The Effectiveness of Dental Protection and the Material Arrangement in Custom-Made Mouthguards

Abstract

Experimental research studies have shown that wearing a mouthguard (MG) is an effective way to prevent tooth or maxillofacial trauma. However, there is a lack of scientific information regarding how the material arrangement within the mouthguard can modify its mechanical response during an impact. Hence, this study aimed to evaluate the influence of material arrangement within custom-made mouthguards on stress transmitted to anterior teeth, bone, and soft tissue after impact. Four 3D finite element models of a human maxilla were reconstructed based on the CBCT of a young patient and analyzed according to the presence or absence of a mouthguard and the type of material arrangement within those with a mouthguard: model NMG with no mouthguard; model CMG representing the conventional arrangement with a single 4 mm-thick ethylene-vinyl acetate (EVA) foil; model FMG presenting layer arrangement with two 1 mm-thick foils of EVA in the outer shell and one 2 mm-thick foil of EVA foam in the core; model HMG presenting a 1 mm-thick compact inner and outer shell of EVA and a 2 mm wide air-filled zone in the core. Linear quasi-static analysis and frontal load were used to simulate an impact with an energy of 4.4 J. Isotropic linear elastic properties were assumed for the bone and teeth but not for the mouthguard protection and oral soft tissues. The results were evaluated and compared in terms of displacement, stretches, and stresses. All the mouthguards analyzed reduced the risk of injury to teeth and bone, reducing the displacement and stress of these structures. However, the implementation of a honeycomb structured layer allowed more significant displacement and deformation of the mouthguard's external layer, thus promoting higher protection of the anatomic structures, namely the root dentin and the bone tissue. Nevertheless, the results also indicate that improving the mouthguard flexibility might increase the soft tissue injuries.

Biomechanical Behavior Evaluation of a Novel Hybrid Occlusal Splint-Mouthguard for Contact Sports: 3D-FEA

“…Similarly, another finite element study indicated the effectiveness of using the rigid occlusal splint to change the distribution of functional load in the treatment of patients with mastication muscle parafunction [ 35 ]. This study corroborates both of these studies in presenting a positive effect to reduce the jaw displacement and teeth stress with use of the hybrid mouthguard (HMG), therefore potentially reducing the trauma effects [ 36 , 37 , 38 ] and the management of injured patients [ 37 ].…”

“…The simulated force was applied in just one direction. However, forces may be applied from other regions that could generate different results [ 3 , 4 , 35 , 38 ]. In addition, the elastic modulus was isotropic, which is different than human tissue [ 7 ].…”

“…The model was based on an adult maxilla with completely formed teeth, perfect dentition, absence of restorations, and ideal occlusion [ 6 ]. There was no aging effect considered in the polymeric material or wear caused by long-term usage [ 8 ] or modification to the design [ 38 ]. There was no consideration of saliva, pH variation, temperature variation, or presence of the tongue [ 6 ].…”

Sports mouthguard overview: Materials, fabrication techniques, existing standards, and future research needs

“…[59][60][61] EVA material variations have included silver nanoparticles to add antibacterial properties, 62 and additions to enhance shock absorbance have included porous rubber, silicone interlayers, 63 silicon nylon mesh, 64,65 and urethane modifications. 66 Additional performance-enhancing adaptations have included internal air cells either alone, 67,68 or combined with hard material inserts, 69 closed cell foam, 67 A-silicone interlayers, 70 and "honeycomb" internal EVA mesh. 68 Other materials considered and used include controlled microstructure polystyrenepolyolefin copolymer-based materials that are proposed to provide enhanced performance compared to EVA, 61,71 increased flexibility afforded by thermosetting ternary novel thiolene "click" polymer systems, modified with urethane as well as acrylate, 55,56 and polyolefin copolymer-based materials that offer lower water absorption and higher impact resistance than EVA.…”

“…Stress absorption assessments have included strain gauge sensors, 18 Fiber Bragg grating strain sensors, 18 film sensors, 83 laser triangulation sensors, 65 laser Doppler vibrometers, 84 solid‐state NMR pulse measurements, 53 and 3D image correlation strain analysis 85 . While largely underutilized, finite element analysis (FEA) of SM function has been described that allows the in silico computational, non‐destructive virtual analysis of complex structures that would be difficult to derive using in vitro methods 9,10,18,59,68,75,86 . Both 2D FEA that can perform planar stress and strain analysis has been reported, 9 as well as 3D FEA that can evaluate biomechanical responses and stress dissipation over wider areas 10,59,68,75,86 .…”