Abnormalities in the differentiation of the dental lamina and the tooth germs (morphodifferentiation) will result in various anomalies related to number, size, and form of teeth. The congenital absence of teeth may be referred to as hypodontia when one or several teeth are missing.¹ The prevalence of congenitally missing tooth/hypodontia varies from 0.2% to 16.2% in Asians.² The most frequently missing teeth are the third molars, upper lateral incisors, second premolars, and lower central incisors.³ Hypodontia may be symmetrical when particular teeth or groups of teeth are involved or haphazard when no pattern is discernible. Agenesis of permanent canines is very rare and the incidence varies from 0.18% to 0.45% as reported in the populations of Japan, Hungary, and Hong kong.⁴,⁵,⁶ Other dental anomalies, i.e., agenesis of other teeth, microdontia, malocclusion, and retained primary teeth might be associated with congenitally missing permanent canines.⁵ Reports of congenital agenesis of permanent canines in both arches are scarce. This article describes a rare case of congenital agenesis of all permanent canines along with the absence of mandibular permanent lateral incisors.

A 12-year-old boy reported to the Private Clinic in Rohtak (Haryana) with the chief complaint of missing teeth and irregularly placed upper and lower front teeth Figure 1. Although his medical history was noncontributory, it was the first visit to a dentist. On intraoral examination, the patient had early mixed dentition, with four erupted permanent first molars, maxillary central and lateral incisors, maxillary right first premolar, maxillary left first and second premolars with two central mandibular incisors. The maxillary canines, mandibular canines, and mandibular lateral incisors were absent as can be seen in his upper and lower dental arch photograph Figure 2. There was evidence of caries on lower deciduous molars. On panoramic radiograph, the primary maxillary and mandibular canines were missing and also there was no evidence of developing permanent maxillary and mandibular canines Figure 3.Figure 1

Clinical photograph (front view) showing oligodontia.

Disorders of development of teeth may be prenatal or postnatal in origin and may be inherited or acquired. Their recognition and evaluation require a thorough knowledge of the normal development and chronology of the human dentition. Tooth agenesis or hypodontia is one of the most common anomalies of the human dentition, which is characterized by the developmental absence of one or more teeth. Congenitally missing teeth is a result of disturbances during the early stages of development. Severe hypodontia is usually associated with genetic disorders such as Witkop syndrome, ectodermal dysplasia, and Rieger syndrome. Mild to moderate hypodontia may occur due to early irradiation of tooth germs, various kinds of trauma of the dental region, Down syndrome, and syndromes associated with cleft lip or palate.⁷ The etiology of tooth agenesis has generated much debate. It supposed to be multifactorial involving several factors such as genetics; environment; or combination of environmental and genetic factors might contribute to the occurrence of dental agenesis. Furthermore, it is suggested that anterior agenesis may depend more on genes while posterior missing might be sporadic. The exact genetic mechanism is still not known. Separate mechanisms might as well account for missing of each tooth.²,⁷

Recent reports have shown that in the Caucasian population, the prevalence of hypodontia in permanent dentition (third molar excluded) is about 4.5%–7.4%. The developmental absence of permanent canines is reported to be higher in women and mostly maxilla affected with the left side.⁷ Agenesis of both maxillary and mandibular permanent canines is extremely rare. Reports of such cases are very scarce in the literature. Fukuta et al.⁴ recorded thirty-seven cases with single absence of the canine and 28 cases of multiple absences in Japanese population. Rózsa et al. reported thirteen participants with permanent canine agenesis; permanent maxillary canine agenesis was found in nine patients, mandibular canine agenesis in four, and in three, both arches were involved in Hungarian population.⁵ In the Chinese population, Cho et al. described the 32 cases of congenitally missing permanent teeth regarding only maxillary canines, among which only nine were bilaterally missing.⁸ However, agenesis is very rare in the Caucasian population, Muller et al. reported 0.037% prevalence among American children whereas 0.14% in black children.⁹ Detailed description pertaining to cases of missing canines from the literature is summarized in Table 1. The present case demonstrated a complete agenesis of all permanent canines and to the best of our knowledge, this is the second case reported in Indian population.{Table 1}

Hypodontia and oligodontia are classified as isolated or nonsyndromic hypodontia/oligodontia and syndromic hypodontia/oligodontia or hypodontia/oligodontia associated with syndromes. Oligodontia is often associated with specific syndromes and/or severe systemic abnormalities, while anodontia is commonly seen in severe cases of ectodermal dysplasia. Congenital absence of teeth may be due to from physical obstruction or disruption of the dental lamina, space limitation, and functional abnormalities of the dental epithelium or failure of initiation of the underlying mesenchyme. Characteristic dental symptoms are a reduced number of teeth, a reduction in tooth size, anomalies of tooth form, and delayed eruption.¹⁷ The past medical history and the family history were not significant in the present case. Extraoral examination revealed no abnormalities of the skin, hair, or nails and there was no abnormality detected on general examination. Therefore, the patient was diagnosed with the congenital absence of permanent canines which could be of nonsyndromic type.

Hypodontia is an anomaly that may result in dental malpositioning, periodontal damage, lack of development of maxillary and mandibular bone height and has significant psychological, esthetic, and functional consequences.¹⁷ Correct diagnosis and an appropriate treatment strategy of such rare conditions are mandatory to prevent future complications. In addition, this rare case might contribute in the future studies of incidence of agenesis of permanent canines.

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