Purpose: Mouthguards worn during sporting competition may influence oral airway flow dynamics and potentially increase airflow resistance during mouth breathing.
Methods: We measured oral airflow resistance (RO) in 10 normal subjects (four men, six women, age 29 +/- 3 yr, mean +/- SEM) wearing two different custom-made maxillary mouthguards.
Results: During tidal mouthpiece breathing (jaw position controlled), inspiratory R(O) (at (1.4 L x s(-1)) increased from 0.22 (0.15-0.46) cm H2O x L(-1) x s(-1) (median and interquartile range) to 0.47 (0.24-0.52) cm H2O x L(-1) x s(-1) with mouthguard 1 (general sports mouthguard) and from 0.34 (0.27-0.51) to 0.46 (0.39-0.86) cm H2O x L(-1) x s(-1) (N = 8) with mouthguard 2 (laminated, field hockey mouthguard, both P < 0.05). With oral only mask breathing (jaw position not controlled), inspiratory R(O) (at 0.4 L x s(-1)) increased to 1.02 (0.42-1.57) cm H2O x L(-1) x s(-1) (P < 0.03, compared with mouthpiece) but was variably affected by both mouthguards. At 1.0 L x s(-1), there was a tendency for both mouthguards to increase inspiratory R(O); however, this effect only reached significance for mouthguard 1 during mouthpiece breathing.
Conclusion: Thus, although maxillary mouthguards do increase R(O) when jaw position is controlled, individual subjects respond differently when in control of mouth opening. This may be related to variable recruitment of compensatory mechanisms (e.g. mouth opening and/or oral airway dilator muscle activity).