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Mandibular Radiation Dose Modifies the Association Between Post-Chemoradiotherapy Dental Extraction Timing and Osteoradionecrosis Risk: A Retrospective Cohort Study
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Department of Radiation Oncology, Faculty of Medicine, Başkent University, Adana 06790, Turkey
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Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Başkent University, Ankara 06490, Turkey
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Department of Periodontology, Faculty of Dentistry, Başkent University, Ankara 06490, Turkey
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Department of Radiation Oncology, School of Medicine, Afyonkarahisar Health Sciences University, Afyonkarahisar 03340, Turkey
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Department of Radiation Oncology, School of Medicine, Koç University, Istanbul 34010, Turkey
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Author to whom correspondence should be addressed.
Cancers 2026, 18(11), 1756; https://doi.org/10.3390/cancers18111756
Submission received: 1 April 2026
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Revised: 14 May 2026
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Accepted: 25 May 2026
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Published: 27 May 2026
(This article belongs to the Special Issue Beyond Cancer: Enhancing Quality of Life for Cancer Survivors (Second Edition))
Simple Summary
Osteoradionecrosis of the jaw (ORNJ) is a serious complication that may occur after radiotherapy or chemoradiotherapy for nasopharyngeal cancer, particularly following tooth extraction. It remains unclear whether the timing of tooth extraction after treatment independently affects this risk. In this study, we examined patients who underwent tooth extraction only after completing chemoradiotherapy and evaluated the combined effect of extraction timing and the radiation dose received by the jawbone. We observed that radiation dose was the main factor associated with risk. At lower dose levels, ORNJ was uncommon regardless of the timing of the tooth extraction. In contrast, at higher dose levels, later extraction was associated with a higher ORNJ risk. These results suggest that the timing of tooth extraction after chemoradiotherapy should not be considered in isolation but rather in relation to radiation exposure to support more individualized decision-making in clinical practice.
Abstract
Background/Objectives: This retrospective study evaluated whether the association between post-CCRT dental extraction timing and osteoradionecrosis of the jaw (ORNJ) risk is modified by mandibular radiation exposure in patients with locally advanced nasopharyngeal carcinoma (LA-NPC) treated with definitive concurrent chemoradiotherapy (CCRT). Methods: A total of 247 patients who did not undergo pre-CCRT dental extraction but underwent post-CCRT extraction were analyzed. Mandibular radiation exposure was quantified using EQD2. Associations between clinical, tumoral, dental, and dosimetric variables and ORNJ were assessed using multivariable logistic regression, including assessment of EQD2–timing interaction. ROC analyses were performed to evaluate discriminative performance and estimate exploratory thresholds. ORNJ developed in 23 patients (9.3%). Mandibular EQD2 was independently associated with ORNJ risk (OR 2.10 per 5 Gy; 95% CI 1.40–3.15; p < 0.001). A significant interaction between EQD2 and extraction timing was observed (OR 1.07; 95% CI 1.03–1.11; p = 0.023). EQD2 demonstrated excellent discrimination (AUC 0.885; cutoff 46.5 Gy), whereas extraction timing showed modest discrimination (AUC 0.691; cutoff 10 months). At <46.5 Gy, ORNJ rates remained low regardless of timing (1.0% vs. 3.9%). At ≥46.5 Gy, delayed extraction was associated with substantially higher ORNJ incidence (31.1% vs. 11.3%). Number of extracted teeth (OR 1.16; p = 0.012) and hemoglobin level (OR 0.62; p = 0.007) were also independent predictors. Conclusions: The effect of post-CCRT dental extraction timing on ORNJ risk is modified by mandibular radiation dose, supporting interpretation in conjunction with mandibular radiation exposure rather than as an isolated factor.
