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The Why

The purpose of this study was to validate the G-force threshold levels of the sensors installed in the Vane mouthguards product, against the G-force measured from the sensors mounted in the headform during the head-drop tests. 

Each mouthguard was equipped with two G-force indicators located near the second molars. Two mouthguard threshold presets were used during the testing: 75 G’s (red-color mouthguard) and 100 G’s (yellow-colored mouthguard).  

 Figure 1a: G-force 

Figure 1a: G-force 

 Figure 1b: Mouthguards with sensors. (75g model shown here)

Figure 1b: Mouthguards with sensors. (75g model shown here)


Headform Drop Test

The first test series was conducted on the headform without the mouthguard by dropping the headform from various heights onto the anvil to determine the height required for the G-forces to be just below and above the two preset thresholds of the sensors.

The headform used for this study contains the dental structure attached to the jaw and maxilla of the headform for mouthguard attachments (Figure 2b). The headform has an accelerometer-array system mounted at the center of gravity of the headform for measuring the G-forces during impact. 

 Figure 2a: Headform drop system

Figure 2a: Headform drop system

 Figure 2b: Modified headform wearing mouthguard that is secured by clamps

Figure 2b: Modified headform wearing mouthguard that is secured by clamps


 Figure 3a: A Kistler calibration drop tower (Model 5015) with a peak G display screen 

Figure 3a: A Kistler calibration drop tower (Model 5015) with a peak G display screen 

 Figure 3b: Drop tower surface for sensor mounting

Figure 3b: Drop tower surface for sensor mounting

Standard Calibration Test

The standard sensor calibration tests were conducted on the sensors removed from the mouthguard to verify whether the sensors could work properly in a simple test setting.

A Kistler calibration drop tower (figure 3a: Model 5015) designed for calibrating G-force sensors for impact measurement was used. To attach the sensor to the drop tower surface, a mounting block was made with a hole to enclose the sensor (figure 3b). The drop was released from about 3-inches, and the corresponding G-force was recorded by two sensors. The status of the mouthguard sensor was reviewed from each test.


Mouthguard After Impact:
The sensor turned red after exceeding the necessary G-force preset on the mouthguard. The noticeable difference in the sensor was right after impact or within an hour post-impact. 

Height Required to Achieve 75 and 100 G’s of Force:

The headform was dropped from multiple heights on the flat, padded anvil. The height producing G-forces of over 75 G’s and 100 G’s were 15 and 22 inches. The headform wearing a mouthguard was dropped at the heights according to the results from test series 1 for each mouthguard type (75 G’s and 100 G’s). A total of 4 mouthguards were tested. Table 1 lists the final results from the headform drop tests wearing the two sets of mouthguards. Insert Table 1 after this paragraph

           Figure 4a: 75 G threshold mouthguard                  Figure 4b: 100 G threshold mouthguard

          Figure 4a: 75 G threshold mouthguard                  Figure 4b: 100 G threshold mouthguard


Conclusion

 Table 1: lists the results from the headform drop tests wearing the two sets of mouthguards with indicator thresholds pre-set as 75g and 100g

Table 1: lists the results from the headform drop tests wearing the two sets of mouthguards with indicator thresholds pre-set as 75g and 100g

The use of the helmet/head-drop system along with a modified headform was a useful procedure to simulate a typical impact someone might receive during contact sports. The mouthguard can capture the G-forces experienced by the head from the drop test, given that the mouthguard is attached correctly and the sensor is calibrated to the necessary threshold.

The mouthguard sensors did activate if the impact exceeded the trigger levels set by the manufacturer (75 G’s or 100 G’s). The sensors changed at the desired G-force: 76 G’s for the 75 G-force threshold indicator, and 102 G’s for the 100 G-force threshold indicator. The sensor indicator (preset at 100 G’s) did respond correctly for the G-force up to 220 G’s (the upper limit of the calibration test tower).

Based on the headform drop tests with the mouthguard, and calibration tests on the sensor alone, the results suggested that the current sensors installed in the mouthguard can indicate the G-forces experienced by the head under impact. It is concluded that the sensors are designed and calibrated for the current application.

 

Disclaimer:

Dr. Zhang’s contributions to this report are limited to verifying the scientific method, data and analysis validity for testing and modeling conducted at WSU. Participation in this research does not comprise an endorsement of the Vane Mouthguards product by Dr. Liying Zhang of WSU.