Teeth eruption is an ongoing physiological process, in which teeth move from their developmental position within the jaws to break the mucosa toward the oral cavity. Researchers consider a tooth as erupted when as any part of the tooth crown penetrates the gingival tissue and is visible in the oral cavity. Parents consider eruption of first primary teeth as an important developmental milestone that has to be achieved by the child and often seek pediatrician opinion if there is a delay. Studies have shown wide variations in the timing of primary teeth eruption.

Studies have shown wide variations in the timing of primary teeth eruption within a given geographic area as well. Numerous factors influence the timing of eruption. These include gender, ethnic origin, racial group, gestational age, systemic diseases, hereditary factors, and nutritional status. Dental age of children widely vary among children and depends on their dental developmental milestones, thus a delay is not necessarily a worry sign for parents. Dental age is also a key factor for implementation of caries prevention programs such as topical fluoride application.