Down syndrome was coined by Dr. John Langdon Down in 1866 (Down, 1995). The condition consists of a chromosomal disorder that is clinically expressed through intellectual disability and distinctive physical features (Akhtar & Bokhari, 2023). Common maxillofacial characteristics associated with Down syndrome include low nasal bridge, large and fissured tongue, and small maxillary arch (Kanamori et al., 2000). Consequently, patients normally present cheilitis, periodontal disease, accumulation of salivary calculus, malocclusion and tooth wear (Bell et al., 2002, Al-Maweri et al., 2015). Contrary to what was initially believed, this syndrome can affect any human population (Ataman et al., 2012).

Genetically, Down syndrome is expressed following the presence of an additional copy of chromosome 21 (Hickey et al., 2012), for which the frequency may depend on population (Akhtar & Bokhari, 2023) and increase based on progressive maternal age (Park et al., 2019). It must be noted that most fetuses diagnosed with Down syndrome are lost before birth (Akhtar & Bokhari, 2023). To improve quality of life of patients with Down syndrome, the oral manifestations of this genetic condition have become a topic of interest and research in Oral Medicine (Moraes et al., 2007, Diz et al., 2011, Moraes et al., 2013, Hala et al., 2016; Van der Linden et al., 2017; Nawawi et al., 2018; Pinchi et al., 2018; Bagattoni et al., 2019; Apriyono et al., 2023; Kurniasih et al., 2023).

While some dental features have been mapped and deemed highly frequent in Down syndrome patients, such as taurodontism, anodontia, and conoid and retained teeth (Moraes et al., 2007), others remain controversial – namely the developmental timing of permanent teeth (Hala et al., 2016; Van der Linden et al., 2017; Bagattoni et al., 2019; Apriyono et al., 2023; Kurniasih et al., 2023). From a somatic development perspective, individuals with Down syndrome are known to exhibit a slower growth pace, for which country-specific growth charts have been developed (Zemel et al., 2015). These charts have supported the monitoring of growth in individuals with Down syndrome relative to their peers and have documented improvements over the past 25 years. Nevertheless, growth disparities compared to non-syndromic individuals remain evident. This prompts the question of whether dental development in children and adolescents with Down syndrome is similarly subject to developmental delays. Elucidating this feature is an important step to promote optimal treatment planning for syndromic children and adolescents in specialized fields like Special Care Dentistry, Pediatric Dentistry, Orthodontics and during forensic investigations.

The existing scientific literature on dental age assessment in individuals with oral or systemic conditions consists mainly of observational studies, including case-control (Diz et al., 2011, Moraes et al., 2013, Topolski et al., 2014, Bezerra et al., 2015, Souza et al., 2015, Santos et al., 2017, Gabardo et al., 2020) and cross-sectional (Moraes et al., 2007, Apriyono et al., 2023, Kurniasih et al., 2023) designs. These studies are mainly based on radiographic analyses of the human teeth using dental age estimation methods that consider ordinal stages of crown-root formation (Nolla et al., 1960; Demirjian et al., 1973; Nicodemo et al., 1974). Normally, their outcomes are two-fold: expressing the average difference between estimate dental ages of syndromic and non-syndromic individuals, and/or expressing the difference between chronological and estimated ages of syndromic individuals.

Specifically for the radiographic analysis of dental development of children and adolescents with Down syndrome, controversy has relied on a possible delay (Diz et al., 2011, Nawawi et al., 2018) of crown-root formation compared to non-syndromic individuals. Given the expressive number of available primary studies and the remaining debate on the topic, systematic review and meta-analyses are justified. The latter being especially useful to quantitatively synthesize the potential differences of dental age estimated between males and females, with and without Down Syndrome. Additionally, the meta-analysis could enable the specific assessment of differences between the chronological and dental ages of syndromic children and adolescents, individually. By doing so, clinical dental treatment based on the assessment of dental development timing could be optimized. Other benefits could be valuable to alternative practices, such as dental age estimation in forensic science. Hence, the present study aimed to revisit scientific literature, compile evidence and contribute to the understanding of dental development in children and adolescents with Down syndrome.