Effect of restraint systems on maxillofacial injury in frontal motor vehicle collisions.

ABSTRACT

PURPOSE: Motor vehicle collisions (MVCs) are the leading cause of maxillofacial fractures. Additionally, maxillofacial injuries are the most common injury related to air bag deployment. We sought to characterize the occupant restraint system (seat belt and air bag) and collision characteristics associated with MVC-related maxillofacial injuries. MATERIALS AND METHODS: The 1991-2000 National (United States) Automotive Sampling System Crashworthiness Data System (CDS) data files were used. The CDS is a national probability sample of passenger vehicles involved in police-reported tow-away MVCs. Analysis was limited to front seat occupants involved in frontal collisions of delta-V (estimated change in velocity) of greater than 15 km/hr. The risk of facial injury was calculated according to occupants' restraint use (unrestrained, seat belt only, air bag only, and seat belt and air bag combined) and compared using risk ratios (RRs) and associated 95% confidence intervals (CIs). RESULTS: Occupants restrained with a seat belt only (RR, 0.48; 95% CI, 0.40 to 0.57) or a seat belt and an air bag (RR, 0.83; 95% CI, 0.73 to 0.94) had a significantly reduced risk of any facial injury compared with completely unrestrained occupants. There was no association for those restrained with an air bag only (RR, 1.19; 95% CI, 0.82 to 1.73). A similar pattern of results was observed for moderate to severe facial injuries and for facial fractures. CONCLUSION: Seat belt use significantly reduces the risk of facial injury in frontal MVCs. Air bag use was not associated with the risk of facial injury.