32 THE SURGICAL ANATOMY OF THE HORSE 



When the incisors are young they stand upright in the alveoli, 

 but as the age advances, the long axis of the exposed portion of the tooth 

 forms a progressively increasing angle with an imaginary line drawn 

 longitudinally through the middle of the horizontal ramus. Thus at the 

 age of ten the angle formed at six is slightly increased. At Jifteen the 

 increase is very perceptible, whilst at twenty the two imaginary lines are 

 almost in a straight line with one another. 



Again, at the age of ten the crown of the tooth is still in wear. 

 From this age, until the age of twenty, the central portion is being 

 worn, whilst after twenty the fang only is utilised. The outline of the 

 upper surface of the exposed portion also varies, therefore, according to 

 that portion of the tooth which is actually in wear. 



The foregoing remarks apply chiefly to the teeth of the inferior 

 maxilla. The infundibula are later in disappearing from the incisors of 

 the upper jaw, the old theory (which, however, does not hold for reasons 

 already stated) being that they disappeared in the upper jaw from the 

 centrals at nine, the laterals at ten, and the corners at eleven. 



It is particularly important to study well the outline of the table, 

 since the change in outline would be definite evidence of an old tooth 

 in cases where the infundibula are unusually deep, and the appearance 

 of which consequently persists. 



"Bishopped" Teeth 



This is the term which is applied to old teeth upon which artificial 

 marks have been made to imitate those found normally on young teeth. 

 The marks are supposed to imitate those of the infundibula. First a 

 little excavation is made with a sharp tool, which excavation is supposed 

 to represent the cavity of the infundibulum. The depth of this cavity 

 is then coloured by means of a hot, pointed iron, and occasionally 

 intensity is given to the colour by the application of nitrate of silver. 



NVhen teeth are suspected of having been " bishopped," the observer 



