SummaryTooth agenesis in the reduction of tooth number which includes hypodontia, oligodontia and anodontia is caused by disturbances and gene mutations that occur during odontogenesis. To date, several genetic mutations that unlock the causes of non-syndromic tooth agenesis are being discovered; these have been associated with certain illnesses because tooth development involves the interaction of several genes for tooth epithelium and mesenchyme odontogenesis. Mutation of candidate genes PAX9 and MSX1 have been identified as the main causes of hypodontia and oligodontia; meanwhile, AXIN2 mutation is associated with anodontia. Previous study using animal models reported that PAX9-deficient knockout mice exhibit missing molars due to an arrest of tooth development at the bud stage. PAX9 frameshift, missense and nonsense mutations are reported to be responsible; however, the most severe condition showed by the phenotype is caused by haploinsufficiency. This suggests that PAX9 is dosage-sensitive. Understanding the mechanism of genetic mutations will benefit clinicians and human geneticists in future alternative treatment investigations.
Introduction: Non-syndromic tooth agenesis defined as developmental absence of more than one tooth that appears as independent congenital oral trait. Its prevalence, pattern and distribution rates vary by populations. The aim of this study was to identify the pattern and distribution of tooth agenesis in permanent dentition among IIUM dental polyclinic patients. Materials and Methods: 3481 patients aged 12 to 60 years who attended IIUM Dental Polyclinic from April 2016 until April 2017 was evaluated. 33 hypodontia and 2 oligodontia were ruled out. Patients were required to undergo clinical and radiographic examinations. Results: On an average, two teeth were missing per patients. Excluding third molar, the prevalence of population under study was 1.005%. Half of the total cases showed missing a single tooth (45.7%), whereas the others ranged from two until nine. The most common missing tooth in maxillary and/or mandibular are lateral incisors (28%) followed by second premolars (26.67%) and first premolars (25.33%). There was no significance difference in missing tooth between male and female (p=0.48). More missing teeth identified at maxilla (54.67%) compared to mandible (45.33%). More teeth were found missing on the right side (54.67%), on the posterior region (53.33%) and also unilaterally (71.42%). Tooth anomalies such as peg-shaped tooth (8.57%) and microdontia (5.71%) were found in some cases. Conclusion(s): In conclusion, mild hypodontia is considered as the most common tooth agenesis. The prevalence studied population was less than the previous studies in Malaysia and lateral incisors were identified as the most common missing tooth.
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