4.1 Oral protection measures should be taken for teenagers to participate in ice hockey
With the 2022 Beijing Winter Olympic Games approaching, the implementation outline of "driving 300 million people to participate in ice and snow sports" issued by the national Ministry of sports in 2018 came into effect. Ice and snow sports are more and more popular among sports lovers. As one of the sports promotion programs for young people, the General Administration of the people's Republic of China issued the "ice hockey program" jointly with the Ministry of education of the people's Republic of China. However, it is not directly proportional to the increase of ice hockey participation enthusiasm that the participants' awareness of sports injury. Ice hockey is one of the fierce antagonistic sports, the incidence of sports injury is high. Oral injury, especially dental injury, has a long-term effect on the function of the wounded, as well as on the external and psychological aspects of the wounded. In recent years, the athletes of antagonistic sports pay more and more attention to the oral protection in sports. According to the statistics of soccer sports injuries by the national electronic injury monitoring system of the United States in 2001, 175000 people in the United States are injured by football every year, of which 43% are aged from 8 to 14 years. Among the wounded, 30% of the injuries are oral and maxillofacial injuries, including tooth avulsion, tooth fracture and jaw fracture [11,12]. Because ice hockey allows a certain degree of reasonable collision, the risk of sports related injury is higher. In this survey, 20 people had periodontal injury (7.14%), 8 people had tooth injury (2.86%).
"Tooth guard" is generally considered to be an effective oral protective device, which can reduce the impact force in sports through significant buffering effect, and reduce the incidence of tooth fracture, tooth avulsion, jaw fracture and other injuries . The National Federation of high schools (NFHS) and the University Sports Association (NCAA) both require the use of mouthguards in four sports, including hockey, rugby, ice hockey and lacrosse [14-15]. The American Dental Association (ADA) and the American Society of Pediatric Dentistry (AAPD) also recommend the use of dental protectors for athletes participating in competitive sports . It is clearly pointed out in the competition requirements of China's 2018 Haidian District Youth Ice Hockey League that participants must wear dental protectors. But in the survey, only 22.17% of the athletes have the habit of wearing tooth guard, and 62.5% of the athletes have never worn it. The investigation in the United States is not optimistic. Collins et al.  in 2017, they conducted a survey on young athletes who participated in basketball, football and other confrontational sports in 21 middle schools. 22.6% of the athletes never knew that they needed to wear tooth protectors, and only 12.3% of them often or used to wear them in sports. Chukwudi et al.  in the survey of Nigeria, 19.16% of young athletes reported wearing tooth guard. It can be seen that although tooth protectors are widely considered to have good protection for teeth, it is still difficult to promote and use them among young athletes. In order to improve the safety of young people participating in antagonistic sports, we should further understand the difficulties and resistance they encounter in self-protection, so as to provide targeted help and guidance.
4.2 Young ice hockey players and their parents lack knowledge of sports related oral injury
Although the wearing rate of mouthguard is not high in this survey, more than half of the respondents know that athletes have the risk of oral injury in sports, but they don't know much about it. 43.58% of the respondents did not know that the risk would occur, and even believed that oral injury would not occur. Our survey results show that 48.10% of the respondents know that they need to wear tooth protectors in ice hockey matches through the notices issued by the ice hockey association. Most of these notices come from the statement of the requirements of the Ice Hockey Association for the athletes' protective gear in the competition requirements, and do not mention the necessity and correct method of wearing tooth protectors. Only 18.31% of the respondents' information came from the coach's guidance. It can be seen that the ice hockey coach's own understanding of the mouthguard is not profound. Although modern medicine pays more and more attention to oral health care, oral health professionals and social health propaganda still lack health guidance for athletes. Among the respondents who reported to be guided by stomatologists, 8 had oral injury history and learned relevant information during oral treatment. Two parents of athletes reported that their occupation was stomatologist. In addition, 8.31% of the respondents had never obtained any relevant information.
In the survey, most of the respondents expressed their hope to know the relevant information through the publicity and requirements of ice hockey coaches or sports associations. Because the respondents think that they should understand the risk of ice hockey, athletes contact them most, it is easier to obtain information, and the athletes have higher compliance to the coach's guidance. Only 10.23% of the respondents chose oral health care personnel as the best way of information dissemination, even lower than the social publicity of ordinary media. This may indicate that at present, China's medical resources are still not rich enough, and the service focus of dental specialist medical staff is still focused on the treatment of oral diseases that have occurred, lack of community service, unable to provide oral routine examination, prevention and treatment of potential oral diseases and other health care services, and there is still a long way to go from the ideal "national oral health". Respondents generally believed that it took a lot of time to wait in line to listen to the professional guidance of stomatologists or nurses, and doctors often did not have time to do detailed health guidance for patients. Without oral diseases, there is no opportunity to meet dental professionals, so it is difficult to get health guidance on exercise through them. In order to achieve the goal of national oral health, dental specialist medical staff must go deep into community hospitals to ensure that the community can get convenient oral health guidance, regular examination and other basic services.
4.3 How to improve the wearing rate of Chinese teenagers' tooth guard
In order to improve the wearing rate of teenagers in China, we further investigated the main factors that affect the wearing of dental protectors. In accordance with our previous analysis, 89.64% of the parents thought that it was the important reason why the athletes didn't wear tooth protectors. This is consistent with the survey results of chukwudi et al. , and it is believed that there is a significant correlation between the wearing compliance of oral protective equipment and the athletes' cognition of the risk and consequences of oral injury. It is suggested that our athletes lack the channels to obtain the information of "oral protective equipment", and the oral health education related to sports is very important.
67.14% of the respondents did not want to be excessively concerned by others because of wearing the mouthguard. Another 17.50% of the respondents were hard to accept the change of the image after wearing the mouthguard. In addition, the discomfort and communication difficulties after wearing the mouthguard also reduce the compliance of the athletes wearing the mouthguard to a certain extent. But in ice hockey, helmet, armor and other protective equipment are very common, there is no movement resistance. Therefore, the perfect and implementation of the relevant regulations of competition requirements and sports safety is the best measure to promote the use of tooth guard. 77.14% of the parents thought that the formulation and enforcement of the standards of the relevant regulatory agencies were the important measures to promote the young athletes to wear the mouthguard. Under the influence of standard and system, coach supervision is more important (54.64%). At present, many countries require the coaches of antagonistic sports to receive the safety education of oral sports related losses before working, and master the emergency treatment measures of tooth avulsion, tooth fracture and other accidents. The coach must pass the strict examination before he can obtain the qualification. This has a good role in reducing the incidence of sports related losses and the adverse consequences of injury, which is worthy of our learning and reference.
To improve the comfort of tooth guard and reduce the cost of wearing is the next direction of oral medical professionals. There are three main types of tooth guard sleeves available：The first type is ordinary tooth guard. It is preformed, ready to buy and wear. It is cheap, but its comfort is very low. It is prone to pain, nausea, dyspnea and other obvious discomfort symptoms. The second type is the heated and occlusive type of tooth guard, which is worn for the first time after being heated in water, so as to make it suitable for different people to wear. This kind of tooth guard is the most popular one at present, and it is more comfortable than the ordinary one. However, due to its large thickness, it may affect the normal communication in sports, and there are also uncomfortable symptoms such as foreign body sensation. The third type is custom-made tooth guard, which is made by professional doctors and technicians after taking film. It has accurate retention and stable wearing. It can prevent oral injury and ensure comfort and durability at the same time. However, athletes need to go to the hospital many times to cooperate with doctors to customize, which takes a long time and costs a lot. Therefore, it is of great significance to develop a kind of tooth guard with strong resistance and easy to wear.