A research team in Brazil has identified genetic variations that could influence whether individuals develop persistent inflammation at the tip of a tooth root, even after undergoing standard endodontic treatment. The findings provide fresh insight into apical periodontitis, a chronic condition affecting the peri-radicular tissue, and suggest potential pathways for more personalised dental care.
The study was conducted by academics from the School of Dentistry at the University of São Paulo in Ribeirão Preto and published in Archives of Oral Biology. It examined subtle alterations in human DNA — known as genetic polymorphisms — which are involved in controlling inflammatory reactions and bone metabolism.
Understanding Uneven Healing Outcomes in Endodontics
In Brazil, apical periodontitis is traditionally managed through root canal therapy, designed to remove infected pulp and seal the canal. Yet despite technically adequate procedures, international literature reports that 10–15% of cases fail to resolve fully, resulting in persistent inflammation.
Researchers noted that patients receiving comparable treatment protocols frequently showed different healing responses. This observation fuelled investigation into whether biological and systemic features — particularly genetic predisposition — play a role in treatment outcomes.
Genetic Influence on Inflammation and Bone Repair
The researchers analysed 423 Brazilian patients, all previously treated with root canal procedures. Of these, 172 developed persistent apical periodontitis, while 251 achieved complete tissue repair. By ruling out clear technical errors, the team focused on molecular factors that might influence healing.
Genetic material was collected from saliva using saline rinses, followed by DNA extraction and real-time PCR analysis to identify variants with high sensitivity.
Multiple genes connected to inflammatory pathways and bone turnover were reviewed, including TNF-α, SOCS1, TNFRSF1A, TNFRSF1B, RANK, RANKL and OPG. These molecules help regulate immune signalling and the reshaping of surrounding bone structures — critical processes in post-treatment healing.
Two specific variants appeared to confer lower risk of persistent inflammation:
• Individuals with the A allele in the TNF-α gene showed reduced susceptibility, aligning with established associations between this allele and dampened inflammatory cytokine production.
• Those with two copies of the T allele in RANKL displayed improved bone remodelling balance.
The team also observed an interactive effect between inflammation-related and bone-regulation genes, suggesting that treatment success may depend on networks of genetic markers rather than isolated mutations.
Moving Towards Precision Dentistry
The findings lend weight to the theory that personal biological characteristics influence endodontic recovery, and that microbial control and surgical precision alone do not determine prognosis.
Researchers caution, however, that the sample population — drawn solely from southeastern Brazil — may limit broader applicability. They emphasise the need for validation across larger and ethnically diverse cohorts, integrating genomic, epigenetic and biological-profiling approaches.
Still, they argue that the results strengthen the rationale for precision dentistry, where clinical decisions incorporate genetic, radiographic and biological data to enhance prediction of healing outcomes.
The research group is developing predictive models designed to support customised treatment planning, aiming to bring personalised dentistry from theory to clinical reality.