title: Effect of mouthguards on impact to the craniomandibular complex.
abstract: BACKGROUND
  The aim of this study was to investigate the effect of wearing a mouthguard and teeth-clenching on impact to the head and temporomandibular joint (TMJ) during a blow to the jaw.
  
  
  METHODS
  A custom-made mouthguard was fabricated for five participants. A 4.1-N impact load was applied to the chin with a pendulum. Two acceleration sensors were attached to the forehead and left TMJ. The amplitudes and durations of the accelerations were obtained under five conditions: mouth-open without mouthguard; light teeth-clenching without mouthguard; maximum voluntary clenching (MVC) without mouthguard; mouth-open with mouthguard and MVC with mouthguard.
  
  
  RESULTS
  Wearing a mouthguard led to significant decreases in the amplitude (mouth-open with mouthguard vs mouth-open without mouthguard, P = 0.035 at forehead, P = 0.022 at TMJ) and duration (mouth-open with mouthguard vs mouth-open without mouthguard, P = 0.043 at forehead, not significant at TMJ). Similarly, teeth-clenching caused significant decreases in the amplitude (mouth-open without mouthguard vs MVC without mouthguard, P = 0.024 at forehead, P = 0.025 at TMJ) and duration (mouth-open without mouthguard vs MVC without mouthguard, P = 0.033 at forehead, not significant at TMJ). Furthermore, wearing a mouthguard in itself provided an impact reduction effect similar to the combination of teeth-clenching and wearing a mouthguard.
  
  
  CONCLUSIONS
  Wearing a mouthguard and/or teeth-clenching reduced the impact to the head and TMJ during a blow to the jaw. However, it should be noted that the findings are the results from a small impact load to the jaw.
authors.affiliation: Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: Yuto
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Tsugawa
authors.affiliation: Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Maeda
mesh_terms: D000054:Acceleration; D000328:Adult; D001732:Bite Force; D002680:Chin; D006259:Craniocerebral Trauma / Q000517:prevention & control*; D004867:Equipment Design; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009064:Mouth Protectors; D018677:Tooth Injuries / Q000517:prevention & control*; D014949:Wounds, Nonpenetrating / Q000517:prevention & control*
keywords: concussion; craniomandibular complex; mouthguard; teeth-clenching; temporomandibular joint