Salivary Flow Predicted Restoration Survival in Head and Neck Cancer Survivors

Edited by Hygienetown staff

Higher unstimulated whole salivary flow independently lowered the odds that a restoration would fail in head and neck cancer survivors treated with radiotherapy, according to a multicenter study published Aug. 15 in the Journal of Dentistry.

Flow was the protective factor in the model, at an adjusted odds ratio of 0.59 with a 95% confidence interval of 0.42 to 0.83. Salivary function was captured three ways: unstimulated whole salivary flow, the Clinical Oral Dryness Score, and the Summated Xerostomia Inventory.

The failure burden those measures helped explain was substantial. Of 423 direct restorations placed after radiotherapy in 115 survivors, 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%.

The cross-sectional analysis drew on survivors treated at three tertiary hospitals, with each restoration assessed against FDI World Dental Federation criteria and analyzed using mixed-effects logistic regression with a patient-specific random intercept.

Five factors independently raised the odds of failure. 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 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