A CLINICAL STUDY OF ODONTOMES. 
7 
It seems more likely that the want of a depending exit 
for the pus in the lower jaw in these cases permits the con¬ 
tents of the cavity to become far more virulent than in the 
upper jaw, and finally escaping into the mouth, causes septic 
infection, rather by ingestion, or absorption through wounds 
of the affected parts, than by inhalation. 
Odontomes in connection with the superior molars are 
more common than with the inferior, and present a greater 
variety in character and symptoms. 
In very young animals, follicular cysts and composite 
odontomes predominate. 
Small follicular cysts are quite common in connection 
with the superior permanent pre-molars in colts aged one to 
three years. They appear, unless complicated by suppuration, 
as sharply defined, painless, hemispherical bony eminences, 
over the fang of the affected tooth. They are usually slow 
in growth, attaining their maximum size in from two to four 
months, when they may remain stationary for some months, 
and then imperceptibly recede ; especially if the shedding of 
the temporary crown, or its surgical removal, lessen the re¬ 
sistance to the eruption of the permanent crown. 
If this resistance is not promptly removed the tumor may 
remain stationary, although the tooth may erupt later, for 
several years ; but usually, unless suppuration or other com¬ 
plications supervene, when the animal reaches adult age, the 
enlargement slowly recedes and finally disappears. 
Follicular cysts of the third pre-molar, and all the molars, 
may, instead of causing a marked swelling of the facial region, 
develop and extend into the sinuses of the face, and, continu¬ 
ing their growth, either extend through the foramen of com¬ 
munication between the sinuses and nasal passages, into the 
latter, or, by pressing the internal wall of the sinus inwards, 
narrow or occlude the nasal passages, and thus produce well 
marked dyspnoea. The cyst, on exploration, is usually found 
to have a thin, tough, fibrous wall, containing a thin, reddish 
or reddish-yellow fluid. Unlike in cases of the filling of the 
sinuses with pus, these cysts do not destroy their resonance 
on percussion so that in some cases the affected side can only 
