Abstract
Aim: Students often injure their teeth during participation in school-based sports clubs. This study examined the frequencies and types of dental injuries sustained at school sports clubs and compared the risk of dental injury among different sports. Methods: Based on injury statistics from the Japan Sport Council of the junior high schools and high schools in seven prefectures during fiscal year 2006, the risk of dental injury was estimated using a rate ratio (RR) by calculating the ratio of occurrence of dental injury under various circumstances. Results: The RRs of exercise-related dental injury for boys and girls in junior high school were 0.7 (P < 0.001) and 1.3 (P < 0.05), respectively, and for those in high school were 2.6 (P < 0.001) and 2.7 (P < 0.001), respectively. In junior high school, softball (RR = 7.7) for boys and handball (RR = 3.9) for girls commonly led to dental injuries. In high school, Japanese-style wrestling (RR = 18.5) and rugby (RR = 7.3) for boys and handball (RR = 6.5) for girls had high risks for dental injury. Crown fracture was the predominant dental injury among boys and girls attending both junior high school and high school. The proportion of alveolar fracture was higher in school sports clubs than outside school sports clubs among high school boys. Contact or limited-contact sports had significantly higher risks for dental injuries than did noncontact sports. Conclusion: The results of this study suggest that teachers and administrators at schools should pay attention to the risk of dental injury among students participating in high-risk sports.
Key words: Dental injury, school sports club, high school students, junior high school students
INTRODUCTION
Physical activity, including sports, is an important element in lifestyle-related disease prevention, and is closely associated with preventing obesity. Therefore, interest in sports has increased recently. Sports and physical fitness contribute to fitness among adolescents1., 2.. In sum, participation in sports is important for junior high school and high school students who are still growing.
Junior high school and high school students have many opportunities to exercise, not only through physical education classes but also in school sports clubs as extra-curricular activities. More than half of all high-school students in the USA participated in athletics during the 2006–2007 academic year3. In Japan, about three-quarters of boys and about half of girls in junior high school participated in school sports clubs, as did half of boys and one-quarter of girls in high school4. Injuries inevitably occur as a result of participation in sports and 45.4% of junior high school students and 52.8% of high school students experienced some kind of injury during activities outside the curriculum in fiscal year 2006, according to data gathered by the Japan Sport Council5. Injuries to junior high school and high school students who are still growing can have a significant, negative impact on their physical and mental well-being.
Most injuries during exercise affect the upper or lower limbs6., 7.; the proportion of dental injuries is low8. However, sports are the most common setting in which dental injuries occur9, and complete recovery may not be possible despite dental treatment because tooth fracture or tooth loss is irreversible. As sports-related dental injuries are concentrated in the upper anterior teeth10., 11., aesthetic problems from dental injury may have psychological implications. Children are more likely to incur dental injuries from sports as their grade in school advances12. Clarifying the hypothesis that the risk of dental injury in students differs among sports, for example, contact sports, will be useful for the development of appropriate preventive measures.
This study investigated the actual occurrence and types of dental injuries incurred in school sports clubs among junior high school and high school students, and assessed the risk of dental injury in school sports clubs by comparing the prevalence of dental injuries in each sport with those occurring in outside sports clubs and according to type of sport.
METHODS
The present study used data on students’ injuries sustained in junior high schools and high schools in seven prefectures (Toyama, Ishikawa, Fukui, Gifu, Shizuoka, Aichi and Mie) in Japan under the jurisdiction of the Nagoya branch of the Japan Sport Council (JSC). Each student who experienced a dental injury went to a dental clinic, and the dentists who treated the injured students made a diagnosis and defined the dental injuries based on the medical insurance system in Japan. We divided the insurance descriptions of the dental injuries into six categories (crown fracture, root fracture, alveolar fracture, concussion, luxation or avulsion) according to the International Association of Dental Traumatology guidelines for the treatment of traumatic dental injuries13. Relatives of the injured students made the co-pay to the dental clinic, which is 30% of the total medical expenses in the medical insurance system in Japan. If the total medical expenses, that is, the sum of the co-pay (30%) and the medical insurance payment (70%) at the time the dental treatment was completed, amounted to ≥ 5,000 Yen (~41 $US), the relatives were reimbursed for the medical expenses paid as the co-pay by submitting the relevant documents to the Injury and Accident Mutual Aid Benefit System of the JSC. The study used all data from the system in the period from 1 April 2006 to 31 March 2007. The total number of junior high school students in the seven prefectures was 523,563 (267,861 boys and 255,702 girls) and that of high school students was 485,539 (244,804 boys and 240,735 girls). Because the JSC data did not specify the gender distribution, and the participation rates in the aid benefit system among junior high school and high school students in Japan in the fiscal year 2006 were 99.8% and 97.9%, respectively5, we used the total number of students in the prefectures in the analyses. As all data used in the present study were anonymous and did not include personally identifiable information, we did not obtain consent from study subjects or their guardians. This study was approved by the Ethics Committee of Aichi Gakuin University, School of Dentistry (authorisation number 208) and was conducted in full accordance with the World Medical Association Declaration of Helsinki.
Data on dental injuries incurred by students when under the responsibility of schools were used for analyses. All analyses were stratified according to the sex of the student and classification of the school. Injury rates (IRs) were calculated as the ratio of dental injuries per 1,000 students. IRs outside school sports clubs were calculated by dividing the number of dental injuries that occurred outside school sports clubs by the number of students, and IRs of injuries incurred during school sports clubs as an extra-curricular activity were calculated by dividing the number of dental injuries that occurred during school sports clubs by the number of members of the clubs.
The risk of dental injury from participating in sports in school sports clubs was determined by calculating the rate ratio (RR1). The following is the RR1 calculation comparing the overall rates of dental injuries incurred during school sports clubs and outside school sports clubs.
The IR of each type of sport was calculated by dividing the number of dental injuries incurred during each sport (swimming; gymnastics; athletics; soccer; tennis; softball; baseball; handball; volleyball; basketball; rugby; table tennis; badminton; judo – Japanese art of self-defence; kendo – Japanese art of fencing; sumo – Japanese-style wrestling; climbing; boating; skiing; and skating) by the number of participants in that sport. The following is the RR2 calculation comparing the overall rates of dental injuries between individual sports and outside school sports clubs.
The proportions of the types of dental injury13 (crown fracture, root fracture, alveolar fracture, concussion, luxation, avulsion, or unclear whether luxation or avulsion) were compared between outside school sports clubs and during school sports clubs, according to sex of student, in each junior high school and high school.
Each sport was classified into three categories based on its contact classification (noncontact: swimming, track-and-field, tennis, table tennis, badminton, climbing and boating; limited contact: softball, baseball, volleyball, judo, kendo, skiing and skating; and contact: gymnastics, soccer, handball, basketball, rugby and sumo)14. The IR for each category of contact sports was calculated by dividing the number of dental injuries in each category (noncontact, limited contact and contact) by the number of participants in each category. The following is the RR3 calculation comparing the overall rates of dental injuries between limited-contact or contact sports and noncontact sports.
Data were analysed using R statistical software (version 3.1.1.). Statistical significance of the RRs was assessed using 95% confidence intervals (95% CIs), not including 1.0. Differences in proportions were evaluated using Pearson’s chi-square test. Values of P < 0.05 were taken to indicate statistical significance.
RESULTS
In junior high school students, the total number of injuries of all parts of the body was 62,911 (38,016 in boys and 24,895 in girls) and that in high school students was 36,873 (23,911 in boys and 12,962 in girls) (Table 1). The proportion of dental injuries among total injuries was ~1.8% (2.0% in boys and 1.3% in girls) in junior high school students and ~1.9% (2.2% in boys and 1.2% in girls) in high school students.
Table 1.
Total injuries and dental injuries in junior high school and high school students
| Variable | Total injury, n (%) | Dental injury, n (%) |
|---|---|---|
| Junior high school | ||
| Boys | 38,016 (60.4) | 768 (69.8) |
| Girls | 24,895 (39.6) | 333 (30.2) |
| High school | ||
| Boys | 23,911 (64.8) | 530 (76.7) |
| Girls | 12,962 (35.2) | 161 (23.3) |
n, number of injuries.
In junior high school students, the IR of dental injury was higher in boys than in girls, irrespective of school sports club participation (Table 2). The IR of dental injury during school sports clubs was lower in boys but higher in girls than that occurring outside school sports clubs (Table 2). In high school students, the IRs of dental injury were higher in boys than in girls in both situations, and the RR1 of dental injury was similar in both boys and girls (Table 3). In both boys and girls, the RR1 of dental injury was higher in high school students than in junior high school students (Tables 2 and 3).
Table 2.
Dental injuries in junior high school students
| Variable | n (%) | Dental injury | Injury rate* | RR1† (95% CI) | P-value |
|---|---|---|---|---|---|
| Boys | |||||
| Total number of students‡ | 267,861 (100) | 498† | 1.86 | 1 | |
| Members of school sports clubs | 217,918 (81.4) | 270¶ | 1.24 | 0.7 (0.6–0.8) | <0.001 |
| Girls | |||||
| Total number of students‡ | 255,702 (100) | 186† | 0.73 | 1 | |
| Members of school sports clubs | 155,691 (60.9) | 147¶ | 0.94 | 1.3 (1.0–1.6) | <0.05 |
95% CI, 95% confidence interval; n, number of students; RR1, rate ratio.
Per 1,000 students.
[(total number of dental injuries incurred during participation in school sports clubs / total number of members of school sports clubs) × 1,000] ÷ [(total number of dental injuries occurring outside school sports clubs / total number of students) × 1,000].
Students who had and had not joined the school sports club.
Outside school sports clubs.
During school sports clubs.
Table 3.
Dental injuries in high school students
| Variable | n (%) | Dental injury | Injury rate* | RR1† (95% CI) | P-value |
|---|---|---|---|---|---|
| Boys | |||||
| Total number of students‡ | 244,804 (100) | 212§ | 0.87 | 1 | |
| Members of school sports clubs | 140,696 (57.5) | 318¶ | 2.26 | 2.6 (2.2–3.1) | <0.001 |
| Girls | |||||
| Total number of students‡ | 240,735 (100) | 90§ | 0.37 | 1 | |
| Members of school sports clubs | 69,250 (28.8) | 71¶ | 1.03 | 2.7 (2.0–3.7) | <0.001 |
95% CI, 95% confidence interval; n, number of students; RR1, rate ratio.
Per 1,000 students.
[(total number of dental injuries incurred during participation in school sports clubs / total number of members of school sports clubs) × 1,000] ÷ [(total number of dental injuries occurring outside school sports clubs / total number of students) × 1,000].
Students who had and had not joined the school sports club.
Outside school sports clubs.
During school sports clubs.
The RR2 values of dental injury among junior high school boys were significantly higher in softball and basketball and were significantly lower in athletics, tennis, baseball, table tennis and kendo compared with dental injury sustained outside school sports clubs (Table 4). Among junior high school girls, handball, basketball and volleyball showed higher risks, and table tennis showed a lower risk, for dental injury compared with injuries sustained outside school sports clubs (Table 5).
Table 4.
Dental injuries incurred by junior high school students (boys) during participation in various sports
| Variable | n (%) | Dental injury | Injury rate* | RR2† (95% CI) | P-value |
|---|---|---|---|---|---|
| Total number of students‡ | 267,861 (100) | 498§ | 1.86 | 1 | |
| Sport | |||||
| Swimming | 4,784 (1.8) | 5 | 1.05 | 0.6 (0.2–1.4) | 0.20 |
| Gymnastics | 285 (0.1) | 2 | 7.02 | 3.8 (0.9–15.1) | 0.06 |
| Track and field | 15,057 (5.6) | 3 | 0.19 | 0.1 (0.03–0.3) | <0.001 |
| Soccer | 30,688 (11.5) | 44 | 1.43 | 0.8 (0.6–1.0) | 0.10 |
| Tennis | 29,713 (11.1) | 27 | 0.91 | 0.5 (0.3–0.7) | <0.001 |
| Softball | 139 (0.05) | 2 | 14.39 | 7.7 (1.9–30.7) | <0.01 |
| Baseball | 43,707 (16.3) | 55 | 1.26 | 0.7 (0.5–0.9) | <0.01 |
| Handball | 5,615 (2.1) | 11 | 1.96 | 1.1 (0.6–1.9) | 0.86 |
| Volleyball | 13,081 (4.9) | 21 | 1.61 | 0.9 (0.6–1.3) | 0.51 |
| Basketball | 26,091 (9.7) | 67 | 2.57 | 1.4 (1.1–1.8) | <0.05 |
| Table tennis | 25,855 (9.7) | 11 | 0.43 | 0.2 (0.1–0.4) | <0.001 |
| Badminton | 3,843 (1.4) | 2 | 0.52 | 0.3 (0.1–1.1) | 0.07 |
| Judo | 5,876 (2.2) | 12 | 2.04 | 1.1 (0.6–1.9) | 0.75 |
| Kendo | 12,862 (4.8) | 8 | 0.62 | 0.3 (0.2–0.7) | <0.01 |
| Sumo | 185 (0.07) | 0 | – | – | – |
| Skiing | 137 (0.05) | 0 | – | – | – |
95% CI, 95% confidence interval; n, number of students; RR2, rate ratio.
Per 1,000 students.
[(total number of dental injuries incurred during participation in each sport / total number of participants in each sport) × 1,000] ÷ [(total number of dental injuries occurring outside school sports clubs / total number of students) × 1,000].
Students who had and had not joined the school sports club.
Outside school sports clubs.
Table 5.
Dental injuries incurred by junior high school students (girls) during participation in various sports
| Variable | n (%) | Dental injury | Injury rate* | RR2† (95% CI) | P-value |
|---|---|---|---|---|---|
| Total number of students‡ | 255,702 (100) | 186§ | 0.73 | 1 | |
| Sport | |||||
| Swimming | 3,067 (1.2) | 3 | 0.98 | 1.3 (0.4–4.2) | 0.61 |
| Gymnastics | 1,666 (0.7) | 0 | – | – | – |
| Track and field | 12,073 (4.7) | 5 | 0.41 | 0.6 (0.2–1.4) | 0.21 |
| Soccer | 535 (0.2) | 1 | 1.87 | 2.6 (0.4–18.3) | 0.35 |
| Tennis | 32,632 (12.8) | 17 | 0.52 | 0.7 (0.4–1.2) | 0.19 |
| Softball | 13,245 (5.2) | 13 | 0.98 | 1.3 (0.8–2.4) | 0.30 |
| Baseball | 199 (0.08) | 0 | – | – | – |
| Handball | 4,225 (1.7) | 12 | 2.84 | 3.9 (2.2–7.0) | <0.001 |
| Volleyball | 30,539 (11.9) | 37 | 1.21 | 1.7 (1.2–2.4) | <0.01 |
| Basketball | 22,690 (8.9) | 47 | 2.07 | 2.9 (2.1–3.9) | <0.001 |
| Table tennis | 17,847 (7.0) | 3 | 0.17 | 0.2 (0.1–0.7) | <0.05 |
| Badminton | 7,761 (3.0) | 3 | 0.39 | 0.5 (0.2–1.7) | 0.28 |
| Judo | 1,866 (0.7) | 2 | 1.07 | 1.5 (0.4–5.9) | 0.59 |
| Kendo | 7,196 (2.8) | 4 | 0.56 | 0.8 (0.3–2.1) | 0.59 |
| Sumo | 2 (0.001) | 0 | – | – | – |
| Skiing | 148 (0.06) | 0 | – | – | – |
95% CI, 95% confidence interval; n, number of students; RR2, rate ratio.
Per 1,000 students.
[(total number of dental injuries incurred during participation in each sport / total number of participants in each sport) × 1,000] ÷ [(total number of dental injuries occurring outside school sports clubs / total number of students) × 1,000].
Students who had and had not joined the school sports club.
Outside school sports clubs.
Among high school boys, many ball games and contact sports had significantly higher risks for dental injury (Table 6). The most common sports showing higher risks for dental injury were sumo (RR2 = 18.5) and rugby (RR2 = 7.3) (Table 6), and kendo also showed a significantly higher risk for dental injury (RR2 = 2.9). High school girls more frequently experienced dental injury during ball games such as handball (RR2 = 6.5) and basketball (RR2 = 6.2), and also when skating, compared with outside school sports clubs (Table 7).
Table 6.
Dental injuries incurred by high school students (boys) during participation in various sports
| Variable | n (%) | Dental injury | Injury rate* | RR2† (95% CI) | P-value |
|---|---|---|---|---|---|
| Total number of students‡ | 244,804 (100) | 212§ | 0.87 | 1 | |
| Sport | |||||
| Swimming | 3,112 (1.3) | 1 | 0.32 | 0.4 (0.1–2.6) | 0.32 |
| Gymnastics | 528 (0.2) | 0 | – | – | – |
| Track and field | 9,680 (4.0) | 3 | 0.31 | 0.4 (0.1–1.1) | 0.08 |
| Soccer | 21,315 (8.7) | 42 | 1.97 | 2.3 (1.6–3.2) | <0.001 |
| Tennis | 21,596 (8.8) | 5 | 0.23 | 0.3 (0.1–0.7) | <0.01 |
| Softball | 738 (0.3) | 1 | 1.36 | 1.6 (0.2–11.2) | 0.66 |
| Baseball | 23,835 (9.7) | 128 | 5.37 | 6.2 (5.0–7.7) | <0.001 |
| Handball | 5,667 (2.3) | 19 | 3.35 | 3.9 (2.4–6.2) | <0.001 |
| Volleyball | 7,811 (3.2) | 18 | 2.3 | 2.7 (1.6–4.3) | <0.001 |
| Basketball | 14,656 (6.0) | 57 | 3.89 | 4.5 (3.4–6.0) | <0.001 |
| Rugby | 3,795 (1.6) | 24 | 6.32 | 7.3 (4.8–11.1) | <0.001 |
| Table tennis | 9,706 (4.0) | 1 | 0.10 | 0.1 (0.02–0.8) | <0.05 |
| Badminton | 6,711 (2.7) | 0 | – | – | – |
| Judo | 4,344 (1.8) | 0 | – | – | – |
| Kendo | 5,495 (2.2) | 14 | 2.55 | 2.9 (1.7–5.0) | <0.001 |
| Sumo | 187 (0.08) | 3 | 16.04 | 18.5 (6.0–57.4) | <0.001 |
| Climbing | 702 (0.3) | 1 | 1.42 | 1.6 (0.2–11.7) | 0.62 |
| Boat | 520 (0.2) | 0 | – | – | – |
| Skiing | 233 (0.1) | 1 | 4.29 | 5.0 (0.7–35.2) | 0.11 |
| Skating | 65 (0.03) | 0 | – | – | – |
95% CI, 95% confidence interval; n, number of students; RR2, rate ratio.
Per 1,000 students.
[(total number of dental injuries incurred during participation in each sport / total number of participants in each sport) × 1,000] ÷ [(total number of dental injuries occurring outside school sports clubs / total number of students) × 1,000].
Students who had and had not joined the school sports club.
Outside school sports clubs.
Table 7.
Dental injuries incurred by high school students (girls) during participation in various sports
| Variable | n (%) | Dental injury | Injury rate* | RR2† (95% CI) | P-value |
|---|---|---|---|---|---|
| Total number of students‡ | 240,735 (100) | 90§ | 0.37 | 1 | |
| Sport | |||||
| Swimming | 1,910 (0.8) | 1 | 0.52 | 1.4 (0.2–10.0) | 0.74 |
| Gymnastics | 1,187 (0.5) | 2 | 1.68 | 4.5 (1.1–18.3) | <0.05 |
| Track and field | 5,912 (2.5) | 0 | – | – | – |
| Tennis | 14,442 (6.0) | 7 | 0.48 | 1.3 (0.6–2.8) | 0.51 |
| Softball | 4,025 (1.7) | 3 | 0.75 | 2.0 (0.6–6.3) | 0.24 |
| Handball | 3,727 (1.5) | 9 | 2.41 | 6.5 (3.3–12.8) | <0.001 |
| Volleyball | 11,306 (4.7) | 22 | 1.95 | 5.2 (3.3–8.3) | <0.001 |
| Basketball | 9,850 (4.1) | 23 | 2.34 | 6.2 (4.0–9.9) | <0.001 |
| Table tennis | 3,767 (1.6) | 2 | 0.53 | 1.4 (0.3–5.8) | 0.62 |
| Badminton | 8,620 (3.6) | 0 | – | – | – |
| Judo | 978 (0.4) | 0 | – | – | – |
| Kendo | 2,895 (1.2) | 1 | 0.35 | 0.9 (0.1–6.6) | 0.94 |
| Climbing | 173 (0.07) | 0 | – | – | – |
| Boat | 319 (0.1) | 0 | – | – | – |
| Skiing | 104 (0.04) | 0 | – | – | – |
| Skating | 35 (0.01) | 1 | 28.57 | 76.4 (11.0–533.3) | <0.001 |
95% CI, 95% confidence interval; n, number of students; RR2, rate ratio.
Per 1,000 students.
[(total number of dental injuries incurred during participation in each sport / total number of participants in each sport) × 1,000] ÷ [(total number of dental injuries occurring outside school sports clubs / total number of students) × 1,000].
Students who had and had not joined the school sports club.
Outside school sports clubs.
Crown fracture was the predominant dental injury among junior high school and high school boys and girls (Tables 8 and 9). The proportions of dental injury types were similar for school sports clubs and outside school sports clubs among junior high school boys and girls and high school girls (Tables 8 and 9). The proportion of alveolar fractures was higher in school sports clubs than outside school sports clubs among high school boys (Table 9).
Table 8.
Types of dental injuries in junior high school students
| Variable | Dental injury incurred during participation in school sports clubs (%) | Injury rate* | Dental injury incurred outside school sports clubs (%) | Injury rate* | P-value† |
|---|---|---|---|---|---|
| Boys | |||||
| Crown fracture | 121 (44.8) | 0.56 | 223 (44.8) | 0.83 | 0.99 |
| Root fracture | 2 (0.7) | 0.01 | 3 (0.6) | 0.01 | |
| Alveolar fracture | 11 (4.1) | 0.05 | 19 (3.8) | 0.07 | |
| Concussion | 15 (5.6) | 0.07 | 29 (5.8) | 0.11 | |
| Luxation | 70 (25.9) | 0.32 | 132 (26.5) | 0.49 | |
| Avulsion | 4 (1.5) | 0.02 | 5 (1.0) | 0.02 | |
| Unclear‡ | 46 (17.0) | 0.21 | 85 (17.1) | 0.32 | |
| Unknown | 1 (0.4) | 0.005 | 2 (0.4) | 0.01 | |
| Total | 270 (100) | 1.24 | 498 (100) | 1.86 | |
| Girls | |||||
| Crown fracture | 53 (36.1) | 0.34 | 63 (33.9) | 0.25 | 0.06 |
| Root fracture | 2 (1.4) | 0.01 | 2 (1.1) | 0.01 | |
| Alveolar fracture | 9 (6.1) | 0.06 | 11 (5.9) | 0.04 | |
| Concussion | 13 (8.8) | 0.08 | 14 (7.5) | 0.05 | |
| Luxation | 25 (17.0) | 0.16 | 72 (38.7) | 0.28 | |
| Avulsion | 2 (1.4) | 0.01 | 3 (1.6) | 0.01 | |
| Unclear‡ | 42 (28.6) | 0.27 | 20 (10.8) | 0.08 | |
| Unknown | 1 (0.7) | 0.01 | 1 (0.5) | 0.004 | |
| Total | 147 (100) | 0.94 | 186 (100) | 0.73 | |
Per 1,000 students.
Compared proportions of types of dental injury using the chi-square test, after exclusion of unclear or unknown data.
Unclear whether luxation or avulsion.
Table 9.
Types of dental injuries in high school students
| Variable | Dental injury incurred during participation in school sports clubs (%) | Injury rate* | Dental injury incurred outside school sports clubs (%) | Injury rate* | P-value† |
|---|---|---|---|---|---|
| Boys | |||||
| Crown fracture | 128 (40.3) | 0.91 | 101 (47.6) | 0.41 | <0.05 |
| Root fracture | 5 (1.6) | 0.04 | 1 (0.5) | 0.004 | |
| Alveolar fracture | 32 (10.1) | 0.23 | 7 (3.3) | 0.03 | |
| Concussion | 8 (2.5) | 0.06 | 9 (4.2) | 0.04 | |
| Luxation | 79 (24.8) | 0.56 | 56 (26.4) | 0.23 | |
| Avulsion | 8 (2.5) | 0.06 | 2 (0.9) | 0.01 | |
| Unclear‡ | 58 (18.2) | 0.41 | 36 (17.0) | 0.15 | |
| Total | 318 (100) | 2.26 | 212 (100) | 0.87 | |
| Girls | |||||
| Crown fracture | 34 (47.9) | 0.49 | 43 (47.8) | 0.18 | 0.88 |
| Root fracture | – | – | – | – | |
| Alveolar fracture | 6 (8.5) | 0.09 | 6 (6.7) | 0.02 | |
| Concussion | 4 (5.6) | 0.06 | 9 (10.0) | 0.04 | |
| Luxation | 14 (19.7) | 0.20 | 20 (22.2) | 0.08 | |
| Avulsion | 2 (2.8) | 0.03 | 2 (2.2) | 0.01 | |
| Unclear‡ | 11 (15.5) | 0.16 | 9 (10.0) | 0.04 | |
| Unknown | – | – | 1 (1.1) | 0.004 | |
| Total | 71 (100) | 1.03 | 90 (100) | 0.37 | |
Per 1,000 students.
Compared proportions of types of dental injury using the chi-square test, after exclusion of unclear or unknown data.
Unclear whether luxation or avulsion.
The risk of dental injury from limited-contact or contact sports was significantly higher than that from noncontact sports among junior high school and high school boys and girls (Tables 10 and 11). Among high school students, dental injuries from limited-contact or contact sports were more frequent in boys than in girls (Table 11).
Table 10.
Dental injuries incurred by junior high school students during participation in sports classified as contact sports
| Variable | n | Dental injury | Injury rate* | RR3† (95% CI) | P-value |
|---|---|---|---|---|---|
| Boys | |||||
| Noncontact‡ | 79,252 | 48 | 0.61 | 1 | |
| Limited contact§ | 75,802 | 98 | 1.29 | 2.1 (1.4–3.4) | <0.001 |
| Contact¶ | 62,864 | 124 | 1.97 | 3.3 (2.1–5.1) | <0.001 |
| Girls | |||||
| Noncontact‡ | 73,380 | 31 | 0.42 | 1 | |
| Limited contact§ | 53,193 | 56 | 1.05 | 2.5 (1.4–4.4) | <0.001 |
| Contact¶ | 29,118 | 60 | 2.06 | 4.9 (2.8–8.6) | <0.001 |
95% CI, 95% confidence interval; n, number of students; RR3, rate ratio.
Per 1,000 students.
[(total number of dental injuries incurred during participation in limited-contact or contact sports / total number of participants in limited-contact or contact sports) × 1,000] ÷ [(total number of dental injuries incurred during participation in noncontact sports / total number of participants in noncontact sports) × 1,000].
Noncontact: swimming, track and field, tennis, table tennis, badminton, climbing, boating.
Limited contact: softball, baseball, volleyball, judo, kendo, skiing, skating.
Contact: gymnastics, soccer, handball, basketball, rugby, sumo.
Table 11.
Dental injuries incurred by high school students during participation in sports classified as contact sports
| Variable | n | Dental injury | Injury rate* | RR3† (95% CI) | P-value |
|---|---|---|---|---|---|
| Boys | |||||
| Noncontact‡ | 52,027 | 11 | 0.21 | 1 | |
| Limited contact§ | 42,521 | 162 | 3.81 | 18.0 (8.1–40.3) | <0.001 |
| Contact¶ | 46,148 | 145 | 3.14 | 14.9 (6.6–33.3) | <0.001 |
| Girls | |||||
| Noncontact‡ | 34,970 | 10 | 0.29 | 1 | |
| Limited contact§ | 19,516 | 27 | 1.38 | 4.8 (1.9–12.6) | <0.001 |
| Contact¶ | 14,764 | 34 | 2.30 | 8.1 (3.2–20.4) | <0.001 |
95% CI, 95% confidence interval; n, number of students; RR3, rate ratio.
Per 1,000 students.
[(total number of dental injuries incurred during participation in limited-contact or contact sports / total number of participants in limited-contact or contact sports) × 1,000] ÷ [(total number of dental injuries incurred during participation in noncontact sports / total number of participants in noncontact sports) × 1,000].
Noncontact: swimming, track and field, tennis, table tennis, badminton, climbing, boating.
Limited contact: softball, baseball, volleyball, judo, kendo, skiing, skating.
Contact: gymnastics, soccer, handball, basketball, rugby, sumo.
Regarding the type of dental injuries according to the contact classification of sports, crown fracture and luxation were predominant, and few root fractures and alveolar fractures were reported in noncontact sports (Tables 12 and 13). In contrast, the proportions of dental injuries other than crown fractures were increased in contact sports (Tables 12 and 13).
Table 12.
Type of dental injuries incurred by junior high school students during participation in sports classified as contact sports
| Variable | Noncontact |
Limited contact |
Contact |
P-value† | |||
|---|---|---|---|---|---|---|---|
| n (%) | Injury rate* | n (%) | Injury rate* | n (%) | Injury rate* | ||
| Boys | |||||||
| Crown fracture | 29 (60.4) | 0.37 | 51 (52.0) | 0.67 | 41 (33.1) | 0.65 | <0.05 |
| Root fracture | – | – | 1 (1.0) | 0.01 | 1 (0.8) | 0.02 | |
| Alveolar fracture | – | – | 4 (4.1) | 0.05 | 7 (5.6) | 0.11 | |
| Concussion | – | – | 7 (7.1) | 0.09 | 8 (6.5) | 0.13 | |
| Luxation | 12 (25.0) | 0.15 | 16 (16.3) | 0.21 | 42 (33.9) | 0.67 | |
| Avulsion | – | – | 2 (2.0) | 0.03 | 2 (1.6) | 0.03 | |
| Unclear‡ | 7 (14.6) | 0.09 | 17 (17.3) | 0.22 | 22 (17.7) | 0.35 | |
| Unknown | – | – | – | – | 1 (0.8) | 0.02 | |
| Total | 48 (100) | 0.61 | 98 (100) | 1.29 | 124 (100) | 1.97 | |
| Girls | |||||||
| Crown fracture | 13 (41.9) | 0.18 | 24 (42.9) | 0.45 | 16 (26.7) | 0.55 | 0.28 |
| Root fracture | – | – | 1 (1.8) | 0.02 | 1 (1.7) | 0.03 | |
| Alveolar fracture | – | – | 5 (8.9) | 0.09 | 4 (6.7) | 0.14 | |
| Concussion | 4 (12.9) | 0.05 | 3 (5.4) | 0.06 | 6 (10.0) | 0.21 | |
| Luxation | 6 (19.4) | 0.08 | 6 (10.7) | 0.11 | 13 (21.7) | 0.45 | |
| Avulsion | – | – | – | – | 2 (3.3) | 0.07 | |
| Unclear‡ | 7 (22.6) | 0.10 | 17 (30.4) | 0.32 | 18 (30.0) | 0.62 | |
| Unknown | 1 (3.2) | 0.01 | – | – | – | – | |
| Total | 31 (100) | 0.42 | 56 (100) | 1.05 | 60 (100) | 2.06 | |
Per 1,000 students.
Compared proportions of type of dental injury using the chi-square test, after exclusion of unclear or unknown data.
Unclear whether luxation or avulsion.
Table 13.
Type of dental injuries incurred by high school students during participation in sports classified as contact sports
| Variable | Noncontact |
Limited contact |
Contact |
P-value† | |||
|---|---|---|---|---|---|---|---|
| n (%) | Injury rate* | n (%) | Injury rate* | n (%) | Injury rate* | ||
| Boys | |||||||
| Crown fracture | 6 (54.5) | 0.12 | 56 (34.6) | 1.32 | 66 (45.5) | 1.43 | 0.77 |
| Root fracture | – | – | 2 (1.2) | 0.05 | 3 (2.1) | 0.07 | |
| Alveolar fracture | 1 (9.1) | 0.02 | 20 (12.3) | 0.47 | 11 (7.6) | 0.24 | |
| Concussion | – | – | 5 (3.1) | 0.12 | 3 (2.1) | 0.07 | |
| Luxation | 2 (18.2) | 0.04 | 42 (25.9) | 0.99 | 35 (24.1) | 0.76 | |
| Avulsion | – | – | 5 (3.1) | 0.12 | 3 (2.1) | 0.07 | |
| Unclear‡ | 2 (18.2) | 0.04 | 32 (19.8) | 0.75 | 24 (16.6) | 0.52 | |
| Unknown | – | – | – | – | – | – | |
| Total | 11 (100) | 0.21 | 162 (100) | 3.81 | 145 (100) | 3.14 | |
| Girls | |||||||
| Crown fracture | 6 (60.0) | 0.17 | 16 (59.3) | 0.82 | 12 (35.3) | 0.81 | 0.54 |
| Root fracture | – | – | – | – | – | – | |
| Alveolar fracture | – | – | 2 (7.4) | 0.10 | 4 (11.8) | 0.27 | |
| Concussion | 1 (10.0) | 0.03 | 1 (3.7) | 0.05 | 2 (5.9) | 0.14 | |
| Luxation | 1 (10.0) | 0.03 | 5 (18.5) | 0.26 | 8 (23.5) | 0.54 | |
| Avulsion | – | – | – | – | 2 (5.9) | 0.14 | |
| Unclear‡ | 2 (20.0) | 0.06 | 3 (11.1) | 0.15 | 6 (17.6) | 0.41 | |
| Unknown | – | – | – | – | – | – | |
| Total | 10 (100) | 0.29 | 27 (100) | 1.38 | 34 (100) | 2.30 | |
Per 1,000 students.
Compared proportions of type of dental injury using the chi-square test, after exclusion of unclear or unknown data.
Unclear whether luxation or avulsion.
DISCUSSION
The present study investigated the circumstances of dental injuries in school sports clubs among junior high school and high school students and compared the risks of dental injury among sports. Dental injury incurred in school sports clubs was observed more frequently in boys than in girls in both junior high school and high school, in agreement with a previous study15. The higher frequency of dental injury incurred by boys than by girls outside school sports clubs is assumed to be a result of more vigorous participation by male students. High school students more frequently injured their teeth through sports participation than did junior high school students of both sexes, as seen in a previous study12. Frequencies of dental injury outside school sports clubs in high school students will decrease because older students generally have higher skill levels compared with junior high school students.
In this study, many ball games, which are classified as contact or limited-contact sports, showed relatively high risks of dental injury (Table 4, Table 5, Table 6, Table 7). Skaare and Jacobsen also reported that the dental injuries sustained whilst participating in the contact sports football, handball and basketball, accounted for ~60% of all dental injuries incurred in sports by schoolchildren12. Among all high school baseball-related injuries in the USA, mouth/tooth injuries accounted for no more than 3.3%7, but about half of dental injuries were caused by baseball, which is a limited-contact sport, in a study examining rare injuries among high school athletes15. Also in the present study, many male students participated in baseball in both in junior high school and in high school, and the risk of dental injury was significantly higher in boys in high school. As the present study shows that the risks of dental injury during ball games categorised as contact or limited-contact sports, especially in high school students, are high, school coaches of these sports should be aware of the risks.
In high school boys, risks of dental injury in contact sports other than ball games, such as rugby and sumo, were high. The efficacy of, and requirements for, mouthguard use among participants in contact sports (such as rugby and hockey) as a preventive measure against dental injuries have been studied16., 17., 18., 19.. Currently, mouthguard use is compulsory for high school rugby players and for some college students, but mouthguard use by other student groups and other sports groups is optional, and the use of mouthguards during practice may not be high. The risk of dental injury among rugby club members will be affected by playing without a mouthguard and also with the intensity of the game. In high school boys, kendo, which is a limited-contact sport, showed a higher risk for dental injury despite the use of protective head gear during competition. In high school kendo, a pass that is banned in junior high school students is used as a skill; this may be related to the increase in dental injuries in high school students participating in this sport.
Among 12- to 14-year-old Canadian school children, the usage rate of mouthguards in league sports was about 20% and that in school sports was only about 5%20. Also, the usage rate of mouthguards in children and adolescents was low in other studies21., 22.. Among professional athletes, the most common reason for not using a mouthguard was ‘not necessary’, and many users and nonusers of mouthguards complained of ‘impaired breathing’ and ‘impaired talking’23. However, as use of custom-fit mouthguards did not affect aerobic performance among soccer or futsal players24, impaired breathing is linked to habituation to, and fit of, the mouthguard. Sport-specific IRs were higher during competition than during practice25. In general, as total hours of practice are longer than total hours of games, it is preferable to use a mouthguard during practice also, to become accustomed to its use. Using a custom-fit mouthguard professionally made by dentists is encouraged for participants in a variety of sports.
A previous study reported that crown fracture is the most frequent dental injury in the permanent dentition26. In the present study, crown fracture occurred frequently, regardless of school sports club activity. In contrast, the frequencies of dental injuries other than crown fracture were increased in contact or limited-contact sports. The proportions of the various types of dental injury occurring outside school sports clubs were similar to those occurring in school sports clubs, but the proportion of alveolar fractures incurred by students during school sports club activities was higher than that incurred by students outside school sports clubs, particularly in high school boys. Although the proportion of avulsion was extremely low, it sometimes occurred in contact or limited-contact sports. If tooth avulsion occurs, the procedures used after the injury are very important for the prognosis of the re-implanted tooth. Although dry periodontal ligament tissue on the surface of an avulsed tooth is associated with a poor tooth re-implantation prognosis, resulting in root resorption and tooth avulsion, soaking the tooth in milk or a physiological solution as quickly as possible after avulsion improves the prognosis27., 28.. Each school and college should provide a physiological solution in a tooth rescue box as a secondary prophylactic method for tooth avulsion27. In addition, school sports club coaches, especially in contact sports, should aim to prevent the occurrence of serious dental injuries.
The JSC is the central organisation specialising in sports promotion activities and the maintenance and enhancement of school children’s health in Japan. The present study used data from the Injury and Accident Mutual Aid Benefit System of the JSC, and the participation rate in the system among students is extremely high. As this study included a large number of students, we were able to demonstrate a risk of dental injury among volleyball players that could not be confirmed in previous studies15., 29.. Team game players are likely to contact other players, and many women’s volleyball injuries occurred from player contact and other contact, for example with balls and the floor30. Because problematic sports environments, such as slippery floors, may lead to the occurrence of dental injury, improving sports environments is important.
There were several limitations to the present study. As this was a cross-sectional study that used only single-year data, there are limits to the interpretation of the causal relationship between sports and dental injury and the reproducibility of the results. The mutual aid benefit system of the JSC pays a benefit against accidental injury that occurs when students are under the supervision of schools if medical costs are over 5,000 yen (~41 $US). Therefore, this study did not include minor injuries with a medical cost of less than 5,000 yen. As this study used secondary data collected for the mutual aid benefit system for students, we could not validate the diagnosis and definition of the dental injuries. Moreover, as the data used in this study included the type and situation of each injury, but not data for individuals, we could not determine whether students were injured more than once. Also, this study did not include all injuries sustained by students because it did not examine injuries that occurred at home or at private sports clubs that were not under the supervision of schools. As the data in the present study did not include information about mouthguard usage at the time of each injury, we could not evaluate the preventive effect of mouthguard use relative to dental injury. Additional studies should seek to clarify the risk of dental injury at school sports clubs in relation to mouthguard use.
CONCLUSIONS
The present study suggests that the risks of dental injury in junior high school and high school students are high in contact and limited-contact sports, including several ball games. In high school boys, contact sports other than ball games showed relatively high risks for dental injury. Students who participate in contact or limited-contact sports in school sports clubs, and their coaches, should be aware of the risk of dental injury and consider preventive measures, including mouthguard use.
Acknowledgements
This work was supported by the department budget of the Aichi Gakuin University, Nagoya, Japan.
Conflict of interest
The authors declare that they have no conflict of interest.
References
- 1.Kvaavik E, Klepp KI, Tell GS, et al. Physical fitness and physical activity at age 13 years as predictors of cardiovascular disease risk factors at ages 15, 25, 33, and 40 years: extended follow-up of the Oslo Youth Study. Pediatrics. 2009;123:e80–e86. doi: 10.1542/peds.2008-1118. [DOI] [PubMed] [Google Scholar]
- 2.Drake KM, Beach ML, Longacre MR, et al. Influence of sports, physical education, and active commuting to school on adolescent weight status. Pediatrics. 2012;130:e296–e304. doi: 10.1542/peds.2011-2898. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.National Federation of State High School Association. Participation statistics 2006–2007 of national federation of state high school association. Available from: http://nfhs.org/ParticipationStatics/ParticipationStatics.aspx. Accessed 8 February 2016
- 4.Ministry of Education, Culture, Sports, Science and Technology (MEXT) Japan. FY 2006 White Paper of Education, Culture, Sports, Science and Technology. Support for school sports club. Available from: http://mext.go.jp/b_menu/hakusho/html/hpab200601/002.pdf#/. Accessed 8 February 2016
- 5.Japan Sport Council. Injury occurs under school responsibility-21 (2006–2007)-key statistics-/summary of kindergarten, preschool, elementary school, junior high school, high school and higher professional school. Available from: http://www.jpnsport.go.jp/anzen/anzen_school//back//tabid/580/Default.aspx. Accessed 8 February 2016
- 6.Marshall SW, Waller AE, Dick RW, et al. An ecologic study of protective equipment and injury in two contact sports. Int J Epidemiol. 2002;31:587–592. doi: 10.1093/ije/31.3.587. [DOI] [PubMed] [Google Scholar]
- 7.Collins CL, Comstock RD. Epidemiological features of high school baseball injuries in the United States, 2005–2007. Pediatrics. 2008;121:1181–1187. doi: 10.1542/peds.2007-2572. [DOI] [PubMed] [Google Scholar]
- 8.Beachy G. Dental injuries in intermediate and high school athletes: a 15-year study at Punahou School. J Athl Train. 2004;39:310–315. [PMC free article] [PubMed] [Google Scholar]
- 9.Huang B, Marcenes W, Croucher R, et al. Activities related to the occurrence of traumatic dental injuries in 15- to 18-year-olds. Dent Traumatol. 2009;25:64–68. doi: 10.1111/j.1600-9657.2008.00685.x. [DOI] [PubMed] [Google Scholar]
- 10.Cetinbas T, Yildirim G, Sonmez H. The relationship between sports activities and permanent incisor crown fractures in a group of school children aged 7–9 and 11–13 in Ankara, Turkey. Dent Traumatol. 2008;24:532–536. doi: 10.1111/j.1600-9657.2008.00647.x. [DOI] [PubMed] [Google Scholar]
- 11.Prabhu A, Rao AP, Govindarajan M, et al. Attributes of dental trauma in a school population with active sports involvement. Asian J Sports Med. 2013;4:190–194. doi: 10.5812/asjsm.34257. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Skaare AB, Jacobsen I. Etiological factors related to dental injuries in Norwegians aged 7–18 years. Dent Traumatol. 2003;19:304–308. doi: 10.1046/j.1600-9657.2003.00211.x. [DOI] [PubMed] [Google Scholar]
- 13.Diangelis AJ, Andreasen JO, Ebeleseder KA, et al. International Association of Dental Traumatology guidelines for the management of traumatic dental injuries: 1. Fractures and luxations of permanent teeth. Dent Traumatol. 2012;28:2–12. doi: 10.1111/j.1600-9657.2011.01103.x. [DOI] [PubMed] [Google Scholar]
- 14.Rice SG. Medical conditions affecting sports participation. Pediatrics. 2008;121:841–848. doi: 10.1542/peds.2008-0080. [DOI] [PubMed] [Google Scholar]
- 15.Huffman EA, Yard EE, Fields SK, et al. Epidemiology of rare injuries and conditions among United States high school athletes during the 2005–2006 and 2006–2007 school years. J Athl Train. 2008;43:624–630. doi: 10.4085/1062-6050-43.6.624. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Garon MW, Merkle A, Wright JT. Mouth protectors and oral trauma: a study of adolescent football players. J Am Dent Assoc. 1986;112:663–665. doi: 10.14219/jada.archive.1986.0063. [DOI] [PubMed] [Google Scholar]
- 17.Chapman PJ. Orofacial injuries and international rugby players’ attitudes to mouthguards. Br J Sports Med. 1990;24:156–158. doi: 10.1136/bjsm.24.3.156. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Caglar E, Kargul B, Tanboga I. Dental trauma and mouthguard usage among ice hockey players in Turkey premier league. Dent Traumatol. 2005;21:29–31. doi: 10.1111/j.1600-9657.2004.00271.x. [DOI] [PubMed] [Google Scholar]
- 19.Quarrie KL, Gianotti SM, Chalmers DJ, et al. An evaluation of mouthguard requirements and dental injuries in New Zealand rugby union. Br J Sports Med. 2005;39:650–651. doi: 10.1136/bjsm.2004.016022. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Fakhruddin KS, Lawrence HP, Kenny DJ, et al. Use of mouthguards among 12- to 14-year-old Ontario schoolchildren. J Can Dent Assoc. 2007;73:505. [PubMed] [Google Scholar]
- 21.Yamada T, Sawaki Y, Tomida S, et al. Oral injury and mouthguard usage by athletes in Japan. Endod Dent Traumatol. 1998;14:84–87. doi: 10.1111/j.1600-9657.1998.tb00816.x. [DOI] [PubMed] [Google Scholar]
- 22.Biagi R, Cardarelli F, Butti AC, et al. Sports-related dental injuries: knowledge of first aid and mouthguard use in a sample of Italian children and youngsters. Eur J Paediatr Dent. 2010;11:66–70. [PubMed] [Google Scholar]
- 23.Lieger O, von Arx T. Orofacial/cerebral injuries and the use of mouthguards by professional athletes in Switzerland. Dent Traumatol. 2006;22:1–6. doi: 10.1111/j.1600-9657.2006.00328.x. [DOI] [PubMed] [Google Scholar]
- 24.Collares K, Correa MB, Mohnsam da Silva IC, et al. Effect of wearing mouthguards on the physical performance of soccer and futsal players: a randomized cross-over study. Dent Traumatol. 2014;30:55–59. doi: 10.1111/edt.12040. [DOI] [PubMed] [Google Scholar]
- 25.Centers F. Sports-related injuries among high school athletes – United States, 2005–06 school year. MMWR Morb Mortal Wkly Rep. 2006;55:1037–1040. [PubMed] [Google Scholar]
- 26.Toprak ME, Tuna EB, Seymen F, et al. Traumatic dental injuries in Turkish children, Istanbul. Dent Traumatol. 2014;30:280–284. doi: 10.1111/edt.12092. [DOI] [PubMed] [Google Scholar]
- 27.Pohl Y, Filippi A, Kirschner H. Results after replantation of avulsed permanent teeth. II. Periodontal healing and the role of physiologic storage and antiresorptive-regenerative therapy. Dent Traumatol. 2005;21:93–101. doi: 10.1111/j.1600-9657.2004.00298.x. [DOI] [PubMed] [Google Scholar]
- 28.Karayilmaz H, Kirzioglu Z, Erken Gungor O. Aetiology, treatment patterns and long-term outcomes of tooth avulsion in children and adolescents. Pak J Med Sci. 2013;29:464–468. doi: 10.12669/pjms.292.3283. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Andrade RA, Modesto A, Evans PL, et al. Prevalence of oral trauma in Para-Pan American Games athletes. Dent Traumatol. 2013;29:280–284. doi: 10.1111/j.1600-9657.2012.01174.x. [DOI] [PubMed] [Google Scholar]
- 30.Agel J, Palmieri-Smith RM, Dick R, et al. Descriptive epidemiology of collegiate women’s volleyball injuries: National Collegiate Athletic Association Injury Surveillance System, 1988–1989 through 2003–2004. J Athl Train. 2007;42:295–302. [PMC free article] [PubMed] [Google Scholar]