Stress Concentration of Hybrid Occlusal Splint-Mouthguard during a Simulated Maxillofacial Traumatic Impact: 3D-FEA

Abstract

Mouthguards (MG) are protective devices that can reduce the risks of facial trauma. However, many athletes do not use them. Additionally, MG wear with coincidental parafunctional activity has not been considered. The aim of this study was to evaluate the stress distribution as a consequence of a direct impact comparing a conventional MG with a novel hybrid appliance (HMG). Using computer-aided design (CAD) software, a human skull was modeled with the teeth inserted into their respective alveolus. The models were divided according to the MG type (conventional or hybrid). The geometries were exported to the computer-aided engineering (CAE) software and the materials were considered isotropic. Fixation was defined at the base of the maxilla. The load was applied using a hockey puck. The total deformation (mm) and the von Mises stress (MPa) results were obtained for the MGs (conventional and hybrid), upper teeth, lower teeth, and maxillary bone. Despite the presence of an MG, it is still possible to observe generated stress in all structures. However, the hybrid design was more efficient than the conventional design in reducing the displacement during the impact and consequently the stress on the upper teeth, lower teeth, and maxillary bone. Higher stress magnitude was more concentrated at the inner portion of the hybrid design than the conventional device. The HMG appliance decreased the stress concentration in the teeth and in the bone, limiting the areas susceptible to injuries to the regions directly impacted by the hockey puck. Although the novel HMG may mitigate injury, some stress will still result, and any possible injury should be evaluated by a dental professional.

Keywords: athletic injuries; finite element analysis; mouthguard; occlusal splint; trauma.

Figure 1

Hybrid occlusal splint mouthguard design (Kalman et al., 2022 [5]). (A) Polycarbonate as a rigid inner portion, (B) ethylene vinyl acetate used in the axial flexible flanges, and (C) the final modulated appliance assembled as the novel HMG.

Figure 2

Schematic illustration of the evaluated MGs: (A) Conventional custom-made mouthguard; and (B) Hybrid mouthguard (HMG) device with combined occlusal splint and flexible axial flanges. (C) Maxillary model without MG and (D) MG in position with hockey puck impact direction.

Figure 3

Boundary conditions in the 3D finite element model: Meshing subdivision and fixed support with impact path restricted to the y-axis.

Figure 4

Total deformation result in the MG. (A) Device displacement with the conventional design and (B) device displacement with the hybrid (HMG) design.

Figure 5

Von Mises Stress result in the MG. (A) Device stress with the conventional design and (B) device stress with the hybrid (HMG) design.

Figure 6

Von Mises Stress result in upper teeth. (A) Isometric view of the upper teeth stresss with the conventional design and (B) isometric view of the upper teeth stresss with the hybrid (HMG) design. (C) Buccal view of the upper teeth stresss with the conventional design and (D) buccal view of the upper teeth stresss with the hybrid (HMG) design.

Figure 7

Von Mises Stress result in lower teeth. (A) Isometric view of the lower teeth stresss with the conventional design and (B) isometric view of the lower teeth stresss with the hybrid (HMG) design. (C) Buccal view of the lower teeth stresss with the conventional design and (D) buccal view of the lower teeth stresss with the hybrid (HMG) design.

Figure 8

Von Mises stress result in the bone tissue. (A) Occlusal view of the maxillary bone stresss with the conventional design and (B) occlusal view of the maxillary bone stress with the hybrid (HMG) design.