Around 2%–3% of adults have a cerebral artery aneurysm, which, if ruptured, can cause a life‑threatening subarachnoid hemorrhage. High blood pressure and smoking are known risk factors, but many patients have no identifiable risks, suggesting that not all contributing factors are yet understood. Previous studies have even detected DNA from oral bacteria in the walls of both ruptured and unruptured aneurysms, hinting at a possible role in disease progression.
In his doctoral research, dentist and oral and maxillofacial surgeon Joona Hallikainen found that widespread gingivitis and severe periodontitis increased both the prevalence and rupture risk of aneurysms over a 13‑year follow‑up. Tooth decay, however, did not show such an association.
The study included patients with unruptured or ruptured cerebral aneurysms treated at the neurosurgery outpatient clinic of Kuopio University Hospital in central eastern Finland. The age- and gender-adjusted participant group from the Health 2000 survey in the Northern Savo region was used as a control group. The Health 2000 Survey is a nationwide study carried out in Finland in 2000–2001 to assess the population’s health, functional capacity, and welfare.
Dr. Hallikainen’s work also confirmed a link between oral bacteria and aneurysms. Blood samples from aneurysm patients contained antibodies against Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, two bacteria typical of periodontal disease. The magnitude of this immune response correlated with aneurysm occurrence and rupture. Histological analysis of two aneurysm wall samples further suggested exposure to P. gingivalis.
According to Dr. Hallikainen’s research, oral bacteria may contribute directly by infiltrating the aneurysm wall, or indirectly through systemic inflammation. His findings highlight the importance of maintaining good oral health—especially gum health—for individuals with unruptured aneurysms. Future research will need to determine whether treating oral diseases could help prevent aneurysm formation or rupture.
Dr. Hallikainen’s dissertation, Role of Oral Infections in Intracranial Aneurysm Pathology, will be examined at the University of Eastern Finland’s Faculty of Health Sciences on December 12. The opponent will be Docent Tero Soukka from Turku University Hospital, and the custos Professor Juhana Frösén from Tampere University.
Additional reading:
Linking the mouth and the brain: Key findings of the study
The dissertation of Dr. Joona Hallikainen aimed to clarify the relationship between oral infectious diseases and intracranial aneurysms through a combination of clinical, epidemiological, and serological data.
The study revealed several clinically significant associations:
- Periodontitis and gingivitis correlate with intracranial aneurysms. Patients with clinical signs of periodontal inflammation were more likely to have intracranial aneurysms (IAs) compared with matched controls.
- Gingivitis and severe periodontitis increase aneurysm rupture risk. Over the 13-year follow-up, individuals with baseline gingivitis or advanced periodontitis showed a higher risk of experiencing an aneurysmal rupture.
- Caries and tooth loss showed no association. Contrary to periodontitis, dental caries and the number of missing teeth were not linked to IA formation or aneurysmal subarachnoid hemorrhage (aSAH).
- Systemic immunization patterns against periodontal pathogens matter. Both IgA and IgG antibody responses to P. gingivalis and A. actinomycetemcomitans were associated with aneurysm presence and rupture. Surprisingly, patients demonstrated low IgG levels, raising questions about impaired systemic defense or chronic infection load.
Implications for dentistry and medicine
The study findings add compelling evidence that oral health extends far beyond the mouth—potentially influencing life-threatening cerebrovascular outcomes. For dental professionals, this reinforces the importance of early periodontal diagnosis, effective treatment, and patient education.
