Most Authors reported that mouth guard is a part of equipment for body-contact sports players. Mouth guards protect orofacial injuries but have some problems in breathing and speaking. Some authors reported that mouth guards have also improve the muscle strength and sport ability. This experiment was performed to study the change of masseter muscle EMG after wearing of mouth guard. 10 D university male base ball players were participated in this study. After impression taking, mouth guards were constructed and weared. Masseter muscle EMG and nasal ventilation after ten day's adaptation were checked. They were requested clenching with or without mouth guard. EMG and nasal ventilation were checked by iworx 104 instrument simultaneousley. The result showed that masseteric EMG were improved and nasal ventilation were stable after wearing mouth guard. It concluded that mouth guard had improved muscle activity and stabilized the nasal ventilation depend on experimental method.

I. 서론
 II 실험 방법 및 재료
 III. 실험결과
 IV. 총괄 및 고찰
 V. 결론
 VI. 참고문헌

• 천재식(단국대학교 치과대학 구강생리학교실) | Gae-Sig, Chun correspondence