Nearly 38% of Restorations Failed in Head and Neck Radiotherapy Survivors

Edited by Dentaltown staff

More than a third of direct restorations placed in head and neck cancer survivors after radiotherapy had failed when examined, and lower salivary flow independently raised the odds of failure, according to a multicenter study published Aug. 15 in the Journal of Dentistry.

The cross-sectional analysis drew on 115 survivors treated at three tertiary hospitals, contributing 423 direct restorations placed after radiotherapy. Each restoration was assessed against FDI World Dental Federation criteria.

Of the 423 restorations, 159 had failed, or 37.6%. Secondary caries accounted for 45.3% of failures, followed by fracture at 20.1% and defective marginal adaptation at 18.2%.

Salivary function was measured three ways: unstimulated whole salivary flow, the Clinical Oral Dryness Score, and the Summated Xerostomia Inventory. In a mixed-effects logistic regression with a patient-specific random intercept, higher unstimulated flow independently reduced the odds of failure, at an adjusted odds ratio of 0.59 with a 95% confidence interval of 0.42 to 0.83.

Five factors independently raised the odds. Restorations spanning three or more surfaces carried the highest risk at 3.83, followed by restoration age beyond 24 months at 3.55, glass-ionomer material at 2.40, endodontically treated teeth at 1.86, and radiotherapy dose at 1.06 per gray. The final model showed an area under the curve of 0.764.

The author concluded that direct restoration failure is common after head and neck radiotherapy and is independently shaped by radiation-related salivary dysfunction, radiation exposure, and restoration characteristics, and that objective salivary assessment may sharpen risk stratification and support individualized preventive and restorative care.

Thamer Almohareb of the Department of Restorative Dental Sciences at King Saud University in Riyadh conducted the study.

The design was cross-sectional, so the 37.6% figure describes the share of restorations found to have failed at a single examination rather than a rate measured across a defined follow-up period. Restorations were not randomly assigned, and material choice may have tracked with case difficulty.

Sources:
Journal of Dentistry, “Direct restoration failure after head and neck radiotherapy: prevalence and independent predictors from a multicenter mixed-effects analysis,” published online Aug. 15, 2026: sciencedirect.com/science/article/pii/S0300571226006500
PubMed, PMID 42603661: pubmed.ncbi.nlm.nih.gov/42603661