148 
C. E. SAYRE. 
of the fang to supply the peridental membrane, and anasta- 
mose with the arteries of the gum. It also has a large nerve 
supply from the fifth nerve, and is the organ of touch of the 
teeth. 
Pericementitis occurs in two forms, acute and chronic ; 
either of these may be local or general; local, when one or 
several teeth are involved, and general when all of the teeth 
in one or both arches are involved in the inflammation. There 
are a number of local causes of pericementitis, the most com¬ 
mon of which is putrescent pulp, due to caries or fractures 
of the teeth ; the pulp dies and decomposes. The gases es¬ 
cape through the apical foramen and cause pericementitis, 
and when it is due to this cause it is nearly always followed 
by an alveolar abscess. But the cause I wish particularly to 
draw your attention to is irregularities of the molars in the 
arch, setting either in or out. This allows food to collect be¬ 
tween them, which decomposes, and causes inflammation of 
the gums, which extends to the peridental membrane, and 
usually assumes a chronic form, resulting in an exostosis on 
the fang of the tooth. This nearly always occurs in the lower 
jaw, and is usually the fifth lower molar on both sides. Gen¬ 
eral pericementitis in our subjects is nearly always due to 
drugs which cause salivation. Osteo porosis is also a cause of 
general pericementitis. 
Symptoms. —Those common to any disease of the mouth, 
salivation, quidding of the food, apparent loss of appetite, but 
usually the horse wants to eat but cannot on account of the pain 
caused by mastication. On examining the mouth, if it is due 
to pericementitis, you will find the gum receding from the 
tooth, and often the tooth is loose. Frequently the disease 
has gone so far that pus has formed, and you have an alveoiar 
abscess discharging around the tooth, or it may burrow 
through into the sinuses. 
Pathology. —First, congestion of the blood vessels; this 
is followed by effusion of same into the membrane, which may 
be absorbed, and the tooth recover, or it may become organ¬ 
ized and undergo calcification and form new cement, or it 
may go through all the stages of inflammation and form pus, 
