Hypodontia is the most common craniofacial anomaly and may be associated with genetic syndromes or isolated, with both genetic regulation and environmental factors involved in its etiology (Polder et al., 2004). The prevalence of tooth agenesis varies according to the region and sex of the analyzed population, being 1.37 times more prevalent in women and with different patterns of missing teeth (Al-Ani et al., 2017). There are a total of 198 known different mutations in 15 genes that are associated with tooth agenesis, with 91.9 % of mutations in seven genes (AXIN2, EDA, LRP6, MSX1, PAX9, WNT10A and WNT10B) and the minority related to the other eight genes (BMP4, DKK1, EDAR, EDARADD, GREM2, KREMEN1, LTBP3 and SMOC2) (Yu et al., 2019). Considering the variety of genetic mutations involved in tooth agenesis, the understanding of dento-orofacial genetics is a useful tool in the preclinical diagnosis of cases and in the improvement of orthodontic therapeutic approaches (Vastardis, 2000). However, the majority of genetic studies have been conducted on syndromic oligodontia, and the genes involved in isolated hypodontia are still poorly understood (Ruf et al., 2013).

The abnormal function of genes involved in epithelial-mesenchymal interactions during the stages of odontogenesis can lead to both tooth agenesis and a variety of other anomalies of shape, number, and structure (Ye & Attaie, 2016). The genetic interrelation of dental anomalies is supported by the frequent clinical association of tooth agenesis with other anomalies, such as microdontia of maxillary lateral incisors, distoangulated mandibular second premolar, delay in the development of permanent teeth, and infraocclusion of the deciduous molar (Choi et al., 2017). There is evidence that also supports the relationship between tooth agenesis and sex of patients with other dental anomalies, except with supernumerary teeth that seem to be independent (Souza-Silva et al., 2018).

Based on the unifying aetiological explanation model of dental abnormalities (Brook, 1984), nonsyndromic patients with agenesis of permanent teeth may have other associated dental anomalies, which suggests the need for a thorough dental evaluation to diagnose these dental anomalies and plan a more complete and individualized treatment. Therefore, this review aimed to systematically analyze the literature on the prevalence of agenesis of permanent teeth associated with other dental anomalies in nonsyndromic patients.