A Case of Unilateral Agenesis of Premolars treated with Simple Mechanics

Agenesis of one or more teeth is the most common anomaly in dental development.1 The incidence for permanent tooth agenesis ranges from 1.6 to 9.6% in the general population excluding third molars.2-6 Third molars being the most commonly missing tooth, opinions vary on the second most commonly missing tooth. Some investigators7-11 believe that this is the maxillary lateral incisor whereas others4,12 believe that mandibular second premolar agenesis has a higher incidence. An interesting correlation on the number of missing teeth and the tooth class has been made by Muller et al.8 They have noted that maxillary lateral incisors are the most frequently missing teeth, when only 1 or 2 teeth are absent; whereas second premolars are the most frequently missing teeth when more than two teeth are absent. Defective MSX1 gene in chromosome 4p was found to be associated with agenesis of second premolar and third molar formation.13 The orthodontic and prosthetic treatment options for the agenesis of premolars depends on the associated malocclusion. This case report deals with unilaterally missing upper and lower second premolars with severe dental midline shifts to the affected side.