The present invention relates, generally, to the field of adaptable mouthguards for protecting subjects against the effects of a craniofacial impact.
The term “adaptable” refers to mouthguards suitable for being shaped in the mouth.
The present invention particularly, but not exclusively, relates to mouthguards suitable for adaptation by means of thermal adaptation with hot water.
The present invention is used, more particularly, but not exclusively, when practising sports involving a risk of orodental, maxillo-facial, brain and neck injuries. It may relate to other fields such as for example that of healthcare for preventing orodental injuries liable to occur during endotracheal intubation.
Sport is one of the main causes of orodental injuries. The American Dental Association and the Academy for Sports Dentistry have drawn up a list of at-risk sports and leisure activities for which they recommend the use of a suitable mouthguard, such as, for example, martial arts, baseball, basketball, boxing, cycling, football, gymnastics, weightlifting, handball, hockey, wrestling, parachuting, rugby, skateboarding, skiing, equestrian sports, squash, surfing, volleyball or water polo.
Mouthguards emerged in the 1890s in the UK and originally were intended to protect boxers from cuts to the lips caused by practising their sport.
From the first role thereof as a protection of the mucosa, the mouthguard has evolved to become primarily a protection of the orodental and maxillary structures, and the role thereof has extended to the prevention of concussion and neck injuries while practising at-risk sports.
Therefore, among other things, a mouthguard is intended to:                reduce the risk of injury to soft tissue (tongue, lips and cheeks);        reduce the risk of injury to maxillary front teeth;        reduce the risk of orodental injury due to a violent inter-arch impact;        reduce the risk of concussion;        reduce the risk of neck injury.        
Furthermore, a mouthguard includes the following properties:                occupying areas with no teeth;        enabling an engagement of the mandibular and maxillary dental arches;        being comfortable;        not exhibiting any protrusions or roughness;        being retentive;        absorbing and dissipating impact energy;        enabling phonation;        enabling oral ventilation with the jaws clamped shut.        
The term “retentive” refers to the ability of the mouthguard to remain in place when the user opens his/her mouth.
The term “engagement” refers to the entry of the antagonist teeth into the occlusal rim of the cradle to obtain the alignment of the mandibular and maxillary arches.
The term “phonation” refers to the user's ability to express themselves verbally.
Three types of mouthguard are currently routinely offered:                Type I: standard model, uni- or bimaxillary. This type of mouthguard is ready-to-use. However, such a mouthguard involves the following drawbacks:        not enabling the engagement of the mandibular and maxillary dental arches;        not being retentive: it only holds in place when the player's jaws are clamped shut;        impeding the player's ventilation and, furthermore, there is a risk of the guard being ejected during exertion and getting stuck in the player's airways.        Type II: adaptable model, uni- or bimaxillary. This type of mouthguard is suitable for being shaped in the user's mouth. However, such a mouthguard involves the following drawbacks:        losing up to 99% of the thickness during the adaptation in the mouth, limiting impact energy absorption and dissipation;        restricting oral ventilation with the jaws clamped shut.        Type III: custom model. This type of mouthguard is produced after taking imprints of the user's mandibular and maxillary dental arches. The (custom) preparation method should be suitable for producing a high-quality mouthguard according to the objective essential criteria and recognised properties for this prevention device. However, according to the operators, some of these mouthguards may have a lower quality than type II cradles in terms of material thickness and ventilation capacity with the jaws clamped shut.        
Type II mouthguards, i.e. suitable for being shaped in the mouth, for example after softening in hot water, represent more than 90% of the mouthguards currently worn by athletes.
Retention of the thicknesses of the mouthguard material is necessary for satisfactory absorption and dissipation of impact-related energies.
Furthermore, ventilatory studies have demonstrated that all types of mouthguards involved more air resistance and reduced the athlete's ability to ventilate with the jaws clamped shut.
This reduction in ventilation with the jaws clamped shut gives rise to hypoxia, hypercapnia and the logical result is a decline in performance.
This reduction in ventilation with the jaws clamped shut gives rise to a mouth opening movement which is essential to reduce the hypoxia and hypercapnia induced by the exertion with the jaws clamped shut. However, this movement causes two major consequences:                an increased risk of injuries after impact on a mandible detached from the face, referred to as “projectile mandible”, such as dental injuries due to inter-arch impact, predominantly postural knockout or mandibular fracture following impact of the posterior region of the temporal eminence of the condylar process.        an increased risk of concussion and cervical spine injury due to a shock to the muscle support for the craniofacial joint and thus an impairment in head and neck support.        
The aim is thus that of providing an adaptable mouthguard for ensuring oral ventilation when the user's jaws are clamped shut and retention of mouthguard thicknesses after the intra-oral shaping procedure.
Of the numerous patents relating to mouthguards, the international patent application WO94/27691 held by E-Z GARD INDUSTRIES, published on 8 Dec. 1994, subject to the priority of an American applications U.S. Ser. No. 08/066,468 filed on May 1993 is known. This application discloses a guard made of composite material, comprising a maxillary cradle made of a thermo-adaptable material and frame made of a non-thermo-adaptable material for absorbing and dissipating impact forces. The structure of this type II mouthguard enables posterior contact (i.e. to the rear of the jaw) on the non-thermo-adaptable material to retain a frontal space (i.e. to the front of the mouth, at the incisors) to breathe and talk. However, the frontal space obtained after shaping the mouthguard may be insufficient to enable satisfactory ventilation when the user clamps the jaws shut. Moreover, the presence of only the non-thermo-adaptable material in regard to the lateral sectors means it is impossible to take an imprint of the mandibular dental arch during the shaping procedure and thus does not enable engagement between the mandibular and maxillary dental arches.
However, athletes need sufficient ventilation while exerting themselves with the jaws clamped shut and the mandible to be correctly engaged and interlocked with the maxillary dental arch to prevent the “projectile mandible” phenomenon.
The international patent application WO98/34574 filed in February 1997 on behalf of WIPSS PRODUCTS INC subject to the priority of an American application U.S. Pat. No. 5,636,379 filed in August 1995 also disclosing a guard made of composite material is also known. One of the drawbacks of this product is that the thinness of the thermo-adaptable material around the frame made of non-thermo-adaptable material does not enable sufficient engagement between the mandibular and maxillary dental arches during the shaping procedure and thus does not enable sufficient locking of the mandible or sufficient mouthguard retention.