Definitions and Epidemiology
Oral injuries account for 30% of sports injuries and each athlete participating in a contact/collision sport has a 10% chance of such an injury.1 Intrusive displacement of the anterior teeth as a result of falls is the most common injury in children with primary dentition, whereas fractures of the crown are the most common injuries in adolescents and adults.1–10 More than half of dental injuries involve maxillary incisors. The highest incidence of oral injuries has been reported in baseball and biking.1–10 The American Academy of Pediatric Dentistry definitions of dento-alveolar injuries are summarized Table 33-1.
Incomplete fracture (crack) of the enamel without loss of tooth structure
An enamel fracture or an enamel–dentin fracture that does not involve the pulp
An enamel–dentin fracture with pulp exposure
An enamel, dentin, and cementum fracture with or without pulp exposure
A dentin and cementum fracture involving the pulp
Injury to the tooth-supporting structures without abnormal loosening or displacement of the tooth
Injury to tooth-supporting structures with abnormal loosening but without tooth displacement
Displacement of the tooth in a direction other than axially. The periodontal ligament is torn and contusion or fracture of the supporting alveolar bone occurs
Apical displacement of tooth into the alveolar bone. The tooth is driven into the socket, compressing the periodontal ligament and commonly causes a crushing fracture of the alveolar socket
Partial displacement of the tooth axially from the socket. The periodontal ligament usually is torn
Complete displacement of tooth out of socket. The periodontal ligament is severed and fracture of the alveolus may occur
Studies over several decades have looked at the factors involved in facial and dental injuries and their epidemiology.1–11 It must be remembered that over the past 20 years many amateur and professional sports organizations have encouraged and/or mandated the use of protective equipment which has resulted in significant reductions in such injuries. Many experts have been quick to point out, however, that as there is no mandatory reporting of such injuries, the true incidence is almost certainly much higher than what is reported in the literature.
Trauma to the face during sports participation may result in several common outcomes. The first of these involves fractures of the facial bones; i.e., the maxilla, the mandible, and/or the dental alveolar ridge. Whenever injuries to the face and dental structures occur there is a possibility for life-threatening injury and the examiner should always follow the ABCs of basic life support.4,12,13 The extent of such an examination depends on the nature of the injury and the clinical presentation of the athlete. One should remember that any injury to the face and dental structures is an injury to the head with potential concussion and/or neurological compromise. Once the ABCs have been appropriately evaluated a brief neurological examination is often indicated.4,12,13
The most frequently encountered physiologic mechanism is “deceleration injury” caused by contact of a moving player with the ground, with another player, with protective equipment, or with obstacles adjacent to the field of play (i.e., the outfield fence in baseball, the goal post in football, or a tree in downhill skiing).12,14–18 The likelihood and severity of injury is determined by many factors including the age and development of the player, the competitive level, and the presence or absence of protective equipment. The second mechanism of injury is “acceleration” type injury caused by contact of the facial structures with a moving object such as a baseball, baseball bat, or hockey stick. Many injuries combine the aspects of acceleration and deceleration as when two outfielders collide when chasing down a fly ball. Given the kinetic energy which is released in such collisions there is greater potential for serious injury to facial structures.
Diagnoses and Treatment
Fractures of the maxilla occur along suture lines and for that reason are fairly easy to understand.17 Such injuries are exceedingly rare and require a great deal of kinetic energy applied to cause such disruption. In fact, maxillary fractures are much more common in motor vehicle accidents than they are in sports. The classification of maxillary fractures was described decades ago by Renee LeFort and is presented in Figure 33-1.17 It should be noted that because of the relative lack of development of the lower and mid-face in the preschooler, maxillary fractures are an uncommon occurrence.
Subsequent to any injury resulting in severe blunt trauma to the face, especially in the presence of abrasions, lacerations, or ecchymoses the examiner should consider the possibility of a LeFort type of fracture.3,12,16,19 Facial asymmetry is the first clue to maxillary fractures. Palpation of the zygomatic arches and the maxilla may reveal “step off” of the bones or mobility of bony segments suggestive of fractures.
It is important to palpate the nasal cartilage and nasal bones: excessive mobility of the entire maxilla or of the nasal bridge may be indicative of a LeFort II or III fracture. Any suggestion of maxillary fracture requires emergent imaging and evaluation by a facial trauma specialist. LeFort I fractures require intermaxillary (maxilla to mandible) fixation with orthodontic brackets and wires. LeFort II or III fractures may also require further fixation of the maxillary segment to the base of the skull. Depending on the findings and the necessary intervention, the athlete will usually be unavailable for 6 to 12 weeks, and the return to play decision is best left up to the trauma specialist involved. Early return to play has been associated with displacement of the maxillary segments and later significant malocclusion.
Because of its relative prominence in older children and adults, fractures of mandible occur at a relatively higher frequency than those of the maxilla. The mid and lower face (mandible) is relatively underdeveloped in the pre-schooler and fractures of the mandible are uncommon.5,7,17 The first part of the examination after trauma to the mandible is, as before, visual inspection to assess asymmetry. The examiner should then palpate along the body, angle, and ramus bilaterally to look for any evidence of bony discontinuity (“step-off”) or mobility. Ask the athlete to open the mouth and assess the degree of opening, since decreased opening of the mouth may indicate damage to the TMJ or mandibular fracture. The athlete should then be asked to close the mouth completely into a “normal bite.” It may be possible to assess the occlusion to see if the maxillary and mandibular teeth articulate correctly.
It is important to note that many athletes may have malocclusion prior to the traumatic injury (Figure 33-2). A simple and reliable way to evaluate for occlusion is to ask the athlete to open and close the mouth several times and to clench the teeth together. If the athlete has a sense that the teeth are not coming together properly or if there is significant pain with clenching, it is a good indicator of fracture or TMJ disruption. If there is any doubt about the diagnosis, continued play is contraindicated and a panoramic x-ray is required.
As with long bone fractures, fracture points of the mandible are located at maximum stress points and “weak areas” related to anatomy. Figure 33-3 shows these stress points which are the angle, the neck, and the anterior symphysis.
Fractures of the zygomatic bones are uncommon before 12 years of age, because they have not yet fully developed. The fracture results from a direct impact to face. The athlete may complain of diplopia and feeling of numbness on the cheek. On examination, there is localized ecchymosis, swelling, and tenderness over the zygomatic bone. Tenderness can be elicited on palpation of the roof of the mouth. In athletes with zygomatic fracture, eye injury should be ruled out and the athlete should be referred to ophthalmology and maxillofacial surgery for further evaluation and management.
Temperomandibular Joint Trauma
The temperomandibular joint is quite unique in structure and function. A glance at Figure 33-4 serves to remind us that the structure is actually a U-shaped long bone with a “ball and socket” joint on each end. The unique feature of the TMJ is the articular disk composed of fibrocartilagenous tissue positioned between the two bones that form the joint. The TMJs are the only synovial joints in the human body with such an articular disk. The disk divides each joint into two compartments. The lower joint compartment formed by the condyle of the mandible and the articular disk is involved in rotational (hinge) movement which accounts for approximately the first 20 mm of mandibular opening. The upper joint compartment formed by the articular disk and the glenoid fossa of the temporal bone is involved in translational movements (sliding the lower jaw forward or side to side). The TMJ is thus a ginglymoarthroidial joint, referring to its dual functions of “hinge” (ginglymo-) and “gliding”(arthroidial-) movement. When mild to moderate direct force is applied to the mandible, damage to the TMJ is much more often the case than is fracture of the facial bones.