## 4 Discussion
The present study found that bilateral agenesis of maxillary lateral incisors (62 cases) was significantly more common than unilateral agenesis of the maxillary lateral incisors (12 cases). This is in agreement with [PERSON] et al. [1], [PERSON] et al. [21] and [PERSON] et al. [42]. Similarly, bilateral agenesis of mandibular second premolars (44 cases) was more common than unilateral agenesis of mandibular second premolars (14 cases). In addition, a higher prevalence rate of bilateral missing maxillary lateral incisors (62 cases),followed by mandibular second premolars (44 cases), was found in our study. This was unlike a report that found a higher prevalence of bilateral agenesis of mandibular second premolar compared with maxillary lateral incisors [43]. A possible explanation for the higher prevalence of bilateral agenesis compared with unilateral agenesis was suggested that unilateral missing teeth is a result of partial expression of the gene responsible for missing teeth, similar to that with microdontia and peg-shaped lateral incisors [3,9,13]. Dental anomalies such as tooth agenesis are an important part of malocclusion diagnosis. Hypodonia causes spacing between teeth and decreased growth of the alveolar process, it influences skeletal patterns and craniofacial structure and soft tissue profiles [44,45]. Tooth agenesis was found to be associated with other dental anomalies such as reduction in tooth size (peg shaped lateral incisors), delayed dental development especially of the mandibular second premolars and palatally positioned maxillary canines [1,2]. The palatal displacement of the maxillary canine, associated with the missing maxillary lateral incisors, was explained by [PERSON] et al. as the \"guidance theory\" where the roots of the maxillary lateral incisors guide the maxillary canine eruption path [46]. Unlike this theory, the genetic theory advocated by [PERSON] et al. [47] as the major factor for the close association between agenesis of maxillary lateral incisors and palatally displaced maxillary canines. Agenesis of teeth is usually associated with other systemic abnormalities and appear as a part of a complex of multiple congenital anomalies such as ectodermal dysplasia or Down syndrome and in cleft lip and cleft palate [7]. The congenital absence of teeth is significantly higher in children with a cleft lip or cleft palate, both in and outside the cleft region. The maxillary lateral incisors are the most commonly missing teeth in the cleft area, followed by the maxillary second premolars in cleft lip and palate individuals [48]. A higher frequency of missing maxillary lateral incisors and second premolars were found in cleft lip and palate individuals, with second premolars absent three times more often in the maxilla than in the mandible [49]. Agenesis of either maxillary lateral incisors or mandibular second premolars presents diagnostic and clinical management challenges to the clinicians. Managing agenesis of maxillary lateral incisors specifically, because of esthetic concerns, is a challenge for all of the medical specialists involved (i.e., orthodonticist, pediatric dentist, prosthodontist, oral surgeon, etc.). The complexities of successfully treating this condition require a multidisciplinary approach to establish not only optimal esthetics but functional and stable occlusion as well [50]. Generally, two conservative approaches can be considered: space closure by canine substitution of the missing lateral incisor [51], or space opening and prosthetic replacement of the missing tooth/teeth with or without endosseous implant support [42,52]. Another treatment option suggested to replace missing teeth in growing individuals is the autotransplantation of teeth with developing roots. The most common transplanted teeth are premolars, with developed roots of \(2/3\) to \(\frac{3}{4}\) of the final root length, into the anterior region of the maxillary arch, following prosthodontic reshaping to resemble anterior teeth.