Nonsyndromic Hypodontia of Maxillary Lateral Incisors, Its Genetics and Its Association with Other Dental Anomalies

Abstract

Congenital absence of maxillary lateral incisors presents a difficult situation for clinicians for restorative and orthodontic purposes. Further, missing lateral incisor agenesis (MLIA) has been associated with other dental anomalies and cancer. Few studies have targeted MLIA as a specific subtype of hypodontia. WNT10A is a candidate gene for MLIA.

The hypothesis was that genetic mutations in WNT10A affect maxillary lateral tooth development and can contribute to other dental anomalies. The first aim was to evaluate patients with congenitally missing maxillary lateral incisors and other tooth anomalies. 240 patients with nonsyndromic hypodontia were identified. The charts were screened for missing teeth, peg laterals, impactions, and transpositions. The second aim was to identify WNT10A mutations as markers of MLIA. Three families with MLIA were recruited and saliva samples were collected and analyzed via PCR and sequence analysis. 

This study found that MLIA presented bilaterally more than unilaterally. In unilateral MLIA, the right and left were affected equally. While more females made up our population of patients, males and females were affected equally in MLIA. 

Of 90 patients missing at least one maxillary lateral, 38 (42.2%) were missing another tooth other than a maxillary lateral. Among nonsyndromic hypodontia patients, peg laterals presented bilaterally more than unilaterally. In unilateral pegs, the left and right were affected equally. When MLIA was unilateral, the contralateral tooth presented as a peg 58.8% of the time on the right and 66.7% on the left. No transposed teeth were present in our patients. An impacted tooth presented 7.5% of the time. Maxillary canines were impacted most frequently. 10% of patients with bilateral MLIA also had an impacted tooth. 

In aim two, we identified one mutation in family 2. This was a single nucleotide variant (493G>A, rs77583146) that resulted in an amino acid substitution (Gly165Arg). Future studies should target MLIA as a subtype of hypodontia and WNT10A should continue to be evaluated in families with MLIA for its role in tooth development as well as other diseases, including cancer.