Abstract: Bacteria and inflammation play a key role in periodontitis. Chewing and swallowing transfer periodontitis-associated microbiota and inflammatory mediators to the gut. Gut microbiota and its metabolites directly enter the brain or indirectly regulate neuroinflammation by affecting the production of inflammatory mediators，forming a gut-brain axis. Alzheimer′s disease（AD）is a common brain lesion that is closely related to microbiota and inflammation. However，the relationships among periodontitis，gut and AD are intricate. This article reviews the relationship between periodontitis-associated flora and the gut-brain axis，the relationship between the gut-brain axis and AD，the relationship between periodontitis-associated flora and AD，and the evidence and possible mechanisms of periodontitis-associated flora affecting AD through the gut-brain axis.

Key words: periodontitis, microbiota, gut-brain axis, Alzheimer′s disease

摘要： 细菌和炎症在牙周炎的发生和发展中起到了关键作用，咀嚼和吞咽会将牙周炎相关菌群和牙周相关的炎症介质转移至肠道。肠道菌群及其代谢产物直接进入脑部或通过影响炎症介质的生成间接调控神经炎症，形成肠-脑轴。阿尔茨海默病（Alzheimer′s disease，AD）是一种常见的脑部疾病，与菌群和炎症存在着密切联系。然而，牙周炎、肠道和AD之间的关系错综复杂。文章就牙周炎相关菌群与肠-脑轴的关系、肠-脑轴与AD的关系、牙周炎相关菌群与AD的关系以及牙周炎相关菌群通过肠-脑轴影响AD的证据和可能机制做一阐述。

关键词: 牙周炎, 菌群, 肠-脑轴, 阿尔茨海默病