Association between severe unaddressed dental needs and developmental health at school entry in Canada: a cross-sectional study

Poor oral health is a worldwide public health problem, with millions of children experiencing caries in their primary teeth [1]. Estimates suggest that 60 to 90% of school-aged children have some form of tooth decay [2] and in Canada, up to half of all children enter kindergarten with tooth decay [3, 4]. While tooth decay is common across the globe [5], it is also a marker for health inequalities, with people of lower socioeconomic status (SES) experiencing poorer oral health [6‐9]. Poverty is related to a higher risk of dental caries, unaddressed dental needs (UDNs), and poor oral health-related quality of life [10]. UDNs are oral health issues, such as dental caries, that have not yet been treated or corrected. In the United States, over 40% of low-income individuals 20 to 64 years of age had untreated dental caries between 2005 and 2008, compared to 16% of high-income people [11]. A Canadian study found a strong SES-based inequity in preventive dental care utilization, with lower-income individuals tending to postpone visits to the dentist [12, 13]. In addition to the inequalities in oral health between the lower and higher SES groups, there is also evidence of a social gradient in oral health [14, 15], where the difference in outcomes is gradual and exists along the full spectrum of SES. UDNs have also been associated with special health needs (SHNs) in children. Children with SHNs are defined as having either a disability, exceptionality, or a functional impairment, such as a visual or hearing impairment, and they typically require additional assistance in the classroom [16]. Research indicates that they have poorer oral hygiene and a greater incidence of caries (both treated and untreated), as well as other oral diseases compared to their non-SHNs peers [17, 18], with reports of 20% of children with a SHN having UDNs [19]. It has been suggested that a lack of training for dental professionals on how to treat children with SHNs [20] is one of the reasons for their poorer oral health, as some of them, such as children with Autism Spectrum Disorder (ASD), appear to face multiple barriers in accessing dental care [21].

Dental caries in young children have been associated with various aspects of their health. For instance, children with caries report experiencing pain [22, 23], impacting their ability to eat and sleep, participate in school activities and learn [23‐25]. Dental caries also affect children’s nutrition and growth which are associated with poorer developmental outcomes. Acs and colleagues [26] found that 3-year-old children with severe dental caries weighed on average 1 kg less than children without caries. Other studies have found an association between dental health and academic achievement [27‐29], as well as psychosocial well-being [22, 25, 28]. Little is known about the association between oral health and children’s developmental health. Developmental health is a concept put forth by Keating and Hertzman [30] that is based on the framework of social determinants of health [31], and is meant to encompass biological aspects of health (i.e., physical), as well as behavioural (emotions, cognitive skills). In doing so, it promotes a holistic view of early childhood, beyond simplistic cognitive-only school readiness or absence of illness [32]. The Early Development Instrument (EDI) is a population-level measure of children’s developmental health at school entry which has been used globally and been well validated [33‐36].

While dental caries and tooth decay are common problems among children, little is known about how teacher identification of UDNs may be related to children’s developmental health at school entry. For children with limited access to dental health care in particular, teacher’s observation of dental needs may be an important marker of overall health needs. We hypothesized that children with UDNs would have a greater chance of having developmental vulnerability than children without such needs. The primary objective of this observational, cross-sectional study was to evaluate the association between teacher-reported UDNs in Canadian kindergarten children and developmental health at school entry based on the total EDI score. Secondary objectives were to examine the association between teacher-reported UDNs and any area of developmental vulnerability on the EDI including physical, socioemotional, language/cognitive, and communication and general knowledge.

In this study of children from across Canada, teacher-reported UDNs were associated with developmental vulnerability on the EDI at the time of school entry. Children with UDNs had greater odds of being vulnerable on all of the EDI developmental domains compared to children without UDNs. Children with UDNs had 4.6 to 8.3 times higher odds of being vulnerable on the EDI domains compared to their non-UDN peers. The odds of developmental vulnerability were particularly high for physical health and well-being, language and cognitive development, and communication skills and general knowledge. These odds are comparable to those experienced by children who have a special needs designation [45, 46].

To our knowledge, this is the first study that examined teacher-reported UDNs and their association with developmental health. Our findings, indicating strong associations between UDNs and child development, suggest that teachers who identify UDNs in their students might be in a good position to advocate for oral healthcare and provide support for concurrent developmental issues. This is particularly important when considering that many children may experience a low access to routine dental care, even in a country like Canada which provides free basic health care [47, 48]. Evidence of a strong association between UDNs and children’s developmental health at school entry in all areas of development may encourage teachers to report and follow up on observed dental needs. This is particularly relevant to children with developmental disorders, such as ASD, who tend to face more obstacles in accessing care compared to typically-developing children [21]. Even though our study was not able to examine a causal pathway, our findings suggest that if a lack of adequate oral health does contribute to developmental vulnerability and is combined with a lack of access to dental care, it may have a detrimental impact on trajectories of both oral and developmental health of children throughout their lifespan.

Our study demonstrated that having UDNs was associated with the highest odds of being vulnerable in physical health and well-being, followed by communication skills and general knowledge. There are various possible explanations for these findings. Chronic pain from untreated dental caries could impact a child’s everyday functioning, including such activities as eating, sleeping, and concentrating on tasks in and outside of the classroom [49]. In addition, persistent toothache may impact speech, from difficulty opening one’s mouth, which would lead to a decreased ability to effectively communicate. UDNs could also increase emotional stress [50], which could manifest itself as either internalizing or externalizing behaviours. Additionally, being unable to concentrate in class from oral pain could decrease knowledge gain and retention, possibly impacting language and cognitive development [28]. Furthermore, severe untreated dental problems have been associated with hearing loss [51, 52]. Stereocilia (hair cells necessary for hearing) can incur damage should bacteria from dental problems enter the bloodstream, causing inflammation and narrowing of the inner ear’s blood vessels [53]. Hearing loss could then result in both expressive and receptive communication problems, as the child may face difficulty in articulating words and understanding speech. Hearing loss could also impact several other developmental domains, including social competence, language and cognitive development, and communication skills and general knowledge. This may also affect their emotional development (e.g., self-esteem), which could again result in lower social competence and communication skills (e.g., underdeveloped conversational skills, antisocial behaviour) [54, 55].

Oral health is an important part of a child’s overall health and well-being. Findings from our study suggest teacher-reported UDNs may be a marker for various developmental needs which schools and health systems might address.

In this study an association between teacher-reported UDNs and children’s developmental health at school entry was identified across all developmental domains, suggesting that UDNs may be an important marker for developmental vulnerability. Teacher-reported UDNs could prompt the school system and health professionals to consider what developmental needs a child might be experiencing across developmental domains. Considering that vulnerability in kindergarten is highly predictive of later academic problems, teacher identification of UDNs, combined with oral and developmental interventions, might positively impact children’s future health, developmental, and educational outcomes.