Prevalence, distribution, and age at clinical detection of missing permanent incisors

To determine the prevalence and distribution of clinically missing permanent incisors, and the age at which they are detected, in school-aged children.

A total of 2573 children aged 4-13 underwent oral health screening on at least one occasion between 2001 and 2017. In order to define a threshold age, after which permanent incisor agenesis could be suspected clinically with reasonable certainty, children who had been seen for at least three consecutive years, with any clinically missing permanent incisor were selected (n = 19). The maximum age of detection among these children was chosen as the threshold age. Based on this, a total of 766 children at or above the threshold age were screened for a cross-sectional epidemiological survey. Chi-squared tests were used to compare the prevalence of clinically missing permanent incisors among boys and girls, comparing unilateral versus bilateral, and right- versus left-sided missing teeth.

Roughly 2% of the sample presented with at least one clinically missing maxillary lateral incisor. This was bilateral in half of cases. Clinically missing mandibular incisors were found in 0.5% of children. Finally, the threshold age for clinical suspicion of maxillary lateral incisor agenesis was set at 11.5 years. Agenesis was confirmed in all of the children attending a follow-up radiographic visit.

Approximately 1 in 50 children present with a clinically missing maxillary lateral incisor. The age at suspicion of maxillary lateral incisor agenesis can sometimes be several years after its expected eruption, perhaps due to significant variation in eruption times.