Influence of intra-oral maxillary sports mouthguards on the airflow dynamics of oral breathing

Purpose: Mouthguards worn during sporting competition may influence oral ai rway flow dynamics and potentially increase airflow resistance during mouth breathing. Methods: We measured oral airflow resistance (R-O) in 10 normal subjects (four men, six women, age 29 +/- 3 yr, mean +/- SEM) wearing two different custom-made maxillary mouthguards. Results: During tidal mouthpie ce breathing (jaw position controlled), inspiratory R-O (at 0.4 L.s(-1)) in creased from 0.22 (0.15-0.46) cm H2O . L-1.s(-1) (median and interquartile range) to 0.47 (0.24-0.52) cm H2O . L-1.s(-1) with mouthguard 1 (general sp orts mouthguard) and from 0.34 (0.27-0.51) to 0.46 (0.39-0.86) cm H2O . L-1 .s(-1) (N = 8) with mouthguard 2 (laminated, field hockey mouthguard, both P < 0.05). With oral only mask breathing (jaw position not controlled), ins piratory R-O (at 0.4 L.s(-1)) increased to 1.02 (0.42-1.57) cm H2O . L-1.s( -1) (P < 0.03, compared with mouthpiece) but was variably affected by both mouthguards. Ar 1.0 L.s(-1), there was a tendency for both mouthguards to i ncrease inspiratory R-O; however, this effect only reached significance for mouthguard 1 during mouthpiece breathing. Conclusion: Thus, although maxil lary mouthguards do increase R-O when jaw position is controlled, individua l subjects respond differently when in control of mouth opening. This may b e related to variable recruitment of compensatory mechanisms (e.g. mouth op ening and/or oral airway dilator muscle activity).