Root Canal Treatment Emerges as a Safe Option for Cancer Patients After Head and Neck Radiotherapy

For decades, dentists have faced an uncomfortable dilemma when treating patients who survived head and neck cancer. Radiation that saves lives also transforms the jaw into fragile territory, and the standard response to an infected tooth in irradiated bone has been extraction, a procedure that itself carries the risk of one of the most feared complications in dentistry. Now a comprehensive scoping review published in Supportive Care in Cancer suggests that this long-standing practice deserves a second look. The review, led by Álvaro Souza Wanderley and Marlos Barbosa-Ribeiro of the University of Pernambuco in Brazil, mapped the available evidence on root canal treatment, known clinically as endodontic therapy, in patients who had previously undergone head and neck radiotherapy, and found that the procedure appears consistently safe, with no reported cases of osteoradionecrosis across the included studies.

The stakes are considerable. According to GLOBOCAN estimates cited in the review, head and neck cancers accounted for roughly 940,000 new cases and about 480,000 deaths worldwide in 2022, and nearly 80 percent of patients are diagnosed at advanced stages, when five-year survival falls from around 95 percent for early-stage tumors to nearly 30 percent. Radiotherapy remains one of the most widely used weapons against these malignancies, but it exacts a heavy oral toll. Patients commonly develop mucositis, trismus, xerostomia, radiation-associated tooth decay, and osteoradionecrosis, a condition in which irradiated bone dies and fails to heal, often triggered by trauma or surgery on already compromised tissue.

The biological logic behind the danger is straightforward. Radiation damages blood vessels, reducing the vascularity of the jaw and impairing its capacity for tissue repair. When radiation-induced caries, driven largely by salivary hypofunction and shifts in the oral microbiota, progresses to pulpal or periapical infection, the traditional recommendation has been to remove the offending tooth. Contemporary guidelines from the ISOO–MASCC–ASCO consortium advocate dental extractions before radiotherapy begins, a strategy that is generally safe when adequate healing time is allowed. But extractions performed after irradiation are recognized as one of the main risk factors for osteoradionecrosis, since surgical trauma can push an already hypovascularized area past its limits.

Against this backdrop, the Brazilian team asked a deceptively simple question: what evidence exists on the effectiveness and clinical and radiographic outcomes of endodontic therapy in patients who underwent head and neck radiotherapy? Following the Arksey and O’Malley framework, informed by the Joanna Briggs Institute Manual for Evidence Synthesis and reported according to PRISMA-ScR guidelines, the researchers searched PubMed, Embase, Scopus, Web of Science, MEDLINE, LILACS, and gray literature sources with no date restrictions. The protocol was prospectively registered on the Open Science Framework. Of 174 identified records, only five studies met the inclusion criteria, comprising three case series, one retrospective cohort study, and one case report. Inter-reviewer agreement was near-perfect, with Cohen’s kappa coefficients of 0.86 for PubMed/MEDLINE, 0.80 for Scopus, and 0.87 for the remaining databases.

The five studies span nearly half a century of dental practice, and their trajectory tells a striking story of technical progress. The earliest investigations, published in the 1970s and 1980s, relied on manual instrumentation, limited irrigation strategies, and conventional obturation techniques, and reported success rates as low as 18 percent, attributed to imprecise instrumentation, saline-only irrigation, and the absence of standardized antibacterial protocols. Yet even under these primitive conditions, no cases of osteoradionecrosis were observed, suggesting that the procedure itself does not directly provoke the complication. Seto and colleagues, writing in 1985, emphasized apical control during obturation and reported improved outcomes of approximately 85 percent, based primarily on clinical criteria.

By 1998, Lilly and coworkers had standardized their protocols further, employing step-back preparation, lateral condensation, and appropriate sealers, and reported success rates exceeding 90 percent, now supported by combined clinical and radiographic evaluation. The most recent study, a 2020 case series by Castagnola and colleagues, deployed the full arsenal of modern endodontics: rotary instrumentation, irrigation with sodium hypochlorite and EDTA, and single-cone obturation with an epoxy resin–based sealer. That study achieved complete clinical success without a single case of osteoradionecrosis, even though treatment was performed as early as one day after completing radiotherapy, on teeth located in anatomical sites considered high-risk for the complication.

The radiation parameters across the studies varied enormously, reflecting the evolution of oncologic practice itself. Earlier reports described doses ranging from approximately 4,500 rads to more than 11,000 rads delivered with Cobalt-60 external beam machines, while later investigations reported total doses of at least 5,000 cGy and contemporary protocols of 65 to 66 Gy, with a mean periapical exposure of 39.36 Gy. Endodontic therapy was performed at intervals ranging from several years after radiotherapy to just a few months, and in one case a single day. Despite this wide variation in dose, timing, and technique, the review found that endodontic therapy was not associated with osteoradionecrosis in any of the included studies, a pattern of clinical stability the authors describe as consistent over time.

Outcome assessment also matured across the decades. Earlier investigations relied predominantly on clinical parameters such as infection control, symptom resolution, and tooth preservation, partly because radiographic interpretation of irradiated bone is inherently difficult. More recent studies incorporated stricter criteria similar to those used for non-irradiated teeth, including the absence of signs or symptoms, the absence of a sinus tract, maintenance of the periodontal ligament space, and the absence of periapical lesions. Only two studies incorporated radiographic assessment, and this methodological heterogeneity, particularly regarding outcome definitions and follow-up duration, makes direct comparison of success rates difficult, even though the safety signal remained uniform.

The authors are candid about the fragility of the evidence base. Classified according to the hierarchy proposed by Stetler and colleagues, the included studies predominantly represent level V evidence, descriptive case reports and case series lacking control groups and limited by small sample sizes. Only the retrospective cohort by Lilly’s group reached level IV. No controlled clinical trials or quasi-experimental studies were identified, a substantial gap in higher-level evidence on both treatment success and osteoradionecrosis risk. The review also notes unresolved biological questions, including the impact of radiotherapy on dentin structure and its implications for sealer adhesion, and highlights the diagnostic challenge that osteoradionecrosis can present with clinical and radiographic findings that overlap with odontogenic and periapical disease, meaning radiographic abnormalities should never be interpreted in isolation from pulpal testing and patient history.

Practical refinements matter in this population. The authors recommend atraumatic technique, careful selection and positioning of rubber dam clamps to avoid gingival compression, and the use of cone-beam computed tomography for three-dimensional treatment planning when conventional imaging proves insufficient. They also call for future studies to stratify outcomes by tooth location, radiation dose received by the corresponding jaw region, and anatomical complexity, distinguishing multirooted molars from simpler teeth. The bottom line, the researchers conclude, is that endodontic therapy performed with contemporary techniques and materials appears to be a safe and conservative option that may reduce the need for invasive procedures in hypovascularized irradiated bone, preserve masticatory function, and align daily practice with supportive oncology guidelines. But the limited and heterogeneous evidence, they caution, means that well-designed prospective and multicenter studies are urgently needed before the approach can be standardized into definitive clinical recommendations.

Subject of Research: Safety and effectiveness of endodontic therapy in patients previously treated with head and neck radiotherapy

Article Title: Evidence supporting endodontic therapy as a safe strategy in patients previously treated with head and neck radiotherapy: a scoping review

Article References: Wanderley, Á. S., de Sousa, W. V., da Costa, M. O., de Mendonça Silva, A. M. S., de Albuquerque, R. F., Silva, I. H. M., Ribeiro, L. N., Albuquerque, D. S., & Barbosa-Ribeiro, M. (2026). Evidence supporting endodontic therapy as a safe strategy in patients previously treated with head and neck radiotherapy: a scoping review. Supportive Care in Cancer, 34(9), Article 913. https://doi.org/10.1007/s00520-026-11139-2

Image Credits: AI Generated

DOI: 10.1007/s00520-026-11139-2

Keywords: endodontic therapy, root canal treatment, head and neck cancer, radiotherapy, osteoradionecrosis, scoping review, dental extractions, radiation-induced caries, supportive care in cancer, xerostomia, periapical disease, University of Pernambuco