The masticatory function comprises a highly organized and complex action, involving several elements, with the teeth being the main one. An adequate functional dentition, defined as a condition that guarantees masticatory function even when the dental arch is not complete, is vital for a good quality of life and general health, influencing nutrition and reducing the risk of chronic diseases. The OMS refers to functional dentition as the preservation of at least 20 natural teeth throughout life without the need for dental prostheses. However, this definition is a quantitative concept. Studies show that tooth loss, malocclusion, and periodontal disease or caries negatively affect masticatory ability, which can lead to broader health problems, including malnutrition and systemic diseases. Therefore, tooth distribution, occlusal contacts, and oral health are fundamental for effective mastication. Research indicates that to provide a dentition that facilitates adequate mastication and meets functional requirements, the presence of at least 10 teeth in each arch, six anterior contacts (i.e., an intact anterior dentition), and at least four posterior occlusal contacts is recommended. In conclusion, a functional dentition is not defined solely by the number of teeth present, but also by their distribution, occlusal contacts, and oral health.

KEY WORDS: Functional dentition; Functional teeth; Eichner index; Shortened Dental Arch.