monophyodont

Monophyodont is a term used in dental biology to describe organisms that develop only a single dentition for their lifetime and do not form a second set of teeth. In a monophyodont species, after the initial eruption of teeth, there is no subsequent replacement or addition of new teeth.

This contrasts with diphyodont species, in which two successive dentitions occur (usually deciduous baby teeth replaced by permanent teeth), and polyphyodont species, in which teeth are continuously replaced throughout life.

Examples: In mammals, most therian mammals (marsupials and placentals) are diphyodont. Some monotremes, such as the platypus and echidnas, are considered monophyodont or even lacking a functional adult dentition, because they lack a permanent adult set of teeth. Juvenile platypuses possess a temporary set of teeth that is not retained into adulthood, illustrating a transient instance of dentition that is not replaced.

Significance: The pattern of tooth replacement is used in phylogenetic and developmental studies, as it relates to growth, jaw development, and feeding strategies.