Ecosystem
The term ecosystem was first used in 1935 in a publication by British ecologist Arthur Tansley. Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment. He later refined the term, describing it as "The whole system, ... including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment". Tansley regarded ecosystems not simply as natural units, but as "mental isolates". Tansley later defined the spatial extent of ecosystems using the term ecotope.
Oral ecology
Oral ecology refers to the organisms that live in a mouth. Bacteria in biofilm were first detected under the microscopes of Antony van Leeuwenhoek in the 17th century. Various bacteria and saliva are two of the major components in oral microbiology, having the capability to be harmful, but also performing beneficial and necessary roles in the immune system. Proper oral hygiene aims to control the harmful effects and prevent disease transmission.