Breathing through the mouth during sleep might be leading to dental erosion and decay through increased acidity levels. The findings of this study are published in the Journal of Oral Rehabilitation.
Dentistry scientists from the University of Otago in New Zealand investigated the levels of acidity in the mouths of participants while they were asleep. It was found that the results would differ as per the mouth being open or closed during sleep.
The team of researchers measured pH levels in the mouths of 10 participants who would sleep with and without a nose clip on alternate nights such that they would breathe through the mouth at one point and through the nose at another. It was found that the average mouth pH during sleep when the volunteer breathed through the mouth was lower than the normal mean during sleep: 6.6 as opposed to 7.0. The researchers explain the difference is statistically significant when compared with the figures from normal sleep conditions.
Lead author Joanne Choi explains that the intraoral pH would decrease gradually over the sleep hours for all the participants regardless of open-mouth or not, but the fall would be greater over a long stretch of time during open-mouth sleeping. For some of these volunteers, the pH dropped to 3.6 — note that the threshold pH for the breaking down of tooth enamel is at 5.5.
Having the mouth open during sleep implies breathing through the mouth. This causes the drying up of saliva which should otherwise be protecting the mouth environment from becoming too acidic. Low pHs are associated with dental erosion that entails the loss of tooth enamel and with bacterial growth that leads to acid production when breaking down food. As a consequence, dry-mouth patients have a higher risk of dental erosion than those with normal salivary secretion.
The researchers, therefore, conclude that mouth breathing might be a cause of dental diseases like enamel erosion and tooth decay.