Does hard insertion and space improve shock absorption ability of mouthguard?

Abstract

Mouthguards are expected to reduce sports-related orofacial injuries. Numerous studies have been conduced to improve the shock absorption ability of mouthguards using air cells, sorbothane, metal wire, or hard material insertion. Most of these were shown to be effective; however, the result of each study has not been applied to clinical use. The aim of this study was to develop mouthguards that have sufficient prevention ability and ease of clinical application with focus on a hard insertion and space. Ethylene vinyl acetate (EVA) mouthguard blank used was Drufosoft and the acrylic resin was Biolon (Dreve-Dentamid GMBH, Unna, Germany). Three types of mouthguard samples tested were constructed by means of a Dreve Drufomat (Type SO, Dreve-Dentamid) air pressure machine: the first was a conventional laminated type of EVA mouthguard material; the second was a three layer type with acrylic resin inner layer (hard-insertion); the third was the same as the second but with space that does not come into contact with tooth surfaces (hard + space). As a control, without any mouthguard condition (NOMG) was measured. A pendulum type impact testing machine with interchangeable impact object (steel ball and baseball) and dental study model (D17FE-NC.7PS, Nissin, Tokyo, Japan) with the strain gages (KFG-1-120-D171-11N30C2: Kyowa, Tokyo, Japan) applied to teeth and the accelerometer to the dentition (AS-A YG-2768 100G, Kyowa) were used to measure transmitted forces. Statistical analysis (anova, P < 0.01) showed significant differences among four conditions of NOMG and three different mouthguards in both objects and sensor. About acceleration: in a steel ball which was a harder impact object, shock absorption ability of about 40% was shown with conventional EVA and hard-insertion and about 50% with hard + space. In a baseball that was softer compared with steel ball, a decrease rate is smaller, reduction (EVA = approximately 4%, hard-insertion = approximately 12%, hard + space = approximately 25%) was admitted in the similar order. A significant difference was found with all the combinations except for between EVA and hard-insertion with steel ball (Tukey test). About distortion: both buccal and lingual, distortions had become small in order of EVA, hard-insertion, and hard + space, too. The decrease rate is larger than acceleration, EVA = approximately 47%, hard-insertion = 80% or more, and hard +space = approximately 98%, in steel ball. EVA = approximately 30%, hard-insertion = approximately 75%, and hard + space = approximately 98% in baseball. And a significant difference was found with all the combinations (Tukey test). Especially, hard + space has decreased the distortion of teeth up to several percentages. Acceleration of the maxilla and distortions of the tooth became significantly smaller when wearing any type of mouthguard, in both impact objects. But the effect of mouthguard was clearer in the distortion of the tooth and with steel ball. Considering the differences of mouthguards, the hard-insertion and the hard + space...

Easy fabrication of a new type of mouthguard incorporating a hard insert and space and offering improved shock absorption ability

“…In earlier studies (21,22), we attempted to develop a mouthguard with sufficient injury prevention ability and ease of clinical application. This mouthguard consisted of an outer and an inner EVA layer and a middle layer of acrylic resin (hard insert), with a space to prevent contact between the inner surface of the mouthguard and the buccal surfaces of the maxillary anterior teeth, which often receive direct horizontal impact in sports and in more than 80% of sports-related tooth injuries (23)(24)(25)(26)(27), or teeth already weakened through prior damage or treatment(7-10)).…”

“…This mouthguard consisted of an outer and an inner EVA layer and a middle layer of acrylic resin (hard insert), with a space to prevent contact between the inner surface of the mouthguard and the buccal surfaces of the maxillary anterior teeth, which often receive direct horizontal impact in sports and in more than 80% of sports-related tooth injuries (23)(24)(25)(26)(27), or teeth already weakened through prior damage or treatment(7-10)). These mouthguards showed more than 95% shock absorption ability in terms of tooth distortion against impact with a steal ball carrying 15.2 kgm 2 /S 2 potential energy (21,22).…”

Application of addition-cured silicone denture relining materials to adjust mouthguards

“…The Federation Dentaire Internationale issued the policy statements that national dental associations promote to the public and to oral health care professionals the benefits of sports mouthguards, including the prevention of orofacial injuries 5) . Mouthguard materials should have the ability to absorb and disperse impact energy to avoid concentrating force around an impact point, and should be durable throughout the season 6,7) . Most mouthguards currently comprise ethylene-vinyl acetate copolymer (EVA).…”

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

“…Takeda et al indicated that mouth guards incorporating a hard insert and buffering space improved their shock absorption ability [26–30]. The concept consisted of using a deformation of the hard insert (similar to a structural feature termed a crumple zone or crush space used in automobiles) to absorb and diffuse the energy of the impact away from the most important area, for example, maxillofacial traumatic injured area (or tissue) and/or the most dangerous area, for example, maxillary anterior teeth.…”