Intraoral pH and temperature during sleep with and without mouth breathing.
Level 2 - randomized trial
Randomized crossover experimental trial in healthy human volunteers
PubMed 26666708 · doi:10.1111/joor.12372
What was done
Ten healthy participants (mean age 25.8 ± 4.3 years) wore a custom-made oral appliance equipped with a pH probe and thermocouple across two 48-hour periods. Continuous pH and temperature measurements were recorded from the palatal aspect of the upper central incisors. To simulate mouth breathing during sleep, participants wore a nose clip for two of the four nights, with sequence balanced across two groups (n = 5 each).
What was found
Mean daytime intraoral pH was 7.3 ± 0.4 and dropped to 7.0 ± 0.5 during normal sleep. During sleep with forced mouth breathing, mean intraoral pH decreased significantly to 6.6 ± 0.5 (P < 0.01), showing a greater and more prolonged fall across the hours of sleep. Mean intraoral temperature was 33.1 ± 5.2 °C during daytime and 33.3 ± 6.1 °C during sleep, with no statistically significant difference between sleep with and without mouth breathing (P > 0.05).
Why it matters
Continuous in vivo monitoring confirms that nocturnal mouth breathing substantially acidifies the oral environment, providing a direct physiological mechanism for the increased risk of dental erosion and caries reported in mouth breathers.
Limits
The study had a very small sample size (n = 10) of young, healthy participants. Nose clips used to force mouth breathing may not fully mirror habitual or pathological mouth breathing, and clinical endpoints like enamel demineralization or caries incidence were not measured.
Cited by
- partial Sleeping with the mouth open causes intraoral pH to drop to 2.8 to 3.0.
- supports Sleeping with an open mouth causes dry mouth that disrupts the oral microbiome, which requires saliva and a neutral pH.