People who breathe through the mouth during sleep have higher risks for tooth decay. Apparently, there are moments when it pays to keep your mouth shut.

Researchers from the University of Otago's Sir John Walsh Research Institute analyzed the oral pH levels of 10 participants. Alternately, these healthy volunteers were asked to sleep with and without a nose clip that forces them to breathe through the mouth.

The average pH level of those who slept with the nose clips was 6.6, which is slightly acidic compared to the neutral 7 of those who breathed through their noses. The team also found a visible pattern on the pH levels and temperature between morning and evening.

"Intraoral pH decreased slowly over the hours of sleep in all participants, but showed greater falls over a longer period of time when participants were forced to mouth breathe," said Ph.D. student and study lead author Joanne Choi.

There are times when the pH levels would drop to 3.6 during sleep when the participants were forced to breathe through the mouth. Choi said the dropped rate is below the critical 5.5 threshold when the tooth enamel starts losing its minerals.

The recent study is the first one to continuously analyze the intraoral pH variations among healthy participants for a certain period. The findings support the theory that open-mouth breathing is associated with dental disease such as tooth decay and enamel erosion.

Tooth decay symptoms include tooth sensitivity, bad breath and toothache. The appearance of black, gray or brown spots on the tooth as well as a bad taste in the mouth can also be signs of tooth decay. Left untreated, tooth decay can result to more serious dental problems including dental abscesses and gum disease.

In another study on tooth problems, a team of dentists found that four out of 10 football players have dental issues including dental cavity and gum disease that can affect the athletes' overall well-being and sports performance. The dental team analyzed 187 footballers from top clubs and found that 77 percent needed tooth fillings. Also, 37 percent had at least one decayed tooth.

Choi's study was published in the Journal of Oral Rehabilitation.

Photo: Jeramey Jannene | Flickr