Risk Factors for Different Types of Traumatic Injuries in Primary Teeth

Objective: To evaluate traumatic dental injuries (TDI) in primary teeth and the association of gender and age with different injuries. Material and Methods: Records of patients with TDI in primary teeth were included. The following parameters were registered: gender and age, place of trauma, cause of trauma, affected tissue and tooth, number of injured teeth, type of injury, and gingival and bone damage. A logistic regression analysis was performed to explore the interaction between gender and age on the occurrence of types of injuries (p ≤ 0.05). Results: The total of 721 records were evaluated and 370 records were included, being 61.6% boys and 60.5% children aged 0–3 years old, with 658 primary teeth affected. The support tissue was most affected (496/658), followed by dental tissue (139/658). Enamel/dentine fracture with pulp exposure (n=51) and intrusion (n=131) were the most common injuries of dental and support tissues, respectively. In general, boys suffered more traumas than girls, regardless of the age range. As for concussion, logistic regression confirms that gender and age are also influencers. Girls (OR=1.822, CI = 1.050-3.164, p=0.033) in the 4–6 year age group (OR=2.15, CI = 1.239–3.747, p=0.007) are more likely to have concussions. Children age 4–6 years were less likely to suffer an intrusion (OR=0.496; CI = 0.278– 0.886; p=0.018). Conclusion: Gender and age influence concussion and intrusion in the primary teeth.


Introduction
Traumatic dental injuries (TDI) are common in children and adolescents, relevant to public health, due to treatment costs and the consequences for oral health [1,2]. Such injuries can directly or indirectly influence the patient's quality of life in terms of aesthetic, functional and psychological changes, which can result in socialization problems [2][3][4]. Moreover, injuries are the reason for the first visit to the dentist in 40% of pre-school aged children [5].
Children with trauma in their primary incisors have more developmental disorders in their permanent successors than individuals without previous trauma. The child's age at the time of injury and severity of injury are associated with more serious developmental disorders. This fact only reinforces the importance of health promotion policies, which must be strengthened to encourage the implementation of preventive strategies to reduce the frequency of TDI in pre-school children [6].
Prevalence involving primary teeth can range from 16.3% to 62.1% [7,8]. In surveys conducted in communities and schools, under-diagnosis of dental trauma often occurs, since they are observed only as sequels after a trauma [9]. Several studies have shown a predilection for males and for younger children [7][8][9][10][11][12][13][14]; however, no reports exist in the literature evaluated at the same time reports were released regarding the relationship between gender and age with a different type of injury in primary teeth.
Thus, the aim of this study was to determine the frequency of TDI and the association of gender and age with different types of injuries in primary teeth of patients who attended the reference Dental Trauma Surveillance Center (DTSC) at the School of Dentistry at Federal University of Rio de Janeiro, Brazil.

Type of Study and Sampling
This retrospective study evaluated dental records of children aged between 0 and 12 years old, who attended DTSC from 2005 to 2010. The inclusion criteria included systemically healthy patients with a history of TDI in primary teeth. Records of children with mental disabilities and those with incomplete data were excluded from the present study.

Clinical and Radiographic Examination and Documentation
Professionals performing the initial examinations and emergency treatments were MSc dental students who had received prior training and were supervised by a professor during the procedures. The MSc students were trained with theoretical and practical classes on diagnosis and treatment of dental trauma using clinical and radiographic images.
At the time of injury, the following parameters were registered on trauma charts: the patient's gender and age (0-3 years old; 4-6 years-old), place of trauma, cause of trauma, affected tissue and tooth, number of injured teeth, type of injury, and gingival and bone damage. For each tooth, clinical information was recorded, which included the color of the clinical crown, dislocation, mobility, tenderness to percussion, percussion tone.
The TDI diagnostic was made per Andreasen's classification [1]. Teeth that presented more than one type of injury were classified per their severity. The authors considered luxations more severe than fractures, except for fracture of enamel and dentin with pulp exposure that was considered more severe than concussion and subluxation.
Statistical Analysis SPSS Statistical Software, version 21.0 (SPSS Inc., Chicago, IL, USA) was used. A logistic regression analysis was performed to explore the interaction between gender and age on the occurrence of types of injuries. Logistic regression was performed in General Linear Models (GEE) to consider the internal correlation of the observations of each patient's teeth (p ≤0.05).

Ethical Aspects
The study was approved by the local Research Ethics Committee (Protocol No. 1.885.653). All the subjects were treated in accordance with the Helsinki Declaration, and each subject participating in this study, along with their parents, signed consent forms with detailed information.

Results
Of the total sample of 721 records, 370 (51.3%) met the criteria for inclusion in the study. The final sample had 61.6% boys and 60.5% of children aged 0-3 years old. The most common cause was fall from own height (51.1%) and the most common place of occurrence was at home (63.8%) ( Enamel/dentine fracture with pulp exposure (n=51) and intrusive luxation (n=131) were the most common injuries of dental and support tissues, respectively. In general, boys suffer more traumas than girls, regardless of age range. However, girls suffer more fractures of dentin enamel without pulp exposure in all evaluated age groups. In addition, girls aged 4-6 years suffer more concussions, while those aged 0-3 years suffer more subluxation than boys (Table 2).   (Table 3).

Discussion
Brazil is considered one of the countries that most research about TDI. Despite the number of studies about dental trauma in primary teeth, better methodological designs are needed to offer a more substantial contribution to clinical practice and contribute to the establishment of preventive strategies to help reduce TDI frequency and its impact on the quality of life of children and their families [15,16].
In the present study, from the total number of patients included, 51.3% had one or more traumatized primary teeth. The frequency of trauma found in this study was higher than those found in the literature [12,14,17,18]. This high frequency is related to the fact that DTSC is a center of reference for the treatment of dental trauma in the city of Rio de Janeiro, making the diagnosis more reliable. When observing only fractures, discoloration and lost teeth, an under-diagnosis of traumatic injuries occurs [9]. In the evaluated sample, boys and children aged 0-3 years experienced the most dental injuries, corroborating with previous studies [7,14,17,19]. The injuries increase substantially with the child's first efforts to crawl and walk, due to lack of experience and coordination. The peak of incidences occurs from 2-4 years of age, followed by a second peak from 8-10 years of age [1].
In accordance with the literature [7,14,[17][18][19], fall from height was the most prevalent cause of trauma in primary teeth and the most common place being in the house. These facts are comprehensible since most preschool children tend to spend most of their time at homes, under the guardianship of family or caregivers, as in most cases they do not have any social commitments. Moreover, as mentioned, children at this age are still maturing their motor skills and tend to suffer falls mostly from height.
The upper arch, due to its anatomic location, is itself more prone to suffering injuries and, in this sense, the central incisors followed by the upper lateral teeth are the most frequently affected teeth, as reported in various studies [7,[18][19][20][21], including the present study.
Support tissue was the most affected in this study, which can be explained because of the resilient bone surrounding the primary teeth. The intrusion was the most common injury in support tissues. These results are contradictory to previous studies [7,[17][18][19]22,23]. Because it is a referral center, the search for treatment is higher in cases of more severe injuries.
The cross-sectional design does allow examining the temporal relationship between variables. The sample was not representative of the population, since they recruited in a dental clinic of the university service.
Nonetheless, the study provided an interesting evaluation about risk factors for dental trauma in deciduous teeth.
Children aged 4-6 years were more likely to suffer concussions but less likely to suffer intrusive luxation. These results are important, since the literature describes the intimate relationship between primary teeth and its successors [1]. Traumas that do not cause a change in tooth position in the arcade have less chance of sequelae in the permanent dentition [6].

Conclusion
Boys and children aged 0-3 years suffer the most TDI. The most common cause is fall from own height; the most common place is in the home, and the support tissue is the most affected. Girls are significantly more prone to suffering concussions than boys. Children aged 4-6 years are more likely to suffer concussions and less likely to suffer intrusive luxation. Therefore, this study concludes that gender and age can be considered predisposing factors to the occurrence of some types of injuries in the primary teeth.