Unilateral agenesis of permanent superior canine in familial peg-shaped lateral incisors: rare case report and literature review.

Agenesis of permanent maxillary and mandibular canines is very rare; one to all four can be missing, isolated or in association with other missing teeth or with dental morphology abnormalities. Such cases can present functional, esthetic, and psychological problems, since the canine's role in functional occlusion and in obtaining an aesthetic smile is crucial. Frequently, the canine's absence from the arch is caused by impaction; its congenital absence is extremely rare in patients with no associated syndrome. The aim of this paper was to present a very rare case of a non-syndromic Romanian adult female patient with a unilateral permanent maxillary missing canine, in association with peg-shaped maxillary lateral permanent incisors, which can have a genetic cause, since the same morphological abnormality was present in her father and her younger sister, who also presented a rare situation of bilateral upper transposition between the canines and lateral incisors. The association of a permanent maxillary canine hypodontia with bilateral "peg laterals" and transposition between the maxillary canine and the peg-shaped lateral incisors is also rare as a family character in healthy patients. Future statistical studies are necessary to establish the incidence of permanent maxillary canine agenesis in Romanian population. Also, the article includes a detailed literature review of reported cases of agenesis of permanent maxillary canines.