What the research is about
Biting down hard on tough foods, grinding your teeth while you sleep, or clenching your jaw can put excessive force on your teeth. When such force damages the tissues that support the teeth, the condition is called traumatic occlusion. Dentists have long believed that traumatic occlusion can make periodontitis (gum disease) worse.
In fact, why traumatic occlusion worsens periodontitis has been debated for more than a century. In 1963, researchers proposed the "co-destruction theory," which suggests that bacterial inflammation and excessive biting forces work together to damage the tissues supporting the teeth. Later studies in monkeys and dogs showed that excessive biting force alone does not cause periodontitis, but it can accelerate bone loss when periodontitis is already present. However, the molecular mechanisms behind this process have remained a mystery.
To investigate this question, Assistant Professor Yosuke Tsuchiya and colleagues at Institute of Science Tokyo (Science Tokyo) created a mouse model with both periodontitis and traumatic occlusion. They examined gene activity separately in the gums, jawbone, and the periodontal ligament-the cushion-like tissue that connects the tooth to the surrounding bone. Using RNA sequencing, a technique that can analyze the activity of thousands of genes at once, the team performed the first comprehensive gene-level analysis of how traumatic occlusion affects periodontal tissues.
Why this matters
The researchers found that traumatic occlusion by itself caused very little bone loss, even over a long period. However, when periodontitis was already present, bone loss became much more severe. In other words, strong biting forces alone are not the main problem-it is the combination of excessive force and gum disease that causes the greatest damage.
One of the biggest challenges was determining which periodontal tissue was most affected. By analyzing the gums, jawbone, and periodontal ligament separately, the researchers discovered that traumatic occlusion has its strongest effects on bone, rather than on the gums or periodontal ligament.
They also found that when excessive biting force acts on bone already affected by periodontitis, genes and pathways involved in inflammation and bone breakdown become much more active. This helps explain why gum disease progresses more rapidly under these conditions.
What's next
This study is the first to reveal how gene activity changes inside the bone when periodontitis and traumatic occlusion occur together. These findings could eventually help researchers identify patients at higher risk of severe periodontitis and support the development of new methods for preventing or treating the disease.
The results also provide strong scientific evidence that successful treatment of periodontitis should address not only bacterial infection but also biting forces. Managing teeth grinding, clenching, and bite problems may become an increasingly important part of protecting the bone that supports our teeth.
Comment from the researcher
Dentists have long known that an unbalanced bite can make periodontitis worse, but exactly how this happens has remained unclear. By comprehensively analyzing changes in gene activity, we have begun to uncover the biological mechanisms behind this process. We hope our findings will raise awareness of the importance of treating both gum disease and bite problems together. Going forward, we will continue this research in the hope of establishing new preventive strategies for periodontitis and strengthening the scientific basis for occlusal treatment.
(Yosuke Tsuchiya, Assistant Professor, Department of Periodontology, Graduate School of Medial and Dentals Sciences, Institute of Science Tokyo)
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