What, if any, are the effects of mouth breathing on jaw growth?

[Mark32]

im pretty sure i was a mouth breather during the day when i was a kid - i remember being teased at school for always having my mouth open. from my early teens, i made an effort to keep my mouth closed, and so breath nasally. however, to this day i have real difficulty, for some reason, breathing through my nose when i lie down and so i've remained a night time mouth breather.

i've read bits and pieces about how mouth breathing can affect facial growth but is any of this conclusive. is there a general pattern to the jaw growth that arrises from this?

i think that i have a narrow, recessive maxilla; a somewhat protruded lower jaw; and maybe a skeletal open bite (if that makes sense). i have longish incisors that only meet edge-to-edge when my posterior teeth come together. i feel that i have a longish, flat chin as well - too much vertical height and little forward projection. 

the thing is though, i've seen this lower facial shape in other people and i wonder if they are mouth breathers too. for that matter i've worked with a few poeple that seemed to breath through their mouths and they too had longish, flat lower faces with seemingly receded maxillas, too much lower jaw and no chin projection. like mine, their lower faces just seemed to have little in the way of definition.

is there anything in this or am i putting 2 and 2 together and getting 5?

[notrain]

the general assumption is, that mouth breathing causes the tongue to sit in the floor of the mouth and not in the roof (palate) where it should be.

This will cause a narrow, crowded maxillary arch and an ogival ( high, narrow ) palate, but in turn an overdeveloped mandibular (lower jaw) dental arch.

However, plenty of people have crowded maxillas and high palates and DO NOT mouth breathe. so as of right now, there is a strong correlation but nothing more. Plenty of mouth breathers also do have normal faces.

as for your "long face" argument:

- approx 15% of the population have "long" faces. this is called dolichofacial type and is not a disorder.

- approx.  another 15% have a brachyfacial type, which is a more short, broad, round face. also not a disorder.

- 70% of the population has a mesiofacial type, which is considered normal and attractive. this facial type has a natural balance to all facial thirds whereas dolico and brachy have a relative long and short lower third of the face.

Now, all malocclusions (class 2, class 3) can occur on all facial types. Jaw surgery aims to correct the malocclusion to a class 1 AND the facial type to a mesiofacial pattern.

I hope this clears things up a bit.

[Mark32]

that's very interesting. what your saying about tongue position is something i've had on my mind. when i wake up in the morning my mouth is somewhat open and my tongue seems to have dropped into my lower jaw. the thing is, though, if i bring my teeth together at this time my lower jaw is a bit further forward when biting against my upper teeth than is normally the case.

during the day, with my tongue being where it should be, my lower jaw comes together with a my upper teeth a bit further back.

the thing i've wondered is, as your tongue is attached to your lower jaw, does the tongue lose a sort of posteriorly directed pull on the lower jaw when it lies in the floor of the mouth during your growing years? when you're mouth breathing. you know, like a sort of restraining force exerted on the mandible as it grows forwards.

that might explain why, in an anterior/posterior direction, my teeth seem to be a better fit during the day than after a night of mouth breathing.