PREVALENCE AND CAUSES OF TRAUMATIC DENTAL INJURIES TO ANTERIOR TEETH AMONG PRIMARY SCHOOL CHILDREN IN SANA'A CITY, YEMEN

Objectives: The current study was conducted to reveal the prevalence and causes of traumatic dental injuries to permanent anterior teeth among mixed dentition of schoolchildren in Sana'a City, Yemen. Methods: A cross-sectional study was performed on 1252 schoolchildren aged 7-12 years in three districts of Sana'a city, Yemen. They numbered 700 males and 552 females from 26 randomly selected public and private schools. Clinical examination of permanent anterior teeth was done according to the classification of Ellis modified by Fried. Results: Prevalence of TDI was 10.30%, with a male ratio of 4.8: female 1, (P <0.05). Most of the children suffered only one damage to the tooth and most of them are in the maxillary central incisors. The TDI increased with older age (10-12 years old) (16.5%) with odds ratio 4.8, (p<0.05). Regarding the site of trauma, most injuries happened in males on the street (44.9%) while in females happened at home (31.81%) and falls were the main cause of TDI. In both sexes, the most common type of injury was class I (enamel fracture) followed by class II (enamel and dentine without pulp involvement). Conclusion: In conclusion, the prevalence of TDI in permanent anterior teeth among mixed dentition of school children in Sana’a was high, higher in males than in females, with a peak age of 10 to 12 years, falls was the common cause, and occurred mostly on the street for boys and home for females. Accordingly, educational programs should be developed that focus on ways to prevent dental trauma and the benefits of seeking urgent treatment to maintain avulsed and fractured teeth.


INTRODUCTION
The child is progressively developing, mentally and physically, characterized by constant change or vigorous activity. Child searches for the ocean, trying to explore, so child 's more likely to fall and be injured. Child quality of life is severely affected by her/his health, especially painful injuries that may directly affect aspects of speech, nutrition, social interaction and psychology 1 . Traumatic tooth injury represents a sharp transfer of energy to the tooth and its sustaining structures, consequential in a fracture and/or displacement of the tooth and the disjointing or crushing of the supporting tissues (gums, periodontal ligament and bone) 2 .
Dental injuries can be caused by an indirect or direct trauma. When the tooth itself is struck, direct trauma occurs. An indirect shock occurs as the lower tooth arch is firmly closed in contrast to the upper part, for instance, a blow to the chin. Direct trauma involves damages in the anterior region, whilst indirect trauma prefers crown or crown root fractures in the premolar and molar regions with the probability of jaw fractures in the condylar regions and symphysis 3 . In permanent teeth, traumatic injuries have been reported to obtain a prevalence rate of 4.1% to 58.6%. The large difference in reported rates can be recognized to several different factors, including study types, trauma classification, methodology, study size and population, differences in ISSN: 2456- 8058 39 CODEN (USA): UJPRA3 cultural behavior and geographical location 4 . Traumatic injuries are the third-largest cause for teeth loss after the caries and periodontal causes and are still on the rise 5 . There is agreement by researchers that traumatic injuries happen more frequently to the upper jaws than to the lower incisors and that the central incisors are more affected than the lateral incisors 6 . The most common causes of these injuries are falls, sports, biking, and traffic accidents. Factors predisposing to dental trauma can be associated with a person's anatomical features such as increased overjet, or insufficient lip covering of the upper front teeth 7, 8 . TDI to primary teeth may finally lead to problems with primary permanent teeth, for instance hypoplasia, discolouration, delayed eruption time, and tooth malformation 9 . Delayed treatment of dental injuries in children is common in many countries. This can be attributed to various factors such as short-lived primary teeth, and the lack of attention required because the child may not show any associated signs or symptoms 10 . Trauma is not always predictable, but a proportion of injuries can be prevented if risk factors are understood and widespread public awareness allowing the development of necessary preventive strategies to improve planning, decision-making and intervention. Its results can help plan effective educational programmers targeting teachers, school children, and parents. Education should be widely provided to individuals who supervise and care for children and who will be near the scene of the traumatic dental injury (TDI) 11 . There are few reports available on epidemiology of child dental injuries in developing countries, especially when compared to epidemiological data on tooth decay and periodontal disease 12 .There is a scarcity of epidemiological data on the prevalence of dental trauma among schoolchildren compared to tooth decay in Yemen. There was only one published data on TDI among schoolchildren in Sana'a, conducted by Al Akwa in 2009. Therefore, this research aimed to study the prevalence and causes of traumatic dental injuries to the anterior teeth among schoolchildren in Sana'a (the Yemeni capital) because dental trauma is a public health concern in Yemen.

SUBJECTS AND METHODS Study Design:
A cross sectional study was conducted. Study Area: The study was done at public and private schools in Sana'a City, which is the capital city of Yemen, located in the center of it. Sana'a consists of ten districts. Three districts were chosen, randomly selected, from the south Al-Safia District, from the nourth Al-Thwarh District and from the middle Old Sana'a District. Study Population: The target population was students of both genders, aged 7-12 years, chosen from public and private primary schools that are located in the three districts. Inclusion Criteria were all primary public and private schools located in these three districts; and students of both genders with average age of 7-12 years old. However, the exclusion criteria were non-Yemeni children, children with traumatic dental injuries in primary teeth; Children with a type of mental anomaly or systemic disease such as epilepsy patients; and/or child with anterior teeth with flurosis and caries. Sampling Technique: The sample size was calculated using version 7 of the EPI, based on the following assumptions: 1-Reference students aged 7 to 12 years in three regions according to the Education Office, 2018 in Sana'a was 50,400. 2-Rates of traumatic dental injuries are expected at 50%. 3-Confidence limit =3%. 4-Confidence level =97%, so the calculated sample size was 1252. Sampling Type: Multistage sampling method which the first Stage: from the ten districts we chosen randomly three districts from the south Al-Safia District, from the north Al-Thwarh District and from the middle Old Sana'a District. The second stage: in each district, we considered that all private and public schools are included in the study, then we randomly selected sixteen public schools and ten private schools which represent nearly 10% of total number of schools according to Education, 2018. The Third stage: In all randomly selected school, we considered that all the classes of students aged from 7 to12 years old are included in the study. Then we randomly selected one class from each level. Finally, all the students in each class were included in the study. Selection from the selected classes was systemically random; so that we can reach the sample size target Data Collection: Data was collected by face-to-face interviews. The Structured questionnaire was about age, gender, cause of injury, place of injury, type of injury and the tooth involved.

Methods of Examination:
Before starting the study, and after it was approved by the Faculty of Dentistry in Sana'a University, ethical matters were taken into considerations. The examination was conducted with permission from the education authorities. Permission was obtained from the Office of Education and the principals of the respective schools, and after obtaining informed consent from parents of the participating children. Clinical examination was performed using a regular oral mirror and gloves. The necessary tools and materials were packed and sterilized in sufficient quantities for each working day.

Data analysis
The data was statistically analyzed using SPSS 21. The data were presented by using tables and figures. Percentage (%) was used to describe the qualitative variables. Pearson's Chi-Square test was used to show the significance of the association between the outcomes at the level of significance less than 0.05 (P).

RESULTS
This study was conducted on 1252 schoolchildren, 700 males and 552 females. The children were divided into two age groups 7-9 and 10-12 years as shows in Table  1 Figure 3. The distribution of dental injuries according to the classification of Ellis modified by Fried showed that the most common type of injury was enamel fracture (51.6%), followed by enamel and dentine (36.1), then enamel and dentine with extensive exposure of pulp (7.1%), then fracture involving complete loss of tooth (avulsion) (2.6%),followed by enamel and dentine with early exposure of pulp (1.9%) , and finally a root fracture (0.6%) and no statistical significant difference between them and gender ( Table  5).   Table 2).
The gender difference was statistically significant, which coincides with most previous studies 12, 25,26,27 . The cause of increased trauma among boys is their participation in recreational and sports activities or because of their more aggressive nature than girls, and the rates of puberty growth in boys and girls are more mature in nature 14, 28 . However, in studies by Rajesh et al., 29 , and Ain et al., 30 there was no significant difference in TDI between male and female, and this result may be due to social changes in the study area that have led to increased participation of girls in sports, which can lead to dental injuries.  Most of the children who had dental injuries in this study had only one damaged teeth, 103 out of 155 infected teeth (Table 3), and the most affected teeth are maxillary central incisors (82.45%) (Figure 3). This result coincides with previous studies 12,15,18,19,30-32 . Perhaps this vulnerable position relates to maxillary central incisors. In addition, these teeth are often protruded and may have insufficient lip coverage 24 .
The study showed that the prevalence of dental injuries increases with the age of 7 to 12 years. The highest exposure to dental trauma occurred in sixth grade (32.56%). The distribution of children's age groups showed that the highest prevalence of dental trauma occurred in the 10-12 age group (16.5%) out of 635, followed by the 7-9 years (3.9%) age group of 617 ( Table 4). The results showed statistically significant differences between groups, consistent with other studies 20,33,34 . The incidence of dental injuries increases during the very active age range because of bicycle riding, skateboarding, and playground and sports accidents 35 .

Figure 1: Distribution of trauma according to gender and location of injuries among schoolchildren
Regarding the trauma site, most TDI occurred on the street (Figure 1). For males (44.9%), this may be due to the presence of a lot of devastating holes and platforms on the streets during play time. In addition, most of the fighting between males took place on the street, causing students to fall, while for females most injuries occurred at home (31.81%) due to Yemeni society traditions that disagree with spending females outside their times as homes. Moreover, the results revealed a significant statistical correlation between sex and place of injuries among children ( Figure 1). This finding is consistent with other studies 36,37 , whereas in other studies 18,21, 32, 38 most of the injuries occurred at home. In the current study, the most common cause of trauma was falls (62.01%) for both sexes ( Figure 2).   Concerning the distribution of dental injuries in this study according to the classification of Ellis modified by Fried, class I (enamel fracture) as the most common type of fracture and accounted for (51.6%) of the total fractures, followed by class II fractures involving (enamel-dentine) with (36.1%) ( Table 5). These results were in accordance with most of the previous studies 16, 20,30, 43 . While a few other studies have shown that the class II is the most common type of fracture 29,32,36,40 . Total traumatized teeth were 155 as shown in ( Figure  3). This result disagrees with study by Akinyamoju et al., 44 , because serious impacts, for instance those resulting from traffic accidents, may proliferate the number of teeth involved with periapical lesion, which are better represented in hospital and institution-based studies 45 . As the present study was conducted in schools and not in the hospitals, less severe cases involving only enamel fractures were more evident.

CONCLUSION
In conclusion, the prevalence of traumatic dental injuries to permanent anterior teeth among mixed dentition of schoolchildren in Sana'a City was high, higher in males than in females, falling was the common cause of trauma, followed by sports in both genders. The peak age DTI was between 10 to 12 years old, most injuries occurred at street for males and at home for females. Most of the children who experienced dental injuries had only one tooth damaged, and the most commonly affected teeth were the maxillary central incisors and Class I (enamel fracture) was the most common class. Therefore, educational programs should be developed that focus on ways to prevent dental trauma and the benefits of seeking immediate treatment to keep avulsed and fractured teeth. These programs should be targeted at the community level as well as in schools. Ongoing educational programs on the latest techniques in trauma dental management should also be arranged for dental and medical practitioners.