Attributes of the oral cavity as a site for basal body temperature measurements.

The thermal topography of the oral cavity of 11 women was mapped with thermocouples in early morning waking conditions. A reference thermocouple was placed in the vagina. No significant difference was found in the time required to reach a steady-state oral temperature and in the achieved steady-state temperature difference (Tv-To) in the preovulatory and postovulatory phases of the menstrual cycle. Location of the thermocouple in the oral cavity had a significant effect on steady-state temperature differences. After equilibration of oral thermometers, women breathed through their mouths for exactly five minutes. Mouths were closed and a second temperature equilibration phase was recorded. Mouth breathing had a significantly greater effect on the temperature of the anterior sublingual and dorsum of the tongue sites than on the posterior sublingual and buccal trough sites.