Radiation Therapy And Teeth: What A New Long-Term Study Found

For clinicians managing head and neck cancer survivors, radiation therapy-induced tooth damage is a long game. A prospective study in Cancers followed 113 patients for a median of 44.77 months after pre-radiation dental clearance. Nearly half still lost teeth, and extractions picked up after the second year.

TL;DR

• A Rome cohort of 113 irradiated head and neck cancer patients lost a mean of 2.12 teeth over nearly four years.

• Caries and periodontitis drove tooth loss almost equally, so recall plans need to target both.

• Age and a maximum buccal mucosa dose above 60 Gy independently predicted tooth loss.

• Six-monthly prophylaxis only partly held the line, which argues for tighter, risk-based recalls.

What Did The Rome Cohort Study Show?

Researchers at Fondazione Policlinico Universitario Agostino Gemelli in Rome published the results in Cancers on October 5, 2026. Patients were enrolled between 2017 and 2021, treated with volumetric-modulated arc therapy and followed for at least two years. Before radiation, each had a clinical and radiographic exam, extraction of teeth with untreatable periodontal, endodontic, or carious lesions, and removal of oral foci of infection.

Follow-up visits took place 45, 90 and 180 days after radiotherapy and every six months after that. Patients received professional prophylaxis twice a year, and those with severe periodontitis received supportive periodontal care every three months.

The DMFt figures need a careful read. Every extracted tooth adds to the missing component, so DMFt rise and tooth loss partly overlap. The decayed component did not rise significantly (1.17 to 1.61), while filled teeth rose by 1.52 and missing teeth by 2.12, which suggests that new lesions were being detected and restored while teeth were still being lost.

Why Did Nearly Half Of Patients Still Lose Teeth?

Forty-nine of 113 patients, or 43.4%, lost at least one tooth despite pre-radiation clearance and a structured recall program. Caries caused 48.5% of extractions, periodontitis 48.1%, and fractures 3.4%. No root-canal-treated tooth failed during follow-up, which the authors attribute to strict asepsis and modern endodontic technique.

The near-even split between caries and periodontitis is the clinically useful detail. Post-radiation protocols often center on fluoride and caries control, yet in this cohort periodontal breakdown removed just as many teeth. A recall plan that tracks caries alone will miss half the problem.

Timing matters for scheduling too. Few teeth were extracted in the first 24 months, after which tooth survival fell steadily and dropped below 80% at about 72 months. Extraction risk therefore keeps building well into survivorship, long after the early post-treatment period.

What Mechanisms Drive Post-Radiation Dental Decline?

The ADA notes that head and neck radiation can permanently impair salivary glands, vasculature, connective tissue, muscle, and bone, and that irradiated tissue repairs less effectively. The study authors describe several overlapping pathways, summarized below.

How Much Does Hyposalivation Contribute?

Radiation-induced hyposalivation, which patients report as xerostomia, reduces clearance, buffering, and the calcium and phosphate supply that supports remineralization. The authors also describe a shift in the oral microbiome toward periodontal disease-associated species.

The cohort produced a surprise here. Hyposalivation, defined as stimulated flow below 0.4 mL/min, developed in 43 patients (38.1%) and was not associated with oral health worsening. The authors suggest volumetric-modulated arc therapy spared the salivary glands better than older techniques, and they cite recent evidence that direct dental dose may predict caries better than salivary measures alone. A patient with acceptable salivary flow is therefore not automatically low risk.

Does Radiation Damage Teeth Directly?

Radiation may also alter dental hard tissues. Research cited by the authors reports reduced microhardness and changes at the enamel–dentin junction that can lead to cracks and enamel delamination. These direct effects help explain the rapid progression and crown fractures typical of radiation-related caries.

What Role Do Vascular And Inflammatory Changes Play?

Radiation damages small vessels in bone and periodontal tissues, leaving them relatively hypoxic and slower to heal. The authors also point to preclinical work showing raised MMP and IL-6 levels after irradiation, mediators linked with periodontal breakdown. They connect this vascular injury to their dose finding for tooth loss.

How Does Radiation Caries Present Clinically?

Radiation-related caries is an aggressive decay pattern after head and neck radiotherapy, and the authors estimate it affects about 30% of patients. Lesions typically start in cervical areas and on lingual surfaces, progress quickly, and can lead to crown fractures. That distribution differs from conventional carious lesions, so surfaces that are usually low-risk need close attention at every recall.

Its etiology is multifactorial. Hyposalivation, microbiome shifts, diet, hygiene, and direct changes to enamel and dentin all contribute, and smoking predicted a larger DMFt increase in this cohort.

What Happened To Periodontal Status?

Periodontal decline was localized. Sites with probing depths of 5 mm or more rose from a mean of 4.20 to 7.48 per patient, while mean probing depth moved only from 2.40 to 2.62 mm. Eight patients progressed from nonsevere to severe periodontitis, a change that did not reach statistical significance.

The authors explain why staging understates the problem. Most patients were already stage IV at baseline, leaving no higher stage to reach, and periodontitis staging and grading is less sensitive to localized deterioration than site-level probing. Mean values can mask meaningful breakdown at individual sites, so full-mouth charting at recall tells you more than tracking averages.

Deeper pockets in irradiated bone carry extra weight. Every extraction they eventually lead to brings osteoradionecrosis risk with it.

How Should Extractions Be Handled In Irradiated Patients?

The ADA describes osteoradionecrosis of the jaw (ORN) as hypovascular, hypoxic irradiated bone at risk of infection and fracture. It generally appears months or years after radiotherapy, occurs rarely below 60 Gy, and has a reported prevalence of 2% to 15%. It can follow extractions or other bone manipulation, though it can also occur spontaneously.

The ISOO-MASCC-ASCO guideline sets out several safeguards for invasive procedures in previously irradiated patients:

• Check whether the planned site received radiation before invasive treatment

• Consider alternatives to extraction, such as root canal treatment, in high-risk areas

• Give oral antibiotics before and after extraction or implant placement in high-risk sites

• Avoid routine prophylactic hyperbaric oxygen before extractions

• Consider pentoxifylline and tocopherol around invasive procedures in cancer-free patients

The cohort's absence of endodontic failures supports root canal treatment over extraction whenever a tooth is restorable.

Does The Radiation Dose To The Oral Cavity Matter?

In multivariate analysis, a maximum dose above 60 Gy to the buccal mucosa organ at risk was independently associated with tooth loss (OR 2.749), along with age (OR 1.042 per year). Mean oral dose did not predict tooth loss, while a minimum dose above 15 Gy was linked to oral health worsening in univariate analysis.

The measure needs careful reading. The buccal mucosa served as a surrogate for oral cavity exposure, and it does not correspond anatomically to the teeth or periodontium. The authors call the finding exploratory because results were inconsistent across dose metrics and many comparisons were run, so it is not a validated threshold for clinical decisions.

The finding still supports requesting dosimetry. The authors suggest radiation oncologists consider limiting unnecessary oral cavity exposure, even for tumors outside the mouth, and call for future studies with dedicated contours of the dental arches and periodontium.

How Strongly Was Smoking Linked To Decline?

Smoking was the only factor associated with oral health worsening among the 49 patients with good baseline oral health, with an odds ratio of 4.7 and a wide confidence interval of 1.27 to 17.37. It was also the only significant predictor of DMFt increase, though it did not independently predict tooth loss.

The wide interval reflects small numbers, with only 17 worsening events. Even so, smoking is the most modifiable risk factor the study identified, and cessation support fits naturally into post-radiation recalls. Our review of smoking and vaping effects on oral health covers the broader evidence.

What Should Pre-Radiation Dental Assessment Cover?

The ISOO-MASCC-ASCO guideline strongly recommends a dental assessment before head and neck radiotherapy, and the ADA cites NCI advice for patients to see a dentist about four weeks before cancer treatment where possible. A thorough workup typically covers:

• A comprehensive examination with radiographs and periodontal charting

• Treatment of active infection and restorable caries

• Identification and extraction of teeth with a poor prognosis

• Impressions for fluoride trays and a home prevention plan

• Oral hygiene instruction

• A documented baseline for later comparison

Where extraction is needed, the guideline advises at least two weeks of healing before radiotherapy, but only when that does not delay cancer treatment. The authors compare their 9.51% tooth extraction rate with the 17.8% tooth failure reported in a recent two-year study, and credit strict screening and follow-up for part of the difference.

How Should Recall And Prevention Be Structured After Radiotherapy?

The authors judged their routine protocol, six-monthly prophylaxis with three-monthly supportive care for severe periodontitis, to be only partly effective. They call for personalized protocols with closer attention to older patients and those who received high oral doses. The measures below draw on current guidance and the study's own suggestions.

What Fluoride Regimen Does Current Guidance Support?

The ISOO-MASCC-ASCO guideline recommends daily prescription-strength topical fluoride for patients at risk of radiation-induced salivary hypofunction, to reduce post-radiation caries and, with it, the need for extractions and the associated ORN risk. The ADA lists 1.1% neutral sodium fluoride or 0.4% stannous fluoride gels used daily for two to three minutes. High-fluoride toothpaste such as Clinpro 5000 is another option, and trays fabricated at the pre-radiation visit make daily gel use easier to sustain.

How Should Hyposalivation Be Managed?

Hyposalivation removes much of the mouth's natural defense against acid and bacteria, so managing it protects teeth as well as comfort. The ADA suggests frequent sips of water, ice chips, sugar-free candy, or sugar-free gum; xylitol gum adds a sweetener that cariogenic bacteria cannot ferment. Saliva substitutes can ease persistent dryness, while the ADA reports limited evidence for pilocarpine. Counsel patients against relieving dryness with sugary or acidic drinks, a habit that accelerates radiation-related caries.

What Periodontal Maintenance Interval Makes Sense?

Periodontitis causes as many extractions as caries, so maintenance has to target both. The ADA recommends a soft toothbrush, a mild-flavored fluoride toothpaste twice daily, and atraumatic daily interdental cleaning, with saline or water as a substitute when toothpaste is not tolerated. Given that three-monthly supportive care for severe cases was only partly protective here, the authors propose testing two-monthly supportive periodontal care in high-risk patients.

How Long Should Intensive Recall Continue?

Extraction risk rose after the second year and kept building through six years of follow-up. Recall intervals should follow each patient's risk profile throughout survivorship, with no automatic step-down once the first post-treatment years pass. The ADA encourages dental teams to identify survivors through the health history and monitor them actively for late effects.

What Should You Ask Every Patient With A Head And Neck Cancer History?

A note that a patient "had radiation to the head and neck" is too little to plan treatment safely. Before any extraction, implant placement, periodontal surgery, or other procedure involving bone, request these details from the patient or their oncology team:

• Radiation field and total dose

• Dates of treatment

• Dose received by the jaws and oral structures

• Tumor site and any oncological surgery

• Chemotherapy history

• Dry mouth symptoms and salivary flow

• Previous extractions and how they healed

• Any history of ORN or exposed bone

These details show whether a planned site sits in a high-dose field and whether ORN precautions apply. Recall visits are also a natural point for the clinical exam central to the ADA's 2026 oral cancer screening guidelines, which carries added weight in patients with a cancer history.

Why Does Dental Risk Persist For Years?

The study's median follow-up was nearly four years, and extractions accelerated after year two. The ADA notes that radiation damage tends to be permanent and that ORN can appear months or years after treatment. Post-radiation dental care is a long-term part of survivorship, and oncology teams are starting to share it.

A UCSF pilot trial is testing fluoride varnish applied during routine cancer surveillance visits for survivors with limited dental access. A separate pilot trains oncology teams to apply varnish and refer patients to dentists. Both projects point toward closer collaboration between dental and oncology care.

What Are The Study's Limitations?

The authors are open about several weaknesses, and each one shapes how far the findings apply to individual patients. The main limitations are:

• No non-irradiated comparison group, so changes cannot be attributed to radiation alone

• High attrition, with 74 of 187 patients lost and 56 deaths, creating survivor bias

• Dropouts were more often smokers with stage 4 cancer and severe periodontitis

• An underpowered primary outcome, with 49 at-risk patients and 17 events

• No data on diet, obesity, or metabolic syndrome

• A dose surrogate that does not map directly onto teeth or periodontium

• Periodontal measurements by one examiner without periodic recalibration

The data also come from a single national referral center using modern radiotherapy and a structured follow-up program. Outcomes in other settings, with less intensive dental follow-up, may differ.

Bottom Line

The Rome cohort shows that pre-radiation clearance and six-monthly recalls leave substantial residual risk. In this study, 43.4% of patients lost teeth. Caries and periodontitis contributed almost equally, and extraction risk rose after the second year. Daily prescription fluoride, site-level periodontal charting, smoking cessation, and risk-based recalls that continue for years offer the best current protection, alongside dosimetry review before any invasive treatment.