Salivary microbiome, metabolome and host immune changes in patients undergoing fixed orthodontic therapy

Patients commonly elect to have braces (fixed orthodontic appliances) to straighten their teeth or fix their bite. Often times, patients have a hard time keeping their teeth clean with braces on because there are many nooks and crannies for food and bacteria to stick to, forming “plaque”. We, as humans, normally have hundreds of bacteria living in our mouths. When our mouths are healthy, these bacteria live in harmony with our body’s immune system. When there is a change in the population of bacteria living in one’s mouth—which happens when there is a build-up of plaque around braces—disharmony ensues, and that person is more likely to get cavities and gum disease. This a problem for patients with braces, so the purpose of our study is to try to understand exactly how bacteria and our body’s immune system change when braces are on so that we might be able to target those particular bacteria in disease prevention.

We collected saliva from four groups of patients: patients without braces and patients who had braces on for 6, 12, and 24 months. In the laboratory, we performed tests to examine the bacteria, metabolites (small molecules released by bacteria), and our body’s immune response, and we compared differences between groups.

We found that patients with braces have a less diverse population of bacteria in their mouths than patients without braces. Patients with braces had more disease-associated bacteria and fewer health-associated bacteria. Early on in braces treatment, metabolites that are associated with cavities and gum disease were most abundant. Later in treatment we saw an increase in markers of inflammation associated with cavities and gum disease. We hope to use our findings, and the findings of future studies, to come up with treatments to prevent cavities and gum disease in patients with braces.