traditional cyst curettage may cause damage to the developing permanent tooth germ and surrounding important anatomical structures. This article reports a case of a large mandibular dentigerous cyst in a 9-year-old female child, which was treated with negative pressure drainage through window decompression surgery. During the operation, a lateral opening drainage tube was prepared and fixed with flowable resin. The cyst significantly shrank 6 months after surgery, and by 2 years and 10 months, the affected permanent teeth spontaneously erupted. This case demonstrates that window decompression combined with negative pressure drainage is an effective method for preserving the permanent teeth and jawbone tissue in the affected area to the greatest extent possible for large mandibular dentigerous cysts in the mixed dentition stage.

Introduction

Dentigerous cysts are the second most common type of odontogenic cysts, frequently affecting the germs of permanent teeth [1]. In pediatric patients with mixed dentition, large cysts can lead to facial swelling, tooth displacement, and potential damage to developing teeth or the inferior alveolar nerve [2]. Traditional curettage is a traumatic procedure that can result in significant bone defects, prolonged healing times, and risks of tooth loss, nerve injury, or pathological fractures. In contrast, window decompression effectively reduces internal pressure within the cystic capsule, promotes bone regeneration, preserves jaw morphology and tooth germs, and facilitates spontaneous eruption [3–7]. We present a case involving a large dentigerous cyst located in the lower jaw of a child during the mixed dentition stage, which was successfully treated using this approach.

Case report

A 9-year-old girl presented with left facial swelling and pain for 5 days, accompanied by fever. There was no relevant medical or family history. Extraoral examination revealed a bulging mass measuring 2 × 2 × 1.5 cm on the left mandible, exhibiting a ping-pong sensation (Fig. 1A). Oral examination indicated that tooth 37 was absent, with gingival protrusion surrounding teeth 75 and 36 (Fig. 1B). A panoramic radiograph and cone beam computed tomography (CBCT) demonstrated a unilocular low-density area (29.93 × 22.39 × 24.43 mm) distal to tooth 36, containing the crown of tooth 37 (Nolla stage 6) (Fig. 2). Based on the clinical and imaging findings, the diagnosis was established as a ‘tooth 37 dentigerous cyst’.

Treatment

First stage: Informing the family of the patient about the condition, treatment plan, and costs, the family is provided with sufficient information to give their informed consent, and they sign the informed consent form. Under local anesthesia, a window was created distal to tooth 36, allowing for the drainage of yellow cystic fluid, which was subsequently irrigated with saline (Fig. 3). A lateral open drainage tube was then placed into the cavity (Fig. 4) and secured to teeth 75 and 36 using flowable resin (Fig. 5).

Short-term follow-up: The Frankl scale is a four-point observer rating tool (scoring from 1 to 4) used to assess children’s overall cooperative behavior during dental treatment, ranging from clearly uncooperative (1 point) to clearly cooperative (4 points). Due to the patient’s low compliance, indicated by a Frankl scale of 1 point, the drainage tube dislodged 1 week post-surgery. Upon examination, the drainage tube was absent from the oral cavity, and a small amount of pus was observed upon gentle compression (Fig. 6). Following the polishing of teeth 75 and 36, a 26# buccal tube was bonded, and the cavity was irrigated with saline until clear (Fig. 7). Subsequently, a lateral-opening drain tube was secured with resin to both the tube and tooth 75 (Fig. 8). Two weeks later, the patient accidentally bit through the tube, resulting in a broken drainage tube, which exhibited yellow discoloration on its interior (Fig. 9). The treatment approach remained consistent with that employed during the 1-week follow-up after surgery.

Long-term follow-up: At 1 month, X-ray showed cyst size reduction and bone reconstruction (Fig. 10). At 3 months, the cyst further shrank, and tooth 37 began erupting (Fig. 11). At 6 months, CBCT showed cyst reduction to 13.25 × 12.82 × 11.61 mm, with new bone filling. According to Nakamura’s criteria, the cyst diameter decreased by 55.73% (good efficacy) (Fig. 12). At 2 years and 10 months, tooth 37 had fully erupted (Fig. 13).

Discussion

The enlargement of a cystic cavity results from increased hydrostatic/osmotic pressure, epithelial proliferation, and bone resorption factors [8]. Window decompression reduces intra-cavitary pressure, balances forces, stimulates osteoblast activity, and promotes bone regeneration, while altered microenvironment transforms cyst epithelium into oral epithelium, leading to cavity shrinkage or elimination [9]. Eruption potential of impacted teeth associated with dentigerous cysts depends on multiple factors: patient age (<10 years favorable) [10], cyst type (central-type shows decreasing axial inclination; lateral-type unaffected) [11], root maturity (less mature roots erupt more easily) [12], tooth tip depth (<9 mm increases probability) [13], inclination angle (<25° favorable) [14], and eruption gap exceeding crown width [15]. In this case, a 9-year-old with a central-type cyst, Nolla stage 6 root development, 7.76 mm tip depth, 11.7° inclination, and adequate eruption gap predicted high spontaneous eruption probability. Drainage tube fixation is critical; poor compliance (Frankl scale of 1 point) led to early detachment, resolved by buccal tube straps and ligatures.

This study presents two primary limitations. First, while histopathological diagnosis is considered the gold standard for the diagnosis of such lesions, it could not be obtained in this case due to the child’s non-cooperation and the parents’ refusal. Consequently, the diagnosis was based solely on clinical, imaging, and intraoperative findings. Second, following the surgery, the child transferred to study in another province, and subsequent assessments of healing were conducted solely through phone consultations and intraoral photographs provided by the parents, which lacked objective imaging verification. These limitations should be carefully considered when interpreting the conclusions.

Conclusion

Window decompression with negative pressure drainage effectively preserves permanent teeth and the jawbone in children with dentigerous cysts during the mixed dentition phase. This technique not only preserves the tooth germ but also encourages natural eruption and stimulates bone regeneration, thereby restoring the morphology of the jawbone. As a minimally invasive method, it significantly supports children’s oral health and holds considerable value for clinical application.

Acknowledgements

We gratefully acknowledge the patient and her family for their informed consent to publish this report, as we strive to advance the surgical care of pediatric dentigerous cysts.

Conflicts of interest

All authors report no relevant conflicts of interest for this article.

Funding

This work was supported by the Central Guidance for Local Science and Technology Development Fund (Grant No. YDZJSX2025D061) awarded to Junyu Liu; the High-Level Talent Special Fund of the Shanxi Provincial Key Laboratory of Stomatology and New Materials for Oral Disease Prevention and Treatment (Grant No. RC2021-04) awarded to Junyu Liu; the National Natural Science Youth Fund (Grant No. 82101078) awarded to Junyu Liu; the Shanxi Province higher education reform and innovation project (Grant No. J20240564) awarded to Xiangyu Wang; the Shanxi Provincial Key Research and Development Project (Grant No. A2021-113) awarded to Xiangyu Wang; and the Shanxi Provincial Science and Technology Department (Grant No. 202302020101009) awarded to Xiangyu Wang.

References

Author notes