1. This test methodology for the impact attenuating characteristics of intra-oral devices uses an articulated or segmented headform, which simulates the jaw joint biomechanics and seven force transducers or load cells strategically placed in the mid-facial and the jaw-joint area of the headform.
    
2. The articulated headform positioned in a helmet is attached to a free fall assembly carriage (fig.16)

   Fig. 16 Schematic of Helmet Drop Assembly

   by an adjustable mounting that allows impacts to be delivered to the prescribed point on the faceguard of the helmet from a 60-inch drop height. The carriage shall be free to slide on vertical guides.
    
3. The recording equipment shall meet the following criteria:
   
   1. The accelerometer is mounted at the center of gravity of the combined test headform (fig.17)

      Fig. 17 - Acceleromater Location in Headform

      and carriage assembly with the sensitive axis aligned to within 5° of the vertical when the helmet and headform are in the impact position. This transducer shall be capable of withstanding a shock of at least 9810 m/s2 (1000 g), without damage.
   2. The flat impact surface shall be a modular elastomer programmer (MEP) 6 in. (152 mm) in diameter and 1 in. (25 mm) in thickness, which is firmly fixed to the top surface of a flat anvil. The MEP required is a 60 ± 5 Durometer Shore A Hardness impact surface. The MEP is mounted on an aluminum plate with a minimum thickness of 0.220 in. (6 mm).
   3. The impact recording system shall be capable of measuring shocks of up to 500 g peak acceleration with an accuracy of ±5 %.
   4. The mounted test headform- helmet

      Fig. 18 - Relative angle impact on impact site of drop assembly

      assembly is oriented in a position (fig. 18) and dropped at a specific velocity and angle onto the MEP impact surface.
   5. Acceleration and time history date are obtained by specific procedures intended to determine the energy absorption characteristics of the intra-oral devices.
   6. Time history and load data obtained by the specified procedures are intended to determine the energy absorption characteristics of the intra-oral devices.

The use of the helmet-faceguard assembly with its force attenuation characteristics greatly reduced the fracture potential of the epoxy headform being subjected to the repeated impact forces of laboratory testing. The protective design of the helmet-faceguard assembly is flawed by the fact that many injury-producing forces are placed on the mandible. In the helmet drop testing procedure, the skull and intracranial injury mechanism is transmitted through the strap-chin-cup retention system of the helmet, which mimics the lower jaw impact syndrome of boxing.

The impact force distribution analysis (fig.19);

Fig. 19 - Distribution (Attentuation Pattern) of Load Forces for Intra-oral Devices Jaw joint protector attenuates load from jaw joint complex and distributes it onto dental arch.

1. Jaw Joint Protector proved to effectively attenuate and the peak resultant forces directed to the jaw joint load cells 1 and 7, 2 and 6. These forces are transferred throughout the dental arch load cells 3 and 5 and the energy managing aspect of the protector. This reduces the severity of the impact to the skull and brain, making contact sports safer.
    
2. Custom Made Mouthguard transmits excessive load forces of the impact to jaw joint load cells 1 and 7, 2 and 6 and consequently increase the severity of impact against the skull. These impact load forces greatly influence the response of brain tissue and are more than enough to cause TBI. The results of this study validate the impact significance of the slide and slam phenomena of mouthguards. There is also a significant elevation in the anterior load cell (4).
    
3. The Over-the-Counter Mouthguard produces forces throughout all the load cell positions greater than those described with the custom- made mouthguard. It also showed a greater elevation in the force load in load cell position (4) directed to the incisor teeth or anterior component of the mouth.

The jaw joint protector absorbs and redistributes those forces of head impact that are transmitted from the condyle, directly impacting the base of the skull and influencing the temporal lobe response of the brain (fig 20). These head impact forces are transferred to the jaw-joint protector and the mandibular and maxillary dental structures. The teeth and jaw-joint protector are more adequately equipped to handle the explosive head impact forces than the thin bones and vital tissue of the jaw joint structure.

With the use of the jaw joint protector, it is considerably easier to prevent jaw joint, basal skull surface and brain injury responses from lower jaw impacts than to repair the manifestations.

Not all brain injury mechanisms or biomechanical dynamics for the jaw joint injury producing phenomena are understood. Reducing the incidence of closed head injuries in sports has been made possible through the collaborative efforts of the scientific community to advance the design of headform test devices. However, the capabilities of current headforms need to be expanded to include and register facial, jaw joint, brain and neck responses and more tests need to be conducted that simulate impacts that occur in the ring or on the field of play.

Fig. 20 - Compares Jaw Relationship of The Normal Class l Mesognathic to a Class lll Prognathic Jaw Relationship.

Note: WIPSS Jaw Joint Protectors are contraindicated for use on athletes with a prognathic jaw relationship. In the prognathic jaw relationship, the mandibular arch is positioned anteriorly to the maxillary arch. Fitting the maxillary and mandibular teeth into the bite channels of the jaw joint protector may in fact force the condyle distally (fig. 21) in the fossa relationship. This in turn will point load the condyle-fossa relationship for greater impact injury from lower jaw impacts.