THE STEP-FORMED MOUTH. 
35 
molars in front and behind these become respectively longer or shorter. 
In the lower jaw they are usually too long, in the upper jaw too short. 
Sometimes the state of things is reversed. 
This form of mouth usually depends on unequal durability of the 
individual teeth, and sometimes on disease of the alveoli. Slight 
inequalities cause little discomfort; but when well developed, and 
especially if the alveoli are involved, mastication is greatly impaired, 
and the sharp points and edges wound the opposing soft parts. Certain 
teeth may be worn down level with the gum, and mastication made 
exceedingly painful. The disease occurring in early life is especially 
serious, as it becomes aggravated with age. 
Treatment. Sharp points and edges must be removed. Excessively 
long teeth which injure soft structures should be shortened or extracted ; 
and the diet should consist mainly of crushed food and slops. 
(d) the step-formed mouth. 
This irregularity is closely allied to the foregoing. The only 
difference between them is that the neighbouring molars vaiy in 
height, not gradually but suddenly, a short one being followed by a 
much longer one, or vice versa. The same cause, viz., unequal hardness, 
seems at work here. The condition may be due to some unknown con 
stitutional peculiarity, as evidenced by its attacking both sides, of the 
mouth. The spaces resulting from loss of teeth are often responsible for 
its production. 
The prognosis depends on the degree and extent of the irregularity. 
Mastication is usually more impeded by this than by the wave-formed 
mouth, because lateral movement of the jaws is heie moie difficult. 
The disease is gravest where the animals are young, the soft tissues 
wounded, or where several teeth have been lost. 
Treatment is merely palliative. Soft food will assist mastication. The 
longest teeth must be reduced or removed. The crowns can. be 
shortened with Moller’s tooth shears. This is preferable to extraction, 
which often presents great difficulties on account of want of 100 m, whilst 
the use of file and chisel demands too much time and care. 
Moller’s shears (fig. 13) have been frequently varied, but not much 
improved. The central screw lying between the limbs of the instrument 
ensures great power without disturbing the position of the instrument. Every 
part must be fashioned very strongly and carefully of the best steel, for, 
owing to the immense power of the screw, it might otherwise break or 
bend With quiet horses one or more front molars may be cut without 
previous casting. But it is better to lay the patient down when it is high- 
couraged or troublesome, or when several teeth or any of the back molais aie 
to be dealt with. After inserting a rather large mouth gag, and drawing the 
D 2 
