Effects of open mouth and rubber dam on upper airway patency and breathing.
Rubber dams increase the quality and safety of dental treatment. However, the condition of a rubber dam over an open mouth may also obstruct the route for respiration. We tested whether an open mouth with or without a rubber dam would affect upper airway patency and breathing pattern. Twenty young healthy volunteers were imaged with a magnetic resonance (MR) system under three conditions: mouth closed, mouth open, and rubber dam with mouth open. Respiration was concurrently monitored with plethysmography. MRI slices of the upper airway were obtained at 5-mm thicknesses, and the size of the cross-sectional area of the upper airway was measured by image analysis software. Respiratory cycle duration and tidal volume were also measured with digital signal analysis software. The volume of the upper airway became significantly decreased with the mouth open. Analysis of each cross-sectional area of the upper airway revealed that while the oropharyngeal area was significantly narrower with an open mouth, the retropalatal and hypopharyngeal areas were not affected. Placing a rubber dam had no additional influence on upper airway patency but was seen to significantly shorten mean respiratory duration and decrease tidal volume. Open mouth position plays the largest role in decreased upper airway patency, and open mouth position with a rubber dam may further disrupt breathing pattern. Breathing pattern may become deteriorated by airway obstruction during dental treatments requiring a rubber dam.