Researchers linked national health records for 652 patients who received antiresorptive treatment between 2013 and 2015. They tracked diagnoses through the end of 2020 using records from the Finnish Institute for Health and Welfare (THL) and the Social Insurance Institution of Finland (Kela).
Among patients who first received bisphosphonates and later switched to denosumab, 15.3% were diagnosed with osteonecrosis of the jaw. The figure was 12.6% for patients treated with denosumab alone and less than 2.2% for those treated with bisphosphonates alone. These percentages cover the follow-up period, not the risk from a single dose or dental procedure. On 14 October 2026, the University of Oulu reported the findings as Finland's first nationwide study of the condition in this patient group.
Medication-related osteonecrosis of the jaw was diagnosed during long-term follow-up. Tooth extraction and root canal treatment were associated with higher risk, but the observational study reports diagnoses and statistical associations, not proof that dental procedures cause the condition.
A dental procedure recorded before diagnosis does not establish cause.
Antiresorptive medicines slow bone breakdown and help prevent skeletal complications when breast cancer has spread to bone. Osteonecrosis of the jaw is a recognised adverse effect of these medicines. Before this analysis, its incidence among Finnish patients in this group had not been examined in a population-based study. The researchers assessed bisphosphonates and denosumab, including patients who received them in sequence.
The registry analysis linked procedures related to oral infections with jaw necrosis, particularly tooth extraction and root canal treatment. A procedure may have been needed because an infection or inflammation was already present. Few patients underwent root canal treatment, limiting what the study could establish about that procedure. Comparisons between treatment groups may also reflect differences in disease severity or treatment duration. The researchers called for more detailed information on dose and duration.
The findings alone do not justify stopping or changing antiresorptive treatment. The University of Oulu research team said clinicians should assess benefits and potential risks for each patient. They stressed identifying and adequately treating possible oral infections before therapy begins. They also highlighted the need to monitor oral health during treatment. Necessary dental care should not be withheld.
For oncology and oral-health teams, timing and communication matter. Dental assessment and necessary care should be considered alongside the start or continuation of antiresorptive therapy. The study does not show how much preventive dental care reduces risk, a question the researchers say needs further study. They also called for precise information on when infections and procedures occur relative to the onset of osteonecrosis. Cases can develop slowly, so follow-up over several years may be needed to capture them.
Prevention efforts also include bringing oral care and education closer to communities, as seen in community outreach in Namibia. The Finnish study focuses on patients receiving cancer treatment who may need coordinated dental monitoring.
M. Kujanpää and colleagues published the study in Clinical Oral Investigations on 29 September 2026. Its title is "Incidence and associated factors of medication-related osteonecrosis of the jaw in breast cancer patients with bone metastases: a nationwide registry study in Finland." The University of Oulu announcement described the study's focus on dental assessment before treatment and continued oral-health monitoring. The research received grants from the Finnish Dental Society Apollonia.
