Why Kids Grind Their Teeth

The ear has three parts.

(1)  The Outer Ear

(2)  The Middle Ear

(3)  The Inner Ear


The 3 Parts of the Ear

The Eardrum separates the Outer Ear from the Middle Ear.  It is important that the air pressure on both sides of the thin membranous Eardrum be equalized.  If there is more pressure in the Middle Ear than there is in the Outer Ear, the patient can feel this as Full, Stuffy, Congested or Itchy ears.  If there is too little pressure in the Middle Ear, then the Middle Ear can fill up with fluid, a condition known as Serous Otitis Media, which is the most common cause of hearing loss in children.


The way that our bodies equalize the pressure on both sides of the eardrum is with the EUSTACHIAN TUBE  (ET).  The ET extends from the anterior wall of the Middle Ear to the lateral wall of the NASOPHARYNX at approximately the level of the Inferior Nasal Concha.  A small portion of the ET, proximal to the Middle Ear, is made of bone, the rest is made of cartilage.


ET connects Middle Ear to the Nasopharynx


There are four muscles associated with the Eustachian Tubes:

  • Levator Veli Palatini (innervated by Vagus nerve)
  • Salpingopharyngeis (innervated by Vagus nerve)
  • Tensor Tympani (innervated by CN V)
  • Tenso Veli Palatini (innervated by CN V)

Under normal circumstances, the ET is closed.  Opening the mouth wide, yawning, swallowing and chewing gum can cause the ET in the Nasopharynx to open which can equalize pressure between the Middle Ear and the outside atmosphere.

The ADENOIDS are a mass of Lymphatic tissue situated in the nasal cavity in the roof of the Nasopharynx just posterior to where the orifice of the ET exits into the throat.


Relationship of Adenoids to ET orifice

The Adenoids lie in the midline of the Nasopharynx and Eustachian tubes from either ear opens to the right and left of the them.


If there is an infection in the sinuses, mouth or throat, the adenoidal tissues can swell to a very large size.  Large, swollen adenoids can block air passage in both the nose and ears.  This obstruction of normal air ventilation can lead to Sinusitis or Otitis Media.


The direction of growth of the Maxilla (upper jaw) is primarily down and forward.


The Maxilla Grows Down and Forward

This is significant because the position of the Adenoids does not change but the ET orifice’s position relative to the lymphoid tissue does.

As the cranium grows, the ears widen apart, their throats enlarge and the angulation of their Eustachian Tubes changes from about 10 degrees to about a 45 degree angle.


Eustachian Tube Angulation in Children and Adults

In young childen, the almost horizontal angulation of the Eustachian Tubes places their orifices next to the Adenoids which allows them to be easily blocked by lymph tissue hypertrophied due to infection.



Child ET Almost Horizontal

Scientific research has shown that in children with excessive middle ear infections and chronic middle ear fluid, there is a high bacterial count in their adenoidal tissue as compared to children without Otitis Media, even if the adenoids were small.

The  Adenoids can act as a reservoir of pathogenic bacteria that cause Middle Ear infections and subsequent Middle Ear Effusions (fluid).


When the opening of the Eustachian Tubes is blocked and the pressure inside of the Middle Ear increases, movement of the mandible back and forth can cause the ET’s to open which will help to eqalize a childs intra-ear pressure.

Research has shown (Bruxism and adenotonsillectomy in children) that removal of Adenoids can decrease bruxism from 25.7% to 7.1%, and that Sleep Disordered Breathing can be improved (Improvement of bruxism after T&A removal) with removal of Tonsils and Adenoids.

If you are an ENT or Otolaryngolosist who deals with ear infections, a Pediatric Dentist or General Dentist who has treated childhood bruxism, please comment below.  All of the readers of this blog would appreciate any input or insights you can give to this realtively common problem.