? The science of epidemiology originally referred to the study of epidemics. And epidemic is a frequency of case occurrence beyond that which is usual for the particular season, place, and population group (santwell, 1973). This book is a compilation of all information and studies conducted on epidemiology of gingival and periodontal diseases along with the basics of epidemiology, Which will really help to the students of Periodontology as well as students of Public Health Dentistry in easy understanding of this subject.