title: [The effect of mouthguard on strength of the musculus deltoideus].
abstract: OBJECTIVE
  To investigate the effect of mouthguard on strength of musculus deltoideus and to observe the possibility of its improving sports ability.
  
  
  METHODS
  The custom mouthguards were fabricated respectively for 8 subjects with soft resin by direct method. The activities of the musculus deltoideus and masseter were tested by means of electromyograph (EMG), while the subjects lay, made maximum voluntary biting with mouthguard and pressed 5 kg. The EMG potentials were transferred to a computer. The data were handled and the integral values of EMG were exported.
  
  
  RESULTS
  The subjects set a great value on the mouthguard's comfort, retention and protection. The EMG values of the musculus deltoideus and masseter of the subjects biting with mouthguards were 1.1600 v/s and 0.3825 v/s, and the values of those biting without mouthguards were 0.6125 v/s and 0.213 8 v/s, respectively. The muscular strength of the former was significantly improved compared with that of the latter (P < 0.01).
  
  
  CONCLUSIONS
  Wearing a mouthguard and maximum voluntary biting can enhance the masseter force and reflectively improve the musculus deltoideus strength.
authors.affiliation: Department of Prosthodontics, School of Stomatology, Tongji University, Shanghai 200072, China.
authors.forename: N
authors.initials: N
authors.lastname: Zhang
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Pan
mesh_terms: D004576:Electromyography; D006801:Humans; D009064:Mouth Protectors; D013177:Sports / Q000502:physiology