Alterations of the oral microbiota and oral clinical findings in dry mouth

BackgroundA large variety of microorganisms colonize the oral cavity. Imbalances in the microbial ecosystem, likely caused by changes in the oral environment, can lead to oral diseases. One change that exacerbates the oral environment is dry mouth, characterized by hyposalivation and/or hyperevaporation of saliva, which may be caused by adverse drug effects, radiotherapy for head and neck cancer, and systemic disease.HighlightIn this review, we discuss the findings of studies reporting relationships between hyposalivation, clinical findings, and the oral microbiota, by using culture analysis and molecular biological analyses. The results of these studies indicate that hyposalivation contributes not only to fluctuations in the number of certain microorganisms, but also influences the composition of the microbiota (the microbial ecosystem) in the oral cavity. These results were reflected by clinical indices, such as the number of decayed, missing, or filled teeth, and the prevalence rate of candidiasis in the patients studied.ConclusionIn order to treat the various dry mouth-associated health concerns, an understanding of the qualitative alterations of the oral microbiota occurring in dry mouth and appropriate prophylaxis of oral disease are required.