Assessment of nose protector for sport activities: finite element analysis

Abstract

– There has been a significant increase in the number of facial fractures stemming from sport activities in recent years, with the nasal bone one of the most affected structures. Researchers recommend the use of a nose protector, but there is no standardization regarding the material employed. Clinical experience has demonstrated that a combination of a flexible and rigid layer of ethylene vinyl acetate (EVA) offers both comfort and safety to practitioners of sports. The aim of the present study was the investigation into the stresses generated by the impact of a rigid body on the nasal bone on models with and without an EVA protector. For such, finite element analysis was employed. A craniofacial model was constructed from images obtained through computed tomography. The nose protector was modeled with two layers of EVA (1 mm of rigid EVA over 2 mm of flexible EVA), following the geometry of the soft tissue. Finite element analysis was performed using the LS Dyna program. The bone and rigid EVA were represented as elastic linear material, whereas the soft tissues and flexible EVA were represented as hyperelastic material. The impact from a rigid sphere on the frontal region of the face was simulated with a constant velocity of 20 m s−1 for 9.1 μs. The model without the protector served as the control. The distribution of maximal stress of the facial bones was recorded. The maximal stress on the nasal bone surpassed the breaking limit of 0.13–0.34 MPa on the model without a protector, while remaining below this limit on the model with the protector. Thus, the nose protector made from both flexible and rigid EVA proved effective at protecting the nasal bones under high‐impact conditions.

Systematic study of Ethylene-Vinyl Acetate (EVA) in the manufacturing of protector devices for the orofacial system

“…Coto et al [6] studied the performance of EVA nasal protectors undergoing the impact of a rigid ball in the face with a 3D FE model (Figure 13). The material used was a combination of 1 mm of rigid EVA with 2 mm of flexible EVA.…”

“…For dental use, it is in the form of rigid or flexible flat plates, in thicknesses of 1-5 mm, without the presence of blowing agents, differently from EVA plates available in the common market. It is indicated as a shock absorber material, for producing mouth and facial protectors for sports practice, as pointed out by Coto et al [6], as well as dental bleaching trays, orthodontic restraints and as the base for facial prostheses.…”

Improvement of the Shock Absorption Ability of a Face Guard by Incorporating a Glass-Fiber-Reinforced Thermoplastic and Buffering Space

“…The forming temperature of the thermoplastic resin is a very important aspect of the FG fabrication process. If the required molding temperature is sufficiently low, expensive vacuum and/or pressure thermoforming machines are not required because the materials can be easily molded using hot water or hot plate in combination with applied finger pressure [11, 15, 16, 21, 22]. However, thermoplastic resins with low molding temperatures exhibit relatively low mechanical properties; therefore, FGs with these thermoplastic resins are generally thicker than those that use thermoset resins [23].…”

Sports dentistry: a perspective for the future

“…e location of the nasal bone is anatomically potentially more vulnerable and to protect this region, it is important which the material used for manufacture the nose shield has the adequate capacity of shock absorption, such as ethylene vinyl acetate (EVA). e shield made with a 2 mm layer of EVA superimposed by a exible sheet of 1 mm EVA disk, the risk of fracture of the nose was reduced by decreasing the stresses in the bone after impact 27 . Protective masks are used after facial fractures, usually individualized and used to protect and prevent recurrent injuries during the healing period.…”

“…Contact sport athletes have up to 10% more probability of su ering orofacial injury when compared to non-practitioners 26 and 33-56% risk of su ering a facial injury during his career 2 . Regarding to hard tissue trauma, nasal bone is one of the most a ected structures in sports accidents, because it is located in a vulnerable area of the face and projected forward in relation to adjacent structures 27 . In cyclists, the zygomatic bone is the most prevalent fracture (30.8%) and fractures of the temporomandibular joint with a rate of 18.8%.…”