Open Mouth Posture and Mouth Breathing

Open mouth posture may indicate incompetent lip closure and refers to the chronic lack of a lip seal when at rest. Individuals that have a habitual open mouth posture may have to strain the muscles to keep the lips sealed.18 Other clinical signs may present with the open mouth posture, including a larger lower lip, untoned oral muscles, inflammation of the anterior gingiva, and/or increased plaque buildup on the anterior teeth surfaces (Figure 7).

Figure 7. Clinical appearance of chronic open mouth posture.

Photo of clinical appearance of chronic open mouth posture.

Courtesy of: Dr. Péter Vályi

Some individuals with open mouth posture may have an additional habit of breathing through the mouth instead of the nose. Categories of mouth breathing include: habitual, seen when a correct nasal breathing behavior was never established; obstructive, as seen with chronic allergies or enlarged tonsils; or anatomic, seen if the individual is simply unable to take in enough air through the nose.19 With a mouth breathing behavior, the individual does not receive the benefits of the nasal cavity’s particulate filtering design. Orofacial consequences of open mouth posture and/or mouth breathing may include increased risk for caries, gingivitis, speech problems, and dental malocclusion.18,20 If left untreated throughout puberty, a mouth breathing habit is believed to contribute to abnormal facial development (Figure 8).21,22

Figure 8. Change in facial development due to allergies and obstructive mouth breathing.

Photo showing change in facial development due to allergies and obstructive mouth breathing.
Courtesy of: Dr. John Mew