THE STEP-FORMED MOUTH. 281 



Treatment. Sharp points and edges must be removed. Exces- 

 sively long teeth which injure soft structures should be shortened 

 or extracted ; and the diet should consist mainly of crushed food 

 and slops. 



THE STEP-FORMED MOUTH. 



This irregularity is closely allied to the foregoing. The only 

 difference between them is that the neighbouring molars vary in 

 height, not gradually but suddenly, a short one being followed by 

 a much longer one, or vice versh. The same cause, viz., unequal 

 hardness, seems at work here. The condition may be due to some 

 unknown constitutional 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 irregu- 

 larity. Mastication is usually more impeded by this than by the 

 wave-formed mouth, because lateral movement of the jaws is here 

 more 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 room, 

 whilst the use of file and chisel demands much time and care. 



Moller's shears (Fig. 281) 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 cast the patient when it is high- 

 couraged or troublesome, or when several teeth or any of the back molars 

 are to be dealt with. After inserting a rather large mouth gag and drawing 

 the tongue away from the part to be operated on, the shears are adjusted 

 on the tooth to be shortened, and the screw turned, while the instrument 

 is held by one or two assistants. After a few turns, made as quickly as 

 possible, the desired portion of the tooth will spring off with a loud noise. 

 At this moment the horse usually makes a movement with its head, but, 

 as the shears are already free, this is of no importance. Moller has cut 

 many strong upper molars without ever having an accident. The tooth 

 breaks off smoothly. In old horses, it may happen that the movement 

 of the head loosens the tooth, and it comes away with the shears, affording, 

 however, the desired relief. Most difficulty is met with in back molars, 

 and where the sides of the teeth have been worn away obliquely. The 

 gag must be wide enough to allow the open shears to be easily introduced. 

 When the shears slide off the sides of the teeth, Moller's tooth screw 



