The etiology of mesiodens is unclear, but males are twice as affected as females in permanent teeth (possibly an autosomal recessive gene), and there is a familial trait. The genetic susceptibility along with environmental factors appears to increase the activity of the dental lamina leading to the mesiodens. The hyperactivity theory appears to be the most accepted possibility, although genetic transmission is also favored. An additional theory is that the tooth bud splits, creating two teeth.