Surgical Outcome of Selective or Complete Curettage Performed in Large Cyst-like Periapical Lesions of Endodontic Origin: A Randomized Controlled Trial

Periapical lesions of endodontic origin are primarily caused by persistent microbial infection within the root canal system. These lesions represent the body’s immunological response to irritants from the necrotic pulp and are typically managed by nonsurgical root canal therapy (RCT), which aims to eliminate the source of infection and promote periapical healing. In most cases, particularly those with lesions of limited size, this approach is sufficient. However, large cyst like periapical lesions (LCPLs) defined by radiographic dimensions exceeding 10 mm or areas greater than 200 mm2 pose a clinical challenge. These lesions are often aspirated as straw colored fluid, are associated with long-standing chronic infections, and may be suggestive of radicular cysts or pocket cysts. However, the definitive diagnosis can only be established after histological evaluation.

Although many LCPLs may resolve with proper endodontic disinfection alone, persistent or symptomatic cases often require surgical intervention. Endodontic microsurgery (EMS), utilizing magnification and microsurgical instruments, is now considered the standard of care for such lesions when nonsurgical options fail. A meta-analysis demonstrated a pooled success rate of 94 percent for endodontic microsurgery (EMS), with a 95 percent confidence interval ranging from 0.8889 to 0.9816, based on a minimum follow-up duration of 12 months (Setzer et al 2012). Furthermore, long-term follow-up extending beyond six years indicated a sustained success rate of 93.3 percent (Song et al. 2012). During EMS, periapical curettage or enucleation is routinely performed to remove the pathological tissue from the periapical area. Traditional protocols favour complete removal of the lesion, aiming to eliminate all epithelial and granulation tissue, which could otherwise act as a nidus for recurrence if the lesion is self-sustaining. Further, complete degranulating the tissue provides adequate haemostasis, making the surgical procedure more efficient. However, this practice is not without limitations. Complete removal may be challenging or risky in lesions that extend close to critical anatomical structures such as the adjacent teeth, nasal floor, maxillary sinus, mental foramen, or neurovascular bundles.

In LCPLs, selective curettage can serve as a conservative surgical technique, involving the removal of about 50 percent to 70 percent of the lesion tissue. This approach is intended to conserve nearby healthy tissues and protect vital anatomical structures. Historically, decompression or tubing method has been advocated for extensive lesions in proximity to vital structures,. Several hypotheses have been proposed regarding the mechanisms by which decompression facilitates healing. It enables continuous drainage, which is essential for initiating the reparative process, and may also mitigate the development of hyperosmotic pressure within the lesion. Furthermore, the inflammatory response induced by the procedure may contribute to the disruption of the cystic epithelial lining, promoting lesion resolution. Despite its benefits, decompression is associated with several limitations, including the need for frequent postoperative adjustments, inflammation of the alveolar mucosa, persistence of the surgical defect at the insertion site, potential for acute or chronic infection, submergence of the drainage tube into surrounding tissue, patient noncompliance, and challenges in obtaining biopsy specimens.

In light of these limitations, Natkin et al. (1984) proposed an alternative approach involving partial removal of the cystic lining. This technique involves intentional rupture of the cystic sac with limited tissue removal, thereby minimizing trauma to vital root apices and adjacent anatomical structures while still permitting adequate drainage and potential disruption of the cyst lining to facilitate healing. The pattern of healing observed may resemble the spontaneous resolution of large cyst-like periapical lesions (LCPLs) following extraction, without surgical enucleation. Wong et al.  subsequently supported this technique in a case series, referring to it as “surgical fenestration.” This method was noted to preserve the principal advantage of decompression protection of adjacent vital structures while offering additional benefits, such as feasibility of biopsy and improved patient compliance.

In the only prospective clinical study to date, Shah et al.  compared surgical fenestration to complete enucleation in histopathologically confirmed radicular cysts during conventional endodontic surgery and reported comparable healing outcomes. Furthermore, surgical fenestration was found to be technically simpler, less time-consuming, and less invasive. More recently, Nesari et al.  and Li et al.  reported case series in which selective curettage, rather than complete removal, was employed for the management of large periapical lesions subsequently diagnosed as periapical granulomas or cysts. Follow up assessments using both two-dimensional and three-dimensional imaging modalities demonstrated satisfactory healing in all cases. These emerging lines of evidence underscore a clinically significant question: Is complete surgical enucleation indispensable for optimal healing of large periapical lesions, or can conservative interventions such as selective curettage yield equivalent therapeutic outcomes.

To date, no study has directly compared the outcomes of selective versus complete curettage in the context of modern endodontic microsurgery. This randomized controlled trial is designed to evaluate and compare both clinician  and patient centred outcomes of selective and complete curettage approaches for the management of large cyst like periapical lesions during endodontic microsurgery.