Traumatic dental injuries in preschool‐age children: Prevalence and risk factors

Abstract This study examined the prevalence, socio‐demographic correlates, and clinical predictors of traumatic dental injuries (TDIs) in the primary dentition among a community‐based sample of preschool‐age children. The sample comprised 1,546 preschool‐age children (mean age 49 [range: 24–71] months) in North Carolina public preschools, enrolled in a population‐based investigation among young children and their parents in North Carolina. Information on socio‐demographic, extraoral, and intraoral characteristics was collected and analyzed with bivariate and multivariate methods, including logistic regression modeling and marginal effects estimation. The prevalence of dental trauma was 47% and 8% of TDI cases were “severe” (pulp exposure, tooth displacement, discolored or necrotic tooth, or tooth loss). In bivariate analyses, overjet and lip incompetence were significantly associated with TDI. Overjet remained positively associated with severe trauma in multivariate analysis, OR = 1.4, 95% confidence interval (CI) [1.2, 1.6], corresponding to an absolute 1.3%, 95% CI [0.7, 1.8], increase in the likelihood of severe trauma, per millimeter of overjet. Children with increased overjet (>3 mm) were 3.8, 95% CI [2.0, 7.4], times as likely to have experienced severe TDI compared with those with ≤3 mm. Overjet is a strong risk factor for TDIs in the primary dentition. Incorporating and operationalizing this information may help TDI prevention and related anticipatory guidance for families of preschool‐age children.

potential sequelae to the developing succedaneous teeth including hypoplastic defects, root dilacerations, and other enamel or developmental disturbances that are not seen until months or years after the injury when the permanent successors erupt (Andreasen, Sundström, & Ravn, 1971;Lenzi, Alexandria, Ferreira, & Maia, 2015).
Overall, consequences of TDIs extend well beyond the traditional clinical implications and can affect the quality of life of those affected and their families. Negative economic, social, and psychological impacts due to TDI have been well documented (Borum & Andreasen, 2001;Fakhruddin, Lawrence, Kenny, & Locker, 2008;Lee & Divaris, 2009;Nguyen, Kenny, & Barrett, 2004), highlighting the public health problem posed by injury to the teeth, face, and jaws.
The high prevalence of TDIs and their negative impact on quality of life have motivated research into possible etiologic factors. It is common ground that dental trauma etiology is multifactorial and complex. In 2009, Glendor suggested that the three main etiologic factors for TDIs can be grouped in the domains of "human behavior," which generally includes risk-taking behaviors, conditions such as attention-deficit/hyperactivity disorder, and others; "environmental determinants," wherein more contextual parameters, such as material deprivation, or an "unsafe" environment are included; and "oral factors," including increased overjet with protrusion, lip incompetence, and other intraoral and extraoral factors (Glendor, 2009). This triad is certainly not an all-inclusive list but offers a helpful categorization of all postulated risk factors for dental trauma. Additional risk factors that do not necessarily fall into one of these three categories but might also increase the risk of TDIs are body mass index (BMI), sex, presence of illness, learning difficulties, physical limitations, inappropriate use of teeth, and oral piercings (Zaleckiene, Peciuliene, Brukiene, & Drukteinis, 2014).
Although previous studies have investigated the prevalence of TDIs and the association of oral factors and other characteristics such as sex, BMI, and nonnutritive sucking habits (Andreasen & Ravn, 1972;Bonini et al., 2012;Feldens et al., 2010;Martins et al., 2014;Norton & O'Connell, 2012;Piovesan et al., 2012;Soriano, Caldas, De Carvalho, & Amorim Filho, 2007), very few studies have examined TDI in the primary dentition in the United States (Jones et al., 1993), and none has actually incorporated this information in a clinically useful risk model. Such a tool could be used for risk assessment and would be beneficial for family education, screenings, personalized prevention, risk reduction, and planning early orthodontic treatment. The present study aimed to address this gap and sought to (a) examine the prevalence of TDIs in the primary dentition among a community-based cohort of preschool-age children, (b) determine the socio-demographic and clinical predictors of TDIs in this population, and (c) use this information to develop a risk model for TDIs.

| Study population
The sample was drawn from the Zero-Out Early (ZOE) Childhood Caries study, a prospective and population-based investigation among young children and their parents in North Carolina (NC). The  TABLE 1 Prevalence of traumatic dental injury in the primary dentition, classification of increased overjet, and estimates of association between trauma and increased overjet Children were excluded from the present analyses if they were <24 months or >71 months of age or had key socio-demographic (e.g., gender) or clinical (e.g., trauma) information missing.

| Data collection
The clinical exams in all ZOE phases followed a previously described accompanied to the dental chair by the recorder while BMI and BMI percentile for age and sex were calculated using a tablet application; (c) the examiner brushed the child's teeth. (d) A clinical examination was done to record tooth-surface conditions including dental trauma using a modified Ellis classification criteria (Ellis & Davey, 1970), on the most-affected upper anterior tooth (if more than one), as follows: simple enamel-only fracture, extensive fracture with dentin and no pulp involvement, traumatic pulp exposure, tooth displacement, necrotic/discolored tooth, and total tooth loss due to trauma. The Ellis' modified classification system provides an anatomical and numerical basis for classification with a hierarchical structure that groups various injuries into categories (Bastone et al., 2000;Feliciano & de França Caldas, 2006;Pagadala & Tadikonda, 2015). Additional information was systematically collected on extraoral (e.g., profile and lip competence) and intraoral (e.g., overjet, overbite, molar, and canine classifica- were female. The prevalence of dental trauma was 47%. Three quarters of TDI cases had enamel-only fractures, whereas a small proportion (12%) showed evidence of more extensive trauma (dentin involvement or worse). The prevalence and distribution of dental trauma diagnoses are presented in Figure 1.
The socio-demographic, intraoral, and extraoral characteristics of study participants, overall and stratified by incidence of severe dental injury are presented in Table 2. In bivariate analyses, lip incompetence and overjet (distribution of values shown in Figure 2) were significantly associated with TDI (P < 0.05), whereas age, BMI, and canine occlusion showed weaker positive associations. The pairwise correlation coefficients between severe trauma and overjet and lip competence were 0.14 and −0.09, respectively, with P < 0.05 after a Šidák correction for multiple testing.
The final multivariable model for severe trauma (extensive fracture with pulp involvement, tooth displacement, necrotic discolored tooth, or total tooth loss due to trauma) is presented in  (Jones et al., 1993). The 47% overall prevalence found in this study is slightly higher than previously reported estimates in the primary dentition. One potential explanation for the higher percentage of TDIs reported in this sample is that all children in this study were from low-income families and were Medicaideligible, as participation to EHS/HS is determined by qualification based on social and economic criteria. Some reports have shown that more children of lower socioeconomic status receive dental injuries compared with those in higher socioeconomic groups (Hamilton, Hill, & Holloway, 1997;Lalloo, 2003

Missing 103
Note. Severe trauma: extensive fracture with pulp involvement, tooth displacement, necrotic/discolored tooth, total tooth loss due to trauma; SD: standard deviation.
This study's results did not show a strong link between sex and incidence of severe trauma, consistent with other studies that suggest that there is no significant difference between sex and TDI in the primary dentition (Bastone et al., 2000;Bijella, Yared, Bijella, & Lopes, 1990;Onetto, Flores, & Garbarino, 1994). In the permanent dentition however, most studies report a higher percentage of dental trauma in males (Bastone et al., 2000;Borum & Andreasen, 2001). BMI, although not included in the final multivariate model, was weakly associated with increased incidence of TDI. Other reports examining postulated links between BMI to TDIs are also inconsistent. Soriano et al. found a statistically significant correlation between obesity and TDIs among a sample of 1,046 Brazilian children (Soriano et al., 2007). In contrast, Martins et al. (2014)    After examination of behavioral, environmental, and oral factors, oral factors and particularly overjet proved to be the most significant predictors of TDI in this sample of preschool-age children.
Orthodontic interventions to reduce overjet, although advocated by some in the mixed dentition, would be focused more on interventions to eliminate nonnutritive sucking habits if present. Incorporating and operationalizing this information may help TDI prevention and related anticipatory guidance for families of preschool-age children.

| CONCLUSIONS
The following conclusions can be made based on this study's findings: 1. The prevalence of TDI among this community-based sample of preschool-age children was 47% and 8% of TDI cases were "severe," defined as pulp exposure, tooth displacement, discolored or necrotic tooth, or tooth loss.
2. Overjet and lip incompetence were strong risk factors for TDIs in the primary dentition.
3. Accounting for age, sex, and lip incompetence, we found that each added millimeter of overjet was associated with 40% increased likelihood of severe dental trauma, corresponding to an absolute 1 p.p. approximate probability increase. Children with increased overjet (>3 mm) were 3.8 times as likely to have experienced severe TDI compared with those with ≤3 mm.

DENTISTS
• A clinically useful risk model for traumatic dental injuries helps pediatric dentists, pediatricians, and parents and caregivers quantitatively assess risk for children.
• A risk model or index for traumatic dental injuries, which includes terms for oral factors, BMI, sex, and behavioral and environmental

FIGURE 3
Final multivariable logistic regression model-predicted probabilities and 95% confidence intervals of severe trauma, for males and females, according to overjet (mm) factors, can be beneficial for family education, screenings, personalized prevention, risk reduction, and planning early orthodontic treatment or intervention.

FUNDING INFORMATION
The ZOE 2.0 study is supported by National Institutes of Health/NIDCR grant #U01-DE025046.