Periodontitis is a complex, multifactorial disease and its susceptibility is genetically determined. The present book systematically reviews the evidence of the association between the genetic variants and periodontitis progression and/or treatment outcomes. Genetic syndromes known to be associated with periodontal disease, the candidate gene polymorphisms investigated in relation to periodontitis, the heritability of chronic and aggressive periodontitis, as well as common guidelines for association studies are described. This growing understanding of the role of genetic variation in inflammation and periodontal chronic disease presents opportunities to identify healthy persons who are at increased risk of disease and to potentially modify the trajectory of disease to prolong healthy aging. The book represents a new concept in periodontology with its pronounced focus on understanding through knowledge rather than presenting the presently valid answers. Connections between genetics and periodontology are systematically reviewed and covered in detail.