The incidence and etiology of facial fractures manifest differently depending on various factors, including environmental, cultural, and socio-economic factors. Among the facial fractures, mandible fractures are common, along with fractures of the nasal bone, the orbital wall, and the zygomaticomaxillary complex (ZMC). The mandible is essential for speaking, biting, and chewing [1]. Like other fractures, mandibular fractures lead to a decrease of the quality of life and cause severe functional disability and social costs. Thus, mandibular fractures must be treated to recover the pretrauma condition [2]. If the displacement is not severe, conservative treatment, including a closed reduction with an intermaxillary fixation, can be performed. However, in case of severe displacement and dysfunction, appropriate reduction and rigid fixation may be necessary [3]. However, if the patient’s general condition is poor, the treatment may be delayed, and the risk of postoperative complications is high. Therefore, assessment of the severity of patient’s condition at the time of the visit is necessary.

Regional trauma centers have been established to provide intensive treatment to severe trauma patients. A regional trauma center refers to a treatment center specialized in treating severe trauma patients with multiple fractures or bleeding due to traffic accidents (TA) or falls, it can provide immediate patient resuscitation, emergency surgery, and procedures, and it is equipped with relevant medical tools and human resources to provide an optimal treatment, such as critical care. In Korea, five institutions were designated as regional trauma center and were supported by the government since 2012. They opened for the first time in 2014, and 15 centers are currently in operation in hospitals nationwide. When a trauma patient visits the emergency room, regional trauma centers assign the injury severity score by considering the affected body region and the severity of each injury. Usually, severe trauma patients are those with a score of at least 15 points [4]. Another method to assess the severity of facial trauma is facial injury severity scale (FISS) (Table 1). FISS is a clinically useful index because it can predict the severity of facial injuries and is an indicator of the hospital length of stay [5].

The purpose of this study was to classify the patients who visited a single regional trauma center for mandibular fracture into severe trauma patients and non-severe trauma patients and to collect data, such as epidemiologic data, mandibular fracture patterns, and accompanying injuries, in order to find its relationship with severe trauma patients. By identifying the trauma that leads to mandibular fractures, predicting trauma severity using significant predictors, and further enabling more efficient allocation of the limited trauma-related resources, this study is expected to help quickly classify and treat patients with high trauma severity.

The mandible is an important facial bone structure that perform many functions, and its fracture can cause severe functional disability and social costs. According to recent research, facial fractures most commonly occur in the third decade of life [6]. In the present study, patients with mandibular fractures were older than in the previous reports, and age was statistically significantly higher among severe trauma patients. This is thought to occur because older people have a higher risk of severe trauma exposure than younger people. Even though men were found to have a higher trauma severity in our data, the difference was not statistically significant. Many recent studies reported that facial fractures most commonly occur in the summer and rarely in the winter [1,7]. This was also thought to be related to the higher outdoor activities during summer, resulting in more frequent trauma. Although a similar trend was seen in this study, season did not have a strong impact on the severity of injury.

It can be expected that the probability of bilateral occurrence of mandibular fractures and the occurrence of multiple fractures would be higher in severe trauma patients. Such a relationship was not found to be significant. Therefore, the severity of patient’s condition and the severity of mandibular fractures are interpreted to be unrelated and independent. Morrow et al. [6] reported that condylar fractures accounts for the highest proportion of mandibular fractures, followed by body fractures, angle fractures, fractures of the symphyseal region, dentoalveolar fractures, ramus fractures, and coronoid fractures. In our study, a proportion of the affected area was different from this trend. The trauma severity was statistically significantly lower if the fracture was located in the angle, the condylar process, or the coronoid process. Descriptive statistics also showed that severe trauma patients had a high proportion of body fractures among the mandibular fractures. Thus, it can be assumed that the trauma severity is higher when the fracture is in the center rather than in the sides of the mandible. Even though concurrence of other facial bone fractures could be expected for severe trauma patients, no statistical differences were found. According to this finding we conclude that concomitant facial fractures do not always correlate with the severity of patient’s condition.

Recently, there is a decreasing trend in facial trauma related to TA in many developed countries because of the strengthening of traffic safety regulations. For this reason, interpersonal violence has shown to relatively increase as an important cause [8-10]. In recent studies, the most frequent cause of injury was assault, followed by falls, sport accidents, TA, work accidents, and other causes [11]. In this study, the most common injury mechanism was in the order of TA, falls, work accidents, and assault. The most common types of TA were in the order of in-car TA, motorbike/bicycle, and pedestrian TA. This is thought to occur because there are more TA and work accidents than in urban regions, given that our hospital is a regional trauma center that also receives patients from the surrounding rural regions. According to the results of the analysis with “in-car TA” as the reference, patients with pedestrian TA and falls would have a significantly low trauma severity. This implies that the severity of mandibular fractures caused by “in-car TA” is relatively high. This hypothesis was generated because the mandible is struck by the steering wheel during “in-car TA,” but in “pedestrian TA,” the trunk and extremity are involved.

Furthermore, because significant soft tissue injury is more common in severe trauma, this study did show that the trauma severity was higher with soft tissue injury, but without statistical significance. It is possible that information about concomitant soft tissue injury was not accurate in the medical record or that the severity could be high even if there was no soft tissue injury due to blunt trauma.

FISS, which is an index that assesses the severity of craniofacial trauma, is a clinically simple but useful indicator that can predict the patients’ severity of the injury, economic burden, and hospital length of stay [5]. In line with recent studies, this study found that higher FISS was associated with higher trauma severity and that the predictions could be made with the most optimal sensitivity and specificity when the cutoff is 4 points. Although the proposed model is quite complex because it includes more predictive variables than the model using FISS, the finding that its performance was significantly better is important.

After the establishment of the regional trauma center, we have classified and treated trauma patients more intensively and faster than before. Our regional trauma center opened on September 22, 2015. Among 48 patients who received mandibular fracture treatment before opening, eight (16.7%) were classified as severe trauma patients; however, after opening, 14 out of 25 patients (56%) were classified as severe trauma patients. Before the opening of the regional trauma center, data were inadequate, and the classification system for severe trauma patients through the injury severity scale was incomplete. It is presumed that with the implementation of a systematic classification system, the data quality will become higher soon. With the expansion of regional trauma centers, the preventable trauma death rate is decreasing. This is the first study that analyzed facial fractures of severe trauma patients at a regional trauma center in South Korea. The role of plastic surgeons for posttraumatic reconstruction and restoration of function is becoming increasingly important. Therefore, plastic surgeons should also have an interest in treating severe trauma patients; thus, this study can be the beginning of the efforts to accomplish that goal. However, the results of this study are limited; there is a possibility of statistical error due to the small sample size, it included only mandibular fractures among facial fractures, and it was conducted in a single center. Therefore, based on this study, it is necessary to analyze regional characteristics carefully through multicenter studies of patients with facial fractures admitted in regional trauma centers across the country.