Influence of pre-laminated material on shock absorption ability in specially designed mouthguard with hard insert and space

We have developed a new type of laminated mouthguard, the Hard & Space mouthguard, which incorporates a hard material insert and a space to prevent contact between the mouthguard and the buccal surfaces of the teeth. The purpose of this study was to investigate the effect of this new design on shock absorption. Three types of mouthguard (a conventional laminated EVA mouthguard and two 3-layer type “Hard & Space” mouthguards made of 1.8-mm or 3.0-mm thick pre-laminated material (Konbiplast) and EVA with a 1.0-mm space) were impacted. Shock absorption was measured by means of a pendulum type steel ball impact testing machine at impact distances of 10, 20, and 30cm and a dental study model with strain gauges attached to the lingual surfaces and an accelerometer fixed to the maxilla. Distortion of the impacted tooth and acceleration of the model were significantly reduced by all types of mouthguard at all 3 impact distances. The effect of the mouthguard was remarkable in terms of tooth distortion: both thicknesses of Hard & Space mouthguard showed more than 90% shock absorption, compared with only approximately 55–78% with an EVA mouthguard. Furthermore, shock absorption with the thicker 3.0-mm Hard & Space mouthguard reached more than 95% at the highest impact power. Within the limitations of this laboratory study, Hard & Space mouthguards showed significantly greater buffer capacity than a conventional EVA mouthguard in terms of tooth distortion at the 3 impact powers tested.