Changes In Kinematic Data Quality Along Instrumented Mouthguards’ Lifespan

The use of instrumented mouthguards (iMGs) to study repetitive head impacts during sports presents many challenges. Normal wear-and-tear and structural damage caused by chewing may affect the mouthguard fit on the athletes’ teeth, potentially leading to a worsening of the quality of the kinematic signals throughout the lifespan of an iMG. This would result in inaccuracies in estimating athletes’ exposure to head impacts. PURPOSE: To assess whether the quality of kinematic signals from iMGs declines over the device’s lifespan. METHODS: Sensor acceleration events (SAEs) were collected using Prevent Biometrics iMGs (V2, primarily custom-fit) for one season of youth tackle football (56 male players, aged 8-12 years). Events with a peak resultant linear acceleration over 10 g and occurring during practice and game times were extracted and time-windowed. Analyses were conducted by iMG, including only those that were used for at least 10 sessions (60 iMGs out of 106) and accounting for whether athletes stopped using them because of malfunction (N = 30) or the season ending (N = 30). The Prevent Biometrics quality indicator (“high”, “moderate”, “low” quality) is based on the signal-to-noise ratio in the raw kinematic data and was used to compare signal quality from the first five sessions to the last five sessions recorded by each iMG. RESULTS: Out of 60,405 recorded SAEs, 8% were high quality, 22% moderate, and 51% low, with quality indicators unavailable for 19%. A linear mixed-effects model showed no significant effect of time (p = 0.39), survival status (p = 0.73), or their interaction (p = 0.88) on the proportion of high-quality SAEs, despite an observed increase from the first five uses (13.2 ± 12.7%) to the last five (17.3 ± 22.3%). Results are limited by the lack of video-verification for practices, and the low number of games to analyze video-verified events. CONCLUSIONS: Based on the Prevent Biometrics quality indicator for time-windowed SAEs, there was no significant change in data quality over the season, or difference between mouthguards that survived and those that failed. However, the high proportion of low-quality events raises concerns about potential accuracy limitations in peak kinematic estimates. Supported by: National Institutes of Health (NIH) Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) ​ R01 ​ (R01HD110401)