"Not only did we find a connection between dental health and depression, we also demonstrated that a dose-response exists between the two conditions, meaning that the more dental conditions one had the greater the severity of their depression," said Deakin's Adrienne O'Neil, M.D.
 

"This relationship held true even after accounting for other factors that could potentially explain the association, such as high body mass index and CRP, a protein that is often used as a general marker of inflammation in the body."

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Depression is considered an inflammatory disorder, meaning that sources of inflammation such as bad dietary habits, being overweight or the presence of other medical conditions can contribute to the biological processes that induce mental disorders from a very early age.
 

To determine if poor dental health, which is a source of inflammation, is linked to depression, the researchers analyzed information from the long-running National Health and Nutrition Examination Survey.
 

They found almost two thirds of participants reporting depression (61 percent) also reported having an aching mouth in the past year and more than half (57.4 per cent) considered their teeth to be in fair or poor condition.
 

"The relationship between dental health and depression is not well understood, with previous studies investigating poor dental health as a by-product of depression, rather than a precursor," Dr O'Neil said.
 

"Although the results of this study provide only a snapshot of this association, they add to emerging theories around the importance of oral health and bacteria in mental health ... if poor dental health is a risk factor for depression, this may have implications for depression management, as well as depression prevention from a public health perspective."
 

The results of this study were published online in the journal General Hospital Psychiatry.