The differences between nasal breathing and mouth breathing are as follows:
Transnasal breathing: under normal circumstances, it is transnasal breathing. The nasal cavity is an important breathing channel, which can warm and humidify the external air, and the external air can pass through the nasal mucosa. There is abundant vascular tissue under the mucosa, which can heat and humidify the air. The air becomes warm and moist after nasal treatment, and the irritation to the lower respiratory tract is reduced, making the breathing more unobstructed and comfortable.
Mouth breathing: its warming and humidifying effects are greatly weakened. The air in the throat is dry and cold. The dry and cold air directly stimulates the mucous membrane of the throat. This is the most direct reason for the complete lack of ventilation in the nasal cavity after a cold and dry mouth and tongue after oral breathing. Long term mouth opening breathing may also have an impact on children's facial development, such as the formation of a series of changes such as uneven dentition, upturned upper lip and maxillary protrusion. Therefore, mouth opening breathing is not a normal physiological state. It is necessary to analyze and correct mouth opening breathing to avoid adverse effects.
What causes mouth breathing?
Mouth breathing, as the name suggests, is breathing with the mouth. Normal people breathe through the nasal cavity, but patients who breathe through the mouth will breathe through the mouth in a relaxed state, such as reading, sleeping and playing, with the upper and lower lips slightly separated. The main reason for oral breathing is the problem of upper respiratory tract, such as common nasal diseases such as rhinitis, maxillary sinusitis, hypertrophy of turbinate and swelling of tonsils. Tonsillar swelling can cause upper respiratory tract stenosis and oral breathing. In addition to the stricture of the upper respiratory tract, there are more common causes, such as bad habits, which are also easy to cause mouth breathing. For example, biting the lower lip with lips and teeth will cause the protrusion of the upper teeth, resulting in the softness and upturning of the upper lip, which will slightly separate the upper and lower lips and cause mouth breathing.
The disadvantages of breathing through the mouth.
The disadvantages of breathing through the mouth include dry mouth, sore throat, easy to cause pharyngitis, respiratory tract infection and affect development, so it should be considered in combination with its causes.
When breathing through the mouth, it has an obvious problem, that is, it is easy to have dry mouth and sore throat, which is easy to cause chronic pharyngitis in the pharynx and skip the nose. In fact, there are good gases in the nasal cavity, one is humidification, and the other is nasal hair or nasal cheeks in the nasal cavity, which will adhere to a lot of gas.
The particulate matter in the air also plays a role of warm humidification and filtration. Once this role is reduced, it will easily cause its respiratory tract infection, especially tracheitis, which will aggravate the risk of infection.
Another is when the child breathes with his mouth open, especially during the development period. If he always breathes with his mouth open when sleeping, he will affect the development of maxillofacial structure. Finally, we should pay attention to why the child breathes with his mouth open. We should check the reasons why he breathes with his mouth open.
For example, whether there is abnormal structure of the nose, swelling of the nasal mucosa, nasal congestion and other symptoms, we need to make a diagnosis and treatment.
Mouth breathing and supplemental oxygen
Oxygen therapy has many benefits, including improved survival when used for more than 15 hours per day. But when comparing nose breathing and mouth breathing, do mouth breathers get the same health benefits from supplemental oxygen?
There are two well-known studies examining oxygen saturation in mouth respirators; each produced conflicting results. The first measured oxygen saturation in 323 mouth breathers. Of these, 34.6% had normal oxygen saturation (95% or higher), 22.6% had oxygen saturation of 95%, and 42.8% had oxygen saturation below 95%. The study concluded that while mouth breathing does not always lead to hypoxia, it does.
In the second study involving 10 healthy subjects, researchers analyzed gas samples taken from the tip of a nasal cannula positioned in the nasopharynx, an area in the back of the throat. The study concluded that subjects who breathed through their mouths while using supplemental oxygen had a significantly higher FIO2 (fraction of inspired oxygen) than those who didn't. However, an editorial published in Respiratory Care disputed the validity of this study, stating that the results were likely to be inaccurate. Under normal circumstances, when a patient breathes supplemental oxygen through a nasal cannula, they breathe a combination of oxygen mixed with room air. During mouth breathing, oxygen delivered through a nasal cannula doesn't mix with room air; it is pushed through the nose and into the nasopharynx where it remains highly concentrated. Gas samples taken from an oxygen-enriched area may yield a higher concentration of oxygen, but they are unlikely to represent a patient's true oxygen concentration because the gas is undiluted by room air.
Mouth breathing therapy
Some people who use oxygen and are mouth respirator try to get around this by putting a nasal cannula in their mouth instead of their nose. Not only is this unhygienic, but as mentioned, it makes delivering oxygen to the lungs significantly less effective.
The best way to treat mouth breathing is a multidisciplinary approach, including your doctor, dentist, and ENT specialist.  Your doctor may also recommend seeing a muscle function therapist, who can help you retrain yourself to breathe through your nose by helping you learn how to chew, swallow, and breathe properly. Depending on the cause, mouth breathing treatments range from treating the cause to correcting facial and dental abnormalities with functional devices to, in rare cases, surgery.  If you identify as a mouth breather, contact your healthcare provider right away for a proper diagnosis so you can determine the cause of your mouth breathing and determine which type of mouth breathing treatment is best for you.