The oral microbiome can alter the balance between health and disease, locally and systemically. Within the oral cavity, bacteria, archaea, fungi, protozoa, and viruses may all be found, each having a particular role, but strongly interacting with each other and with the host, in sickness or in health. A description on how colonization occurs and how the oral microbiome dynamically evolves throughout the host's life is given. In this chapter the authors also address oral and nonoral conditions in which oral microorganisms may play a role in the etiology and progression, presenting the up-to-date knowledge on oral dysbiosis as well as the known underlying pathophysiologic mechanisms involving oral microorganisms in each condition. In oral pathology, oral microorganisms are associated with several diseases, namely dental caries, periodontal diseases, endodontic infections, and also oral cancer. In systemic diseases, nonoral infections, adverse pregnancy outcomes, cardiovascular diseases, and diabetes are among the most prevalent pathologies linked with oral cavity microorganisms. The knowledge on how colonization occurs, how oral microbiome coevolves with the host, and how oral microorganisms interact with each other may be a key factor to understand diseases etiology and progression.

口腔微生物组可以局部和全身性地改变健康与疾病之间的平衡。在口腔内，可能会发现细菌，古细菌，真菌，原生动物和病毒，每种细菌都有特定的作用，但是在疾病或健康中彼此之间以及与宿主之间具有很强的相互作用。关于定殖如何发生的描述，以及给出了口腔微生物组在宿主整个生命中如何动态进化的信息。在这一章中，作者还讨论了口腔微生物和非口腔疾病，其中口腔微生物可能在病因和进展中起作用，介绍了有关口腔营养不良的最新知识以及在每种情况下涉及口腔微生物的已知潜在病理生理机制。在口腔病理学中，口腔微生物与几种疾病有关，即龋齿，牙周疾病，牙髓感染以及口腔癌。在系统疾病中，非口腔感染，不良妊娠结局，心血管疾病和糖尿病是与口腔微生物相关的最普遍的病理。关于定植如何发生，口腔微生物组如何与宿主共同进化的知识，