DEPARTMENT OF SURGERY. 
813 
necrosis in almost every case, and therefore at the end of four 
weeks the necrotic spots should be exposed and treated. 
—(L. A. M.) 
Osteoma of the Superior Maxilla .—The case of osteoma of 
the maxilla reported from Professor Dewar’s surgical clinic by 
veterinary student J. J. O’Connor, in the January Veterinarian , 
page 904, opens up the very interesting question of origin of 
these mysterious tumefactions. In a supplementary note Pro¬ 
fessor Stockman unhesitatingly asserts that their cause is “ still 
unknown,” and apparently clinches the assertion by referring 
to their occurrence in old horses, in which instance prolifera¬ 
tion of cells that have lain dormant for years can not readily 
be accounted for. 
Let us see if a glance at the osteology of the region will not 
materially lead us to some logical conclusion. The bone of the 
region (the jaw) consists of two comparatively thin plates en¬ 
closing the deep and large alveolar cavities. Now, if we con¬ 
sider that within these cavities two sets of teeth—temporary 
and permanent—develop from very small to very large and 
hard bodies which eventually find their way into the oral cavity 
by sheer force of their expansion, is it a wonder that this thin 
incasement (the bones) occasionally suffers ? 
PTirthermore, osteomata of the maxilla most frequently 
occur over the third molar—the last of the temporary teeth to 
erupt. This is due to the demonstrable fact that when the third 
molar seeks admission to the level of the arcade it occasionally 
finds its way blocked by the narrowness of the space between 
the second and fourth teeth, both of which have previously 
erupted and are now firmly located. Thus the force of its con¬ 
tinued expansion is felt at the other extremity and an osteoma 
results. I11 much the same manner osteomata occur over the 
first and second molars from the resistance offered by their 
temporary analogues and probably also, like the fourth, which 
is rarely effected, from obscure forces. The fifth and sixth are 
never the cause of such processes because of their remoteness 
from the skull plate. It is not rare to find two or more of the 
anterior molars involved simultaneously in the causation of 
these tumefactions and not rarely the condition is bilateral. 
In describing the semiology, Mr. O’Connor states : “ There 
seemed to be a wider space than usual between the second and 
third molars.” As perfect contiguity is indeed seldom inter¬ 
rupted in the dental arcades of the horse the words “ wider 
space than usual ” make the assertion rather confusing. But 
